Ube Industires, Ltd.

Seishi Yajima, Deceased

Kiyohito Okamura

Yoshio Hasegawa

Akiko Noda, Heir

Takemi Yamaura

Continuous inorganic fibers consisting substantially of Si, Zr and C and optionally of O, said fibers being composed of (1) an amorphous material consisting substantially of Si, Zr and C and optionally of O, or (2) an aggregate consisting substantially of ultrafine crystalline particles of .beta.-SiC, ZrC, a solid solution of .beta.-SiC and ZrC and ZrC.sub.1-x wherein 0&lt;x&lt;1 and having a particle diameter of not more than 500.ANG., in which amorphous SiO.sub.2 and ZrO.sub.2 sometimes exist in the neighborhood of these ultrafine crystalline particles, or (3) a mixture of said amorphous material (1) and said aggregate (2) of ultrafine crystalline particles. The aforesaid continuous inorganic fibers can be produced by the following steps: a first step of preparing a semi-inorganic block copolymer comprising polycarbosilane blocks having a main chain skeleton composed mainly of carbosilane units of the formula --Si--CH.sub.2 --, each silicon atom of said carbosilane units having bonded thereto a side-chain group selected from the class consisting of hydrogen, lower alkyl and phenyl, and zirconoxane units of the formula --Zr--O--; a second step of preparing a spinning dope of said semi-inorganic block copolymer and spinning the dope; a third step of subjecting the resulting ribers to a treatment of rendering them infusible under tension or under no tension; and a fourth step of firing the infusible fibers at a temperature of 800.degree. to 1800.degree. C. in vacuum or in an atmosphere of an inert gas or a reducing gas.

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Higashihiroshima, Japan

Seishi Yajima, Deceased