Grinding performance and parameter optimization of laser DED TiC reinforced Ni-based composite coatings

Abstract

Laser directed energy deposition (DED) in situ synthesized ceramic-reinforced composite coatings exhibit great potential for application in the surface strengthening or remanufacturing of critical components. However, the step and sticky powder effects of composite coatings result in poor surface quality. Therefore, it is of great significance to study the grinding machinability of composite coatings and to improve their surface quality. In this study, laser DED TiC reinforced Ni-based composite coatings were synthesized in situ by adding Ti and Ni-coated graphite powder to the Ni-based alloy. Besides their microstructures and properties were analyzed to provide support for grinding machinability analysis. Subsequently, the effects of the grinding speed, feed rate, and cutting depth on the surface quality and grinding force were investigated using variance and signal-to-noise ratio analysis. Finally, Taguchi and grey correlation analyses were applied for the multi-objective optimization of the grinding parameters. The surface roughness (Ra), and tangential and normal grinding forces using the optimized process parameters are decreased by at least 7.18 %, 4.28 %, and 2.35 %, respectively. The ground surface was dominated by continuous plow-like grooves, and no craters or bumps caused by brittle spalling were observed. The bonding strength between the ceramic particles and matrix in the in situ synthesized composite coating was significantly improved. The peeling and extraction of ceramic particles on the ground surface were significantly decreased, resulting in surface roughness as low as 0.543 μm. In summary, laser DED in situ ceramic-reinforced composite coatings exhibit good machinability, providing theoretical and technical support for further practical applications.