Background

Throughout the world many reinforced concrete bridges are in a dilapidated state. There are many reasons for this, but one of the more common is cracking of the concrete leading to exposure of the steel reinforcement structure. When this is coupled with increasingly heavy traffic loads the state of the bridge rapidly deteriorates. However, the cost of replacing or repairing all the damaged bridges using conventional means, even in prosperous western European countries, is prohibitive and, if conventional approaches are taken, the possibility of the concrete structure’s deterioration over time remains.
Alternative Technology to Reinforced Concrete Bridges

In an attempt to solve these problems a European funded project was set up. Called Advanced Structural Systems for Tomorrow’s Infrastructure’ (ASSET), the project consisted of a European consortium led by Mouchel (UK) and included Fiberline Composites (Denmark), Skanska (Sweden), Oxfordshire County Council (UK), HIM (The Netherlands), IETCC (Spain) and Kungl Hogskolan (Sweden). The objectives of the project were to develop a competitively priced structure with distinct user benefits, such as durability, lightweight and a speedy and developed system of construction. This depended on the development of an optimised profile as a structural member capable of carrying various loads and made of glass/carbon fibres and thermosetting resin, manufactured by pultrusion. In turn this required the development of the pultrusion process for mass production of the profile and ways of connecting all the components of the bridge. The final part of the four year project was to design and test large-scale bridge deck structures, built using the technology developed, in real-life service conditions in the UK road network.
Design Parameters for the Fibre Reinforced Plastic Bridge

The depth, size and profile of the decking planks were the result of several considerations. At an early stage it was decided that the decking would span the main longitudinal beams - following the study of typical bridge decking applications, a length of two metres was determined as the most useful. With regards to the loads that the profile would have to carry, it was decided to apply British standards, as these were the most demanding, while depth and cross-sectional size was chosen as approximately 250mm x 500mm as these would ensure maximum compatibility with existing bridges and would ensure suitability for manufacture by pultrusion.
Pultrusion as the Manufacturing Process

Pultrusion was chosen because the process ensures stability of the dimensions, it is cost-effective with consistent quality and is a process that lends itself to mass production. The geometry for the individual ASSET planks that would make up the decking were determined by their functionality, efficiency, production friendliness, resistance and their cost of manufacture. According to Danish-based Fiberline, the partners who produced both the profiles and load carrying beams (figure 1), one of the biggest problems in manufacturing profiles of such a size (about 30kg per metre) is the very large pulling force required. However, development work carried out with a trial tool reduced the pulling force to the extent that modification of an existing line, rather than the building of a complete new line was all that was required. The final design of the profile came out at 300mm wide by 225mm deep and has the ability to be glued or bolted together, although during construction the bolted joint was found to be considerably more complicated than the bonded joint. The beams to carry the profiles were far more traditional in shape - four 240mm square sections were bonded together to provide rigid box section.

AZoM - Metals, Ceramics, Polymer and Composites : Fibre Reinforced Plastics bridge sections produced via pultrusion

Figure 1. A pultruded deck section made from fibre reinforced plastics.
Testing of Fibre Reinforced Sections

Before the profiles could be used they had to be thoroughly tested. Carried out at IETCC in Spain, the profiles were subjected to static flexure, static shear, fatigue, creep and impact testing. Small-scale coupon tests were carried out on the GRP composite material and the decking was analysed using 3D finite element model analysis. Additionally, static, fatigue and creep testes were carried out on single and multiple profiles over one and two spans, and in all cases the profiles matched their expected performance to within 5%, with only slight thickening of one of the diagonals required.
Trialling the Fibre Reinforced Bridge Design

All that was needed to complete the project was a client who wanted a bridge, and who was prepared to act as a trail-blazer for the technology. West Mill Bridge in Oxfordshire was built in the 1870s and carried a single lane of traffic over the river Cole. Oxfordshire County Council was a member of the ASSET consortium, so when the bridge was due for renewal it was an obvious candidate for the new technology. Owing to the dilapidated condition of the existing abutments and the need for increased carriageway width, it was decided that the existing abutments would be demolished and reconstructed in reinforced concrete - while this was taking place the deck was to be constructed on site for lifting into position once the abutments were completed.
Construction of the New Bridge

Once the existing bridge had been removed, sheet pile cofferdams were installed on either side of the river. Alongside the bridge, a fabrication area was constructed with temporary works erected to support the deck under a humidity-controlled tent. Here, the longitudinal beams were placed and the edge beams cast in concrete. ASSET profiles, prebonded into seven sections, were then placed on top, ready for bonding. Once glued into position, ‘L’ profiles were bonded to their sides to form the edges of the footpath and optical sensors and strain gauges installed at key locations to enable real-time, in-service monitoring to take place. With the completion of the abutments, a 200 tonne mobile crane was a positioned to lift the completed deck into position. When in place, final carriageway works were completed, including the reconnection of a gas main. The bridge deck surfacing comprised of polymer concrete topping, which was finished with a 6mm thick anti-skid, epoxy wearing surface supplied by HIM.

AZoM - Metals, Ceramics, Polymer and Composites : Fibre Reinforced Plastics bridge sections being lifted into position and under the load of a sherman tank.

Figure 2. The fibre reinforced polymer deck section being lifted into position (left) and being tested under the load of a Sherman tank (right).
Summary

Overall, the client, construction team, pultruder and project management team were all pleased with the final result. The ASSET profile construction system proved to be faster and cheaper to construct than comparable concrete or steel structures and the bridge should be more durable, as well as being almost maintenance-free. Already there are plans for the wider use of the ASSET profile in jetties, helipads, industrial plants, car parks and further bridges. The plastic bridge in Oxfordshire looks set to be the start of a construction revolution.

Abstract

In this paper, we investigated the photolithographic properties of poly(N-tetradecylmethacryl-amide-co-t-butyl 4-vinylphenyl carbonate) [p(TDMA-tBVPC)] thin films prepared by Langmuir-Blodgett (LB) technique. The copolymer forms a stable monolayer on a water surface and LB films with any desired number of layers. The copolymer has a structure being subject to the main chain scission and deprotection of t-butoxycarbonyloxy group by deep UV irradiation. The positive-tone patterns of the p(TDMA-tBVPC56) LB film with 60 layers could be obtained by deep UV irradiation followed by development with alkaline aqueous solution. The resolution of the pattern was 0.75 mm, which is the resolution limit of the photomask employed. The etching resistance of p(TDMA-tBVPC56) LB film was also investigated permitting etching of the gold film.
Keywords

Langmuir-Blodgett films, Copolymer, Photolithography, Etching
Introduction

The continuing trend toward higher circuit density in microelectronic devices has motivated research efforts in varieties of high-resolution lithography techniques, including electron beam (EB), X-ray, and deep UV irradiation. Use of ultra-thin films and new materials have been proposed as approaches to improve resolution in lithography. The Langmuir-Blodgett (LB) technique is very effective method used to prepare well-defined ultra-thin film with controlled thickness and orientation at a molecular level. Therefore, LB films are expected to realize ultra-high resolution photolithography [1-4].

