激光功率对Cr7C3-Fe2C/MS2镍基多元涂层组织与性能的影响

Effect of laser power on microstructure and properties of CrC-FeC/MS Ni-based composite coatings

为提高304不锈钢表面的摩擦学性能,采用激光熔覆技术,选取不同激光功率,在304不锈钢表面原位衍生了Cr7C3-Fe2C/MS2镍基高温耐磨自润滑复合涂层,利用X射线衍射仪(XRD)、扫描电镜(SEM)和显微硬度计等分析测试了复合涂层的物相组成、显微组织和显微硬度,使用HT-1000型高温摩擦磨损试验机测试了涂层在600℃高温下的摩擦磨损性能。结果表明:激光功率对涂层物相组成影响不大,涂层物相组成为Cr0.19Fe0.7Ni0.11固溶体、Cr7C3/Fe2C、Ti2SC/CrS和少量WS2相;激光功率为1.8 kW时,涂层组织晶粒细小均匀,涂层平均显微硬度302.0 HV0.5,比不锈钢基体提高了约17.4%,涂层平均摩擦系数为0.35,磨损性能相比基体提高了约1倍;随着激光功率的提高,导致稀释率增加,涂层组织缺陷明显,涂层硬度低于基体。在高温600℃环境下,功率1.8 kW时制备的涂层磨损机理主要为润滑转移膜的形成与剥离、黏着磨损、氧化磨损,表现出优异的高温耐磨自润滑性能。

Cr7C3-Fe2C/MS2 nickel-based high-temperature wear-resistant self-lubricating composite coatings were prepared on the surface of the 304 stainless steel by laser cladding technology with different laser powers to improve its tribological properties. The phase composition, microstructure and microhardness of the composite coatings were studied by means of X-ray diffractometer(XRD), scanning electron microscopy(SEM) and microhardness meter, and the friction and wear properties of the coatings at 600 ℃ were tested by HT-1000 high temperature friction and wear tester. The results show that the laser power has little effect on the phase composition of the coatings, and the coatings are composed of Cr0.19Fe0.7Ni0.11 solid solution, Cr7C3/Fe2C carbides, Ti2SC/CrS sulfide and a small amount of WS2 phase. When the laser power is 1.8 kW, the microstructure of the coating is fine and uniform, the average microhardness is 302.0 HV0.5, about 17.4% higher than that of the stainless steel substrate, the average friction coefficient is 0.35, and the wear performance is about 1 times higher than that of the substrate. With the increase of laser power, the dilution rate increases, the microstructure defects of the coating are obvious, and the hardness of the coating is lower than that of the substrate. At 600 ℃, the wear mechanism of the coating prepared under laser power of 1.8 kW is mainly the formation and peeling of lubricating transfer film, adhesive wear and oxidation wear, and the coating shows excellent high temperature wear resistance and self-lubricating performance.