Electroless Ni-Cu-P Deposition and Effects of Heat-treatment on Microstructure and Hardness of the Deposits
- 化学化工－已发表论文 
从弱碱性化学镀溶液中化学沉积 Ni- Cu- P合金 ,并用差热分析 (DSC)、X-射线衍射 (XRD)和透射电镜 (TEM)研究了晶化处理对镀层结构及硬度的影响 .结果表明 ,镀液中 Cu SO4 · 5H2 O浓度对合金组成有显著影响 .在化学沉积过程中 ,Cu的优先析出使镀层中 Cu/ Ni摩尔比远远高于镀液中Cu2 + / Ni2 + 摩尔比 .镀液中 Cu SO4 · 5H2 O浓度低时 ,沉积速度随其浓度增加而增大 ,但 Cu SO4 ·5H2 O浓度过高又使自催化反应停止 .Ni- 6 .5Cu- 6 .0 P非晶态合金在 30 0～ 4 0 0℃温度范围形成 Ni-Cu固溶体及 Ni5P2 亚稳相 ;在 4 31.5℃时则由 Ni5P2 亚稳相转变成稳定的 Ni3 P相 ,晶化过程中未发现有 Cu- P化合物生成 .镀层硬度随热处理温度发生显著变化是由于硬化相 Ni3 P的沉淀、聚集的结果 .The electroless Ni Cu P alloys have been deposited from weak alkaline bath. The microstructure and hardness of the deposits after annealing were studied by DSC, XRD and TEM. The results show that the concentration of CuSO 4·5H 2O in the bath greatly affects the Cu content of Ni Cu P deposit and thus the Ni and P contents. The Cu/Ni atomic ratio in the deposit is always much larger than that in the solution because copper was preferentially deposited during electroless deposition. In the range of low CuSO 4·5H 2O concentration, the deposition rate increases with increase of CuSO 4·5H 2O concentration in the bath, but an excess CuSO 4·5H 2O will impede the deposition reaction. The results also show that the weak DSC peak in the range of 300~400 ℃ is ascribed to the formation of Ni Cu solid solution and Ni 5P 2 phase from amorphous Ni 6.5Cu 6.0P deposit.The strong DSC peak which occurred at 431.5 ℃ is mainly caused by the transformation of Ni 5P 2 to Ni 3P. The Cu P compounds were not found in the Ni 6.5Cu 6.0P deposit after heat treatment. With heat treatment temperature increasing, the hardness of the Ni 6.5Cu 6.0P deposit increases significantly to a maximum at 400 ℃, above which it decreases drastically. The increase in hardness after heat treatment is mainly due to the precipitation of Ni 3P, but the decrease above 400 ℃ is ascribed to grain coarsening.