Effect of tungsten carbide reinforcement phase on the abrasive wear performance of metal matrix composites deposited by laser cladding

The laser cladding process is a technique for depositing abrasion resistant coatings due to the low dilution and microstructural characteristics found in the deposited material. One option to improve abrasion resistance has been the use of carbide reinforcing phases in the coating. Due to the lack of research relating different metallic matrices and different proportions of reinforcing element, this study aims to detail the tribological performance of metal matrix composites using two nickel-based metallic matrices and one iron-based matrix deposited via laser cladding, as well as the high proportion of tungsten carbide (0, 20 and 30 vol%), as a reinforcing element, applied to the ASTM G65 standardized test. Laser processing parameters, hardness and abrasive wear performance were studied by changing the volumetric fraction. The results indicate that the increase in the fraction of WC in the metallic matrix provides a smaller volumetric loss and greater resistance to abrasion, reaching a volumetric loss of up to 95% lower when compared to the composite material with the matrix in its pure state. This resistance is also related to the microhardness and anchoring performance of the hard WC particles in each metallic matrix. However, there is a processability limit when using a high percentage of reinforcement phase, generating chemical and thermal reactions in the metallic matrix, causing structural defects in the deposited composite coating. In addition, the different mechanisms of abrasive wear are influenced by the hardness and the change in the chemical composition of the metallic matrix, which can lead to adhesive and brittle wear, generating greater volumetric losses during the abrasive test.