6061铝合金表面激光熔覆稀土CeO_2+Ni60组织及耐蚀性

Microstructure and corrosion resistance of laser cladding rare earth CeO_2+Ni60 alloy coatings on 6061 Al alloy

为了提高6061铝合金材料的表面性能,利用激光熔覆技术在6061铝合金表面制备了添加有稀土CeO2的Ni60合金熔覆层。分析了激光熔覆稀土CeO2+Ni60熔覆层的显微组织及硬度,研究了其耐腐蚀性能,并与Ni60合金熔覆层和6061铝合金基体进行了对比研究。结果表明,加入2%的稀土氧化物CeO2可有效地减少熔覆层中的裂纹、孔洞和夹杂物,促进晶粒细化,提高熔覆层的组织均匀性、表面硬度及耐腐蚀性能;电化学腐蚀测试表明,在1 mol/L H2SO4中,Ni60熔覆层、铝合金基体的自腐蚀电流密度分别是CeO2+Ni60熔覆层的1.67倍和76.6倍;在3.5%NaCl溶液中,Ni60熔覆层、铝合金基体的自腐蚀电流密度分别是CeO2+Ni60熔覆层的1.6倍和44.5倍;在1 mol/L NaOH溶液中,Ni60熔覆层、铝合金基体的自腐蚀电流密度分别是CeO2+Ni60熔覆层的1.3倍和81倍。

To improve surface properties of 6061 aluminum alloy,a rare earth CeO2+ Ni60 alloy cladding layer metallurgically bonded to substrate was prepared on the surface of 6061 aluminum alloy by laser cladding. Microstructure and microhardness of the CeO2+ Ni60coatings on the aluminum alloy were investigated,its corrosion resistance was studied and discussed,a comparative study on Ni60 alloy cladding layer and aluminum alloy was made. The results show that the cracks,holes and inclusions in the coatings are reduced by the addition of 2% CeO2,the grain becomes small,the uniformity of the microstructure improves,the hardness and corrosion resistance of the coatings increases. Electrochemical corrosion tests show that,in 1 mol /L H2SO4solution,the self-corrosion current density of Ni60cladding layer and untreated aluminum alloy are 1. 67 times and 76. 6 times as that of CeO2+ Ni60 cladding layer; in 3. 5% NaCl solution,the self-corrosion current density of Ni60 cladding layer and untreated aluminum alloy are 1. 6 times and 44. 5 times as that of CeO2+ Ni60 cladding layer; in 1 mol /L NaOH solution,the self-corrosion current density of Ni60 cladding layer and untreated aluminum alloy are 1. 3 times and 81 times as that of CeO2+ Ni60 cladding layer.