Abstract: A sintered titanium boride ceramic body consists essentially of a matrix having a three-dimensional net-work structure and consisting essentially of TiC and at least one MB selected from transition metals in a mixing crystals and solid solutions condition, TiB.sub.2 particles separately placed in the matrix, and a grain boundary formed in the periphery of each of the TiB.sub.2 particles. The grain boundary is in a mixing crystals and solid solutions condition of TiB.sub.2 and M boride. M denotes a metal.
Abstract: Silicon nitride whiskers having a long fiber length in which .beta. type silicon nitride is well developed are produced by reacting a mixture of silica, carbon and cryolite in the specific molar ratio in a mixed gas atmosphere of N.sub.2 and NH.sub.3 by heating the mixture at a temperature of 1,250.degree.-1,450.degree. C. Kira of a ceramic industry waste may be used in place of silica and in this case N.sub.2 alone is used as a nitriding atmosphere.