Addressing processing limitations in SiC-based ceramic composites: A review of hybrid approaches and perspectives

This review presents an up-to-date overview of hybrid processing techniques for silicon carbide (SiC) matrix composites. These materials are widely used in systems where high temperatures, mechanical stress, and oxidation are serious concerns, such as in aerospace and energy applications. Although there are well-established fabrication methods for SiC composites, such as chemical vapor infiltration (CVI), polymer infiltration and pyrolysis (PIP), and reactive melt infiltration (RMI), each has its limitations. For example, while PIP is relatively simple, it often results in residual porosity. Additionally, CVI can yield high-quality microstructures, but it is a slow process and may still leave behind microporosity. Furthermore, RMI can deliver high densities, but may also cause fiber damage or leave behind residual silicon. Given the individual limitations of CVI, PIP, and RMI, hybrid approaches may be deployed to gain the benefits of multiple techniques. Most commonly, CVI and PIP are combined for hybrid processing, but other combinations of CVI, PIP, and RMI are possible. This review discusses how these combined processes are applied to various SiC-matrix composites, including carbon fibers in SiC matrix (Cf/SiC), carbon fibers in a matrix of C and SiC (Cf/C-SiC), and SiC fibers in SiC matrix (SiCf/SiC). The main contribution of this review is summarizing how hybrid techniques influence porosity, microstructure, fiber-matrix bonding, and the overall thermal-mechanical properties. Many recent studies are also included in the topics of improved fiber architectures, polymer chemistries, and infiltration steps. While hybrid methods often lead to improved properties, there are still open questions, especially regarding internal oxygen from PIP, long processing times for CVI, and phase stability after many cycles at high temperatures. This review concludes with potential future directions for research efforts to make hybrid SiC-matrix processes more effective, scalable, and reliable.