In previous studies, [5-7] we have found that N-octadecylacrylamide forms a uniform LB film with a highly ordered structure, and yielded a fine negative pattern by photopolymerization. Furthermore, we have also succeeded in the preparation of preformed polymer LB film that has a cross-linking group [8]. By the cross-linking reaction with deep UV and electron beam irradiation we obtained a fine negative pattern consisting of two-dimensional network. All of these polymer LB films resulted in negative-tone photopatterns. On the other hand, we also obtained positive type photopatterns using poly(N-tetradecylmethacrylamide)(p(TDMA)) LB films without any development process (self-development) [9, 10]. It was found that the higher sensitivity could be obtained by changing the alkyl side chain to the short-branched type [11]. In addition, the deprotection reaction of t-butoxycarbonyloxy group has also been used in positive patterning of polymer LB films [12-14]. Combining these interesting properties, the improvement of not only the sensitivity but also the imaging quality can be expected. In this work, we prepared the copolymers of photodegradable N-tetradecylmethacrylamide (TDMA) with t-butyl 4-vinylphenyl carbonate (tBVPC) (Figure 1) aiming at the fabrication of a new type of positive resist taking place both main chain scission and polarity change caused by t-butoxycarbonyloxy group deprotection.

AZojomo - The "AZo Journal of Materials Online" Chemical structure of p(TDMA-tBVPC)

Figure 1. Chemical structure of p(TDMA-tBVPC).
Experimental

The copolymer (p(TDMA-tBVPC)) was prepared by free-radical copolymerization of N-tetradcylmethacrylamide (TDMA) with t-butyl 4-vinylphenyl carbonate (tBVPC) in toluene at 60˚C. Measurement of surface pressure ( p) - area (A) isotherm and deposition of monolayers were carried out at 15˚C with a Langmuir trough system (FSD-50 and 51, USI) with a compression speed of 14 cm2/min. The rate of deposition was set at 10 mm/min at both up- and down-strokes. Deionized pure water (Milli-QII, MILLIPORE) was used as the subphase. The copolymer was dissolved in chloroform at a concentration of ca. 1 mM and the solution was spread on the water surface. The glass, quartz, and silicon slides on which LB film was deposited were initially cleaned by a UV-O3 cleaner (NL-UV253, Nippon Laser Electronic); then they were made hydrophobic with n-octyltrichlorosilane. UV absorption measurements were recorded with a Hitachi U-3000 UV-Vis spectrophotometer. The molar ratio of the tBCPV in the copolymer were determined from 1H NMR of p(TDMA-tBVPC). Molecular weight was determined with a Toyo Soda gel permeation chromatography (GPC) using a polystyrene standard. IR spectra were measured with a JASCO-IR 230 spectrometer. Deep UV irradiation was carried out with a deep UV lamp (UXM-501MA, USHIO) through an IR-cut filter. The thickness of copolymer LB film was determined with surface profilometry using a Sloan Dektak 3ST. Gold film was deposited onto a glass substrate with a vacuum evaporator (V-KS200, Osaka Vacuum, Ltd).
Results and Discussion
Formation of Copolymer LB Films

The molecular weight of p(TDMA-tBVPC) are summarized in Table 1. The copolymer(p(TDMA-tBVPC)) was spread on the water subphase from chloroform solution (ca. 1mM) to measure surface pressure (p) - area(A) isotherms (Figure 2). The copolymer p(TDMA-tBVPC) monomers have collapse pressure. Their curves stand sharply. We can conclude that they can form a condensed monomer on the water subphase. The p(TDMA-tBVPC) monolayer could be transferred onto a solid substrate with a transfer ratio of almost unity. UV absorption spectra of p(TDMA-tBVPC56) LB film on quartz were measured as a function of the number of layers (Figure 3). The absorbance at 193 nm apparently increases linearly with the number of layers deposited, indicating the regular deposition of the copolymer monolayer onto the solid substrate.

Abstract

In this paper, we investigated the photolithographic properties of poly(N-tetradecylmethacryl-amide-co-t-butyl 4-vinylphenyl carbonate) [p(TDMA-tBVPC)] thin films prepared by Langmuir-Blodgett (LB) technique. The copolymer forms a stable monolayer on a water surface and LB films with any desired number of layers. The copolymer has a structure being subject to the main chain scission and deprotection of t-butoxycarbonyloxy group by deep UV irradiation. The positive-tone patterns of the p(TDMA-tBVPC56) LB film with 60 layers could be obtained by deep UV irradiation followed by development with alkaline aqueous solution. The resolution of the pattern was 0.75 mm, which is the resolution limit of the photomask employed. The etching resistance of p(TDMA-tBVPC56) LB film was also investigated permitting etching of the gold film.
Keywords

Langmuir-Blodgett films, Copolymer, Photolithography, Etching
Introduction

The continuing trend toward higher circuit density in microelectronic devices has motivated research efforts in varieties of high-resolution lithography techniques, including electron beam (EB), X-ray, and deep UV irradiation. Use of ultra-thin films and new materials have been proposed as approaches to improve resolution in lithography. The Langmuir-Blodgett (LB) technique is very effective method used to prepare well-defined ultra-thin film with controlled thickness and orientation at a molecular level. Therefore, LB films are expected to realize ultra-high resolution photolithography [1-4].

In previous studies, [5-7] we have found that N-octadecylacrylamide forms a uniform LB film with a highly ordered structure, and yielded a fine negative pattern by photopolymerization. Furthermore, we have also succeeded in the preparation of preformed polymer LB film that has a cross-linking group [8]. By the cross-linking reaction with deep UV and electron beam irradiation we obtained a fine negative pattern consisting of two-dimensional network. All of these polymer LB films resulted in negative-tone photopatterns. On the other hand, we also obtained positive type photopatterns using poly(N-tetradecylmethacrylamide)(p(TDMA)) LB films without any development process (self-development) [9, 10]. It was found that the higher sensitivity could be obtained by changing the alkyl side chain to the short-branched type [11]. In addition, the deprotection reaction of t-butoxycarbonyloxy group has also been used in positive patterning of polymer LB films [12-14]. Combining these interesting properties, the improvement of not only the sensitivity but also the imaging quality can be expected. In this work, we prepared the copolymers of photodegradable N-tetradecylmethacrylamide (TDMA) with t-butyl 4-vinylphenyl carbonate (tBVPC) (Figure 1) aiming at the fabrication of a new type of positive resist taking place both main chain scission and polarity change caused by t-butoxycarbonyloxy group deprotection.

AZojomo - The "AZo Journal of Materials Online" Chemical structure of p(TDMA-tBVPC)

Figure 1. Chemical structure of p(TDMA-tBVPC).
Experimental

The copolymer (p(TDMA-tBVPC)) was prepared by free-radical copolymerization of N-tetradcylmethacrylamide (TDMA) with t-butyl 4-vinylphenyl carbonate (tBVPC) in toluene at 60˚C. Measurement of surface pressure ( p) - area (A) isotherm and deposition of monolayers were carried out at 15˚C with a Langmuir trough system (FSD-50 and 51, USI) with a compression speed of 14 cm2/min. The rate of deposition was set at 10 mm/min at both up- and down-strokes. Deionized pure water (Milli-QII, MILLIPORE) was used as the subphase. The copolymer was dissolved in chloroform at a concentration of ca. 1 mM and the solution was spread on the water surface. The glass, quartz, and silicon slides on which LB film was deposited were initially cleaned by a UV-O3 cleaner (NL-UV253, Nippon Laser Electronic); then they were made hydrophobic with n-octyltrichlorosilane. UV absorption measurements were recorded with a Hitachi U-3000 UV-Vis spectrophotometer. The molar ratio of the tBCPV in the copolymer were determined from 1H NMR of p(TDMA-tBVPC). Molecular weight was determined with a Toyo Soda gel permeation chromatography (GPC) using a polystyrene standard. IR spectra were measured with a JASCO-IR 230 spectrometer. Deep UV irradiation was carried out with a deep UV lamp (UXM-501MA, USHIO) through an IR-cut filter. The thickness of copolymer LB film was determined with surface profilometry using a Sloan Dektak 3ST. Gold film was deposited onto a glass substrate with a vacuum evaporator (V-KS200, Osaka Vacuum, Ltd).
Results and Discussion
Formation of Copolymer LB Films

The molecular weight of p(TDMA-tBVPC) are summarized in Table 1. The copolymer(p(TDMA-tBVPC)) was spread on the water subphase from chloroform solution (ca. 1mM) to measure surface pressure (p) - area(A) isotherms (Figure 2). The copolymer p(TDMA-tBVPC) monomers have collapse pressure. Their curves stand sharply. We can conclude that they can form a condensed monomer on the water subphase. The p(TDMA-tBVPC) monolayer could be transferred onto a solid substrate with a transfer ratio of almost unity. UV absorption spectra of p(TDMA-tBVPC56) LB film on quartz were measured as a function of the number of layers (Figure 3). The absorbance at 193 nm apparently increases linearly with the number of layers deposited, indicating the regular deposition of the copolymer monolayer onto the solid substrate.

