COATED EXHAUST VALVE SPINDLE OF DIESEL ENGINE USING THE MIXED COATING COMPOSITIONS OF INCONEL-NI-CR SYSTEM AND THE COATING METHOD FOR IMPROVING CORROSION RESISTANCE THEREOF

摘要

The present invention relates to an Inconel-nickel-chrome-based coating mixture for improving corrosion resistance of an exhaust valve spindle for a diesel engine, an exhaust valve spindle coating method using the same, and an exhaust valve spindle where a coating mixture is coated. A compact and homogeneous coating film is formed by HVOF spray coating a coating mixture containing Inconel 625 nickel alloy powder, and nickel-chrome-based cermet powder, and basalt-based mineral powder in the neck and the bottom of a head of the exhaust valve spindle for a diesel engine. Therefore, the high temperature corrosion resistance is equipped. According to the present invention, the exhaust valve spindle coating method comprises: a preprocessing step for removing surface impurities by ultrasonic cleaning the neck and the bottom of a head of the exhaust valve spindle for a diesel engine; a surface treating step for forming a concavo-convex in a surface of a basic material by blasting the neck and the bottom of a head of the spindle, where surface impurities are removed, with Al2O3 powder; and a coating step for forming a coating film by HVOF spray coating the coating mixture in the surface where the concavo-convex is formed. In the coating step, the coating mixture used for coating comprises 40-60 vol.% of Inconel 625 nickel alloy powder, 30-40 vol.% of basalt-based mineral powder, and 10-20 vol.% of nickel-chrome-based cermet powder.