Pre-placed laser cladding of metal matrix diamond composite on mild steel

Finding an alternative way to fabricate higher performance and more cost effective diamond tools can revolutionize tooling industry. Laser cladding due to its unique features such as low interaction time and high cooling rate can be a better alternative. In this paper the deposition of metal matrix diamond composite on mild steel substrate is investigated. Pre-mixed powders of copper, tin, titanium, and diamond with the weight ratio of 54%, 13.5%, 7.5%, and 25%, respectively, were deposited on mild steel substrates by the use of pre-placed laser cladding using a continuous wave and a pulsed laser. The effect of scanning speed and laser power on the clad–substrate bonding, porosity and micro-cracks in the deposit, diamond graphitization, chemical bondings between diamond particles and the matrix, and distribution of diamond particles are discussed. Development of an interfacial layer between diamond particles and the matrix was detected. The layer was characterized as titanium carbide by the use of EDS analysis and nanoindentation. The effects of scanning speed and laser power on the thickness of the titanium carbide layer are discussed. Results of deposition by a continuous wave laser are compared with those of a pulsed laser and it is concluded that with the same laser power and scanning speed, the deposit by the pulsed laser had a slightly lower diamond graphitization and thinner TiC layers.