Crystallography is an extremely useful tool for analysing conventional materials. Using techniques such as x-ray diffraction, long range order and symmetry can be determined using principles such as Bragg’s law. The peaks produced in the associated diffraction patterns can yield valuable information about the atomic structure of these materials.

However, these techniques are generally not suited to nanomaterials as they lack long range order and produce few if any diffraction peaks, while the diffraction patterns themselves are often diffuse. A technique called atomic pair distribution function can be used on nano-sized materials. This non-conventional technique reads the information between the peaks produced using standard x-ray diffraction data.

Researchers at the Brookhaven National Laboratory have successfully used this technique to look at cesium ions in the nano-sized pores of a silicon-oxide zeolite (Si32O64). They were able to show that the cesium ions existed in zig-zag chains with short range order. They were also able to confirm that CsxSi32O64 was a room temperature stable inorganic electride.

Electrides are a novel family of materials that have recently begun to stimulate interest amongst the materials community. It is thought that they may be useful in the synthesis of materials as a reducing material or as a low energy electron emitter due to their electronic properties.

Background

Fused Magnesia (MgO) is normally manufactured by the electric arc melting of caustic calcined magnesia, deadburned magnesia or raw magnesite in furnaces at temperatures in excess of 2750°C, producing a refractory product whose altered crystalline structure is such that its characteristics and performance are superior to competing materials.
Magnesite

Magnesite (MgCO3), the naturally occurring carbonate of magnesium (Mg) is one of the key natural sources for the production of magnesia (MgO) and subsequently fused magnesia. Magnesite occurs in two distinct physical forms: macrocrystalline and cryptocrystalline. Cryptocrystalline magnesite is generally of a higher purity than macrocrystalline ore, but tends to occur in smaller deposits than the macrocrystalline form.

At present, there is only one producer of fused magnesia in Australia, QMAG, majority owned by Australian Magnesium Corporation. QMAG is a producer of refractory grade fused magnesia.
High Grade Magnesia Production

Historically, and due principally to the small size of most known cryptocrystalline deposits, production of high grade magnesia products was mainly by extraction from natural brines or seawater (synthetic MgO), a high cost and energy intensive process. High quality deposits, provide an alternative source of supply to the high cost seawater-sourced magnesia.
Uses of Fused Magnesia

Magnesia products (calcined, deadburned and fused) are widely used in a range of market applications.
Calcined Magnesia

Is used in agricultural and industrial applications, eg, as a feed supplement to cattle, fertilisers, electrical insulations, industrial fillers, and in flue gas desulphurisation.
Deadburned Magnesia

Is used almost exclusively for refractory applications in the form of basic bricks and granular refractories. Deadburned magnesia has the highest melting point of all common refractory oxides and is the most suitable heat containment material for high temperature processes in the steel industry. Basic magnesia bricks are used in furnaces, ladles and secondary refining vessels and in cement and glass making kilns.
Fused Magnesia

Fused magnesia is superior to deadburned magnesia in strength, abrasion resistance and chemical stability. Major applications are in refractory and electrical insulating markets. Producers of fused magnesia commonly fall into one of two categories: those producing refractory grades and those producing electrical grades. Few producers serve both markets on a mainstream basis.
Refractory Grade Fused Magnesia

The addition of fused magnesia grains can greatly enhance the performance and durability of basic refractories such as magcarbon bricks. This is a function of a higher bulk specific gravity and large periclase crystal size, plus realignment of accessory silicates. Refractory grade fused magnesia has exacting specifications and is normally characterised by the following:

· Generally high magnesia content (minimum 96 per cent MgO and up to/exceeding 99 per cent MgO)

· Low silica; lime:silica ratios of 2:1

· Densities of 3.50 g/cm3 or more

· Large periclase crystal sizes (>1000 microns)

Due to its excellent corrosion resistance, refractory grade fused magnesia is used in high wear areas in steel making, eg, basic oxygen and electric arc furnaces, converters and ladles.

Ultra high purity (>99 per cent MgO) grades have been used in high-tech applications such as optical equipment, nuclear reactors and rocket nozzles.
Electrical Grade Fused Magnesia

Fused magnesia is also used as an electrical insulating material in heating elements. Although electrical grades of fused magnesia have very tight specifications, they do not necessarily require the highest MgO contents or densities. Impurities such as sulphur and iron are particularly undesirable, but the product should contain sufficient silica to enhance its electrical properties. The following are characteristic of electrical grade fused magnesia:

· Low levels of boron, sulphur, iron and trace elements.

· Lime: silica ratios of 1:2 (opposite to refractory requirements).

· Used as electrical insulating material in ceramic sheaths for heating elements.

Producers manufacture three categories of fused magnesia, each related to the environment of application:

· High Temperature (up to and in excess of 950°C) requiring high purity fused magnesia of 94-97 per cent MgO and low silica and calcium contents, eg, for stove grills.

· Medium Temperature (up to 800°C) with magnesia contents of 93-96 per cent MgO, eg, for elements in ovens.

· Low Temperature (<600°C) with <90 per cent MgO, eg, immersion elements.

Electrical grade cements can be produced by blending electrical grade fused magnesia and plasticisers and hardeners for use in hot plates, toasted sandwich makers and electric irons. Electrical grade fused magnesia can be given a uniform silicon coating for greater resistance to moisture absorbance during heating element manufacture; this also improves the cold insulation resistance of low duty elements exposed to conditions of humidity. Electrical grade magnesia is tested for its electrical and thermal properties, eg, high electrical resistivity and high thermal conductivity.
Fused Magnesia Production Process

Magnesite (magnesium carbonate MgCO3) is converted into magnesia by the application of heat which drives off carbon dioxide (CO2), thereby converting the carbonate to the oxide of magnesium (MgO).

Magnesite, from both natural sources (primarily magnesite) and synthetic sources (seawater, natural brines or deep sea salt beds), is converted into caustic calcined magnesia by calcining to between 700°C and 1000°C, driving off 96-98 per cent of the contained carbon dioxide. Caustic calcined magnesia is both an end product and an intermediary step in the chain of magnesia products.

Further calcining of magnesite at higher temperatures between 1750-2200°C results in the largely inert product, deadburned magnesia. Heating to this level drives off all but a small fraction of the remaining carbon dioxide to produce a hard crystalline non reactive form of magnesium oxide known as periclase. Deadburned magnesia exhibits exceptional dimensional stability and strength at high temperatures.

Fused magnesia is produced in a three phase electric arc furnace. Taking high grade magnesite or calcined magnesia as raw materials, 12 hours is required for the fusion process at temperatures in excess of 2750°C. The process promotes the growth of very large crystals of periclase (>1000 microns compared with 50-100 microns for dead burned magnesia) with a density approaching the theoretical maximum of 3.58g/cm3.

