Research On The Corrosion And Wear Performance Of The Nitriding And Sherardizing Complex Treatment Layer In Oil Output Liquid

This paper, studied the new technology of the nitriding and sherardizing complex treatment; analyzed the main component and organization of the composite layer; investigated the behavior and mechanism of corrosion and friction of nitriding,sherardizing and complex treatment in oil output.The main content and achievements of this paper are as follows:1. The nitriding and sherardizing complex treatment technology had been studied. After nitriding and then sherardizing, the complex treatment layer was prepared on 45 steel.2. By Studying the composition and organization of the complex treatment layer, we found the main components is Fe4Zn9,FeZn6.67 and Fe8N, from the surface to the bottom of layer wereδ1 phase,Γphase of Zn-Fe alloy layer and nitriding diffusion layer. The hardness in nitriding diffusion layer in remarkably higher than that in the pure sherardizing matrix which forms a good hardness gradient to improve the behavior of wear resistance. Meanwhile, we discussed formation mechanism of complex penetration layer.3. The corrosion behavior of several penetration layers had been studied. The Tafel curve for 45 Steel, sherardizing layer of 45 Steel, nitriding layer of 45 Steel layer and nitriding and sherardizing complex layer of 45 Steel had been measured and the corrosion potential and corrosion current density had been obtained in oil output. The sherardizing treatment and the complex treatment can be used as sacrificial anode substrate on the 45 steel to provide protection, the nitriding cann't provide this protection. Complex layer has better performance of corrosion resistance than that of the nitriding layer.4. Simulate the effect of the environment in oil output, research temperature and pH value to corrosion resistance behavior in the penetration layer in CO2 and O2 corrosion solution system. The corrosion current and corrosion rate increase with the diminution of pH value for the complex layer, sherardizing layer and nitriding layer. In CO2 corrosion solution system, the corrosion current and corrosion rate were increased with temperature increasing for the complex layer, and had those maximum at 70℃, then they would decrease with temperature increasing. However, in nitriding layer, they will always increase with the temperature increasing. The result shows that complex penetration layer is very suitable in oil output liquid, (mostly T=80℃).5. The efforts of sherardizing, nitriding and complex treatment on the friction and wear behavior had been studied. The results showed that:the loss wear of the penetration layer increase with the sand content of oil output liquid, the wear mechanism of is three-body abrasive wear. The wear rate of the complex treatment samples was larger than nitriding samples, but the wear rate of complex treatment samples was lower than sherardizing samples.6. The complex treatment has excellent antiwear and corrosion resistance properties.