Study On Preparation And Tribological Properties Of Fe-based Amorphous Coating Deposited By Arc Spraying

With the development of modern industry, higher and higher demands on the performance of mechanical parts are needed in actual working conditions. The coatings with special properties were deposited on the surface of mechanical parts, which could not only improve the surface properties of materials to extend the life of the workpiece,but also save precious materials and reduce costs.It was high hardness, good wear-resistance and good corrosion resistance that the amorphous alloy coating deposited by thermal spraying has a good potential application in surface modification of materials.In this paper, the Fe-based amorphous alloy coating was prepared by arc spraying on 45steel substrate. The effects of different process parameters on coating properties were investigated; the microstructure of coating deposited by arc spraying method was analysised. The tribological properties were studied under the conditions of the different sliding speed and different contacting pressure. Moreover, the tribological properties between the coating and the substrate as well as the coatings of different thickness were comparative studied.The results indicated that: While the current was at 200A, and the voltage changed in 29V~37V, little effect on the hardness of the coating, but a greater impact on the coating porosity, and when the arc voltage was at 33V or 35V, the porosity of the coating was minimum, mean of 5%. While the arc voltage was at 33V, arc current ranged to 100A~200A, the hardness of coatings increased with the current increasing, and porosity reduced with the current increasing. Furthermore, it was the arc voltage of 33V and the arc current of 200A that obtained the best performance of the arc sprayed coating.Amorphous phase and microcrystalline-phase were coexistence in the Fe-based amorphous coating deposited by arc spraying. The composition structure of the coating, which showed a typical layered structure of thermal spray coatings, was uniformity and dense, but containing a small amount of pores. With the increase of sliding velocity, the friction coefficient first increased, and then decreased after 40m.s-1, but tends to be stable in the 60m.s-1; addition, the wear rate of the coating increased. As the contacting pressure increasing, the friction coefficient of the coating decreased, while the wear rate was increasing. With the speed and contact pressure increasing, the wear mechanisms of the coating transited from mild adhesive wear to abrasive wear and adhesive wear as well as surface fatigue spalling wear, and eventually become adhesive wear and surface fatigue wear together.The wear resistance of the coating is better than 45steel substrate; the wear mechanism of Fe-based amorphous coating mainly was exfoliation, and 45 steel was adhesive wear for the main. Micro-hardness of amorphous coatings whose thickness were 0.80 and 2.11mm were both in excess of 1000HV0.2, and porosity were about 5~6%. The friction coefficient of the 0.80mm coating was lower than the other coating (2.11mm). This was because the increasing of the coating's thickness leaded to more greater residual stress and more microcrackes in the coating.