Rotor surface treatment process

Abstract

The invention provides a rotor surface treatment process, and relates to the technical field of surface treatment.The rotor surface treatment process is characterized in that a coating sequentially comprises a soft layer A, a hard layer B and a toughening layer C from a base body to the outside; the soft layer A is a metal lubricating composite layer formed by metal Mo or W and C or S with increasing content; the hard layer B is formed by metal nitride or carbonitride; a continuous component and structure gradient region is arranged between the soft layer A and the hard layer B; and the toughening layer C is a nanocrystalline-amorphous mixed structure formed by solid micro-diffusion of the hard layer B at 320-420 DEG C. Periodic micro-pits are formed in the surface of the toughening layer C and can be used for storing a lubricating medium. Through component gradient design and process hardening and tempering, the binding force, the wear resistance, the impact resistance and the stripping resistance of the coating are remarkably improved, the service life of the coating is prolonged, and the service life of the coating is prolonged. The method is suitable for high-load and high-friction working conditions such as vacuum pump rotors.

Description

Technical Field

[0001] This invention relates to the field of surface treatment technology, specifically a rotor surface treatment process. Background Technology

[0002] Vacuum pump rotors are subjected to a variety of coupled conditions such as friction, impact, thermal stress, and corrosion during actual operation. Existing surface strengthening technologies, such as single hard coatings (e.g., DLC, TiN, CrN), generally suffer from high brittleness and poor adhesion to the substrate; multilayer coating technologies often employ simple stacked structures with abrupt interlayer interfaces, which easily lead to peeling; while gradient coating technologies rely on complex multi-source evaporation equipment or high-energy ion beam control, resulting in high costs and narrow process windows.

[0003] Therefore, there is an urgent need to develop a rotor surface treatment technology that has strong bonding force, good wear resistance, strong impact resistance, and simple process. Summary of the Invention

[0004] The purpose of this invention is to provide a rotor surface treatment process that aims to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: the rotor surface treatment coating, from the substrate outward, includes a soft layer A, a hard layer B, and a toughening layer C in sequence; The soft layer A is a metal lubricating composite layer formed by metal Mo or W with an increasing amount of C or S; Hard layer B is formed of metal nitrides or carbonitrides; The region between soft layer A and hard layer B is a continuous composition and structural gradient region; The toughening layer C is a nanocrystalline-amorphous hybrid structure formed by solid-state micro-diffusion of the hard layer B at 320–420℃.

[0006] Furthermore, the metal in the metal nitride or carbonitride is Ti, Cr, or Zr.

[0007] Furthermore, the adhesion of the coating is not less than 70 N.

[0008] Furthermore, the thickness of the toughening layer C is 0.8–1.2 μm.

[0009] The present invention also provides a method for preparing the above-mentioned coating, comprising the following steps: (1) Matrix pretreatment and ion cleaning; (2) A soft layer A with increasing composition is formed by reactive sputtering using a dual-source metal target and a trace amount of reactive gas; (3) By dynamically controlling the reaction atmosphere, a continuous gradient transition from soft layer A to hard layer B is achieved, forming hard layer B; (4) Under vacuum conditions, the hard layer B is subjected to diffusion tempering at 320-420℃ for 20-50 minutes to form the toughening layer C; (5) Periodic micro-pits are formed on the surface of the toughening layer C, and the micro-pits can be used to store the lubricating medium; (6) Perform post-processing, including low-energy nitrogen plasma passivation.

[0010] Preferably, the reactant gas is C2H2 or H2S, and its content does not exceed 1%.

[0011] Preferably, the matrix bias voltage is gradually increased from -40-80 V to -120-160 V during the deposition process.

[0012] Preferably, the cooling rate during the diffusion conditioning process is 5–8 °C / min.

[0013] Preferably, the thickness of the soft layer A is 1–3 μm, and the thickness of the hard layer B is 3–8 μm. The beneficial effects of this invention are: By employing a continuous compositional gradient design between soft layer A and hard layer B, a smooth transition of mechanical properties is achieved from the substrate to the coating interface, avoiding stress concentration and peeling problems caused by abrupt interface changes in traditional multilayer coatings. Soft layer A combines high ductility with lubrication, effectively buffering external impacts and thermal stress, and improving the overall bonding strength of the coating.

[0014] The hard layer B adopts a metal nitride / carbonitride nanocrystalline structure, exhibiting excellent hardness and wear resistance. Simultaneously, the C or S elements introduced into the soft layer can form a self-lubricating phase, playing a role in reducing friction during the friction process. Examples show that the coating friction coefficient can reach as low as 0.12–0.26, making it suitable for high-speed, high-load friction conditions.

[0015] The toughening layer C is formed in situ on the surface of the hard layer through a solid-state diffusion tempering process, without the need for additional deposition materials or complex equipment. This process can achieve the controllable construction of a nanocrystalline-amorphous hybrid structure under mild conditions of 320-420℃, which significantly improves the impact resistance and fatigue resistance of the coating and avoids brittle fracture.

