Processing Routes for Ceramic Matrix Composites (CMCs)

This article presents a short review of processing routes for ceramic matrix composites (CMCs). Solid phase processes accounts for around 50% of all technologies that are used for fabrication of CMCs and comprise dry or wet sintering processes, usually at high temperatures. Novel sintering techniques have been emerging promising significant improvements, as well as lower processing temperatures, including Microwave (MW) sintering, Flash sintering, Spark plasma sintering (SPS), Flash cold sintering, Cold sintering process (CSP) and Cold sintering (CS). Liquid phase processes comprise traditional methods: sol-gel and reactive melt infiltration (RMI), whereas direct melt oxidation (DIMOX) and liquid silicon infiltration (LSI) are the most common RMI techniques. In gas phase processes, Chemical Vapor Infiltration (CVI) is widely used. Processing of powders, particles, platelets and whiskers is presented, including glass fibers, carbon fibers, graphene and different materials that can be used as matrix/fiber interphase, by either coating the fibers or depositing thin layers on the matrix. Additive manufacturing (AM) in production of CMCs has been reviewed, with short list of available technologies and current developments in CMCs. Advanced ceramics in smart materials are presented, including crack arresting and self-healing behavior, Functionally Graded Materials (FGM) and nanostructured surface coatings. Fabrication of surface composites by Friction Stir Processing (FSP) is shown, as one of the low cost technologies for deposition of CMCs in thin surface layers. Future research directions are elaborated, indicating some issues with processing of CMCs and design of hybrid composites as one of the development directions in CMCs. Design of composites inspired by nature materials indicated some less costly solutions of composite processing and fabrication. Nanotechnology in CMCs development showed significant advancements, especially related to addition of carbon nanotubes (CNTs) and graphene platelets as reinforcements.