Study On The Preparation And Properties Of Wear-resistant And Corrosion-resistant Coating For Pipeline Valves

Pipeline valve devices are widely used in various industrial fields,playing a role of control in the fluid delivery system,and are one of the indispensable mechanical equipments.During the service of the valve,there are often working conditions in which gas,liquid and solid coexist,and even with high temperature and high pressure working conditions,which are prone to wear and corrosion damage,affecting the sealing effect of the valve,and even causing leakage accidents.The use of coating protection technology in the field of surface engineering to protect key components from wear and corrosion is the most economical and effective method,which is of great significance to the long-term safe service of pipeline valve system.In this paper,three-cathode plasma spraying equipment is used to prepare tantalum coating on Cu Cr Zr alloy.Utilizing the continuous and adjustable characteristics of plasma flame flow,by adjusting the auxiliary gas(Helium)flow rate during the spraying process,the oxidation of the tantalum coating can be reduced,and a high-strength,dense structure and pure tantalum coating with good wear resistance can be prepared,and the effects of auxiliary gas flow parameters on the microstructure,phase composition,mechanical properties,wear resistance and corrosion resistance of the coating were sdtudied.Then by cold spray technology,two powder forms of angular tantalum powder and irregular tantalum powder are used to deposit pure tantalum coating under different gas temperature parameters.The effects of powder morphology and gas temperature on the microstructure,mechanical properties,wear resistance and corrosion resistance of cold sprayed tantalum coatings were studied.And through comparative analysis to obtain the optimal process parameters.The main results are as follows:(1)When the auxiliary gas flow is 70 L/min,the plasma spray coating oxidation is the lightest;the porosity rate is 0.21±0.10%;the binding strength is up to 59.3 MPa;The wear resistance of the coating increases first and then decreases with the increase of auxiliary gas flow rate;when the auxiliary air flow is 70L/min,the coating wear rate is 0.0012mm~3/(N·m),and the coating wear resistance is optimal.When the auxiliary gas flow is 70 L/min,the coating self-corrosion level is-270 m V;the minimum self-corrosion current density is3.82E-03 m A/cm~2.Comprehensive analysis shows that when the auxiliary gas flow rate is70 L/min,the coating has the best corrosion resistance.(2)Compared with irregular tantalum powder,the tantalum coating deposited by cold spraying of angular tantalum powder is denser and has a smoother surface;the spraying gas temperature is set to 600℃,and the bonding strength of the tantalum coating deposited by angular tantalum powder is up to 93 MPa,and the abrasion and corrosion resistance are the best.(3)There are no oxidation and phase change in the deposited process of cold spray tantalum coating;the coating phase is only Ta phase.Plasma spray tantalum coating has Ta phase and Ta2O5 phase,but the oxide content is less.