In fused magnesia production, the main constraints on capacity are the size and number of electric arc furnaces, and the cost of energy. The manufacture of fused magnesia is very power intensive with electricity consumption varying between 3500-4500 kWh/tonne; fused magnesia producers often quote total capacity based on utilising off peak power.
Raw Materials

Commercially acceptable magnesite should contain at least 95% MgCO3. The most important magnesite deposits in New South Wales, Australia are located at Thuddungra (about 30 km northwest of Young). Other known deposits are located at Fifield (northwest of Condobolin), Lake Cargelligo and Attunga; these are smaller and less pure than the Thuddungra deposits.
Markets

The emergence of China as a major producer of low priced fused magnesia has impacted on the market share and profitability of Western manufacturers of the product. However, it is the increased availability of competitively priced Chinese fused magnesia that has bolstered global demand for this refractory raw material, and higher grade fused magnesia has developed a niche market to some degree due to its lower iron content.

AZoM - Metals, ceramics, polymers and composites: magnesia, magnesium oxide, MgO production flow diagram

Figure 1. Fused Magnesia Process Flow Chart

The 1990’s heralded a period of expansion in the fused magnesia sector in response to accelerating consumer demand, with several new players entering the market. Outside of China, key producers of fused magnesia in the refractory market include QMAG of Australia, Baymag of Canada, Tateho Dead Sea Fused Magnesia of Israel and Kombinat Magnesit of Russia. In 2000, with the growing dominance of the Chinese producers, the fused magnesia business has become an intensely competitive environment, with profit levels much tighter than they were previously.

There are now over 500 magnesia producers in China and over 100 companies produce fused magnesia. Whilst difficult to obtain accurate figures on Chinese production, it is estimated that fused magnesia production in China is in the order of 500 000 tpa of which 250 000-300 000 tpa are destined for the export market. However, despite a more competitive environment and declining specific refractory consumption in steel making, the outlook for fused magnesia compared with some other refractory raw materials is relatively bright, with more fused magnesia being used in refractory brick formulations. The recent upturn in demand for fused magnesia can at least in part be attributed to the recovery of world steel markets.

With the current strength of global steel markets, increased prices for Chinese fused grades as a result of rising Chinese electricity costs and disruptions to supply from China, a window of opportunity exists for new and existing non Chinese refractory magnesia producers.

Higher electricity costs in China are expected to add a premium of US$30-50 per tonne to the cost of fused magnesia. Uncertainties over energy costs have resulted in shortages of material, with producers either temporarily shutting down production or simply not selling the material. Fused magnesia sales from QMAG, for example, increased by 35 per cent in the June quarter 2000 over the March quarter partly in response to this disruption to Chinese supply.

The price of fused magnesia depends significantly on its quality.

At the lower end of the scale, Chinese fused magnesia (97.5% MgO) is being sold at around US$300 per tonne into Europe, whereas 98.5% material would sell at around US$450-550 per tonne. At the other end of the scale, highest quality fused magnesia with MgO contents of greater than 99%, would sell for around US$1200-1400 per tonne (April 2001).

As indicated by the variation in price, one type of fused magnesia based on its quality and properties is not necessarily in competition with another type of fused magnesia of different quality and with different market applications. For example, Tateho Dead Sea Fused Magnesia, which manufactures an extremely high purity product, does not compete against lower quality Chinese fused magnesia. Customers choosing the Tateho product require a product with extremely low impurities for use in very heat intensive refractory applications.

13/3/01 Morgan Crucible report a strong set of results in their 2000 preliminary announcement.

Commenting on the results, Ian Norris, Group Chief Executive, said: "After the major business restructuring and disposal programme of the last two years, Morgan has emerged in strong shape to face the future. More than 50% of Group turnover now comes from businesses which grew organically at more than 5% last year and our strategic entry into the magnetics market in 1999 with the acquisition of Vacuumschmelze has been particularly successful. The balance between growth and mature businesses within our portfolio has clearly improved and assuming no significant worsening in the current rate of slowdown across a number of sectors in the United States, we shall demonstrate continued progress in 2001."

Financial Results

Strategic Progress

Fuel Cell Development, Technical Ceramics and Superconductors

Carbon

Electrical Carbon

Engineered Carbon

Precision Coatings
Magnetics

Ceramics Division

Technical Ceramics

Insulating Ceramics
Financial Results




2000


1999


% Growth

Group Turnover £m


1051.1


862.4


+21.9%

Underlying Operating Profit * £m


111.3


94.6


+17.7%

Underlying Pre-Tax Profit *£m


95.1


81.1


+17.3%

*Before goodwill amortisation of £5.8 million (1999 : £2.0 million) and operating exceptionals of £6.9 million (1999: £17.5 million). * Underlying Pre-Tax Profit* increases by 17.3% to £95.1 million (1999 : £81.1 million).
Strategic Progress

In 1999, Morgan extended its advanced materials skills base by the strategic entry into the magnetics market with the acquisition of a world leading magnetics business, Vacuumschmelze GmbH ("VAC"), based in Germany and the smaller Crumax Magnetics Inc. in the USA. These have been merged to form a technically driven organisation providing high-performance magnetics solutions.
Fuel Cell Development, Technical Ceramics and Superconductors

The fuel cell development team has been further strengthened and is developing new design capability and manufacturing processes which are expected to contribute greatly to a dramatic cost reduction for bi-polar plates. The technical ceramics business continues in partnership with one of the world's leading data storage manufacturers to provide a piezo-electric solution to enable a substantial increase in the data storage capacity of disk-drive devices. The development of high temperature super-conducting materials continues with the aim of providing the future solution to transporting high volumes of electrical power across great distances.
Carbon

The Carbon Division which comprises Electrical Carbon, Engineered Carbon and Magnetics businesses achieved total sales of £563.8 million (1999 :£322.2 million), an increase of £241.6 million or 75.0%. Encouraging organic growth in sales was achieved across all businesses although £200.7 million of the total increase arises as a result of having a full 12 months trading of VAC compared to 1 month in 1999.

Underlying operating profit was £66.5 million (1999 : £48.2 million) with underlying operating margins at 11.8 % (1999 : 15.0%). Some decline in underlying margins was experienced in both the Electrical and Engineered Carbon businesses. The principal factor behind the overall decline in underlying operating margins for the division has, however, been the contribution from the Magnetics business where operating margins were below the divisional average, although ahead of expectations.
Electrical Carbon

Turnover within Electrical Carbon increased to £197.9 million (1999 : £189.1 million) and included organic growth of 2.2%. Underlying operating profit fell, however, to £26.3 million (1999 : £30.3 million) yielding an underlying operating margin of 13.3% (1999 :16.0%).

The Group is taking steps to address the decline in margin by increasing the proportion of product sourced from lower cost plants in China and India. Performance was also adversely impacted in the industrial and rail traction segment where the much reported disruption to the UK rail network at the end of the year contributed to a deferral of orders for replacement traction brushes.

The automotive and consumer markets performed strongly until close to the year-end when the slow down in the United States, particularly in the automotive market, had a notable impact. Plans were implemented at the beginning of 2001 to substantially reduce costs to compensate for the anticipated market weakness. Nevertheless, positive organic growth was still achieved with only a slight decline in overall operating margins. A number of successes were recorded during the year with orders received for the supply of fully integrated assemblies including brush, commutator and bonded magnets. This represents a major growth opportunity for the long term.
Engineered Carbon

Engineered Carbon achieved turnover of £124.9 million (1999 : £108.8 million)with organic growth of 6.2%. Underlying operating profits grew slightly to £16.6 million (1999 : £16.4 million) with underlying operating margin of 13.3% (1999 : 15.1%).

