Preparation method of high-strength high-toughness wear-resistant mechanical seal ring

Abstract

The application discloses a preparation method of a high-strength high-toughness wear-resistant mechanical seal ring and belongs to the technical field of mechanical seals, and specifically comprises the following steps: rough machining of a precipitation hardening stainless steel raw material to form a seal ring blank; solid solution aging treatment of the blank; finish machining of the blank to remove the surface oxides and sand blasting roughening and surface cleaning of the surface; explosion spraying of hard alloy powder to the surface of the part; and mechanical machining of the hard alloy coating to meet the mechanical seal requirements in terms of roughness and flatness. The mechanical seal ring prepared by the method has excellent strength, toughness and tribological properties and meets the use requirements of the mechanical seal ring under harsh working conditions such as high load strength and high vibration impact.

Description

Technical Field

[0001] This invention relates to the field of mechanical seals, and more particularly to a method for preparing a high-strength, high-toughness, and wear-resistant mechanical seal ring. Background Technology

[0002] Mechanical seals rely on one or more pairs of end faces perpendicular to the axis to prevent leakage of the sealing medium and the entry of impurities under the action of fluid pressure, elastic elements, and auxiliary sealing elements. They have advantages such as low leakage, long service life, wide applicability, and high reliability, and are widely used in energy, power, metallurgy, mining, and petrochemical industries. As the core component of a mechanical seal, the mechanical seal ring's performance directly determines the sealing performance, reliability, and service life of the entire system. With the continuous development of modern industrial equipment towards high speed, high load, and high power density, mechanical seal rings face severe challenges such as increased load intensity, intensified dynamic impact, and extreme service environments.

[0003] Currently, ceramics and cemented carbide are widely used as common materials for mechanical seal rings in the industrial field. However, traditional ceramic and cemented carbide seal rings struggle to simultaneously possess excellent mechanical and tribological properties, and their performance under complex and extreme working conditions needs further improvement. While silicon carbide and other ceramic seal rings possess ultra-high hardness (microhardness ≥1800HV), their bending strength is ≤450MPa, and their fracture toughness is only 3.5-4.5 MPa√m, making them prone to brittle fracture under high pressure, variable load, and vibration / impact conditions. Although cemented carbide possesses high bending strength (≥2200MPa), its fracture toughness is limited to only 10-12MPa√m due to the characteristics of the cobalt binder phase, failing to meet the requirements for mechanical seals under vibration and impact conditions. Therefore, to achieve reliable operation of mechanical seals under high load intensity and high vibration / impact conditions, a high-strength, high-toughness, and wear-resistant mechanical seal ring needs to be developed.

[0004] 17-4PH steel is a typical martensitic precipitation-hardening stainless steel, widely used in aerospace, aviation, and nuclear power due to its high strength, high toughness, and good machinability. Explosive spraying is a spraying method that involves igniting a gas mixture at a specific frequency, causing it to explode in a pulsed manner. The energy generated by the explosion heats the spray powder to a molten or semi-molten state, and then the shock wave from the explosion accelerates the molten or semi-molten powder onto the substrate surface to form a coating. Compared with technologies such as supersonic flame spraying and plasma spraying, explosive spraying produces coatings with higher bonding strength, lower porosity, and less flaking. Furthermore, explosive spraying causes less thermal damage to the substrate and is not limited by the size or shape of the workpiece. If a hard alloy coating can be explosively sprayed onto the surface of 17-4PH precipitation-hardening stainless steel to obtain a high-strength, high-toughness, and wear-resistant mechanical seal ring, it will greatly improve the service life of the mechanical seal under extreme conditions such as high-load impacts. A search revealed no reports on methods for preparing mechanical sealing rings by spraying cemented carbide powder onto the surface of 17-4PH precipitation-hardening stainless steel as a substrate using explosive spraying. Summary of the Invention

[0005] This invention overcomes the shortcomings of existing technologies and provides a method for preparing a high-strength, high-toughness, and wear-resistant mechanical seal ring, solving the problems of poor strength and low fracture toughness in existing mechanical seal rings. The method described in this invention can prepare mechanical seal rings with excellent strength, toughness, and tribological properties, meeting the requirements for use in harsh conditions such as high load intensity and high vibration and impact.

