A high-entropy alloy / ceramic composite anti-cavitation and anti-abrasion coating and a preparation method thereof

Abstract

To address the cavitation and abrasion problems of the flow components at the Qingtongxia Hydropower Station, this invention discloses a high-entropy alloy / ceramic composite anti-cavitation and anti-abrasion coating and its preparation method. The high-entropy alloy / ceramic composite coating powder, by mass percentage, comprises: WC powder: balance, Fe powder: 6.5–10.4%, Cr powder: 4.1–6.2%, Ni powder: 2.6–5.0%, Al powder: 0.8–1.7%, and Ti powder: 0.8–1.7%. Using this formula as raw material, the coating is prepared on the surface of the workpiece requiring cavitation and abrasion treatment via atmospheric supersonic spraying, ultimately forming a coating of 0.1–0.4 mm. The coating of this invention is dense and uniform, with a porosity below 0.5% and a microhardness of 800–1300 HV. 0.2 The bonding strength between the substrate and the coating is 75–89 MPa. Under the same cavitation erosion test parameters, the coating's resistance to cavitation erosion is 4–8 times that of the substrate; under the same abrasion test parameters, the coating's resistance to abrasion is 12–14.5 times that of the substrate. The preparation method of this invention is reliable and has stable performance, effectively solving the problems of cavitation erosion and abrasion in flow-through components such as water turbines and pumps.

Description

Technical Field

[0001] This invention relates to a high-entropy alloy / ceramic composite anti-cavitation and anti-wear coating and its preparation method, and more particularly to an atmospheric supersonic spraying preparation method, which is suitable for application on flow-through components of hydraulic equipment such as water turbines and water pumps. Background Technology

[0002] Cavitation cavitation and particulate erosion in hydroelectric turbines have long been problems hindering stable operation and extending maintenance cycles. my country suffers from the most severe sediment abrasion in its hydroelectric turbines, a problem present to varying degrees in all operational hydroelectric power stations. The Qingtongxia Hydropower Project, located in Qingtongxia City, Ningxia Hui Autonomous Region, at the mouth of the Qingtongxia Gorge on the Yellow River, is the last cascade hydroelectric power station in the Longqing section of the upper Yellow River's hydroelectric cascade development plan. Due to its location on the sediment-laden main stream of the Yellow River, the Qingtongxia Hydropower Station faces extremely harsh operating conditions. Its average annual sediment load is 220 million tons, with a maximum annual sediment load of 529 million tons, and an average annual sediment concentration of 9.83 kg / m³. 3 The maximum sand content was 431.35 kg / m³. 3 The sediment contains sand particles with a diameter of 0.015–0.02 mm, and quartz and feldspar comprise 40%–90% of the sand particles, with prismatic and semi-circular shapes accounting for 70%–90%. After a period of operation, the turbine blades of the power station experience extensive abrasion under the impact of high-sand-content water flow. Furthermore, due to the influence of early infrastructure construction conditions, the actual suction height of the turbine during operation is less than 50% of the design value, significantly reducing the turbine's cavitation coefficient, even to below the critical cavitation coefficient. Cavitation erosion occurs on the turbine blade surface. The superposition of abrasion and cavitation erosion exacerbates the damage to the steel alloy material on the blade surface, severely impacting the stability and service life of the turbine.

[0003] Currently, domestic and international solutions for cavitation erosion prevention mainly include: improving the toughness of the base material, applying organic coatings, carburizing and nitriding, surface shot peening and nano-sizing, and flame spraying to improve the cavitation and abrasion resistance of hydraulic equipment. However, the effectiveness of these methods in solving the cavitation erosion problem of hydraulic machinery is not ideal.

