结晶器铜板表面耐磨纳米复合镀层的制备及性能

目的提高连铸坯质量,延长结晶器的服役时间,节约铜资源。方法采用纳米复合镀技术在结晶器铜板表面制备了Ni/Al_2O_3纳米复合镀层,并通过扫描电镜(SEM)观察了复合镀层表面形貌。采用单因素变量法研究了镀液中纳米Al_2O_3添加量、阴极电流密度及镀液温度等对纳米复合镀层显微硬度的影响。对结晶器铜板表面的纯Ni镀层和纳米复合镀层进行了摩擦磨损实验。结果在结晶器铜板表面制备出了高硬度、耐磨损的纳米复合镀层。随着镀液中纳米颗粒添加量的增加,镀层的硬度先升高后降低,且当纳米颗粒添加量为40 g/L时,复合镀层的显微硬度达到最大值384HV。因镀液中纳米颗粒的存在,随着电流密度和镀液温度的变化,纳米复合镀层的硬度变化不大。在相同的摩擦磨损条件下,纳米复合镀层和纯Ni镀层的摩擦系数分别约为0.41和0.7,纳米复合镀层的磨损量约为纯Ni镀层的1/2。结论在Ni基镀层中加入纳米Al_2O_3材料,能显著地提高复合镀层的硬度、耐磨损性能。

Preparation of Wear Resistant Nano Composite Coating on Surface of Copper Crystallizer

The work aims to improve quality of continuous casting billet, extend service life-span of crystallizer and save copper resource. Ni/Al2O3 nano composite coating was prepared on the surface of copper crystallizer by adopting nano composite electroplating technology, and surface morphology of the composite coating was observed with SEM. The effects of nano Al2O3 addition, cathodic current density and electroplating bath temperature on microhardness of the composite coating were studied in single factor method. The friction and wear tests were carried out on pure Ni coating and nano composite coating. A nano composite coating of high hardness and wear resistance was prepared on the surface of copper crystallizer. Microhardness of the composite coating first increased and then decreased as the addition of nano particles increased. When 40 g/L of nano Al2O3 particles was added, microhardness of the composite coating reached the maximum value of 384HV. As nano particles were present in the electroplating bath, the microhardness changed little with the change of current density and electroplating bath temperature. Provided with the same friction and wear conditions, the friction coefficient of nano composite coating and pure Ni coating was about 0.41 and 0.7, respectively; wear loss of nano composite coating was about 1/2 of that of pure Ni coating. The addition of nano Al2O3 material in Ni-based coating can significantly improve hardness and wear resistance of composite coating.