纳米WC-Co激光熔覆层的磨损析出相及其析出部位

Friction-Induced Phase Precipitation of Laser Cladding Nanoscale Tungsten Carbide Reinforced Nickel-Based Composite Coating on Mild Steel and the Precipitation Location

为了探讨45钢上纳米WC/Ni60B激光熔覆层在磨损过程中出现的相变及析出位置,采用MM-200磨损试验机,将纳米碳化钨增强的Ni基激光熔覆层与硬质合金磨轮进行对磨,采用MX2600FE场发射扫描电镜对熔覆层表/截面组织、磨损后的表/截面组织以及磨屑进行观察分析。结果表明:熔覆层磨损表面和距离磨损区表面约10μm的亚表层析出纳米级颗粒,磨屑中也有类似的析出颗粒,析出颗粒的形貌为白色球状,粒径尺寸为数十至数百纳米。

Nanoscale WC reinforced Ni-based composite coating(denoted as WC/Ni60B)was prepared on 45 steel substrate by laser cladding.As-prepared WC/Ni60B laser cladding coating was then coupled with hardalloy abrasive wheel to assemble a frictional pair that was tested with an MM-200 friction and wear tester.The microstructures of the original surface and cross-section and worn surface and cross-section of the composite coating as well as the morphology of the wear debris were observed with an MX2600FE field emissionscanning electron microscope.Furthermore,phase transformation involved during the friction and wear process of WC/Ni60B laser cladding coating as well as the locations at which phase precipitation occurs is analyzed.Results show that nanoscale precipitates are generated on worn surface and subsurface(about 10 μm beneath the worn surface) of the composite coating,and similar precipitate is also observed in the wear debris.Besides,the granular precipitates appear as white spheres with a diameter of tens to hundreds of nanometers.