[0004] High-entropy alloys possess unique alloy phase structures and excellent properties, such as high strength and hardness, good wear resistance, good plasticity and toughness, and corrosion resistance. This provides a new approach to solving cavitation erosion of hydraulic equipment blades. This invention combines the properties of FeCrNiAlTi high-entropy alloys and WC ceramic powder, utilizing atmospheric supersonic spraying to prepare a novel surface modification technology. This technology exhibits advantages such as low porosity, strong adhesion, and high resistance to cavitation erosion and abrasion. Therefore, the use of atmospheric supersonic spraying to prepare high-entropy alloy / ceramic composite coatings has unique advantages in solving cavitation erosion and abrasion in hydraulic equipment. Summary of the Invention

[0005] The purpose of this invention is to address the cavitation and abrasion problems of the flow components at the Qingtongxia Hydropower Station by providing a high-entropy alloy / ceramic composite anti-cavitation and anti-abrasion coating and its preparation method, especially a method for preparing the coating by atmospheric supersonic spraying.

[0006] The technical solution adopted in this invention is as follows:

[0007] A high-entropy alloy / ceramic composite anti-cavitation and anti-wear powder, by mass percentage, has the following composition: WC powder: balance, Fe powder: 6.5~10.4%, Cr powder: 4.1~6.2%, Ni powder: 2.6~5.0%, Al powder: 0.8~1.7%, and Ti powder: 0.8~1.7%.

[0008] Using the above-mentioned formula as raw material, a coating is prepared by atmospheric supersonic spraying equipment to obtain an anti-cavitation and anti-abrasion coating. The preparation method includes the following steps:

[0009] Step 1: Fe powder, Cr powder, Ni powder, Al powder, Ti powder, and WC powder are mixed in the specified proportions. The powder can be prepared by mechanical mixing, spray drying, or gas atomization. The particle size of the prepared high-entropy alloy / ceramic composite powder is 5~35μm.

[0010] Step 2: Spread the high-entropy alloy / ceramic composite powder separately and dry it at a temperature of 100~120℃ for 2~4 hours.

[0011] Step 3: Clean the surface of the substrate with acetone or alcohol and dry it at 50~60℃ to remove oil stains and dirt from the surface.

[0012] Step 4: Use pneumatic sandblasting to remove rust and roughen the surface of the substrate. Use 20-30 mesh white or brown corundum for sandblasting. The pressure of compressed air during sandblasting is 0.4-0.6 MPa, the sandblasting distance is 100-150 mm, and the sandblasting angle is 65°-90°.

[0013] Step 5: Set up an atmospheric supersonic spraying process to prepare a high-entropy alloy / ceramic composite coating.

[0014] Furthermore, the thickness of the high-entropy alloy / ceramic composite coating prepared by atmospheric supersonic spraying is 0.10~0.4mm.

[0015] Furthermore, the preferred parameters for the atmospheric supersonic spraying process are: compressed air: 85~92 PSI, propane: 75~86 PSI, nitrogen flow rate: 20~30 slpm, hydrogen flow rate: 30~40 slpm, powder feeding rate: 40~80 g / min, and spraying distance: 170~250 mm.

[0016] This invention solves the problem of coating performance degradation caused by cavitation and abrasion in flow-through components such as water turbines and pumps. The invention has low production costs, a reliable preparation method, and stable performance. It is suitable not only for flow-through components of hydraulic machinery such as water turbines and pumps in freshwater environments, but also for large-scale application in flow-through components of marine facilities such as steam turbines, ocean current power generation, and ships.

[0017] The beneficial effects of this invention are:

[0018] This invention, through continuous exploration of the selection of high-entropy alloy / ceramic composite powder components and coating preparation methods, utilizes atmospheric supersonic spraying to prepare a dense and uniform high-entropy alloy / ceramic composite coating with a porosity below 0.5% and a microhardness of 800~1300 HV. 0.2 The bonding strength between the substrate and the coating is 75-89 MPa. Under the same cavitation erosion test parameters, the coating's cavitation erosion resistance is 4-8 times that of the substrate; under the same abrasion test parameters, the coating's abrasion erosion resistance is 12-14.5 times that of the substrate. Furthermore, the composite coating's preparation method is reliable and its performance is stable, making it suitable for application in abrasion and cavitation erosion resistance fields such as water turbines and pumps, especially in high-siltation water flow environments. Detailed Implementation

[0019] To make the technical problems, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. In the embodiments of this invention, the substrate for spraying can be ZG06Cr13Ni5Mo steel, 45 steel, Q345 steel, or 2205 stainless steel.

