Experimental Research On Electrochemical Deposition Of Nickel On Selected Area Surface

Surface modification technology has been widely used in the preparation of metal tools.Various surface coating technologies are used to prepare metal or non-metal composite films on the surface of cemented carbide tools（such as TiN,TiC,Al2O3,TiCN）.Obtain single or multiple components with high hardness and excellent wear resistance.TiAl N,TiAl CN,etc.can better solve the conflict between the strength and hardness of cemented carbide tools,and combine the strength and hardness of the base material with the wear resistance of the coating material to improve the overall performance of the cemented carbide tools.As a chemical and thermal barrier,the coating can prevent element diffusion and chemical reaction between the cemented carbide tool matrix and the cutting workpiece,and prevent the cemented carbide tool from sinking due to the high friction between the layers,thereby reducing wear and tear.Significantly extend the life of cemented carbide tools.Generally,the life of a coated tool is about 1-5 times the life of an uncoated tool.However,in the process of preparing metal surface coatings by electroplating,due to the complex functions of the plated parts,the requirements for modification of different parts are different.It is difficult for the traditional electroplating method to modify the surface of the selected area for the parts in a specific area,which restricts the further development of equipment manufacturing technology.In response to the above problems,this research constructed the physical model and mathematical model of the electrochemical deposition system.Based on the 3D printer system,the electrochemical deposition was selected and controlled,the three-dimensional electroplating system was designed,and the single-point selection area electroplating experiment and the multi-point selection area were designed.Research on electroplating experiment.According to the theory of pulse electroplating and the principle of metal electrodeposition,the electrochemical deposition process is theoretically analyzed,and the physical and mathematical models of the electroplating system are established.In order to ensure the smooth implementation of the electroplating process,the influence of the average current density and the bath temperature on the electric field distribution during the Hull cell electroplating process were be simulated,the finite element simulation software COMSOL Multiphysics was used in the process.The research results show that:the average current density is 1.8A/dm²,and the bath temperature is 40℃is the best electroplating condition,which can make the quality of the plated parts reach a better level.In order to obtain the optimized process parameters of electrochemical deposition electroplating in pulsed selective area,the Hull cell electroplating experiment was carried out with the 45#steel substrate as the cathode,and the influence of the concentration of the plating solution on the surface characteristics of the coating was studied.The research results show that when the concentration of the plating solution is not higher than 160g/L,as the concentration of the plating solution increases,the density of the plating layer continues to increase.The grain size is gradually uniform,and the quality of the coating is improved;when the concentration of the plating solution is higher than 160g/L,as the concentration of the plating solution increases,the crystal grains gradually become coarser,the density of the coating decreases,and the quality of the coating decreases.The optimal concentration of Ni SO₄ in the plating solution is 160g/L.According to all the best electroplating process parameters obtained,an electrochemical single-point nickel deposition experiment was carried out in selected areas,and the effect of electrode spacing and the use of different power sources on the quality of the coating was studied.The research results show that if the electrode spacing is too small,the current between the electrodes will be too large,which will cause plate burns and the result of too coarse grains;when the electrode spacing is too large,the current between the electrodes will be too small,which will cause the grains to be too small and the plating efficiency will be low.The problem.The optimal electrode spacing is 3mm.When using DC power supply for experiments,the coating has more pores and the porosity is too high;when using the pulsed power supply and using a combination of electroplating parameters with a duty cycle of 20%and 0.5k Hz for the experiment,the quality of the coating is better,and the single-point deposition is microscopic The morphology presents a spiral rising shape,and the surface has no defects such as pores,and the bonding strength of the coating matrix is high.Using single-point deposition experiment parameters and computer-controlled 3D printer guide rails to conduct multi-point selective area control electrochemical deposition experiments.The experiment took 8 hours.The friction and wear performance of the coating was studied.The results showed that the multi-point selective area electrochemical deposition coating has higher friction and wear performance.Compared with the matrix,the wear resistance is increased by 2.89 times.An electron microscope was used to observe the surface morphology of the coating,and the results showed that the coating was closely combined with the substrate and the structure was compact.The 3D printer guide rail system is used to control the electrochemical deposition of nickel coatings with higher quality.