Studies on Oxidation and Wear Resistance of Hard Surfacing Produced by Gas Thermal Spray of Modified Nickel Base Eutectic Alloy Powder

A commercially available Ni base eutectic alloy powder (EWACI005EC) was modified by mechanical mixing of 2wt.% Al powder with it. Hard surfacing of mild steel substrate was carried out by gas thermal spraying of both the original & modified powders. Oxidation resistance of the hard surfacing produced by using both the original & modified powders was studied under constant heating at temperatures of 800, 850 and 900°C for 8 hours and also under cyclic heating up to 15 cycles where, each cycle was designed as heating for a period of 2 hours at temperature of 800°C followed by cooling down to temperature of 300°C. The characteristics of microstructure and hardness of base metal and both the coatings of original and modified powders were studied. Wear resistance of the hard coatings of both the powders were studied at ambient temperature using “PIN on DISC” wear testing method at nominal loads of 2.5 and 3.5 kg. It was found that at all the test loads, the coating of the original powder is having comparatively better wear resistance than that of the coating of the modified powder Under the cyclic heating original powder coating was marked to be comparatively better oxidation resistant than the modified powder coating. But, at a given temperature the hard coating of the modified powder was found comparatively better oxidation resistant than the same produced by spraying the original powder.