铝合金表面激光熔覆CeO_2+Ni60A熔覆层的组织及耐磨性

利用激光熔覆技术,在6063铝合金表面制备了添加不同CeO2含量的Ni60A合金熔覆层,分析了CeO2+Ni60A熔覆层的显微组织及硬度,筛选了最佳稀土添加量,并研究了其耐磨性能。结果表明:Ni60A熔覆层中稀土CeO2含量低于2%(质量分数)时易出现气孔,高于2%时易开裂;添加CeO2的含量为2%时,熔覆层的组织缺陷较少,表面硬度较高,微观组织均匀且晶粒细小;熔覆层中稀土的含量不宜超过4%,过量的CeO2对硬度的提高作用不大,而CeO2的含量在0%~2%的范围内随着其含量的增加,硬度升高明显;在相同磨粒磨损条件下,2% CeO2+Ni60A熔覆层的耐磨性是铝合金基体的7.1倍,是Ni60A熔覆层的1.6倍;激光熔覆Ni60A可以显著降低表面摩擦系数,而添加Ce能提高熔覆层的摩擦系数稳定性,从而改善耐磨性能。

Microstructure and Wear Resistance of CeO2+Ni60A Composite Coating on Aluminum Alloys by Laser Cladding

Ni60A cladding layers with different contents of rare earth CeO2 were prepared on the surface of 6063 aluminum alloys using a laser cladding technique. Then the microstructure and hardness of CeO2+Ni60A cladding layers were analyzed. The optimal content of rare earth was selected, and the wear resistance of CeO2+Ni60A cladding layers was analyzed. The results show that Ni60A cladding layers with less than 2% CeO2 are prone to pores, but more than 2% are prone to cracks. When 2% CeO2 is added, the cladding layer has better quality and least microstructure deficiencies, and also higher surface hardness. Rare earth content should not be more than 4%, and an excess of CeO2 has little effect on improving the hardness of the cladding layers; when the CeO2 content ranges from 0% to 2%, the hardness increases significantly with the increases of content. In the same abrasive wear conditions, the wear resistance of 2% CeO2 + Ni60A cladding layer is 7.1 times as that of aluminum alloy substrate, and 1.6 times of that of Ni60A cladding layer. The surface friction coefficient can be greatly reduced by laser cladding Ni60A layer, and adding Ce can improve the stability of the cladding layer friction coefficient, thereby improving the wear resistance.