Electrodeposition Preparation Of Ni-Co/Al₂O₃ Composite Coating And Performance Research

With the development of modern industry,we had more and more requirements on the performance of mechanical industry.Ni-Co composite coatings had excellent mechanical properties and electromagnetic properties,The results showed that the Ni-Co composite coating was not only good in abrasion resistance and corrosion resistance,but also had a life span of 20% to 100% at high temperature.However,because of the high cost of cobalt,resulted in high cost of plating.Consequently,In this paper,nano-AlR2ROR3 R particles were added to reduce the content of Co,while maintaining good wear resistance and corrosion resistance.However,in our country,using AlR2ROR3 R as a coating of composite additive less,technology was not mature,so in this paper,by simultaneous electrodeposition of cobalt nickel alloy coating,AlR2ROR3 R nanoparticles were introduced into Ni-Co composite coating,it was very meaningful.The experiment was divided into four parts,in the first part,the effects of NiSOR4 R.6HR2RO concentration,CoSOR4 R.7HR2RO concentration,current density and pH on the properties of Ni-Co composite coatings were investigated.By orthogonal test,polarization curve,AC impedance,surface morphology and friction coefficient were obtained under the fifth group of experimental conditions?NiSO₄-6H₂O 250g/L?CoSOR4R·7HR2RO 3.0g/L?Current density 3.0 A/dmP2P?pH 3.0?Stirring speed 200 r/min?Ni-Co composite coating was better?The second part was based on the first part,Ni-Co/AlR2ROR3 R composite coating was prepared by adding nano-AlR2ROR3 R to the bath ? The effects of nano-AlR2ROR3 R concentration,temperature and nano-AlR2ROR3 R on the properties of Ni-Co/AlR2ROR3 R composite coatings were investigated.Through the polarization curve,AC impedance,surface morphology and friction coefficient:The preparation of Ni-Co/AlR2ROR3 R composite coating was better when the concentration of AlR2ROR3 R was 4g / L,the temperature was 40? and the particle size of AlR2ROR3 R was 10 nm.Hardness of 535 Hv,friction coefficient of 0.35,passivation interval of 0.63 V.The third part was under the pulse condition.The effect of duty cycle on the properties of Ni-Co/AlR2ROR3 R composite coatings was studied.By measuring the hardness,polarization curve,AC impedance,scanning electron microscopy and friction coefficient of the composite coating in turn: With the increase of duty cycle,the hardness of the composite coating was increased first and then decreased,When the duty cycle was 0.5,Hardness of 597 Hv,the friction coefficient of 0.3,the most dense composite coating,uniform,With the increase of duty cycle,the self-corrosion current of the composite coating gradually increases,the corrosion voltage decreases gradually,the passivation interval increases first and then decreases,When the duty cycle was 0.5,the passivation interval was 0.65 V.The corrosion resistance of the composite coating was better.Finally,the Ni-Co/AlR2ROR3 R composite coating obtained by Ni-Co composite coating under direct current condition and Ni-Co/AlR2ROR3 R composite coating obtained under pulsed conditions were compared,By measuring their hardness,corrosion resistance,wear resistance,surface morphology and other data obtained from the experimental data analysis,The hardness of Ni-Co/AlR2ROR3 R composite coating was 597 Hv,the friction coefficient was 0.3,the passivation interval was 0.65 V.DC Ni-Co/AlR2ROR3 R composite coating was 535 Hv,the friction coefficient was 0.35,the passivation interval is 0.63 V,Ni-Co composite coating hardness was 480 Hv,the friction coefficient was 0.45,the passivation interval was 0.6V.Ni-Co/AlR2ROR3 R composite coating was better than Ni-Co composite coating,and the hardness,corrosion resistance,surface morphology and wear resistance of Ni-Co/AlR2ROR3 R composite coating were better.DC Ni-Co/AlR2ROR3 R composite coating than Ni-Co composite coating hardness,corrosion resistance,surface morphology,wear resistance and other performance was better.