镀液成分对化学镀镍-磷镀层热膨胀系数的影响

Influence of Bath Composition on Thermal Expansion Coefficient of Electroless Nickel-Phosphorus Coating

为了研究酸性化学镀液中主盐硫酸镍、还原剂次亚磷酸钠浓度及pH值对化学镀镍-磷镀层热膨胀系数的影响,在增材制造SiCp/Al合金表面上化学镀镍并进行200℃退火处理,通过XRD物相分析及热机械分析进行研究。研究结果表明,在200℃退火后,硫酸镍质量浓度为25~35 g·L^(-1)区间内,镀层的热膨胀系数随硫酸镍质量浓度的增大而增大,但增加幅度不明显;在次亚磷酸钠质量浓度为20~40 g·L^(-1)区间内,镀层的热膨胀系数随次亚磷酸钠质量浓度的增高而降低;在pH为4.3~4.9时镀层热膨胀系数随着pH的增高而增高。

The paper aims to study the influence of the concentration of the main salt nickel sulfate,the reducing agent sodium hypophosphite and the pH value of the acidic electroless plating bath on the thermal expansion coefficient of the electroless nickel-phosphorus coating.Electroless nickel plating was performed on the surface of the SiCp/Al alloy produced by the additive manufacturing.The processed surface was annealed at 200℃.And then the XRD phase analysis and thermomechanical analysis were made.The results are as follows.After having been annealed at 200℃,when the nickel sulfate concentration is in the range of 25~35 g·L^(-1),the thermal expansion coefficient of the coating increases,but not obviously,with the nickel sulfate concentration.With the sodium hypophosphite concentration in the range of 20~40 g·L^(-1),the thermal expansion coefficient decreases with the increase of sodium hypophosphite concentration.When the pH is from 4.3 to 4.9,the thermal expansion coefficient increases with pH value.