In the present investigation, electroless Ni-Cu-P/n-TiN composite coating was prepared using alkaline citrate-based bath. X-ray diffraction (XRD), scanning electron microscopy(SEM), energy-dispersive spectroscopy(EDS), electrochemical measurements, weight loss tests and Raman spectrometer were used to character the properties of the coating. As the Cu content increased from 7.3 wt% to 24.8 wt%, the corrosion current density of the Ni-Cu-P/n-TiN coating decreased from 10.80 to 4.34 μA. And the inclusion of Cu in Ni-P alloy resulted in refinement and less porosity in microstructure. The addition of TiN resulted in a slight decline in anti-corrosion property of the coating. As the mass loss test showed, Ni-24.8%Cu-P exhibited perfect corrosion resistance. Studies by Raman spectroscopy on coatings proved that Cu(II)3(PO4)(OH)3, Cu(OH)2and CuO were examined while no compound of nickel was found, and Cu exhibited preferred corrosion in saline solution, providing cathodic protection to Ni alloy.%本文以碱性柠檬酸为镀液,通过化学镀方法,制备了Ni-Cu-P/n-TiN复合镀层.分别采用XRD、SEM和EDS分析镀层的物相组成和组成形貌,采用电化学测试、失重试验、拉曼光谱仪来表征镀层的耐腐蚀性能.实验结果表明:Cu 可细化 Ni-Cu-P/n-TiN 胞状组织并减少其结构中的孔隙率,当Cu含量在7.3 wt%~24.8 wt% 时,复合镀层Ni-Cu-P/n-TiN的自腐蚀电流从10.80 μA下降至 4.34 μA;而TiN的掺杂会使复合镀层Ni-Cu-P/n-TiN的耐腐蚀性能降低.失重试验表明,当Cu含量为24.8wt%时,镀层Ni-Cu-P的耐腐蚀性能较好.通过拉曼曲线分析可知,复合镀层中Cu表现出优先腐蚀机制,形成了Cu(Ⅱ)3(PO4)(OH)3、Cu(OH)2和CuO等Cu金属的腐蚀产物,为镍合金提供了很好的阴极保护作用.
展开▼
