COMPOSITE LUBRICANT FOR POWDER METALLURGY, POWDERY MIXTURE FOR POWDER METALLURGY EXCELLENT IN DIMENSIONAL STABILITY AND PRODUCTION OF SINTERED PRODUCT USING THE POWDERY MIXTURE

摘要

PROBLEM TO BE SOLVED: To reduce the dispersion of dimensions in a sintering stage among the batches of powdery mixtures for powder metallurgy and to increase the dimensional stability therein by blending higher fatty acid metallic salt powder with a wax lubricant as a dewaxing promoter. ;SOLUTION: As for a wax lubricant, the one showing viscosity lower than that of higher fatty acid metallic salt in a sintering process to promote dewaxing, and the one in which, in metallic powder, higher fatty acid metallic salt powder is contained as a lubricant, and furthermore, a wax lubricant is contained as a dewaxing promoter for higher fatty acid metallic salt powder are preferable. As for the production of the sintered product, sintering is executed preferably in an atmosphere of a denatured gas essentially consisting of a town gas and/or a natural gas after compacting. It is required that, ordinarily, dewaxing is completed in a low temp. region before the arrival to a dewaxing temp. region of about 600°C. For this purpose, in the case, together with stearic acid metallic salt powder, the wax lubricant of an amt. less than the equivalent to that of the stearic acid metallic salt powder is used, the dewaxing is accelerated by the wax lubricant to suppress the dispersion of the rate of the dimensional change.;COPYRIGHT: (C)1999,JPO