紫铜上激光熔覆镍基自熔合金组织和性能研究

Microstructure and Properties of Laser Cladding NiCrBSi-WC Coating on Copper Substrate

采用万瓦横流CO2激光器在紫铜表面熔覆镍基自熔合金熔敷层,并采用SEM、XRD、OM和显微维氏硬度计进行组织结构和硬度分析。结果表明:在紫铜表面完全可采用激光熔覆的方法制备镍基自熔合金的熔覆层,熔覆层与铜基体形成冶金结合,组织致密、晶粒细小、无裂纹、孔隙夹杂等缺陷,熔敷层内具有等轴晶、树枝晶及胞状晶等不同结构,并有WC、W2C、Ni3B等强化相颗粒。同时,与采用超音速火焰喷涂(HVAF)涂层进行对比,结果表明激光熔覆层硬度虽然低于喷涂涂层,但磨擦系数小,耐磨损性能有明显的提高。

The NiCrBSi coating was carried out on copper surface by ten-thousand-watt laser cladding process. After that the microstructure and properties were studied by means of SEM, XRD, optical microscope, and micro-hardness meter. The results showed that it was possible in industry to get laser cladding layer on copper substrate, and the laser cladding layer had advanced properties such as denser structure, smaller grain, crack-free, porosity-free, and slag inclusion free, etc, because of the fully alloying function. The laser cladding layer, which consisted of isometric grain, dendritic structure and parasporal crystal, including enforced particles such as WC, W2C, and Ni3B, etc, was metallurgically bonded each other and with the copper alloy substrate. The laser cladding presented remarkably wear-resistance character compared to the cupper substrate or HVAF sprayed coating although the micro-hardness decreased a little bit, but the frication coefficient decreased. The wear mechanism of the layers was typical grain-abrasion.