ALUMINUM ALLOY MEMBER HAVING THERMALLY SPRAYED COATING FILM EXCELLENT IN WEAR RESISTANCE AND SEIZURE RESISTANCE

摘要

PURPOSE: To improve the wear resistance and seizure resistance of parts made of Al alloy by forming a film composed of high carbon high chromium steel having specific composition on the surface of machine parts made of Al alloy by the high speed gas flame spraying method. ;CONSTITUTION: Fine powder having 5-55μm grain size of an alloy steel, having a composition consisting of, by weight, 40-65% Cr, 0-15% Ni, 0-1.0% B, 0.5-1.0% C, 2.0-3.0% Si and the balance Fe, and also having ≥8.0 density and ≤1550°C melting temp., is thermally sprayed on the valve face surface of a vehicle engine valve made of lightweight Al alloy, by a high speed gas flame spraying method at ≤3000°C flame temp. at ≥1300m/sec flame speed by using gaseous hydrogen, propylene and commercial propane as combustion gas and also using oxygen as combustion improver gas. By this method, a thermally sprayed coating film, having 0.5-5wt.% oxygen content and 160-700 hardness Hv and excellent in wear resistance and seizure resistance, is formed, and the durability of the engine valve is improved.;COPYRIGHT: (C)1996,JPO