Surface-hardening treatment method of sealing pairs and friction pairs of titanium and titanium alloy ball valves

Abstract

The invention discloses a surface-hardening treatment method of sealing pairs and friction pairs of titanium and titanium alloy ball valves. The sealing pairs are related sealing parts at all sealing positions in a valve, a ball and a valve base, and the friction pairs are related friction parts at all transmission connection positions in the valve, the ball and the valve base. The surface-hardening treatment method relates to chemical heat treatment and a vapor deposition hard coating. The chemical heat treatment and the vapor deposition hard coating are simultaneously used for the sealing pairs and the friction pairs of titanium and titanium alloy ball valves so that the problem that surface hardness of the titanium and titanium alloy ball valves treated by a single chemical heat treatment process is low. Based on the chemical heat treatment, the vapor deposition hard coating is adopted so that a hardness difference of a chemical heat treatment infiltrated layer is reduced. The vapor deposition hard coating further improves bonding strength of the chemical heat treatment infiltrated layer and improves surface hardness of the titanium and titanium alloy ball valves. Even if the vapor deposition hard coating is damaged in actual use, a hardened layer formed from the chemical heat treatment infiltrated layer still has a protection effect so that dual protection is realized.

Description

technical field [0001] The invention belongs to the technical field of alloy surface hardening treatment, and in particular relates to a surface hardening treatment method for a sealing pair and a friction pair of a titanium and titanium alloy ball valve. Background technique [0002] Titanium and titanium alloy ball valves usually include a valve body, a ball and a valve seat. The sealing pair of a titanium and titanium alloy ball valve refers to the sealing part of each seal in the ball and the valve seat. The friction pair of a titanium and titanium alloy ball valve refers to the ball and the valve. The friction parts of each transmission and connection in the seat, the friction pair usually includes the friction between the valve stem and the packing, the friction between the ball and the support plate, the surface hardening mainly deals with the internal parts of titanium and titanium alloy ball valves, and generally does not deal with titanium and titanium alloy ball va...

AI Technical Summary

Problems solved by technology

[0007] Chinese patent CN102031482A discloses a method for ion nitriding on the surface of medical CoCrMo alloy, which uses pure ammonia NH 3 As a gas source, a nitride ceramic layer is formed on the surface of the cobalt-chromium-molybdenum CoCrMo alloy. The nitride ceramic layer is composed of dense nanostructured chromium nitride Cr 2 The composition of N and chromium nitride CrN compounds improves the surface hardness of CoCrMo alloy to a certain extent, effectively improves the wear resistance of the alloy, and reduces the failure problem caused by the release of toxic cobalt Co and chromium Cr ions. It is used in biomedical and other fields. It has great application potential, but the coating has limited wear resistance and high wear rate, which cannot meet the wear resistance and long-term sealing requirements of titanium and titanium alloy ball valves

[0008] Chinese patent CN202628301U discloses a combined piston ring with a plasma nitriding layer. A nitrided layer with a thickness of 0.01-0.15mm and a hardness of 300-550HV is formed on the outer surface of the first piston ring and the second piston ring by plasma nitriding. , to a certain extent, solves the problem of poor wear resistance of piston rings, but the hardness is low, and the sealing pair of titanium and titanium alloy ball valves is hard friction. Grinding demand

[0009] Chinese patent CN102719691A utilizes nitrogen plasma beam to form Ti+TiH 2 The thin sheet-shaped compact is subjected to scanning heating and nitriding treatment to form a porous structure and obtain dense and continuous TiN and Ti surrounding the Ti skeleton matrix on the Ti skeleton between the holes. 2 N coating, the surface microhardness is 1270 ~ 1430HV, good wear resistance and corrosion resistance, but the thickness of the nitride layer is only 2 ~ 2.5μm, the tolerance of thin coating is limited, if the hardness difference between the substrate and the coating is too large Large, under the action of large friction force, local abrasions are also prone to occur, peeling off from the interface of the surface layer of the substrate, unable to achieve long-term wear resistance requirements

[0010] Titanium and titanium alloy ball valves are used in harsh conditions in the petrochemical industry, especially in PTA. They not only have to withstand the corrosion of acetic acid at about 200 ° C, but also require good wear resistance at the sealing pair of the ball and the valve seat. Scuffing, high requirements are put forward for the wear resistance and corrosion resistance of titanium and titanium alloy ball valves. At present, the commonly used spraying materials are chromium carbide Cr 3 C 2 , Carbide WC and Stellite, the coating is not resistant to acetic acid corrosion, and the conventional low-temperature nitriding treatment is difficult to achieve on titanium ball valves, and a higher temperature must be reached to form a deep enough carburized layer and a hardness that meets the requirements. TiN wear-resistant coating

[0011] So far, there has been no relevant report on the application of chemical heat treatment and vapor deposition hard coating to the surface hardening treatment of titanium and titanium alloy ball valve sealing pairs and friction pairs.

Images