双层化学镀镍工艺研究

Study on Double Eleetroless Nickel Plating

本文试图用双层化学镀镍的方法,镀取两层电位不同的化学镀镍层来提高化学镀镍磷合金的防蚀性能。第一层采用酸性Ni-P镀液,配方为镍盐30g/L,次磷酸盐10g/L醋酸盐15g/L,pH=5-5.5,T=81°±l℃,t=0.5h,s/v=0.3dm^2/L,镀速18μ/h,镀层含P=6.88％。对饱和甘汞的电位为-212mv。第二层采用碱性Ni-P镀液,配方为镍盐20 g/L,次磷酸钠NaH_2PO_2 18g/L,Na_3C_6H_5O_7·2H_2 O20g/L,pH=8-9.5,T=48-48℃,镀速6μ/h,镀层含P=4.15％,对饱和甘汞的电位为-278mv。两层镀层电位差66mv。从测试结果来看,它的结合力及抗蚀性均不错。

In order to improve the corrosion resistance of electroless Ni-P alloy platings. a double layer electroless Ni-plating process is developed to obtain two layers of electroless nickel coatings with different potentials. For the first layer. an acidic Ni-P bath is adopted. The formula was: nickel salt 30g/L. hypophosphite 10g/L, acetate 15g/L, PH=5-5.5, T=81±1℃.t=0.5 h,s/v=0.3dm_2/L, deposition rate 18μ/h, P content of the coating=6.88%, potential to saturated calomel=-212mV. As to the second layer, the alkaline Ni-P bath is employed, where nickel salt 20g/L, sodium hypophosphite 18g/L, Na_3C_6H_5O_7·2H_2O 20g/L, pH=8-9.5, T=43-48℃, deposition rate 6μ/h, P content of the coating=4.15％, potential to saturated calomel=-278mV, potential difference between the two layers equal to 66mV. It can be seen from the test results that both its adherence and corrosion resistance are acceptable.