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Abstract: A PRC-3 kW continuous wave CO2 laser was used to clad a MoS2/TiC/Ni coatings on the surface of a 1045 low carbon steel substrate. The microstructure and phase composition of the composite coating were studied. The typical microstructure of the composite coating is composed of multi-sulfide phases including binary element sulfides, ternary element sulfides, Ni, TiC and Mo2C. Wear tests were carried out using a FALEX-6 type pin-on-disc machine. The results showed that the MoS2/Ni coating (as a contrasted sample) exhibited the lowest friction coefficient and the largest weight loss in comparison to other investigated specimens. The friction coefficient of the MoS2/TiC/Ni coating is lower than that of quenched 45 steel and weight loss is only one-sixth of that of 45 steel. The worn surface of MoS2/TiC/Ni laser cladding coating is so clean and smooth (no noticeable groove and scratches visible) that the microstructure of coating is identified after dry wear test of 40 min. [Copyright &y& Elsevier]

The high temperature wear behavior of Ni–W–Co/SiC composite brush plated coatings deposited on a hot work die steel has been investigated using a plate-on-ring test rig. The microstructure and wear characteristics of coating have been analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that typical microstructure of Ni–W–Co/SiC composite coating consists of Ni-based solid solution and SiC particles. The TEM observation of Ni–W–Co/SiC composite coating has revealed the fine SiC particles of nano-size in the brush plated coatings and the matrix of Ni–W–Co plated coating is composed of a mixed crystalline and amorphous structure. The worn surface morphology of the plated coating is observed by SEM and laser profile analysis. In the temperature range 400–600 °C, wear rate and average friction coefficient of the Ni–W–Co/SiC brush plated composite coatings are lower than that of the 3Cr2W8V (ASTM H21) hot work die steel. Abrasive and adhesive wears are the major wear mechanisms of brush plated composite coating at high temperature. [Copyright &y& Elsevier]

Various weight ratios of TiC particulate nickel-based composite coatings were produced on carbon steel substrates by laser cladding. The experimental results showed that the coating was uniform, continuous and free of cracks when a CaF2 flux was used. Excellent bonding between the coating and the medium carbon steel substrate was ensured by the strong metallurgical interface. The microstructures of the coating were mainly composed of γ-Ni dendrites, M23C6, a small amount of CrB, and dispersed TiC particles. The morphologies of TiC particles changed from the globular, cluster to flower-like shape. The volume fraction of TiC particles and the microhardness gradually increased from the bottom to the top of the coating, and the volume fraction of TiC particles increased with increasing of volume fraction of Ti and C. The maximum microhardness of the coatings with 10, 15 and 20 wt.% (Ti+C) in the preplaced alloy powder was approximately HV0.2750, HV0.2850 and HV0.2920, respectively, which was much larger than that of the steel substrate, HV0.2240. [Copyright &y& Elsevier]