[0006] A method for preparing a high-strength, high-toughness, and wear-resistant mechanical seal ring includes the following steps: (1) The precipitation-hardening stainless steel raw material is rough processed to make a sealing ring blank; (2) Solution treatment and aging of the rough embryo; (3) The rough blank is finished to remove the oxides on the surface, and the surface is roughened by sandblasting and cleaned. (4) Apply cemented carbide powder to the surface of the part by explosive spraying; (5) The hard alloy coating is machined to achieve the required roughness and flatness for mechanical seals.

[0007] Furthermore, the precipitation-hardening stainless steel grade is 17-4PH, and the cemented carbide powder is WC-10Co4Cr powder with a particle size range of 15-45μm, sphericity ≥90%, and oxygen content ≤0.3%.

[0008] Furthermore, the parameters for the solution treatment and aging process in step (2) are: solution treatment temperature 1050℃, holding time 1h, oil cooling; aging treatment temperature 580℃, holding time 4h, air cooling.

[0009] Furthermore, the sandblasting roughening uses white corundum sand with Al2O3≥99% and a particle size of 250-300μm. The sandblasting compressed air pressure is 0.4-0.5MPa, the incident angle is 75-85°, the sandblasting distance is 100-150mm, the scanning speed is 50-60mm / s, and the sandblasting mode is intermittent sandblasting, with each sandblasting session lasting 30s and an interval of 10s. After sandblasting, the surface roughness of the sealing ring is 3.5-4.5μm.

[0010] Furthermore, the surface cleaning is performed using a NaOH solution with a concentration of 40-50 g / L, heated to 60°C and kept at that temperature. The sealing ring is then completely immersed in the solution for 15 minutes. After removal, the sealing ring is immediately rinsed with deionized water at 65°C and allowed to air dry.

[0011] Furthermore, the fuel used in the explosive spraying is acetylene at a pressure of 0.12-0.14 MPa; the combustion-supporting gas is oxygen at a pressure of 0.45-0.55 MPa, and the volume ratio of acetylene to oxygen is 1.1-1.25:1.

[0012] Furthermore, in the explosive spraying process, the deflagration frequency is 4-8Hz, the single deflagration energy is 1.8-2.2KJ, the spraying distance is 140-180mm, and the spraying angle is 75°-90°; the powder feeding and protective gas is nitrogen with a purity ≥99.999%, a pressure of 0.3-0.35MPa, and a powder feeding rate of 35-45g / min.

[0013] Furthermore, the explosive spray gun used in the explosive spraying is a variable diameter explosive spray gun, with a combustion chamber inlet diameter of Φ25mm, a contraction section diameter of Φ18mm, a throat diameter of Φ8.5mm, an outlet diameter of Φ38mm, a contraction section cone angle of 22°, and an expansion section cone angle of 12°.

[0014] Furthermore, the coating obtained by the explosive spraying has a thickness of 200μm-800μm, a bonding strength of ≥90MPa, a porosity of ≤0.8%, and a microhardness of ≥1250HV.

[0015] Furthermore, in step (5), the surface roughness Ra ≤ 0.05 and the flatness ≤ 0.9 μm.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses precipitation hardening stainless steel 17-4PH as the matrix of mechanical seal ring. Through solution aging heat treatment, the mechanical seal ring achieves tensile strength Rm≥1000MPa, yield strength Rp0.2≥865MPa, elongation after fracture A≥13%, reduction of area Z≥45%, Charpy impact energy KV2≥22J, and fracture toughness K_lc≥75MPa√m, which greatly improves the strength and toughness of mechanical seal ring.

