Processing CMCs With Controlled and Variable Matrix Composition
VENKATACHALAM V. 1, BINNER J. 1
1 School of Metallurgy and Materials, University of Birmingham, Birmingham, United Kingdom
Ultra-high temperature ceramic matrix composites (UHTCMCs) based on borides with continuous carbon fibres are an exciting new class of materials that have the potential to be utilised in demanding environments. Based on the different potential applications, the materials can be designed with the required features such as the UHTC composition and content, directionality of the fibre reinforcement, and level of porosity (if required).
For dense composites, a flexible technique based on three-dimensional preforms and a matrix composition that is graded may be best. Most composites have an homogenous matrix and are manufactured by stacking 2D fibre sheets, however, impregnating 2.5D fibre preforms can be designed so that the local composition and/or particle size can be varied. This has been investigated in this study to create high-quality UHTCMCs with a view to determining the potential for manufacturing functionally graded materials. Chemical vapour infiltration, CVI, of carbon has been used to complete the infiltration of the matrix and then the mechanical and thermo-ablative qualities of UHTCMCs formed has been determined.