Controlling ceramic-reinforcement distribution in laser cladding of MMCs

Abstract

Laser cladding (LC) using blown powder is an important technique among laser deposition processes, able to perform coating, repair, manufacturing and prototyping. However, deposition of fine ceramic-reinforced MMC clads is challenging due to the divergence of fine particles. This leads to a non-uniform distribution of reinforcements and reduced clad performance. The high laser reflectivity of some metals such as Al also limits material deposition efficiency. In this work, the effect of a powder satelliting process on improving laser-deposited Al–TiC clads on aluminium 6082-T6 substrates was investigated. A simple-blended feedstock was also deposited for comparison. The effect of process parameters of laser energy and powder deposition density on clad characteristics of clad area, dilution and porosity were evaluated, and optimised parameters were identified. Two deposition mechanisms are proposed to explain the differences in the behaviour of both feedstocks within LC. The satellited clads yielded an increase of 29% and 113% in the deposition efficiency and TiC fraction, respectively, compared to the blended clads. The satellited clads yielded a mean increase of 60% in matrix microhardness and a mean reduction of 64% in specific wear rate compared with the blended clads indicating a clear improvement in the mechanical properties.