Study On The Technology And Properties Of Ni/W-graphene Composite Coating By Ultrasonic Electrodeposition

With the development of society and economy,the demand for material performance has been improved gradually.The material of single performance has been unable to meet the needs of people.The composite materials with excellent comprehensive performance have received extensive attention.Composite electrodeposition technology can add insoluble particles into the solution to prepare composite coatings,so as to solve the problems of poor wear resistance and corrosion resistance of common steel products.As a new carbon material,graphene has excellent mechanical,optical,thermal and electrical properties.It was added to the composite coating as the second phase particle to improve the performance of the coating.The influence of the addition of graphene on the surface morphology,micro-hardness and corrosion resistance of the coating was studied,and the electrodeposition mechanism of graphene was made a certain degree of explanation.The process parameters of Ni-W alloy coating are optimized.The best process was:nickel sulfate 50 g/L,sodium citrate 80 g/L,sodium tungstate 60 g/L,sodium saccharin 2 g/L,twelve alkyl sodium sulfate 0.2 g/L,nickel chloride 10 g/L,temperature 60°C,pH 6~7,average current density 1.5 A/dm~2,electrodeposition time 2 hours,ultrasonic stirring ginseng80KHz and 300W,and the duty ratio 0.4.Under scanning electron microscope,the surface of Ni-W alloy coating prepared by using this experimental parameter was compact and uniform,without cracks and pinholes.Graphene oxide was prepared by improved Hummers method and characterized by Raman spectroscopy and infrared spectroscopy.Then the prepared graphene oxide was added to the plating solution to prepare Ni/W-graphene composite coating,and its micro-hardness and corrosion resistance were further improved than that of the Ni-W alloy coating.The carbon materials in the composite coating were characterized by Raman and infrared spectra.It was found that the number of oxygen functional groups in the electrodeposition process reduced and restored to graphene into the composite coating.The micro-hardness and corrosion resistance of the Ni/W-graphene composite coating were influenced by the content of graphene oxide in the plating bath.With the increase of the content of graphene oxide in the bath,the micro-hardness of the composite coating increased gradually,and the corrosion resistance in the 3.5wt%NaCl solution was gradually improved.When the content of graphene oxide reached 0.6 g/L,the micro-hardness of the composite coating was the highest and the corrosion resistance was the best.With the further increase of the content of graphene oxide,the micro-hardness of the composite coating decreased slightly,and the corrosion resistance also decreased.By changing the current density and the angle of the flow direction of the cathode plate and the bath,the content of the carbon elements in the coating was measured by EDS,and the influence of the electric field factors and mechanical factors on the electrodeposition of graphene was studied.It was found that when the graphene oxide was in the solution solely,it was electronegative and moved to the anode under the effect of applied electric field.Adding graphene oxide to the nickel base plating solution,it moved to the cathode under the action of electric field.The increase of electric field intensity and cathode angle were beneficial to electrodeposition of graphene on cathode.