Microstructure and abrasive wear of cobalt-based laser coatings

Notwithstanding the superior hardness of several types of Stellite laser coatings, their abrasive wear resistance in the rubber wheel abrasive test is not as good. This fact is explained by the lower fracture toughness of the Stellite laser coatings compared to stainless steel, which results in different wear mechanisms. The increase of the fracture toughness with volumetric dilution explains the better wear resistance of the diluted coatings. Moreover, the inverse rule of mixtures applies for the different Stellite laser coatings, when the Co matrix and the metal carbides are considered. In the comparison of the different Stellites it is concluded that the wear resistance is proportional to the hardness and the carbide volume content of the coatings.