DIRECTIONALLY CRYSTALLIZED CERAMIC FIBER-REINFORCED BORIDE COMPOSITES

摘要

Contemporary materials science is directing more and more attention to the creation of composite systems consisting of metallic or polymer matrixes with continuous or discrete fibers or whiskers uniformly distributed in them in order to realize higher physicomechanical characteristics than those of the individual components forming them, for example, a high strength, crack resistance, heat resistance, resistance to abrasive wear, and other properties. Various and often quite contradictory properties can be realized in composite materials consisting of several individual components each of which, first, should possess specific useful characteristics, and, second, should provide specific new properties of the material as a whole due to their interaction.An effective structural method for reinforcing structural heat-resistant materials is the formation of composites with a quite perfect matrix phase and fibers (whiskers) of a second high-modulus reinforcing phase uniformly distributed in it. Simulations have shown that in order to limit the propagation of cracks in such materials the optimum size of fibers in the cross section should be 0.5 - 1.0 #mu#m and their length should be 50-100 #mu#m or more. The uniformity of the distribution and homogeneity of the reinforcing fibers, their volume fraction, the degree of perfection of the structure of the matrix and the fibers, the adhesion on the fiber-matrix interface, and the physical characteristics of the phase components are very important also (1).