Study On Ni-SiC-MoS₂ Composite Electroplating On The Surface Of Aluminum Alloy

As a new type of electroplating technology,composite electroplatinghas been widely used in the field of manufacturing.Adding different kinds of particles to the plating solution can produce a composite coating.SiC particles have high hardness.MoS₂ particles have excellent self-lubricating property.Adding both SiC and MoS₂ to the plating solution may improve the hardness and wear resistance of the composite coating at the same time.In this paper,Ni-SiC-MoS₂ composite coating was prepared by using composite electroplating technology.The effects of current density,plating temperature,stirring speed,and the amount of MoS₂ in the solution on the microstructure,composition,plating speed and hardness of Ni-SiC-MoS₂ composite coating were investigated.The primary and secondary sequences of the effects of various factors on the hardness,plating speed and wear rate were studied by orthogonal experiments.Combining single factor experiment,the optimized process for preparing Ni-SiC-MoS₂ composite coating was obtained.The friction and wear properties of Ni-SiC-MoS₂ composite coating under the optimal process scheme were studied.The Ni-SiC-MoS₂ composite coating prepared in this paper presents silver grey color.In the scope of this study,the mole fraction of SiC in the Ni-SiC-MoS₂ composite coating ranged from 4.08%to 16.83%,and the MoS₂ mole fraction ranged from 0.26%to 1.28%.Among the factors of current density,plating temperature,stirring speed,and MoS₂ amount in solution,the current density and stirring speed have the greatest influence on the plating speed;the plating temperature has the greatest influence on the plating hardness;the current density has the greatest influence on wear rate.According to single factor experiment,an optimized Ni-SiC-MoS₂ composite coating can be obtained when the current density is 5A/dm²,the plating temperature is 50?,the stirring speed is 200r/min and the addition amount of MoS₂ in solution is 6g/L-8g/L.The coating surface is flat and has good bonding with the substrate.SiC and MoS₂ particles distributes uniformly in coating matrix.The highest hardness of Ni-SiC-MoS₂ composite coating reaches to 430.1HV_0.01.Coating wear resistance was tested at room temperature under the condition of dry friction and absolute sliding with a load of 1N.The friction pair was 45#steel ball.The Ni-SiC-MoS₂ composite coating shows good wear resistance.Its wear rate is about0.2920mg/m,which is lower than those of pure Ni?0.4481mg/m?coating and Ni-SiC composite coatings?0.3633mg/m?by about 34.85%and 20.79%,respectively.The average friction coefficient?0.2510?of the Ni-SiC-MoS₂ composite coatings was respectively reduced by 34.96%and 24.96%compared with the pure Ni?0.3982 at the first 400s during wear?and Ni-SiC composite coatings?0.3345?.