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Influence of MoS2 on the Microstructure and Properties of Laser Clad NiCrBSi Coatings
T.G. Zhang, R.L. Sun, Y.W. LEI, W. Niu and Y. Tang

Laser cladding was carried out on H13 steel using NiCrBSi pre-alloyed powders and mixture of NiCrBSi+Ni/MoS2 powders as clad material. The microstructure, hardness and tribological properties of the coatings were investigated and the influences of MoS2 addition on the microstructure and properties of the coatings were discussed. The results show that NiCrBSi coating consisted of γ-Ni solid solution, γ-Ni+Ni3B eutectic, CrB particle and Cr7C3 dendrite, while NiCrBSi+Ni/MoS2 coating is composed of γ-Ni dendrite, g-Ni+NiMo eutectic and CrxSy compound. Due to the dispersion strengthening of uniformly distributed CrB and Cr7C3 hard phases, NiCrBSi coating possesses higher hardness (700 to 870 HV) than that of NiCrBSi+Ni/MoS2 coating (570 to 650 HV). The wear mass loss of NiCrBSi coating is 33% of NiCrBSi+Ni/MoS2 coating. Due to the lubrication of CrxSy particles, the NiCrBSi+Ni/MoS2 coating presents lower friction coefficient (0.15 to 0.25) than that of NiCrBSi coating (0.30 to 0.37).

Keywords: CO2 laser, H13 steel, MoS2, NiCrBSi, laser cladding, powder, coating, microstructure, mechanical properties

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