化学复合镀镍封/微孔铬工艺试验

Tests of Composite Electroless Plating Nickel-Seal/Microporous Chromium Technology

为提高装饰铬耐蚀性能,试验了化学复合镀镍封工艺和循环超声分散装置,比较了Cu/Ni/（Ni-P）-SiO2/Cr与Cu/Ni/Ni/Cr两种装饰铬的微观形貌和耐蚀性。用紫外/可见分光光度计和钯盐法测试镍封镀液吸光度和稳定性,扫描电子显微镜测试镀层形貌,粒径分布仪、电化学工作站和盐雾试验评价镀层耐蚀性。结果表明：循环超声分散装置对镍封镀液的间歇分散效果明显,镀覆7h后镀液吸光度基本不变。镍封镀液中SiO2微粒粒径约100nm,工艺温度68-71℃,钯盐试验稳定时间18-25min。SiO2微粒占镍封镀层质量分数为2.4%,镍封镀层的硬度为620 HV0.2,厚度为0.4-0.7μm。得到的微孔铬结晶细致,微孔密度为5万-8万个/cm^2。比普通装饰铬的镍层厚度减少30%后,微孔铬组合镀层腐蚀电位仍正移0.19V,盐雾试验耐蚀等级还高1级。说明化学复合镀镍封工艺可以提高装饰铬的耐蚀性能。

To improve the corrosion resistant performance of the decorative chromium,the composite electroless plating nickel-seal technology and dispersion device of cycle ultrasonic were studied.The microstructures and corrosion resistance of Cu/Ni/（Ni-P）-SiO2/Cr and Cu/Ni/Ni/Cr platings were designed as contrast tests.The absorbance and stability of nickel-sealing baths was tested by UV/visible spectrophotometer and palladium salt.The morphology and corrosion resistance of the coating was evaluated by scanning electron microscope,particle size distribution-meter,electrochemical workstation and salt spray tests.The results show that the dispersion device of cycle ultrasonic is effective on intermittent disperse nickel-seal baths and the absorbance of the baths maintains stable after 7hours plating.SiO2 particle sizes are about 100 nm in nickel-sealing baths,the temperature of the baths is 68-71℃and the stabilized time of PdCl2 testing is 18-25 min.The hardness of the plating reaches 620HV0.2and the thickness is 0.4-0.7μm while the mass of SiO2 particles is2.4%that of the nickel-sealing plating.The crystal of the obtained microporous chromium is more meticulous than ordinary decorated chromium and its microporous density is 50 000-80 000cm^-2.The corrosion potential of the microporous chromium is positively shifted 0.19 Vand the corrosion resistance grade of salt spray test is improved by grade 1than ordinary decorated chromium while the nickel thickness of the microporous chromium is reduced by 30%.The composite electroless plating nickel-seal technology can improve the corrosion resistance of decorative chromium.