The mechanical carbon business, providing a range of tribological solutions, showed organic growth of more than 6% although at some expense to operating margins. The specialty graphite sales grew strongly particularly in the USA benefiting from exposure to the semiconductor equipment manufacturing market. An investment project was initiated to bring European and Asian specialty graphite plants up to the same level of technical excellence as the United States facilities.
Precision Coatings

The Group's precision coatings business, which provides a full range of solutions from solid film lubricants to diamond coatings, had a successful year growing both sales and profits. A plant is currently being established in continental Europe, and plans are also being developed for similar investment in Asia. Shortly after the year-end Diamonex Inc. was acquired in the United States for a total consideration of US$13.8 million. With this acquisition, the Morgan Group has acquired technology protected by over 40 patents for commercial diamond and diamond-like coatings which provide properties of exceptional resistance to wear as well as the ability to rapidly dissipate heat. These properties provide superior wear resistant coatings solutions for products such as diesel fuel injectors, storage discs in hard disc drives and heat dissipation devices for the semiconductor and power electronic industries.
Magnetics

In its first full year as part of Morgan, the performance of the Magnetics business demonstrated a turnover of £241.0 million (1999 : £24.3 million). Organic growth for the business overall was 23.4%. The two acquisitions made last year, Crumax Magnetics Inc. in the United States and the much larger VAC headquartered in Hanau, Germany, are now operating under a common global team.

Crumax provides a stronger North American presence as well as the technology to use magnetic and resin bonded materials within the substantially broader technical base of VAC. Certain of Crumax's range of products have been exited during the year which has had the effect of understating the strong underlying growth experienced by our magnetics business overall. Looking at the results of VAC alone, record sales were achieved with an underlying sales growth of 27.9% and an operating margin of 11.8%.

A key driver of this performance was the growth achieved by permanent magnets sold into the growing data storage market. This has been strongly supported by the sale of fully integrated assemblies incorporating magnetic cores into the specialist niche sectors of telecommunications markets and the provision of soft magnetic materials to the retail security sensor market.

Underlying operating profits were £23.6 million (1999 : £1.5 million) with this year having received the benefit of a full years trading. At 9.8% underlying operating margins, though below the average for the Group, were ahead of expectations for the year.
Ceramics Division

The Ceramics Division comprises the Technical Ceramics and Insulating Ceramics businesses. Total sales of the division were £457.0 million (1999 : £428.1 million), an increase of 6.8% with organic sales growth achieved by each of the businesses. Underlying operating profits rose by 5.9% to £42.9 million (1999 : £40.5 million) giving an underlying operating margin of 9.4% (1999 : 9.5%) for the division as a whole.
Technical Ceramics

Turnover within Technical Ceramics increased by £20.5 million to £139.8 million (1999 : £119.3 million), with organic growth of 14.8%. Underlying operating profits also advanced strongly rising by 51.5% to £15.0 million (1999 : £9.9 million) with underlying operating margin improving to 10.7% (1999 : 8.3%).

A major restructuring programme was carried out in the North American advanced ceramics business during 1999 with all of the plant based sales teams merged into one focused organisation. Advanced ceramics achieved organic sales growth in the year of 13.6% although within this, growth in North American sales was 16.9%. Particular market focus has been directed towards the fast growing sectors of medical equipment, telecommunications and semiconductor equipment manufacture. The European businesses within advanced ceramics were refocused towards the end of the year along similar lines to those in North America.

Shortly after the year-end, the Group completed the acquisition of Performance Materials Incorporated ("PMI") in the United States for an initial consideration of US$18.5 million. Based on exacting performance criteria, an earn-out formula is in place which could increase the consideration to a maximum of US$50.0 million. PMI's expertise is in the provision of high purity components, formed by chemical vapour deposition, to the semiconductor hardware market.

The electro-ceramics business also had a very good year with organic sales growth of 22.9%. The share in the piezo electric automotive parking sensor market moved ahead strongly. Progress was made on bringing a number of new initiatives closer to market commercialisation. These include a revolutionary new design of a fuel injector utilising multi-layer ceramic actuators and a piezo electric actuator application to micro-position the read write head of disc drive devices, thus enabling a substantial increase in data storage capacity. Both of these products are being developed with customers who lead in their respective fields.
Insulating Ceramics

Insulating Ceramics turnover was £317.2 million (1999 : £308.8 million), showing marginal organic sales growth of 0.7%. Underlying operating profits declined, however, to £27.9 million (1999 : £30.6 million) as a result of operational difficulties within the thermal operations in the Americas. Underlying operating margin declined from 9.9% to 8.8%.

The thermal ceramics business encountered difficulties with the commissioning of a Mexican manufacturing facility which led to manufacturing variances and capacity shortages in North America. These shortages were met by shipping product from European and Asian facilities at considerable expense.

The future strategic position of the thermal business has been the subject of a major review in the year. A restructuring plan has been developed which will enhance the cash generating capability of this business and concentrate efforts in areas with attractive margin and growth prospects such as our world leading soluble fibre technology. Low growth and low margin parts of the business will be subject to further review.

Our crucibles business delivered a particularly creditable performance given the fundamental restructuring implemented during the year. Our French manufacturing facility has now been closed and the UK facility substantially overhauled.

Background

Concern about carbon dioxide emissions and world hydrocarbon fuel reserves means that there is considerable interest in technologies that reduce fuel consumption for passenger cars. In the area of vehicle design, body weight is the most important target for improvement, as a reduction in the weight of a vehicle’s body means that a smaller engine, and a lighter drive train and assembly can be used. This ‘benign spiral’ leads to further mass reductions, so much so that various studies have indicated a potential for savings of up to 65% by using carbon fibre composites instead of steel wherever possible.
Racing Cars versus Passenger Cars

The Aero-Stable Carbon Car (ASCC) programme has been investigating the limitations to maximising fuel economy in a lightweight car manufactured using carbon fibre composites (CFC). Current lightweight composite vehicles, such as racing cars, use a monocoque stressed-skin design for both weight and manufacturing cost reasons. However, for passenger cars with large ‘cut-out’ areas for access, the approach of using a space-frame supporting fairing panels offers the opportunity for a more efficient structure compared to the monocoque approach. It also offers the potential to incorporate localised loads, such as those from the suspension, engine and door mountings, seat and seat belts, more easily than with a thin-section stressed-skin approach.
Manufacturing Space-Frame Using a Carbon Fibre Composite Material

Manufacturing the space-frame using carbon fibre composite materials provides a very lightweight structure. But using current manufacturing techniques, the labour cost for bonding sections together and material lay-up limits the use of a framework approach for all but the most expensive niche vehicles.
Fabrication Process and weight Savings

In response to this, a novel design and materials approach was conceived and developed. The approach uses a novel form of textile preform, laminated to form a single-piece integrated frame structure. Lightweight panels are bonded to the assembled frame after systems fitting. This approach results in a total bodyweight of about 125kg, which compares to around 320kg for a similar-sized steel car.
Collaborators and Project Objectives

The Cranfield University Centre for Lightweight Composites, in collaboration with Lotus Engineering (CAD and body pattern manufacture), Cranfield Impact Centre (impact considerations), Tenax Fibers (carbon fibre and preforming advice), Vantico (epoxy resin, tooling materials and adhesives) and BT1 Europe (carbon fibre fabrics), worked on the design and development of a lightweight composite body for a medium‑sized (Ford Focussized) car demonstrator. The project objective was to design and manufacture a carbon fibre composite structure for the ASCC at minimum weight, while providing greater stiffness in all aspects than for current steel bodies.
Materials Developments

