沿海水闸活塞杆表面激光熔覆Ni基涂层组织及其抗磨耐蚀性能

Microstructure and Wear/Corrosion Resistance of Laser Cladding Ni-Based Coating on Hydraulic Piston Rod for Coastal Sluice

开发环保且涂层性能优良的电镀铬替代技术是表面技术领域的研究难点,为提高沿海水闸活塞杆的抗磨耐蚀性,通过同轴激光熔覆技术在材质为45钢活塞杆表面制备NiCrBSi涂层。采用X射线衍射仪、能谱仪、扫描电子显微镜等手段表征了涂层的物相成分、元素分布和微观形貌。采用维氏硬度计和干滑动摩擦磨损试验机测试了涂层的显微硬度和摩擦磨损性能,并分析了其磨损机理。此外,在模拟海水中通过电化学测试对比研究了激光熔覆NiCrBSi涂层、热喷涂NiCr-Cr3C2涂层、电镀硬铬、04Cr13Ni5Mo不锈钢及45钢基材的耐蚀性能。结果表明:激光熔覆NiCrBSi涂层主要物相成分为γ-Ni树枝晶、共晶组织及CrB、M23C6等硼化物和碳化物;涂层组织致密均匀,与基材形成良好的冶金结合;涂层硬度及耐磨性随激光功率提高而降低,当功率为3.2 kW时,熔覆层平均硬度达620 HV2 N,平均摩擦系数为0.581,其磨损机理为黏着磨损;涂层耐蚀性随激光功率升高而提高,4.0 kW功率下涂层的自腐蚀电位和自腐蚀电流与04Cr13Ni5Mo不锈钢的相当,优于电镀硬铬的和NiCr-Cr3C2涂层的。

NiCrBSi coatings were prepared on piston rods made of 45 carbon steel by coaxial powder feeding laser cladding.The phase compositions,elements distribution and microstucture were characterized by X-ray diffractometer,energy dispersive spectrometer and scanning electron microscope.In addition,the microhardness and friction wear property were tested by Vickers hardness tester and dry sliding friction wear tester,and the wear mechanism was analyzed.Furthermore,the corrosion resistance of NiCrBSi coatings by laser cladding,NiCr-Cr3C2 coating by HVAF,hard-chromium coating by electroplating,04Cr13Ni5Mo steel and 45 steel was studied by electrochemical tests in the simulated ocean water.Results showed that laser cladding NiCrBSi coating was mainly composed of γ-Ni dendrite,eutectic,carbide and boride such as CrB,M23C6 and others.The coating microstructure was compact,uniform and metallurgically boned with the substrate.The hardness and wear resistance decreased with the rise of laser power.When laser power was 3.2 kW,the average hardness was as high as 620 HV2 N,and the average friction coefficient was as low as 0.581,as well as the main friction wear mechanism was adhesive wear.The corrosion resistance of the NiCrBSi coatings increased with the rise of laser power,and the corrosion potential and corrosion current densities of the coatings at 4.0 kW were similar to those of 04Cr13Ni5Mo steel,and superior to those of electroplating hard chromium and NiCr-Cr3C2 coating.