Production method of the high sinterring characteristic lanthanum calcium chromite powder which features

摘要

PROBLEM TO BE SOLVED: To obtain the subject powder having stable sinterability and giving sintered material having high density by calcining a raw material for lanthanum calcium chromite and decreasing the content of Cr(VI) below a specific level by extraction. ;SOLUTION: Elements of La, Ca and Cr are compounded at molar ratios satisfying the formula 1.00(La+Ca)/Cr≤1.03. The obtained lanthanum calcium chromite raw material is calcined at ≤900°C to effect the reaction of the elements. Subsequently, Cr(VI) is extracted and removed to decrease the Cr(VI) content to ≤0.30%. The extraction of the Cr(VI) compound is carried out e.g. by slurrying the compound with water and repeating the filtration of the slurry once or twice or spraying water to the calcined powder. The Cr(VI) compound existing in the lanthanum calcium chromite powder produced by controlling the calcination temperature to ≤900°C is mainly easily soluble CaCrO₄ which is easily removable by extraction.;COPYRIGHT: (C)1997,JPO