The application of carbon or epoxy composites to a lightweight primary structure is not new, but the process has to date been employed exclusively within the prestige sports and racing car industry. An example of this is the McLaren Fl, the structure of which is reported to have required well over 1,000 man-hours of skilled labour to mould the composite components. The transfer of aerospace composites technology has been shown to provide very effective structures although at an unaffordable cost for consumer markets.
Reasons for High Manufacturing Costs of Composite Car Bodies

The very high manufacturing costs of lightweight composite car structures is principally due to three factors:

the high cost of raw materials, both in the use of pre-impregnated fabrics and the very high waste level in laminating complex shape components

The high labour cost required to manufacture weight-optimised components, which need careful draping and alignment of very thin (typically 0.4mm) layers with the thickness tailored to suit load distribution

Very high cycle times for both lay-up and resin curing, hence low production rates from each tool set.
Manufacturing Composite Car Bodies on a Commercial Scale

A suitable manufacturing process for higher volume production (between 1,000 and 10,000 units per annum) of automotive primary structure requires lower cost raw material, use of automation for reinforcement application and impregnation, lower process cycle time and moulded surfaces that require no hand finishing.
Composite Car bodies in Crash Situations

Another current issue for composite car bodies is the insufficient experience of impact behaviour other than for small racing car monocoques. This results from the complex, non-plastic failure of the material, which is difficult to model or predict. Any structure for an automotive application needs to satisfy a number of performance criteria, namely:

Suitable torsional rigidity for ‘regular’ driving

Sufficient stiffness and strength to protect the occupant in the event of a low-speed (<30mph) collision

• progressive and controlled failure of the structure in order to reduce the risk of injury in a highspeed (>30mph) collision.

Typically, the first two of these criteria can be easily met by an advanced composite structure. The third requirement is more difficult to achieve, as the materials tend to behave in a linear-elastic way until failure, which is then instant and catastrophic, leaving minimal residual strength. The area of impact performance of lightweight carbon fibre structures justifies extensive investigation, since carbon fibre composites can provide exceptionally high levels of crash energy absorption if structures are engineered effectively.
Development of a Novel Materials and Manufacturing Process

As a result of the need for a lightweight, low-cost crashworthy structure, a completely novel materials and process concept was conceived and developed. A lightweight single-piece composite structural framework and simple, lightweight bonded panels replace the conventional moulding and assembly of complex shape-stiffened panels. This approach offers several potential manufacturing and performance advantages over the conventional approach, including:

Very substantial materials cost reduction through the use of low-cost textile platforms and liquid resin

Automation of reinforcement pre-form manufacture, application to mould tools and impregnation process and hence very substantial reductions in the labour costs of moulding

Rapid and low labour cost vehicle body assembly with minimal fixtures

Improved crashworthiness.
Difficulties Associated with the Novel Process

However, this approach presented some difficult manufacturing technology challenges since frameworks have complex geometry and joining of composite primary structures is a very labour-intensive process.
The Design of the Composite Passenger Car

The monocoque approach having been discarded, a more efficient design that does not need to transfer large loads through panel joints, is to use a very stiff framework of complex shaped beams and struts, covered by thin panels, bonded using low stiffness adhesives. This approach also offers benefits in vehicle assembly and fitting, since loading and attachment points can be provided on the framework and the panels can be attached near the end of the process to provide clear access through frame apertures.

However, realisation of this design concept was difficult, since current material forms and processing solutions are developed for thin skins and not suited to framework structures.
Composite Framework Design

The resultant framework design comprises a single highly-integrated moulding. This defines the outer shape of the passenger compartment. The majority of the side impact strength is provided by the sill sections, which are up to 300mm deep. The front suspension is attached to the space frame via a bolted aluminium sub-frame, so protecting it from damage during low-level collisions. The engine and rear suspension will be attached to the space frame via a rear bulkhead and a steel sub frame.
Use of Hollow and Foam-Cored Members

The only appropriate structural approach for this framework is through the use of hollow or foam-cored beams connected by very stiff joints. Attempts to engineer carbon fibre composite framework components, such as bicycle frames, has resulted in extremely high labour costs. This results from having to integrate beam-ends at joints or produce and bond complex jointing elements. To overcome this problem, so as to enable the volume production of complex framework structures, a novel materials and design approach was conceived and subsequently patented.
The Patented Process

A conventional beam comprising a fabric of large diameter braid wrapping or enclosing a lightweight foam core is replaced by an array of foam cores, each with a braided carbon fibre sleeve. This ‘biomimetic’ type assembly is impregnated and bonded using a very low viscosity, tough two-part epoxy There are three manufacturing cost advantages that result from using this approach:

1. Through the use of a continuous feedstock applied in a series of foam-filled braided tubes, rather than manipulation of large pieces of fabric, deposition into a mould tool has the potential to be automated.

2. The use of a narrow conformable sleeve also allows joints to be formed by taking the feedstock around curves into connected sections.

3. The avoidance of cutting fabrics to conform to complex shapes and join beams results in a very low level of reinforcement waste. This should be in the order of around 2%, compared to a minimum of 30% for conventional approaches.
Determining Framework Section Sizes

Each section of the framework was manufactured from different configurations of cored sleeves, the number and their arrangement around the joints determined by the required load transfer. To establish an understanding of joint stiffness, a detailed experimental programme was carried out to establish design and manufacturing details for generic ‘T’ piece structures. The parameters of braid style, tow size, wall thickness, array arrangement and joint impregnation process conditions were all examined, and established the need to provide additional material at the surface of the ‘T’ intersection to locally thicken the surface wall thickness.
Panel Manufacture
Approaches to Panel Manufacture

For the panel manufacture, several approaches were investigated. These included multi-axial LIBA-type fabrics, using high-strength type carbon fibres from BTI Europe with Vantico LY 564 resin and HY 2962 OE curing agent, SP Systems’ SPRINT fabric, resin film, syntactic foam and surfacing layer one ply sandwich fabric and Hexcel Composites’ pseudo-thermoplastic prepreg. The roof, floor and rear bulkhead use a sandwich structure comprising one layer of multi-axial fabric each side of a toughened PVC foam core.
Panel Moulding and Fixation

The panels are moulded using a resin infusion process and the prepreg material panels by conventional vacuum bag / oven curing. The requirement to be able to remove any panels without damage to the frame, combined with a caution about bonding preparation for structural joints, resulted in the decision to use ductile adhesives. All of the panels, including the roof, floor and bulkhead, will be bonded using a polyurethane adhesive similar to those used in current windscreen fitting.
Space Frame Strength and Crash Resistance

The project is due for completion at the end of November. The resultant space frame is expected to have a weight of 92kg and an associated torsional rigidity of around 15,00ONm/degree. For crash energy absorption and reduction of crash deceleration rate, two frontal impact systems will be used, in addition to an aluminium subframe attaching to the front suspension, a dedicated crash member will be attached to this sub frame. Consequently, the space frame and occupants should not be subjected to a critical peak load. Side impact crash safety is provided through the very deep sections in the sill areas of the framework. These will deform progressively through the use of thin-walled tubular arrays, yet provide extremely high stiffness and strength to avoid catastrophic failure during the crash.
Summary

In the finished car the frame, panels and doors will have a weight of around 140kg, and a total kerb weight of around 570kg. The project also established a novel design and manufacturing technology for carbon fibre composite car bodies, expected to be viable from a manufacturing perspective for producing up to 20,000 cars per annum. The cycle time limitation is the resin impregnation and curing time, so annual production volumes up to 50,000 cars per annum would be possible using a different matrix of polymers and impregnation/curing technology with greater tooling investment.

