| Résumé : |
This paper describes the development of electrically-heated ceramic composite tooling, aimed primarily at the manufacture of large composites structures, for aerospace or for wind energy. The tooling is designed to operate at temperatures up to 300°C, but has the potential to be used at temperatures up to 500°C and above. The ceramic material is an aluminosilicate material, reinforced by continuous fibres and thermoplastic polymer, and laid up with embedded electrical heaters. The ceramic and reinforcing layers are laid up by hand at room temperature, on a standard pattern and cured initially to 60°C, followed by a free-standing post-cure, in stages to approximately 400°C. Special-purpose gel-coats and surface sealing layers are employed to ensure a smooth, vacuum-tight surface. The tooling is lightweight, strong and durable, and has a low coefficient of thermal expansion. Electrical heating power per square metre of tool surface is typically between 5.0 and 15.0 KW/sq.m. Examples are given of the use of the tooling to manufacture 12.6 metre long glass-fibre/epoxy and glass-fibre/PBT wind turbine blades (250KW machine). Aerospace carbon-fibre epoxy prepregs are also processed on the tooling successfully. In all cases, the materials need to be processed between 180°C and slightly above 200°C. The integrally-heated ceramic composite tooling provides a more cost-effective tooling system for processing thermoplastic or thermoset composites at these temperatures than standard metal tooling. |
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Electrically-heated ceramic composite tooling for out-of-autoclave manufacturing of large composite structures in SAMPE JOURNAL, Vol. 47, N° 4 (06-07/2011)
