PRODUCTION OF SINTERED COMPACT OF CAST IRON TYPE HIGH DENSITY POWDER

PROBLEM TO BE SOLVED: To provide a method of obtaining a sintered compact of a cast iron type high density powder free from pores, by a single process in the air without using a lubricant, by performing heating and pressurizing operations at and under low temp. and low pressure, respectively. SOLUTION: An iron-(iron carbide) type powder, prepared by rapidly solidifying a molten cast iron and practically free from free carbon, is used. A metal mold is filled with the powder, and heating is performed up to 500-700 deg.C and also pressurization is carried out, by which the iron carbide in a nonequilibrium state is decomposed to precipitate carbon at the surface of the powder. On the other hand, the resultant precipitated carbon is allowed to react with compound oxygen in an oxide layer at the surface of the powder to dissipate the oxide layer and to allow sintering among the grains of the packed powder to proceed. Further, by applying annealing to the resultant sintered compact, a high strength sintered compact can be obtained.