稀土对化学镀Ni-W-P镀液及镀层性能的影响

Influence of rare earth on bath and deposit properties of electroless Ni-W-P plating

研究了4种稀土元素Nd、Pr、Ce、La的硫酸盐及其氧化物对化学镀Ni W P镀液的沉积速度和镀层耐硝酸滴定变色时间的影响。结果表明,4种稀土的硫酸盐均降低了镀液的沉积速度,并使镀层的耐蚀性能下降;Nd、Ce、La的氧化物亦使镀层的耐蚀性下降,而当ρ(Pr2O3)为4mg/L时,镀液的稳定性为未加Pr2O3时的2倍,其沉积速度明显加快,镀层的耐硝酸滴定变色时间超过2000s,硬度明显增大,SEM图表明该镀层呈现致密而均匀的胞状形貌,表面质量优于未加稀土的镀层,X-射线衍射图也表明Pr2O3促进了镀层的非晶态化程度,从而提高其耐蚀性能。

The effect of NdPrCe and La sulphates and oxides on deposition rate of bath and deposits of electroless Ni-W-P plating were studied. The results show that the deposition rate and corrosion resistance are all reduced by adding the rare earth sulphate into bath, and corrosion resistance of deposits was reduced too when Nd_2O_3Ce_2O_3 and La_2O_3 were added. But the stability of solution shows a two times increase by adding Pr_2O_3 (ρ(Pr_2O_3)=4 mg/L)into bath, and nitric acid dropping corrosion time is longer than (2 000) s while the hardness and the deposition rate were improved distinctly. The SEM photos show that the deposit was of dense and uniform cystiform structure, and the appearance quality was better. The x-ray diffractograms further shows that Pr_2O_3 can accelerate the amorphous structure of deposits and so its corrosion resistance is increased.