Research On The Process Of Electroless Ni-WP Alloy Plating On Aluminum Alloys

Research shows that the comprehensive performance of composite coating is better than that of the traditional coating.On the basis of the traditional electroless nickel plating process,a multi-element composite coating with high wear resistance and good corrosion resistance is prepared by adding metal salts and nanoparticles,which is suitable for special application environments and is important for material modification and application.Some technologies are used in the article as evaluation indicators,including deposition rate,coating microhardness,coating porosity,etc.And the goal is to prepare multi-element composite coatings with excellent performance.Scanning electron microscopy,XRF surface composition test,electrochemical polarization curve and XRD analysis are used to observe the appearance the morphology,chemical composition,corrosion resistance and structure of the coating.The main results were concluded with the following aspects:First of all,the process of electroless Ni-W-P plating was determined by single factor experiment,and then the process was optimized by orthogonal experiment.The results show that the optimal bath composition for electroless Ni-W-P plating is 20g/L for nickel sulfate,18g/L for sodium tungstate,28g/L for sodium hypophosphite,14g/L for sodium acetate,6g/L for lactic acid,30g/L for sodium citrate,and the composition of stabilizer is 1.5mg/L thiourea and 80mg/L potassium iodate.The plating process parameters:temperature is 80?,p H value is 8.0.Under these conditions,the plating effect is as follows:the deposition rate is 13.42mg·cm^-2·h^-1,the microhardness of the coating can reach 655.9HV,and the porosity reaches a minimum of 0.42/cm².Then,nanoparticles and surfactants were added to the plating solution to investigate their influence on the process,and the response surface method was used to further optimize the addition process.The result is:adding Fe₃O₄nanoparticles to the plating solution,adding anionic surfactant sodium alginate,non-ionic surfactant Tween-80,when the concentration of Fe₃O₄is 0.75g/L,sodium alginate 40mg/Land Tween-80 30mg/L,the deposition rate is 12.86mg·cm^-2·h^-1,the coating microhardness is 617.4HV,and the porosity is 0.30/cm².Finally,heat treatment and passivation treatment on the plated parts after plating to study its effect on the performance of the coating.Heat treatment at 400?,the corrosion resistance of the coating will increase.Passivating the plated parts,the corrosion resistance of the coating is also improved to a certain extent.The corrosion resistance of the coating is greatly improved by passivation treatment.