[0017] (2) The present invention uses a variable diameter explosive spray gun to control the ratio of acetylene to oxygen, and strongly compresses the high-energy detonation fluid to improve the energy density and speed of the sprayed powder, while reducing the oxidation of the sprayed powder and the burning loss of low-temperature elements. The porosity is ≤0.8%, thus achieving high density of hard alloy coating.

[0018] (3) The present invention uses explosive spraying technology to prepare a hard alloy coating with uniform thickness on the surface of precipitation hardening stainless steel 17-4PH of mechanical seal ring. The bonding strength between the coating and the precipitation hardening stainless steel 17-4PH substrate is ≥90MPa. Compared with supersonic flame spraying and plasma spraying technology, it has higher bonding strength.

[0019] (4) The high-strength and high-toughness mechanical sealing ring prepared by the present invention has excellent strength, toughness and tribological properties, and excellent comprehensive performance. Detailed Implementation

[0020] The embodiments of the present invention will now be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] A preferred embodiment of the present invention provides a high-strength, high-toughness, and wear-resistant mechanical seal ring and its preparation method, comprising the following steps: (1) Roughly process the precipitation hardening stainless steel 17-4PH raw material, leaving a 2mm allowance on one side.

[0022] (2) The sealing ring is subjected to solution aging treatment at 1050℃ for 1 hour and oil cooling; the aging treatment is subjected to 580℃ for 4 hours and air cooling.

[0023] (3) The sealing ring is precision machined to remove oxides generated by solution aging treatment and ensure the size of the sealing ring.

[0024] (4) Before spraying, the surface of the sealing ring is roughened by sandblasting and cleaned. For sandblasting roughening, white corundum sand (Al2O3≥99%) with a particle size of 250-300μm is used. The compressed air pressure for sandblasting is 0.4-0.5MPa, the incident angle is 75-85°, the sandblasting distance is 100-150mm, the scanning speed is 50-60mm / s, and the sandblasting mode is intermittent sandblasting, with a 30s interval between sandblasting sessions and a 10s interval. After sandblasting, the surface roughness of the sealing ring is 3.5-4.5μm. For surface cleaning, a NaOH solution with a concentration of 40-50g / L is heated to 60℃ and kept at that temperature. The sealing ring is completely immersed in the solution for 15min. After removal, the sealing ring is immediately rinsed with deionized water at 65℃ and allowed to air dry.

[0025] (5) WC-10Co4Cr cemented carbide powder is sprayed onto the surface of the sealing ring substrate using explosive spraying technology to obtain a coating. The WC-10Co4Cr cemented carbide powder has a particle size range of 15-45μm, a sphericity ≥90%, and an oxygen content ≤0.2%. In the explosive spraying process, the fuel is acetylene, with a pressure of 0.12-0.14MPa; the combustion-supporting gas is oxygen, with a pressure of 0.45-0.55MPa, and the volume ratio of acetylene to oxygen is 1.1-1.25:1. In the explosive spraying process, the deflagration frequency is 4-8Hz, the single deflagration energy is 1.8-2.2KJ, the spraying distance is 140-180mm, and the spraying angle is 75°-90°; the powder feeding and protective gas is nitrogen, with a purity ≥99.999%, a pressure of 0.3-0.35MPa, and a powder feeding rate of 35-45g / min. The explosive spray gun used is a variable diameter explosive spray gun, with a combustion chamber inlet diameter of Φ25mm, a contraction section diameter of Φ18mm, a throat diameter of Φ8.5mm, and an outlet diameter of Φ38mm. The contraction section cone angle is 22°, and the expansion section cone angle is 12°. The coating thickness obtained by explosive spraying is 200μm-800μm, with a bonding strength ≥90MPa, a porosity ≤0.8%, and a WC-10Co4Cr microhardness ≥1250HV.

[0026] (6) The hard alloy coating on the surface of the mechanical seal ring is precision ground and polished, and the surface roughness Ra of the seal ring is ≤0.05 and the flatness is ≤0.9μm.

