Inorganic fiber-reinforced ceramic composite material

Claim 1

An inorganic fiber-reinforced ceramic composite material comprising a matrix of a ceramic and inorganic fibers as a reinforcing material, characterized in that (a) the inorganic fibers are inorganic fibers containing silicon, either titanium or zirconium, carbon and oxygen and being composed of (i) an amorphous material consisting substantially of Si, M, C and O, or (ii) an aggregate consisting substantially of ultrafine crystalline particles with a particle diameter of not more than 500 Å of β-SiC, MC, a solid solution of β-SiC and MC and MC 1-x , and amorphous SiO 2 and MO 2 , provided that in the above formulae, M represents titanium or zirconium, and x is a number represented by 0<x<1, or (iii) a mixture of the amorphous material (i) and the aggregate (ii), (b) the ceramic is at least one material selected from the group consisting of carbides, nitrides, oxides, glass ceramics, graphite and inorganic materials containing silicon, either titanium or zirconium, carbon and oxygen and composed of (i) an amorphous material consisting substantially of Si, M, C and O, or (ii) an aggregate consisting substantially of ultrafine crystalline particles with a particle diameter of not more than 500 Å of β-SiC, MC, a solid solution of β-SiC and MC and MC 1-x , and amorphous SiO 2 and MO 2 , provided that in the above formulae, M represents titanium or zirconium, and x is a number represented by 0<x<1, or (iii) a mixture of the amorphous material (i) and the aggregate (ii), (c) the inorganic fibers have an initial reaction degradation speed of not more than 0.35 kg/mm 2 .sec -1 and a tenacity reduction ratio of not more than 40% during the production of the composite material, (d) the composite material has a critical stress intensity factor about 2 to 7 times as high as that of said matrix alone, and (e) the composite material has a bending strength reduction ratio, measured by a thermal shock fracture resistance measuring method, of not more than about 10% after it is heat-treated in air at 800° to 1300° C. immediately then dipped in water at room temperature, and then dried.