乳酸-丙酸体系化学镀低磷镍-磷合金镀层的研究

以沉积速率、镀层中磷的质量分数、孔隙率和硬度为评价指标,研究了乳酸、丙酸单独作配位剂及两者复配时镀层及镀液的性能。基础镀液配方及工艺条件为:NiSO_4·6H_2O 28g/L,NaH_2PO_2·H_2O 23g/L,CH_3COONa·3H_2O 20g/L,十二烷基硫酸钠8mg/L,硫脲2mg/L,pH值5.0±0.2,温度(80±2)℃,时间1h。结果表明:单独使用乳酸或丙酸作配位剂时,无法获得性能良好的化学镀低磷镍-磷合金镀层;只有将两者复配使用,才能获得理想的化学镀低磷镍-磷合金镀层。最佳的复配方案为乳酸18mL/L+丙酸10mL/L。此时,镀层中磷的质量分数为3.81%,沉积速率为16.31μm/h,孔隙率为0.70个/cm2,硬度为2 946MPa。

Study on Electroless Low-Phosphorus Nickel-Phosphorus Alloy Coatings in Lactic Acid-Propionic Acid System

With the deposition rate,mass fraction of phosphorus in the coating,porosity and hardness as evaluation indicators,the properties of the coatings and plating bath were investigated when lactic acid and propionic acid were used as complexing agent separately and in combination.The formulation of basic bath and process conditions were as follows:NiSO4·6H2O 28g/L,NaH2PO2·H2O 23g/L,CH3COONa·3H2O 20g/L,sodium dodecyl sulfate 8mg/L,sulfur urea 2mg/L,pH value 5.0±0.2,temperature(80±2)℃,plating time 1h.The results showed that low-phosphorus nickel-phosphorus alloy coatings with good properties can not be obtained when lactic acid and propionic acid were used as complexing agent separately,and the ideal low-phosphorus nickel-phosphorus alloy coating can be obtained only when the two complexing agent were used in combination.The best compounding scheme was lactic acid 18mL/L+propionic acid 10mL/L.In this case,mass fraction of phosphorus in the coating was3.81%,deposition rate was 16.31μm/h,porosity was 0.70 pore per cm2,and hardness was2 946 MPa.