中温酸性化学复合镀镍–磷–纳米氧化铝

Acidic electroless plating of nickel–phosphorus–alumina nanocomposite at medium temperature

在中温酸性条件下,研究了镀液中Al2O3纳米颗粒浓度、搅拌速率和pH对铝合金上化学复合镀Ni–P–Al2O3镀速、镀层中Al2O3含量及镀层性能的影响。镀液组成为:n(NiSO4·6H2O)∶n(NaH2PO2·H2O)=0.36∶1,C3H6O310ml/L,CH3COOH10mL/L,促进剂6g/L,稳定剂1g/L。最佳工艺条件为:Al2O3360mg/L搅拌速率500r/min,pH5.0。在最佳工艺条件下,分别对铝片和铝合金片进行施镀,性能测试表明,镀层显微硬度均大于720HV,与Ni–P合金镀层的相对耐磨性均大于4.8,耐硝酸点蚀时间均大于120s,镀层中磷的质量分数分别为4.54%和5.45%,Al2O3质量分数分别为14.0%和14.5%。

The effects of Al2O3 nanoparticles concentration in acidic bath,stirring rate and pH on deposition rate as well as Al2O3 content and properties of Ni–P–Al2O3 composite coating obtained on aluminum alloy substrate at medium temperature were studied. The plating bath is composed of NiSO4·6H2O and NaH2PO2·H2O by the molar ratio of 0.36：1,C3H6O3 10 mL/L,CH3COOH 10 mL/L,accelerator 6 g/L and stabilizer 1 g/L. The optimal parameters are：Al2O3 360 mg/L,stirring rate 500 r/min,and pH 5.0. The properties of the coatings respectively deposited on aluminum and aluminum alloy sheets are as follows：micro-hardness are above 720 HV;relative wear resistance are above 4.8 compared to the Ni–P alloy coating;phosphorus contents in the composite coatings are 4.54% and 5.45% respectively;and the mass fractions of Al2O3 in the composite coating are 14.0% and 14.5%,respectively.