[0016] The micro-pits on the surface of the toughness layer C can store lubricating medium (oil / grease) for continuous lubrication, capture wear particles to reduce abrasive wear, and enhance surface heat dissipation to reduce frictional temperature rise. Attached Figure Description

[0017] Figure 1 This is a flowchart of the rotor surface treatment process. Detailed Implementation

[0018] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0019] Example 1: Ti-Mo-C coating.

[0020] The base is a ductile iron vacuum pump rotor, with dimensions of 85mm × 120mm.

[0021] Step 1: Preprocessing Ultrasonic degreasing (acetone 15 min, alcohol 10 min) → hot air drying → Ar ion bombardment cleaning (400 eV, 8 min).

[0022] Step 2: Soft layer A deposition.

[0023] Dual-source DC magnetron sputtering was employed, with Mo and graphite C as the target materials. Substrate bias -60V; working gas Ar 40sccm + C2H2 (dynamically varying from 0.5 to 1sccm); The Mo target power was gradually increased from 1.0 kW to 1.2 kW, with a deposition thickness of 2 μm.

[0024] Step 3: Hard layer B deposition.

[0025] Switch to Ti target, the reaction gas is Ar / N2 / C2H2=40 / 10 / 1sccm; The substrate bias voltage was increased to -150V, and the deposition thickness was 5μm.

[0026] Step 4: Formation of toughening layer C.

[0027] The temperature was raised to 380℃ in a vacuum environment, held for 35 minutes, and cooled at a rate of 5℃ / min to form a toughening layer of about 1μm thickness.

[0028] Step 5: Surface treatment of toughening layer C.

[0029] Periodic micro-pits were fabricated on the surface of toughening layer C by laser micro-nano processing. The pit diameter was 20-50 μm, the depth was 5-15 μm, and the areal density was 15-30%.

[0030] Step 6: Post-processing.

[0031] Passivation with low-energy nitrogen plasma for 2 minutes.

[0032] Performance test results: Bonding force 76N, coefficient of friction 0.26, wear rate 1.9×10 -5 mm³ / N•m, no spalling after impact.

[0033] Example 2: Cr-WS coating.

[0034] The soft layer A uses a W target and a trace amount of H2S, the hard layer B is CrN, and the toughening process is 350℃×40min.

[0035] The coefficient of friction can be as low as 0.12 to 0.18.

[0036] Example 3: Zr-Mo-NC coating.

[0037] The soft layer A is MoCx, the hard layer B is ZrCN, and the toughening process is 400℃×25min.

[0038] The corrosion resistance is significantly improved, and the weight loss is only 2mg after soaking in 3% HCl for 48 hours.

[0039] The above embodiments demonstrate that the coating of the present invention has excellent adhesion, wear resistance, impact resistance and corrosion resistance, and is suitable for high-performance rotor surface protection.

[0040] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

Claims

1. A rotor surface treatment coating, characterized in that, The coating, from the substrate outwards, comprises: a soft layer A, a hard layer B, and a toughening layer C formed by diffusion tempering, wherein: The soft layer A is a metal lubricating composite layer formed by metal Mo or W with an increasing amount of C or S; Hard layer B is formed of metal nitrides or carbonitrides; The region between soft layer A and hard layer B is a continuous composition and structural gradient region; The toughening layer C is a nanocrystalline-amorphous hybrid structure formed by solid-state micro-diffusion of the hard layer B at 320–420°C; Periodic micro-pits are formed on the surface of the toughening layer C, and these micro-pits can be used to store lubricating media.

2. The coating according to claim 1, characterized in that, The metal in the metal nitride or carbonitride is Ti, Cr, or Zr.

3. The coating according to claim 1, characterized in that, The adhesion of the coating is not less than 70N.

4. The coating according to claim 1, characterized in that, The thickness of the toughening layer C is 0.8–1.2 μm.

5. A method for preparing a rotor surface treatment coating as described in any one of claims 1 to 4, characterized in that, Includes the following steps: ① Matrix pretreatment and ion cleaning; ② A soft layer A with increasing composition is formed by reactive sputtering using a dual-source metal target and a trace amount of reactive gas; ③ The gradient transition from soft layer A to hard layer B is achieved through dynamic control of the reaction atmosphere, forming a dense hard layer B; ④ Under vacuum conditions, the hard layer B is subjected to diffusion tempering at 320–420°C for 20–50 minutes to form the toughening layer C; ⑤ Periodic micro-pits are created on the surface of toughening layer C using laser; ⑥ Perform post-processing, including low-energy nitrogen plasma passivation.

6. The method according to claim 5, characterized in that, In step ②, the reaction gas is C2H2 or H2S, and its content does not exceed 1%.

7. The method according to claim 5, characterized in that, In steps ② and ③, the substrate bias voltage is gradually increased from -40-80V to -120-160V.

8. The method according to claim 5, characterized in that, The cooling rate during the diffusion conditioning process is 5–8 °C / min.

9. The method according to claim 5, characterized in that, The thickness of the soft layer A is 1–3 μm, and the thickness of the hard layer B is 3–8 μm.

10. The method according to claim 5, characterized in that, The total thickness of the soft layer A and the hard layer B is 4–11 μm.

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