PURPOSE: To form a good composite valve seat with uniform adhesion without microcracks by subjecting a base material for the valve seat formed by molding powder and sintering the molding and a working face material to grasping under pressure or rolling pressurizing in dies to a specific density or above and subjecting the same further to resintering.
CONSTITUTION: A powder-molded base material for a valve seat having heat resistance and high crushing strength and a working face material consisting of heat- and wear resistant powder are both subjected to preliminary sintering. Both materials are superposed and are inserted into dies, by which the materials are subjected to uniaxial compression or rolling pressurization permitting strong compression to ≥90% true density. The compressed body obtd. in such a way is resintered in a vacuum furnace kept at ≥1,100°C to form the composite valve seat having uniform quality without microcracks.
TAKEMURA KAZUTOSHI
SHIBANO MOTOAKI
AKAZAWA TOSHINORI
Next Patent: JOINING METHOD OF DIFFERENT KIND OF MATERIAL