纳米Al_2O_3对电刷镀Ni-P复合镀层耐蚀性能的影响  

Effect of Nano-Al_2O_3 on Corrosion Resistance of Ni-P Composite Coating by Electro-brush Plating

作　　者：周宏明[1,2] 胡雪仪 李荐[1,2] 

机构地区：[1]中南大学材料科学与工程学院,长沙410083 [2]湖南省正源储能材料与器件研究所,长沙410083

出　　处：《表面技术》2017年第7期32-38,共7页Surface Technology

基　　金：清远市科技计划项目(2015D009);清远市清城区科技计划项目(2015B04)~~

摘　　要：目的为延长油墨刮刀的使用寿命,提高刮刀的耐蚀性能。方法采用电刷镀方法在高碳钢基体表面制备了Ni-P镀层和共沉积纳米Al_2O_3的Ni-P/Al_2O_3复合镀层。通过动电位极化曲线、腐蚀失重曲线和交流阻抗谱等方法研究了Ni-P镀层和Ni-P/Al_2O_3复合镀层在3.5%NaCl溶液中的腐蚀行为,采用扫描电子显微镜和能谱仪对两种镀层腐蚀前后的显微组织和成分进行分析。结果纳米Al_2O_3在Ni-P镀层中的共沉积,使镀层的腐蚀电位由-0.318 V正移到-0.237 V,自腐蚀电流密度由6.04μA下降到5.75μA,这是因为纳米Al_2O_3标准电位比Ni更正,在镀层中的均匀分布能使腐蚀电位正移,在腐蚀过程中形成Ni-P合金作为阳极、Al_2O_3粒子作为阴极的腐蚀微电池,促进阳极极化。共沉积纳米Al_2O_3后,Ni-P/Al_2O_3复合镀层的电化学反应电阻Rct值由1.066×104?·cm^2增大至2.864×104?·cm^2,双层电容Cd I值由43.45μF/cm^2下降到27.36μF/cm^2。与Ni-P镀层相比,Ni-P/Al_2O_3复合镀层表面结构更致密,缺陷更少,在腐蚀过程中,P和O元素在Ni-P镀层表面富集形成钝化膜,抑制腐蚀的进行。结论共沉积Al_2O_3纳米颗粒能有效改善Ni-P镀层的耐蚀性能。The work aims to extend service life and improve corrosion resistance of ink scraper. Ni-P coating and Ni-P/Al2O3 composite coating co-depositing nano Al2O3were prepared in electro-brush plating method.Corrosion behavior of Ni-P coating and Ni-P/Al2O3 composite coating in 3.5% NaCl solution by means of potentiodynamic polarization curve, corro-sion weight loss curve and AC impedance spectroscopy. Microstructure and composition of the two coatings before and after corrosion were analyzed with scanning electron microscope （SEM） and energy-dispersive spectroscope （EDS）. Corrosion poten-tial of Ni-P coating, which was codeposited with nano-Al2O3, shifted positively from？0.318 V to？0.237 V, and self-corrosion current density decreased from 6.04μA to 5.75μA since standard potential of namo Al2O3was more positive than that of Ni, uniform distribution in coating led to positive shift of corrosion potential and formed corrosion microbattery with Ni-P alloy as anode and Al2O3 particle as cathode, and thereby promoted anodic polarization. After codeposition of nano Al2O3, the electro-chemical reaction resistanceRct of Ni-P/Al2O3 increased from 1.066×104？·cm2 to 2.864×104？·cm2, double-layer capacitance Cdl decreased from 43.45μF/cm2 to 27.36μF/cm2. Compared with the Ni-P coating, the surface structure of the Ni-P/Al2O3 composite coating was more compact and the defects were less. In the process of corrosion, the phosphorus and oxygen ele-ments were enriched on the surface of Ni-P coating to form a passive film which inhibited the corrosion. Codeposition of Al2O3 nanoparticles can effectively improve corrosion resistance of Ni-P coating.

关 键 词：电刷镀 纳米AL2O3 耐腐蚀性能 显微结构 钝化膜 均匀腐蚀 

分 类 号：TG174.442[金属学及工艺—金属表面处理]