Ni-Al_2O_3复合镀工艺及镀层性能的研究

Technology for Ni-Al_2O_3 Composite Coating and Its Properties

介绍了NiAl2O3耐磨复合镀的制备工艺,讨论了工艺参数对镀层质量的影响。研究表明,电流密度增大不利于提高镀层中纳米颗粒的含量,pH值增大会使复合含量降低,电镀时适当搅拌或适当改变搅拌方式可以使复合镀层中的纳米颗粒含量提高。Al2O3颗粒的加入能有效阻止镍晶粒的生长,且在颗粒附近复合镀层的硬度比镀纯镍成倍的提高,Al2O3颗粒越细小作用越明显。目的是提高不锈钢表面的耐磨性,制备的复合镀层耐磨性高于镀纯镍。确定了适宜的工艺范围:纳米粉体质量浓度为10～20g/L,电镀时间10～15min,电流密度1.5～2.0A/dm2,pH值为4.0～5.0,机械搅拌速度120r/min,超声波功率200W,电镀温度45℃。

The process for the electroplating of Ni-Al_2O_3 composite coating was briefed, and the effect of technological parameters on the properties of the composite coating was investigated. The results showed that the content of nano-Al_2O_3 content in the composite coatings decreased with increasing current density and pH value of the plating bath as well. Contrary to the above, the content of the nano-Al_2O_3 in the composite coating could be increased in the presence of strengthening stirring and/or changing stirring mode. Moreover, the growth of Ni crystals was significantly retarded by the introduction of Al_2O_3 particulates in the plating bath, and the composite coating had much larger microhardness and wear resistance than electrodeposited nickel coating. Specifically, the Al_2O_3 particulates of a smaller size were more effective in increasing the microhardness of the composite coating, which could be related to the small-size effect of the nanoparticles and their reinforcing action.