STUDIES ON HARD SURFACING OF STRUCTURAL STEEL BY GAS THERMAL SPRAYING PROCESS

Abstract

In this work hard surfacing of structural steel was carried out by dry thermal spraying process using Co- alloy powder and any acetylene gas regulated to give a neutral flame. During the hard surfacing preheating of the base plate was varied at 300°C and 350°C. After hard-surfacing some of the samples were given a post spray heat treatment of temperature 650, 750 and 850°C and rest of the samples were not given any post spray heating. The geometry of hard-surface coating produced under different preheating were studied. The effect of no post spray heat treatment and post spray heat treatment at. different temperature on the hardness of the Co-alloy particles and the matrix of the coating obtained under different preheating were thoroughly investigated. The wear resistance of the coating was determined ary correlated with the post spray heat treatment of the coating obtained with the preheating temperatures 300°C and 350°C. The increase of preheat temperature, reduced the coating thickness at its center but spread on the substrate. The increased in post spray heating temperature enhanced the hardness of the coating. - The wear resistance of the coating surface reduced with the increase in post spray heating temperature but increased with the increase of preheating