ANALYSIS OF OCCURRENCE, PROPERTIES, AND METHODS OF MINIMIZING PRODUCTION DEFECTS IN CERAMIC COMPOSITES WITH AN SiC-MATRIX PREPARED BY LIQUID-PHASE SILICIDING

摘要

The main production defects typical for ceramic-matrix composites (CMC) with an SiC matrix prepared by liquid-phase siliciding are formulated: bulk and surface CMC cementation, nonuniformity of the siliciding process, degradation of carbon and SiC fibers due to molten Si, the presence of microcracks, open and closed pores, and internal cracking and swelling of the final CMC. Reasons for their occurrence are analyzed and it is shown that most of the defects are the result of complex physicochemical and thermophysical phenomena accompanying the basic modifications of this technology. Practical recommendations are formulated for the main production defects to prevent them or minimize their impact on the operational characteristics of the final material. The requirement for special studies to optimize the composition of semi-finished products and regimes for all stages of the production processes with the aim of preparing CMC with minimum defects and the best performance properties is demonstrated