FABRICATION OF TITANIUM CARBIDE AND DIBORIDE SPECIMENS BY THE METHOD OF SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS FOR PLASMA-ARC GROWTH OF SINGLE CRYSTALS

摘要

Fabrication of long cylindrical specimens of TiB_2 and TiC by burning homogeneous pressings of Ti + 2B and Ti + C mixtures with an additive of final combustion products (up to 30 percent) in quartz shells with the aim of growing single crystals by the method of plasma-arc remelting is considered. Dependences of the ultimate bending strength of rods of TiB_2 and TiC on the percentage of the ballast, the dispersity of the components, and the density of the specimen are presented. Problems of shrinkage of the rods in the process of synthesis, contamination of the internal surface of the shells, repeated use of quartz molds, and withdrawal of SHS rods from the shells and the distribution of impurities over their length are discussed. It is shown that self-cleaning in the process of SHS using the shells reduces the content of some impurities in the rods by a factor of 2 - 3.