Abstract

Thermal sprayed chromium carbide (Cr3C2)-25% NiCr (Ni-20%Cr) coatings are extensively used in wear resistant applications especially under conditions wherein operating temperatures are likely to be higher than 500°C . The performance of the Cr3C2-NiCr coatings under such conditions depend on a variety of coating properties like the porosity, microstructure, extent of decarburization of Cr3C2 phase and hardness. One of the parameters which affects the above mentioned coating properties is the characteristics of the powder utilized for thermal spraying. In the present study, Cr3C2-25% NiCr powders obtained from four different sources has been utilized to form Cr3C2-NiCr coatings on steel substrates utilizing the detonation spray coating (DSC) system. The Cr3C2-NiCr powders utilized vary from each other in terms of manufacturing route employed (sintered and crushed, pre-alloyed, blended, etc.), particle size distribution, particle shape and even phases present. The influence of each of these powder characteristics on the coating microstructure, porosity, hardness, extent of carbide dissolution and ultimately on coating performance (i.e. sliding and abrasive wear resistance) has been evaluated.

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