Processing and performance of continuous fiber ceramic composites by preceramic polymer pyrolysis:II-resin transfer molding

摘要

Vacuum Assisted Resin Transfer Molding(VARTM)was used in conjunction with preceramic polymer pyrolysis to manufacture Continuous Fiber Ceramic Composites (CFCCs).Two VARTM techniques were used:(a)the use of injection presure in the presence of a vacuum and (b)the use of vacuum only without be injection pressure.After initial testing,eight CFCC tubes were fabricated using these techniuqes.The matrix material used was Blackglas~(TM) in the form of woven fabric and BN-Nextel 312in the form of braided textile were used as reinforcements.C-Nicalon~(TM) CFCC tubes with 4%-6% porosity,55%-57% fiber folumbe fraction,and 2.12-2.18g/cm~3 density reached convergence by weight in 10 cycles(with about 17 hours per cycle),while BN-Nexlet 312CFCC tubes with 4%-6% porosity,70%-72% fiber volume fraction,and 2.42-2.48g/cm~3 density converged by weight in 8 cycles.The VARTM processing time averaged 15 minutes for each tube.The mechanical performance of the components was evaluated at room and high temperatures using a C-ring test.Scanning Electron Nicroscopy(SEM)was employed to study the microstructure of the parts.The results show that the without injection pressure technique offers a promising method to produce tubular CFCCs in terms of lower manufacturing costs,part uniformity,and enhanced mechanical properties.BN-coating performs better at high temperature compared with C-coating.Also,a combination of BN-coating and a textile braided architecture of fiber preform proved to enhance the performance of the manufactured CFCCs.Finally,the mechanical performances of the manufactured CFCC tubes using VARTM technique were comparedwith those using a cure-on-the-fly filament winding technique for a similar geometry using the same materials.