Background

When you are sailing at the elite level in a one-design class of boat such as Laser dinghies, finding that extra edge over the competition is hard. Not only do you need to be supremely fit and agile, you are looking to have equipment that will meet the demands of high performance sailing.
Design Aspects

Sailing a Laser dinghy is probably the most competitive form of one-on-one sailing that any dinghy sailor can aspire to. Today there are more than 170,000 of these dinghies sailed world-wide. The class rules of this one-design dinghy have been designed to ensure that all competitors are matched evenly against one another with the same equipment, and that it is the skill of the sailor that wins through. Even so there are one or two areas where an individual sailor can bring technology to bear to his or her advantage. To get the best from your boat you need to concentrate your mass near the centre of gravity of the whole structure and minimise the pitching effects. Removing weight from the ends of a boat or the top section of the mast will naturally help. And in the Laser dinghy - which is of glass fibre construction - about the only scope you have for this is with the tiller and tiller extension. It is now becoming increasingly common for both these items to be made in carbon fibre reinforced plastic (CFRP) rather than the traditional aluminium that is sold with every new boat.
Composites in Small Boats

So what does a Laser sailor look for in these parts that will give him the edge? To answer this you must first understand the idiosyncrasies of the design of the boat. While beating to windward in anything of a breeze, you are looking to extract as much power from the sail as possible. Keeping the leach (or back edge) of the sail tight is essential to stop spilling wind. The novel design of the aft traveller, which controls the mainsheet (rope), directly governs the power you can get from the sail. Because the rudder tiller passes directly beneath this traveller, figure 1, it is preferable to have the tiller as low to the deck as possible. In this way you can in turn keep the boom low and the leach tight. Any tiller must therefore be very slim in profile, low to the deck and as stiff as possible so that it will not deflect. The high strength, high stiffness (Young’s modulus) and low weight of (CFRP) makes it the natural material of choice for this application.

Figure 1. A competition laser dinghy.

Similarly, in the Finn single-handed dinghy, one of the oldest racing dinghies, there have been moves made to bring this dinghy up to date with more modern materials. Consequently it is no surprise to see the mast made of (CFRP) and, even the headboard on the sail is now (CFRP) This is all in the interest of reducing the pitching moment of the boat so that, should the helmsman run into the back of a wave on a downwind leg, the mast will not fly forward or pitch pole the whole boat
Composites in Large Boats

In big boats, the benefit of composites has long been recognised in the construction of hulls. Classic examples of such boats that have made extensive use of carbon fibre include Mari Cha III, which broke the transatlantic speed record at the end of 1998. This boat made extensive use of structural carbon and aramid epoxy materials in the hull which had an overall thickness of about 200 mm. Pete Goss was also planning to make a record breaking attempt with a catamaran made from (CFRP) the Goss Challenger. His aim was to be the person to bring home the cup from the ultimate Millennium Race, that started on December 31st in the year 2000. Prior to that he hoped to break the Jules Verne record in the winter of 1999/2000.
Carbon Fibre Boat Components

As (CFRP) has come of age, so more and more applications have been found that take advantage of its exceptional properties. Key fixtures and fittings of the boat are now being made from these materials. Steering wheels and wind transducers are some of the most recent advances.
Manufacturing Aspects

Since many offshore yachts are individual designs, or at least made in only small production runs, the cost of tooling has always been a major part of the total cost. Similarly with items like steering wheels. These are often custom made to fit a particular space envelope in the cockpit of the hull. Making individual moulds for each and every different-sized steering wheel would be prohibitively expensive. By adopting a modular approach it has been possible to make steering wheels of different sizes from just a few key components. Standard components comprise the inner and outer hub, spokes (made to one length but cut to the required size) and spats (to join the spoke and wheel rim). The only item that has to be custom made is the wheel rim. These wheels, developed in just 15 days, were first shown at the Amsterdam Boat Show in November 1998 by Whitlock Marine, figure 2, and are now in full production.

Figure 2. Carbon fibre reinforced steering wheel and wind transducer.

Instrumentation is becomingly increasingly sophisticated on offshore racers and cruisers. However, there is still a need to know the fundamentals, like direction and speed of the wind. To get an accurate reading of both speed and direction, any transducer should ideally be placed well out of any interference from either the mast or sail, as updraught from either of these sources can affect the true readings. In an effort to overcome this a forward-looking wind transducer is mounted at the head of the mast, figure 2. Such a transducer is largely out of sight and mind of the helmsman until something goes wrong. It sits some 15 m in the air and can be subject to 50 g loadings when pitching and rolling in a violent storm. Weighing just 60 g these (CFRP) arms carry the direction vane an anemometer and must be capable of taking these high ‘g’ loadings.
Origins of Carbon Fibre Composites

Carbon fibre composites came of age in the aerospace industry. Their true worth was recognise many years ago when aerospace engineers saw the weight savings that could be made compared with traditional materials like metals. Table 1 illustrate this quite clearly by showing the structural efficiency of a variety of materials that might be used in bending and compression (as in a strut).

Table 1. The efficiency of various materials in different roles.

Material


Young’s Mod
E (GN.m-2)


Density
ρ (g.cm-3)


Spec. Stiffness E/ρ


√E/ρ

Steel


210


7.8


26.9


5.2

Titanium


120


4.5


26.7


5.2

Aluminium


73


2.8


26.0


5.1

High Strength CFRP


138


1.6


86


9.3
Why use CFRPs?

It will be noted that for the majority of traditional structural materials - steel, titanium, aluminium the specific stiffness (E/ρ) is constant, whereas CFRPs offer far higher efficiencies for stiffness or deflection critical structures. When carrying a compression load, as in a column, the efficiency of the structure is governed by √E/ρ and here again the benefit of using carbon fibre composite materials is demonstrated.

While the basic stiffness of steel is far greater than (CFRP) the massive weight saving that can be made by using the material provides a tremendous driving force to choose (CFRP). No matter which metal is chosen for use, the specific stiffness (Young’s modulus divided by specific gravity) of all metals remains stubbornly fixed at 25-26 GN.m-2. It is not until we look at ceramics and high performance fibres that this barrier can be broken. And with a specific stiffness of at least 86 GN.m-2 it is easy to see why aerospace engineers wanted to take full advantage of this so-called wonder material. Price has for a long time been the Achilles heel associated with (CFRP). Fortunately, with the increasing demand for (CFRP) the price has steadily declined over the years with increasing applications in the sporting goods area and more general engineering industries.
Other Benefits of using CFRPs

Of course the other great benefit of using (CFRP) is the fact that the structural properties can be tailored to the application. Because the basic building block material is a unidirectional tape or fibre, or a woven fabric, individual plys can be laid down and oriented in the direction of the principle stresses. Further, these plys can be dropped off, or staggered, along the length of a structure such that the fibres really are where they are wanted - in much the same way as the branch of a tree has more material at the base than it does at the tip.
Manufacturing of CFRPs

And when it comes to manufacture, there are techniques suited to one-off and medium or high volume applications. Parts such as tillers, steering wheels and wind transducers for small and large boats alike are all readily made using low-cost metal moulds and internal pressure bags. At the other extreme, high volume parts can be stamped using thermoplastic composite materials. By coupling this with injection moulding, hundreds of parts per hour can be readily achieved.
Summary

The combination of stringent performance demands, materials with high specific properties and competitive manufacturing techniques suited to both low and high volumes will ensure the growth of advanced composite materials.

