摘要
对镁合金进行化学镀,主盐对镀层性能有重要影响。分别以Ni(CH3COO)2.4H2O,NiSO4.6H2O,NiCO3.2Ni(OH)2.4H2O为主盐,在AZ31镁合金表面化学镀。分别采用扫描电镜(SEM)、能谱分析仪(EDS)和X射线衍射仪(XRD)分析镀层表面形貌、成分和物相结构,并用电化学工作站测量镀层在3.5%的NaCl溶液中的动电位极化曲线和电化学交流阻抗谱来评价镀层的耐蚀性。结果表明:以Ni(CH3COO)2.4H2O为主盐的镀液所得镀层表面有微裂纹,而以NiSO4.6H2O和NiCO3.2Ni(OH)2.4H2O为主盐的镀液所得镀层均匀、完整、致密;3种镀液所得镀层均属于高磷镀层;以NiSO4.6H2O和NiCO3.2Ni(OH)2.4H2O为主盐的镀液所得镀层为非晶态,而以Ni(CH3COO)2.4H2O为主盐的镀液所得镀层出现少量纳米晶;以Ni(CH3COO)2.4H2O为主盐的镀液所得镀层的耐蚀性最差,而以NiCO3.2Ni(OH)2.4H2O为主盐的镀液所得镀层的耐蚀性最好。
Electroless Ni-P alloy coatingswere prepared on the surface of AZ31 magnesium alloy from thebaths containing three different types of major salts includingnickel sulfate hexahydrate,nickel carbonate basic tetrahydrateand nickel acetate tetrahydrate.The morphology,phosphoruscontent and phase composition of the coatings were studied bymeans of scanning electron microscopy,energy dispersive spec-trometry and X-ray diffraction.The corrosion resistance of thecoatings was evaluated by measuring both electrokinetic polariza-tion curves and alternating current impedance spectra in aqueoussolution of 3.5% NaCl.Results show that the Ni-P coatings ob-tained from the baths containing three kinds of major salts are allhigh-P coatings with a P content of more than 10 wt%,and havedifferent micro-morphologies.The Ni-P coating prepared from thebath containing Ni(CH3COO)2.4H2O had micro-cracks,andthose prepared from the baths containing NiSO4.6H2O andNiCO3.2Ni(OH)2.4H2O were smooth and compact.The for-mer coating contained a small amount of nano-sized crystals,andthe latter two coatings were amorphous.Besides,the Ni-P coat-ing obtained in the presence of Ni(CH3COO)2.4H2O as themajor salt had the poorest corrosion resistance,while that ob-tained in the presence of NiCO3.2Ni(OH)2.4H2O as the ma-jor salt showed the best corrosion resistance.
出处
《材料保护》
CAS
CSCD
北大核心
2010年第2期29-32,共4页
Materials Protection
