| 304 stainless steel has been widely used in the fields of construction,automobile,pipeline transportation,and ship due to its excellent machinability,strength,and corrosion resistance.However,due to its low hardness,it is easy to be worn during service,resulting in component failure.Brush plating technology is widely used in surface strengthening and repairing of devices due to its advantages of fast deposition rate and no limitation of site and workpiece size.In this paper,Ni-SiC composite coating was prepared on 304 stainless steel substrate by brush plating technology to improve the surface wear resistance of the material.By studying the preparation process,microstructure,and properties of the coating,the following research results were obtained:（1）The effects of different process parameters on the deposition rate and surface morphology of the coating were studied,and the effect of CTAB concentration in the bath on the amount of SiC in the coating was studied.The results show that the deposition rate of the coating increases with the increase in voltage and temperature.When the brush plating rate is low,ablation is easy to occur.As the brush plating rate increases,the deposition rate decreases and the coating is denser,but too high brush plating rate will lead to splashing of the plating solution.With the increase of CTAB concentration in the plating solution,the amount of SiC increased.Finally,the optimal brush plating process was determined as follows:voltage 10 V,bath temperature 50°C,brush plating rate 8 m/min,and CTAB concentration 300 mg/L.（2）Under the optimal process conditions,Ni-SiC composite coatings with different SiC contents were prepared by adjusting the SiC concentration in the bath.The microstructure and properties of the coatings were analyzed.It was found that with the increase of SiC concentration（5～15 g/L）in the bath,the amount of SiC in the coating increased,the lattice constant and grain size of the matrix metal Ni decreased,the microhardness of the coating increased,and the adhesion decreased.When the concentration of SiC is more than 20 g/L,the delamination phenomenon occurs between the coating and the substrate,and the bonding force decreases sharply.In addition,under the condition of dry friction at room temperature,the average friction coefficient of the coating decreases with the increase of SiC concentration,and the wear rate decreases.The results show that when the concentration of SiC in the plating solution is 15 g/L,the composite coating has the best comprehensive performance,the hardness reaches 457 HV0.1,the wear rate is 0.03×10-4 mm3/（N·m）,and the adhesion to the substrate is 46 N.（3）The effects of environmental parameters on the friction and wear behavior of Ni-SiC composite coatings were studied under the optimum process and the optimum SiC concentration.The results show that in the rotary friction and wear experiment,with the increase of ambient temperature,the average friction coefficient and wear rate of the coating increase,and the wear resistance of the coating decreases.Through reciprocating friction experiments in different media,it is found that the wear rate of the coating is the smallest under dry friction conditions,the wear rate is the largest in5 wt.%HCl solution and the wear is more serious.In 5 wt.%Na OH solution and 3.5wt.%Na Cl solution,it shows excellent wear resistance.Therefore,the coating should avoid working in high-temperature environments and acidic conditions.（4）The corrosion resistance of the composite coatings in 3.5 wt.%Na Cl solution was studied.The results showed that the corrosion potential of each coating was higher than that of the stainless steel substrate,indicating that the presence of the coating improved the corrosion resistance of the stainless steel substrate to a certain extent.With the increase of SiC content in the coating,the corrosion current density and annual corrosion rate of the coating increase,and the corrosion resistance of the coating decreases. |
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