Ni-氧化石墨烯纳米复合镀层的力学及抗腐蚀性能研究

Mechanical Properties and Corrosion Resistance of Ni-graphene Oxide Nanocomposite Coatings

目的探究镀液中氧化石墨烯(GO)含量对于Ni-GO复合镀层的组织结构、力学性能、耐腐蚀性能的影响,并以此来确定GO的添加量。方法采用电沉积技术制备Ni-GO复合镀层,并采用正交试验的方法找到Ni-GO复合镀层的优化制备工艺。通过SEM、EDS、XRD、XPS、拉曼等技术对GO和制备的Ni-GO复合镀层的形貌、组织结构进行表征分析,采用硬度仪、摩擦磨损试验仪、电化学工作站等对Ni-GO复合镀层的力学性能及耐蚀性进行分析。结果采用正交试验的方法得到了Ni-GO复合镀层优化制备工艺条件,GO质量浓度为1.0 g/L,阴极电流密度为5 A/dm^(2),镀液温度为60℃,电镀时间为50 min。基于优化工艺条件下镀层的硬度为596.5HV,沉积速率为6.583 g/(dm^(2)·h)。其中镀液中氧化石墨烯浓度对Ni-GO复合镀层性能影响最大。结论研究发现,Ni-GO复合镀层底部是Ni含量比较多的菜花头结构,在菜花头上面主要是石墨烯与Ni晶粒镶嵌在一起的尺寸不一的珊瑚状结构。当镀液中GO质量浓度为1.0 g/L时,制备出的Ni-1.0GO复合镀层中石墨烯含量最高,珊瑚状结构连接缝隙变小,组织致密性最好,孔隙缺陷最少。与Ni镀层相比,Ni-1.0GO复合镀层的硬度提高了37.7%,磨损质量损失减少了73.5%,耐蚀速率降低了44.8%。

Graphene oxide(GO)is a derivative of graphene and is the most promising particle to be added to nanocomposites.GO was added to the plating solution as the second phase particle,and then reduced to graphene in the composite coating,so that the material showed good performance in lubrication and mechanical strength.In order to explore the effect of GO content in the plating solution on the microstructure,mechanical properties and corrosion resistance of Ni-GO composite coatings,the GO content was determined.Different concentrations of GO(0.4,0.6,0.8,1.0,1.2 and 1.4 g/L)were added to the nickel-based plating solution.GO was reduced to graphene at the cathode in one step and entered the composite coating by electrodeposition.The effects of GO concentration,pH value,electroplating time and cathodic current density on the deposition rate and microhardness of Ni-graphene composite coating were studied by a four-factor and five-level orthogonal test table,and the optimized process parameters were found.The optimized preparation conditions of Ni-GO composite coating obtained by orthogonal test were:GO concentration of 1.0 g/L,cathode current density of 5 A/dm^(2),bath temperature of 60℃,and plating time of 50 min.The hardness of the coating was 596.5 HV and the deposition rate was 6.583 g/(dm^(2)/h).The concentration of graphene oxide in the plating solution had the greatest influence on the performance of Ni-GO composite coating.On the basis of optimizing the process parameters,by changing the concentration of GO in the plating solution,the content of graphene in the coating was tested by EDS.It was concluded that the content of graphene in the coating was not proportional to the content of GO in the plating solution,showing a trend of first increasing and then decreasing.When the GO content reached 1.0 g/L,the graphene content in the composite coating reached the maximum of 0.258 wt%.The morphology and microstructure of GO and prepared Ni-GO composite coatings were characterized and analyzed by SEM,XRD,XPS and Raman techniques.When the GO concentration was 1.0 g/L,the connection gap of the coral-like structure became smaller.The coating had the best compactness;the grain size of the coating was the smallest.The mechanical properties and corrosion resistance of Ni-GO composite coating were analyzed by a hardness tester,a friction and wear tester and an electrochemical workstation.When the concentration of GO was 1.0 g/L,the hardness of Ni-GO composite coating reached the maximum of 596.5 HV.The friction coefficient of Ni-1.0GO composite coating reached the minimum value of 0.485;compared with Ni coating,the wear loss weight of Ni-1.0GO composite coating was reduced by 73.5%.Compared with the corrosion potential of Ni coating,the self-corrosion potential Ecorr(-0.5259 V)of Ni-1.0 GO composite coating was more positive,and the corrosion current Icorr(3.715×10-6 A/cm^(2))was the smallest,and the passivation zone was more obvious.At the same time,the grain of Ni-1.0 GO composite coating was refined,and the graphene nanosheet was evenly distributed in the Ni matrix.The inherent mechanical properties of graphene improved the mechanical properties of the composite.It could be seen that the composite coating had good corrosion resistance under the condition of GO concentration of 1.0 g/L.The bottom of the Ni-GO composite coating is a cauliflower head structure with more Ni content,and the coral-like structure with different sizes of graphene and Ni grains is mainly on the cauliflower head.When the concentration of GO in the plating solution is 1.0 g/L,the content of graphene in the prepared Ni-1.0GO composite coating is the highest,the connection gap of the coral-like structure becomes smaller,the microstructure is the best,and the pore defects are the least.Compared with Ni coating,the hardness of Ni-1.0GO composite coating is increased by 37.7%,the wear loss weight is decreased by 73.5%,and the corrosion resistance rate is decreased by 44.8%.