Study On The Process And Properties Of Ni-Fe-W Alloy Coatings Produced By Pulse Electrodeposition

The paper investigates the mechanism of alloy codeposition, and finds that nickel,iron,tungsten can be deposited together with proper complexing agent.Then,the effects of the concentration of NiSO₄·6H₂O,Na₂WO₄·2H₂O,FeSO₄·7H₂O and temperature on the quality of Ni-Fe-W alloy coatings are also addressed.Based on the analysis of hardness,thickness and appearance of the coatings, the optimal process conditions of pulse electrodeposition are screened out by orthogonal experiment.Besides,the contents of complexing agent,additive and parameters of the power supply are investigated.The effects of deposition contents,current density and additive on the topographies are studied;the frictional and wear performances of alloy coatings under different conditions are also investigated on the Ball-Disk frictional and wear tester.Finally, Ni-Fe-W alloy coatings are achieved with higher hardness,better wear resistance and nice appearance.Observing the microstructure of the coatings indicates that iron can reduce the microcracks.The X-ray diffraction experiments support that the structure of the coatings change from crystal to mixed crystal and then to amorphism with the increasing content of W in the alloy coatings. The amorphous mechanism is explained.Two equations of alloy coatings'frictional coefficient are obtained under lubrication and dry friction by Response Surface Methodology.The frictional and wear mechanism is proposed by analyzing the microstructure of the grinding cracks. The results clearly show minor abrasive wear under lubrication and adhere wear with high load under dry friction. The micro-penetration hardness shows a remarkably increase after the experiment in the frictional contact area.It finds that some new hardened compounds are formed in the contact area using EDAX. The hardening mechanism is also discussed.