SURFACE TREATMENT OF SINTERED PARTS

摘要

PURPOSE:To improve the corrosion resistance of iron-base sintered parts by subjecting the surfaces of the sintered parts to zacrotizing under specified conditions and coating with fluororesin. CONSTITUTION:Iron-based sintered parts are dipped in a treating liq. prepd. by dispersing a mixture of Zn and/or Al with a sexivalent Cr feeding substance, a reducing agent for the substance and a surfactant in a liq. medium. The volatile components on the sintered parts are burned by heating to 250-400 deg.C to form films consisting of particles of Zn and/or Al enclosed with a tervalent Cr polymer. The surfaces of the sintered parts having the films are further coated with fluororesin at about 300-400 deg.C. The corrosion resistance of the iron-based sintered parts is improved, the service life is considerably prolonged and parts utilizable for various machines such as automobiles and household electrical appliances are obtd.