Kureha Chemical Industry Company, Limited

Yoshio Ishii

Saburo Hori

Alumina-titania composite powder comprising spherical particles each of which contains about 30 to 80 wt % of .gamma.- phase or .delta.-phase alumina and about 70 to 20 wt % of titania comprising rutile-phase in the majority and is substantially free from X-phase (3Al.sub.2 O.sub.3 -TiO.sub.2) and aluminum titanate-phase. These alumina-titania composite powders are prepared by blowing a vapor mixture of AlCl.sub.3 and TiCl.sub.4 into a burning flame to effect oxidation, which is characterized in that a temperature of a mixing section, where a combustible gas, an oxidizing gas, AlCl.sub.3 gas, TiCl.sub.4 gas and a carrier gas are mixed and subjected to combustion, is kept at about 1450.degree. C. or higher and lower than a melting point of aluminum titanate; a temperature of an outlet portion of a reacting section connected to the mixing section is kept at about 800.degree. C. or higher; and an average total gas retention time in the mixing section and the reacting section are 20 to 500 msec.

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Iwaki, Japan

Yoshio Ishii