稀土铈对Ni-P镀层组织和性能的影响

Effect of Rare Earth Ce on Microstructure and Properties of Ni-P Coating

目的研究稀土铈对Ni-P镀层表面组织、沉积速率和耐腐蚀性能的影响,提高沉积速率,改善镀层表面质量,进而提高镀层的耐腐蚀性能。方法采用酸式化学镀方法在50钢基体表面制备了添加稀土铈的Ni-P合金镀层,研究稀土铈的添加量对Ni-P合金镀层表面组织形貌和性能的影响。采用金相显微镜观察镀层表面组织形貌,参照GB/T 13913—2008计算镀层沉积速率;使用HV-1000Z型显微硬度计测定合金镀层的硬度,采用均匀腐蚀全浸试验法测试合金镀层在5%NaCl溶液和10%NaOH溶液中的耐蚀性能。结果稀土铈的添加量为40 mg/L时得到的合金镀层组织细小、均匀、平整、致密,沉积速率达到最大值10.4 mg/(cm^2·h)。随着稀土铈添加量的增加,镀层硬度明显增大,在稀土铈质量浓度为60 mg/L时,最大硬度值达到487.2HV,硬度提高了13.5%。Ni-P合金镀层在5%NaCl和10%NaOH溶液中耐腐蚀实验结果表明,未添加铈的镀层腐蚀速率最大,添加稀土铈的镀层腐蚀速率呈现先降低后增加的趋势,稀土铈质量浓度为40 mg/L时,镀层的腐蚀速率最低。结论稀土铈可以明显改善镀层表面质量,提高镀层沉积速率、硬度和耐腐蚀性能。

The work aims to study the effect of rare earth cerium on the surface microstructure,deposition rate and corrosion resistance of Ni-P coatings and improve the deposition rate to enhance the surface quality and corrosion resistance of coatings.Ni-P alloy coatings with rare earth cerium were prepared on the surface of 50 steel by acid electroless plating.The effect of the amount of rare earth cerium on the surface morphology and properties of Ni-P alloy coatings was studied.The surface morphology of the alloy coating was observed by metallographic microscope,and the deposition rate was calculated.The hardness of the alloy coating was measured by HV-1000Z microhardness tester.The corrosion resistance of the alloy coating in 5wt%NaCl and 10wt%NaOH solution was tested by uniform corrosion full immersion test.When the addition of cerium was 40 mg/L,the coating had fine,uniform,smooth and compact structure and the deposition rate reached the maximum of 10.4 mg/(cm^2·h).With the increase of rare earth cerium content,the hardness of the coating increased obviously.When the concentration of rare earth cerium was 60 mg/L,the maximum hardness reached 487.2HV,increasing by 13.5%.The corrosion resistance of Ni-P alloy coatings in 5wt%NaCl and 10wt%NaOH solutions showed that the corrosion rate of the coatings without cerium was the highest.The corrosion rate of the coatings with rare earth cerium decreased firstly and then increased.When the concentration of rare earth cerium was 40 mg/L,the corrosion rate of the coatings was the lowest.Therefore,rare earth cerium can significantly improve the surface quality of the coating,and enhance the deposition rate,hardness and corrosion resistance of the coating.