Background

The favourable strength to weight ratio and generally excellent mechanical properties of carbon fibre has led to its use in many aerospace, sports goods and transportation applications. Another well recognised, but less often used, property of carbon fibre is its electrical conductivity. Work in the area of electrically conductive fabrics by US company Thermion Systems International has led to the development of a proprietary carbon fibre heating fabric, which is currently being used in the aerospace industry for in-flight de-icing.
Structure of the Heating Fabric

Thermion, is a resistive heating material comprised of nickel coated non-woven carbon fabric, figure 1. Research and development has shown that coating the carbon in nickel gives the fabric an appropriate resistivity and superior corrosion resistance compared to other possible coatings. Its resistivity can be tailored by varying several parameters to suit the required application.

AZoM - Metals, Ceramic, polymers and composites : Carbon Fibre Based Heating Elements, nickel coated carbon fibres

Figure 1. A SEM image of showing the nickel coated carbon fibres.

Although the thickness and weight of the material is dependent on the required resistivity, Thermion is nonetheless very thin and flexible, with typical thickness values of between 0.08-1.27mm. Its low thermal mass means it can deliver swift thermal cycle times in both heat up and cool down, and the flexibility of the fabric makes it suitable for relatively complex geometries. Power can be supplied to the material by attaching leads, which use either alternating or direct current, at power levels ranging from a few volts to hundreds of volts, or by inductive methods.
Aircraft Applications

Already in use for wing de-icing on the McDonnell Douglas MD-80 commercial airliner, the Thermion technology is now being tested for aircraft propeller and helicopter rotor blade de-icing applications. Incorporated into Thermion heaters, figure 2, the unique ‘self heating laminate’ technology is highly controllable and able to deliver precise levels of heat almost instantly to airfoil surfaces of wings, propellers and rotor blades.

AZoM - Metals, Ceramic, polymers and composites : Carbon Fibre Based self heating panel

Figure 2. Self heating laminate panel.
Industrial and Consumer Heaters

The industrial and consumer heaters are made from a mass produced laminate of Thermion in a broad variety of thermoplastics such as PEEK, PEI and PU, and thermosets such as epoxy. Secondary lamination in elastomeric materials has also been performed. The lamination process provides chemical and environmental resistance, and glass fibre non-woven mats may be incorporated for extra electrical insulation and for improved mechanical properties. In most cases the temperature capacity of the heater is only restricted by the temperature capacity of the material within which it is laminated.
Advantages over other Heating Elements

The benefits of Thermion compared with other heating elements, such as wire or foil, include even heating, damage tolerance, being lightweight and having low thermal inertia. Figure 3 shows the thermal signatures produced by foil, wire and Thermion heaters respectively. Unlike foil or wire heaters, these heaters do not become inoperative as a result of single small local failures. This is a particularly important property in aerospace applications, in which electrothermal heaters are used for wing, propeller and rotor blade de-icing. The ease of installation either before or after manufacture, FOD (foreign object damage) tolerance, high controllability and ability to deliver precise levels of heat to specific areas means the heaters are ideally suited for use as part or all of an ice protection system. The French Air Force is currently testing the heaters for effective in-flight de-icing of aircraft, and application development projects are also underway with a number of major aerospace companies such as Boeing, GKN (Aerospace Composite Technologies), Hamilton Sundstrand, British Aerospace and Ratier-Figeac.

AZoM - Metals, Ceramic, polymers and composites : Carbon Fibre Based Heating Elements, thermal signatures

Figure 3. Thermal signatures produced by (from left) foil, wire and Thermion heaters (right).
Future Applications

Thermion Systems International's European affiliate, Thermion Systems Europe, based in Luton, UK, is currently focusing on the design, development and large scale manufacture of industrial and commercial heaters for a number of potential applications in which the heaters are being considered as superior, low cost alternatives to existing technology, including:

· Diverse heating applications in trucks and automobiles

· Heaters to prevent condensation during shut down in heat producing mechanisms, such as electric ovens or motors

· Heating of moulds during manufacturing processes specific heating applications in domestic appliances, laboratory and hospital equipment

· Heating of containers for transport and storage of liquids and semi-solids

· Diverse heating requirements in the processing industries.
Limitations of the Technology

While solving many of the limitations of existing heating elements, the temperature capability of the heaters is restricted by the temperature limitations of the material in which it is encapsulated. Easily processable polymers that can cope with temperatures of up to 200°C are available, but the choice of encapsulant becomes restricted when temperatures above this are required. As part of an ongoing programme of research, work is currently underway, investigating the incorporation of the technology into high temperature materials such as ceramics so that the full temperature range of the heating capability of Thermion may be realised.

Provide below are properties for carbon fibre reinforced vinylester resin.

Properties Carbon/Vinylester Tube
Property			Value
Compressive Strength - Longitudinal	MPa		900-1100
Density	g.cm-3		1.5-1.65
Flexural modulus - Longitudinal	GPa		65-85
Flexural strength - Longitudinal	MPa		800-1000
Tensile modulus - Longitudinal	GPa		136
Tensile strength - Longitudinal	MPa		900-1200
Ultimate Tensile Strain - Longitudinal	%		1.4
Volume fraction of fibres	%		55-60
Properties Carbon/Vinylester Rod
Property			Value
Compressive Strength - Longitudinal	MPa		900-1100
Density	g.cm-3		1.5-1.65
Flexural modulus - Longitudinal	GPa		65-85
Flexural strength - Longitudinal	MPa		800-1000
Tensile modulus - Longitudinal	GPa		136
Tensile strength - Longitudinal	MPa		900-1200
Ultimate Tensile Strain - Longitudinal	%		1.4
Volume fraction of fibres	%		55-60

Mechanical and electrical properties are supplied for a carbon – carbon composite consisting of carbon fibres in a carbon matrix. The composite is made from high performance cloth densified by chemival vapour deposition (CVD) techniques.

Key Properties

Property Value Coefficient of thermal expansion (20-1000°C)-para. x10-6 K-1 1.5 Coefficient of thermal expansion (20-1000°C)-perp. x10-6 K-1 6 Compressive Strength - parallel to plane MPa 120-200 Compressive Strength - perp. to plane MPa 60 - 150 Density g.cm-3 1.3-1.8 Flexural modulus - parallel to plane GPa 10 - 20 Flexural strength - parallel to plane MPa 80 - 200 Shear strength - in-plane MPa 20 - 30 Tensile modulus - parallel to plane GPa 20 - 30 Tensile strength - Longitudinal MPa 40 - 70 Tensile strength - Transverse MPa <10 Thermal Conductivity - parallel to plane W.m-1.K-1 250 - 300 Thermal Conductivity - perp. to plane W.m-1.K-1 50 - 100 Electrical Resistivity µohm.com 3000

In the ongoing battle to reduce greenhouse emissions, Toshiba Corp and Toshiba Ceramics Co, have developed a new lithium silicate based material that can absorb up to 400 times its own volume in carbon dioxide (CO2).

The major development with this material is that its rate of CO2 absorption is faster then has been achieved previously, and absorption can be carried out at room temperature. Furthermore, the materials can be cycled over 500 times without suffering any deterioration in absorption properties.

The development of the lithium silicate materials are a progression from lithium zirconate materials developed by Toshiba in 1998. These materials can also absorb 400 times their volume in CO2, which at the time was an improvement by a factor of ten.

The advantage of the lithium silicate materials over the lithium zirconate materials is that they can absorb CO2 30 times faster at higher temperatures. They are also cheaper and can absorb CO2 at room temperature.

Until today, the lithium silicate materials were only available in cylindrical form which had some performance issues. Toshiba have developed technology to produce lithium silicate in spherical and granular forms which offer performance gains.

One of the target applications for this material is in thermal power plants, where they will help to reduce CO2 emissions. The captured CO2 could then be recycled by beverage companies, where it is used as an ingredient.