等离子喷涂-重熔NiCrBSi涂层的显微组织与耐磨性能

采用等离子喷涂和等离子重熔技术，在2Cr13基体表面制备2mm厚的自熔性NiCrBSi涂层。利用扫描电镜、X射线衍射仪和能谱仪研究涂层形貌、微观组织和微区成分的演变规律，采用拉伸和硬度试验测试涂层的结合强度和显微硬度，通过室温和高温摩擦磨损试验评价和比较涂层与基体的耐磨性能。结果表明，重熔前后涂层都是由γ-Ni固溶体以及Ni₃B，CrB，Cr₂B，Cr₇C₃和Cr₂₃C₆等组成；重熔涂层由层状喷涂态转变为致密的铸造态，涂层组织和力学性能大大提高，结合强度和显微硬度分别高达200MPa和1010HV。重熔涂层的耐磨性显著优于2Cr13基体，其600℃时的磨损体积仅为基体的20%。

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.