Claims

1. A method for preparing a high-strength, high-toughness, wear-resistant mechanical seal ring, characterized in that, Includes the following steps: (1) The precipitation-hardening stainless steel raw material is rough processed to make a sealing ring blank; (2) Solution treatment and aging of the rough embryo; (3) The rough blank is finished to remove the oxides on the surface, and the surface is roughened by sandblasting and cleaned. (4) Apply cemented carbide powder to the surface of the part by explosive spraying; (5) The hard alloy coating is machined to achieve the required roughness and flatness for mechanical seals.

2. The method for preparing the high-strength, high-toughness, and wear-resistant mechanical seal ring according to claim 1, characterized in that, The precipitation-hardening stainless steel grade is 17-4PH, and the cemented carbide powder is WC-10Co4Cr powder with a particle size range of 15-45μm, sphericity ≥90%, and oxygen content ≤0.3%.

3. The method for preparing the high-strength, high-toughness, and wear-resistant mechanical seal ring according to claim 1, characterized in that, The parameters for the solution treatment and aging process in step (2) are: solution treatment temperature 1050℃, holding temperature for 1h, oil cooling; aging treatment temperature 580℃, holding temperature for 4h, air cooling.

4. The method for preparing the high-strength, high-toughness, and wear-resistant mechanical seal ring according to claim 1, characterized in that, The sandblasting roughening process uses white corundum sand with Al2O3≥99% and a particle size of 250-300μm. The sandblasting compressed air pressure is 0.4-0.5MPa, the incident angle is 75-85°, the sandblasting distance is 100-150mm, the scanning speed is 50-60mm / s, and the sandblasting mode is intermittent sandblasting, with each sandblasting session lasting 30s and an interval of 10s. After sandblasting, the surface roughness of the sealing ring is 3.5-4.5μm.

5. The method for preparing the high-strength, high-toughness, and wear-resistant mechanical seal ring according to claim 1, characterized in that, The surface cleaning process uses a NaOH solution with a concentration of 40-50 g / L, heated to 60°C and kept at that temperature. The sealing ring is then completely immersed in the solution for 15 minutes. After removal, the sealing ring is immediately rinsed with deionized water at 65°C and allowed to air dry.

6. The method for preparing the high-strength, high-toughness, and wear-resistant mechanical seal ring according to claim 1, characterized in that, The fuel used in the explosive spraying is acetylene at a pressure of 0.12-0.14 MPa; the combustion-supporting gas is oxygen at a pressure of 0.45-0.55 MPa, and the volume ratio of acetylene to oxygen is 1.1-1.25:

1.

7. The method for preparing the high-strength, high-toughness, and wear-resistant mechanical seal ring according to claim 1, characterized in that, The deflagration frequency in the explosive spraying process is 4-8Hz, the single deflagration energy is 1.8-2.2KJ, the spraying distance is 140-180mm, and the spraying angle is 75°-90°. The powder feeding and protective gas is nitrogen with a purity ≥99.999%, a pressure of 0.3-0.35MPa, and a powder feeding rate of 35-45g / min.

8. The method for preparing the high-strength, high-toughness, and wear-resistant mechanical seal ring according to claim 1, characterized in that, The explosive spray gun used in the explosive spraying is a variable diameter explosive spray gun with a combustion chamber inlet diameter of Φ25mm, a contraction section diameter of Φ18mm, a throat diameter of Φ8.5mm, an outlet diameter of Φ38mm, a contraction section cone angle of 22°, and an expansion section cone angle of 12°.

9. The method for preparing the high-strength, high-toughness, and wear-resistant mechanical seal ring according to claim 1, characterized in that, The coating obtained by the explosive spraying has a thickness of 200μm-800μm, a bonding strength of ≥90MPa, a porosity of ≤0.8%, and a microhardness of ≥1250HV.

10. The method for preparing the high-strength, high-toughness, and wear-resistant mechanical seal ring according to claim 1, characterized in that, In step (5), the surface roughness Ra ≤ 0.05 and the flatness ≤ 0.9 μm.