化学复合镀Ni-P-SiO_2机制的研究

Study on the Mechanism of Electroless Composite Plating of Ni-P-SiO_2

采用开路电位-时间曲线、阴极极化曲线、不同测试电位下的交流阻抗图谱等电化学测试手段,对化学复合镀Ni-P-SiO_2的机制进行了研究。结果表明:基体在化学复合镀Ni-P-SiO_2溶液中具有最佳的反应时间,不考虑温度时最佳的反应时间为4 000s。向镀液中加入SiO_2微粒可以增加膜电阻,对Ni-P合金的沉积具有阻化作用。通过研究次磷酸钠的阳极氧化行为发现,交流阻抗曲线由高频的电感弧和低频的电容弧组成。加入Ni 2+可使电化学反应电阻明显降低,使得次磷酸钠的氧化反应更容易进行。

The mechanism of electroless composite plating of Ni-P-SiO2 was studied by means of electrochemical methods,such as open circuit potential-time curve,cathodic polarization curve and AC impedance curves under different test potential.The results showed that the substrate has the best reaction time in Ni-P-SiO2 electroless composite plating bath,and the best reaction time was 4 000 sif the influence of temperature was not considered.The addition of SiO2 to the plating bath can increase the film resistance,and it has the effect of inhibiting the deposition of Ni-P alloy.Through the study of anodic oxidation behavior of sodium hypophosphite,it was found that the AC impedance curve consist of an inductance arc in the high frequency range and a capacitive arc in the low frequency range.Ni2+ can obviously decrease the electrochemical reaction resistance,which promote the oxidation reaction of sodium hypophosphite.