Improving integrally heated composite tooling through cold sprayed copper coatings and heat transfer simulations.

摘要

Integrally heated composite tooling (IHCT) is seen as a low cost alternative to autoclave manufacturing of polymer matrix composites. IHCTs consist of a composite tool heated by surface heaters; temperature distribution is ensured by a thermally conductive metallic sheet. The main original contributions of this thesis was the development of a new method for applying copper coatings onto carbon fibre/epoxy PMCs, the production of larger size samples, and the characterisation of the performance of the coatings and laminates obtained. It was shown that this method shows potential for producing the thermally conductive layer in an IHCT. Another contribution was the characterisation of parameters affecting temperature distribution across IHCTs through heat transfer simulations, leading to guidelines for IHCT design.;Work aimed at fulfilling the following objectives: 1) produce copper coatings on carbon fibre/epoxy composites using Pulsed Gas-Dynamic Spraying, 2) characterise the mechanical and thermal behaviour of the coated composites, 3) manufacture an IHCT with coated composites and comparing it to other types of heated tooling, and 4) identify parameters affecting temperature distribution in IHCT using heat transfer simulations.;Throughout the work, it was showed that Pulsed Gas-Dynamic Spraying could be used effectively for applying copper coatings on composites. This was made possible by co-curing an intermediate layer on the surface of the composite prior to spraying. Coating density was maximised by varying the spray gas pressure and temperature of the coating process.;Mechanical characterisation was performed through Vickers hardness testing, short-span bending, and low frequency cycling. It provided strength values for coated composites and showed that the coating were brittle but harder than bulk copper. Additionally, thermal characterisation showed that coated composites could sustain temperatures up to 250°C.;An IHCT was fabricated using coated composites. Comparison with other heated tooling revealed that the copper coating significantly improved in-plane conductivity and temperature uniformity compared to bare composite tooling. The coating was slightly less conductive than the copper sheet of a conventional IHCT.;Simulation work showed that temperature uniformity across IHCTs can be improved by mitigating convective losses, increasing the copper thickness, and by distributing the heat source over a greater surface.;In the end, the work demonstrated that coated composites can be effectively used as IHCT materials, leading to a composite tooling viable for small production series. The work also provided key parameters for improving temperature distribution in IHCTs, leading to potential improvements for composite parts manufacturing consistency using IHCTs.