Microstructure and wear-resistance of NiCrBSi coating sprayed-remelted by plasma process

By means of plasma spraying and plasma remelting process, a self fluxed NiCrBSi coating with thickness of 2 mm was fabricated on 2Cr13 stainless steel. The evolutions of morphology, microstructure and micro-area composition of the coating were investigated through scanning electron microscope, X-ray diffraction and energy dispersive spectrometer. Tensile and hardness tests were adopted to measure bonding strength and micro-hardness of the coatings. Tribological experiments were conducted to evaluate the wear resistance of the remelted coating and 2Cr13 substrate at room temperature and elevated temperature (600 ℃). The results show that both of the as-sprayed coating and remelted coating mainly consist of γ-Ni, Ni3B, CrB, Cr2B, Cr7C3 and Cr23C6. After remelted, the coating changed from layer-like as-sprayed state to compacted as-cast state that resulted in improvements in microstructure and mechanical properties of the coating with bonding strength of 200 MPa and microhardness of 1 010 Hv. The wear resistance of remelted coating was better than that of 2Cr13 substrate. At 600 ℃, wear volume lose of the remelted coating was just 20% of that of 2Cr13 substrate.