JEC COMPOSITES MAGAZINE - Issue #53 - November/December 2009 - 33

FEATURE “Automotive” High temperature User-friendly composites that take the heat For high-temperature composites, finding a good balance between performance, convenience and cost is a recurring challenge. With a new generation of glass-ceramic matrix composites processed like CFRP and designed for temperatures up to 1000ºC, Pyromeral Systems is opening new opportunities for composites in high-temperature applications. CHRISTOPHE BUCHLER VP SALES AND MARKETING PRESIDENT – NORTH AMERICAN OPERATIONS DR. MAGALI ROLLIN DIRECTOR OF R&D glass-ceramic matrix composites are reinforced with continuous silicon carbide fibres, which are chosen depending on the desired level of material performance. These inorganic polymers are generally processed similarly to organic thermoset systems such as epoxy resins. PyroSic materials are processed by hand lay-up of prepregs, although other techniques can also be used (filament winding, braid lay-up or compression moulding). The initial curing temperature in an autoclave is typically less than 180ºC, and the required pressure is usually less than 9 bar. Thanks to these operating conditions, no special tooling materials such as Invar are necessary. Instead, conventional tooling materials such as machinable boards, graphite/epoxy tools or coated aluminium can be used both for prototypes and production parts. A postcure cycle at high temperature is usually needed to stabilize the glass-ceramic matrix. However, this treatment is conducted in air and in freestanding conditions, therefore eliminating the need for ultrahigh-temperature tooling and complex furnaces. Unlike most high-temperature composites (ceramic matrices or glassceramic matrices), there is no need for chemical vapour infiltration, iterative densification or hot isostatic pressing. igh-temperature composites are a major area of research today. Composite materials have been successfully used in many applications where temperature resistance is not an issue (i.e. exposed to temperatures under 300ºC), while helping reduce the weight of components and optimize their design. However, with the need to further reduce the weight of systems used in aerospace, defence, space, automotive or motorsports applications, there has been a growing interest for composite materials capable of replacing metals in areas exposed to heat or fire. Despite advances both in the field of organicmatrix composites and ceramic-matrix composites, practical solutions are still being sought for lightweight materials capable of replacing titanium, steel or Inconel in the 3001000ºC temperature range. The purpose of this article is to present a class of glass-ceramic matrix composites marketed under the name PyroSic®, which specifically target this temperature range. These composites combine heat and fire resistance with good mechanical properties. They are also easy and affordable to use because the resulting parts are designed and processed with the same techniques and tools as conventional carbon-fibre reinforced plastics (CFRP). Examples of applications are also presented. H Properties Selected physical, thermal and thermo-mechanical properties of PyroSic glass-ceramic matrix composites are shown in Table 1 and Figure 1. Table 1: Main physical and thermal properties of PyroSic composites Property Density Coefficient of thermal expansion Thermal conductivity (through thickness) Thermal conductivity (in-plane) Value 1.8 to 2.2 g/cm3 3 x 10-6 /K 0.90 w/m.K 0.95 w/m.K Description and processing PyroSic materials are glass-ceramic matrix composites based on inorganic thermoset polymers. The glass-ceramic matrices specifically feature a glassy phase containing silicon oxide nanoparticles. These matrices are derived from geopolymeric systems and inherently resistant to heat and fire. PyroSic No53 November - December 2009 / jec composites magazine

JEC COMPOSITES MAGAZINE - Issue #53 - November/December 2009

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #53 - November/December 2009