Influence of laser metal deposition direction in the abrasive and adhesive wear resistance of Ni-Cr-B-Si coatings

Abstract

Problems related to component wear are one of the biggest challenges faced by industrial sectors such as agriculture, mining, and oil and gas. Coating application has been a good alternative to mitigate these problems. Ni-Cr-B-Si alloys are recognized for their abrasion and adhesion resistance properties. In this context, a comparison between the mechanical wear of Ni-Cr-B-Si 1545-00 deposited via laser metal deposition is performed in two setups. The goal was to study the effect of the cladding direction in the coating wear resistance. The coated samples were prepared according to the dimensions required by ASTM G65, a dry sand/rubber wheel test standard. Using procedure A of ASTM G65, pauses were done every 5 min for volumetric loss measurement. In parallel, the coating cross section was metallographically prepared and evaluated via optical microscopy and scanning electron microscopy (SEM)-x-ray dispersive energy spectroscopy (EDX). Vickers microhardness profile was also measured, and its value reached 580 HV1. Worn surfaces were evaluated via SEM-EDX; however, this time the microscopy technique was used to characterize wear mechanisms. In the microhardness profile analysis, the average was much lower in the diluted region and the heat-affected zone. As to the tribological test results, volumetric loss increased in proportion to the test time. In the first setup, coating presented an average volumetric loss of 37% higher than the second setup. This result can be attributed to the dry sand/rubber wheel test direction. This work's outcome indicates that a coated component's lifetime may be improved when attention is given to coating orientation and component preferential mechanical wear direction.