[0020] Example 1

[0021] (1) Take the following components by mass percentage: WC powder: balance, Fe powder: 7.2%, Cr powder: 6.2%, Ni powder: 4.7%, Al powder: 1.5%, Ti powder: 1.1%, and prepare high-entropy alloy / ceramic composite powder;

[0022] (2) The high-entropy alloy / ceramic composite powder is laid out separately and placed in a heat preservation box for drying. The heat preservation temperature is 100℃ and the drying time is 4 hours.

[0023] (3) Clean the surface of the substrate with acetone or alcohol and dry it in an insulated box at 50°C to remove oil stains and dirt from its surface.

[0024] (4) The above-mentioned substrate surface is derusted and roughened by pneumatic sandblasting. 20~30 mesh white corundum or brown corundum is selected for sandblasting. The pressure of compressed air during sandblasting is 0.4~0.6MPa, the sandblasting distance is 100~150mm, and the sandblasting angle is 65°~90°.

[0025] (5) Atmospheric supersonic spraying process parameters: compressed air: 85 PSI, propane: 82 PSI, nitrogen flow rate: 23 slpm, hydrogen flow rate: 35 slpm, powder feeding rate: 70 g / min, spraying distance: 240 mm;

[0026] (6) The prepared high-entropy alloy / ceramic composite coating has a thickness of 0.32 mm, a porosity of 0.37%, and a microhardness of 1164 HV. 0.2 The bonding strength between the substrate and the coating is 81 MPa. Under the same cavitation erosion conditions, the cavitation erosion resistance of the coating is 7.49 times that of the substrate ZG06Cr13Ni5Mo stainless steel (cavitation erosion weight loss of the coating is 0.00071 g, and cavitation erosion weight loss of the substrate ZG06Cr13Ni5Mo stainless steel is 0.00532 g); the erosion resistance is 12.05 times that of the substrate ZG06Cr13Ni5Mo stainless steel (erosion erosion weight loss of the coating is 0.01489 g, and erosion erosion weight loss of the substrate ZG06Cr13Ni5Mo stainless steel is 0.17948 g).

[0027] Example 2

[0028] (1) Take the following components by mass percentage: WC powder: balance, Fe powder: 6.8%, Cr powder: 5.5%, Ni powder: 4.8%, Al powder: 1.4%, Ti powder: 1.0%, and prepare high-entropy alloy / ceramic composite powder;

[0029] (2) The high-entropy alloy / ceramic composite powder is laid out separately and placed in a heat preservation box for drying. The heat preservation temperature is 120℃ and the drying time is 2 hours.

[0030] (3) Clean the surface of the substrate with acetone or alcohol and dry it in an insulated box at 60°C to remove oil stains and dirt from its surface.

[0031] (4) The above-mentioned substrate surface is derusted and roughened by pneumatic sandblasting. 20~30 mesh white corundum or brown corundum is selected for sandblasting. The pressure of compressed air during sandblasting is 0.4~0.6MPa, the sandblasting distance is 100~150mm, and the sandblasting angle is 65°~90°.

[0032] (5) Atmospheric supersonic spraying process parameters: compressed air: 86 PSI, propane: 81 PSI, nitrogen flow rate: 23 slpm, hydrogen flow rate: 33 slpm, powder feeding rate: 60 g / min, spraying distance: 220 mm;

[0033] (6) The prepared high-entropy alloy / ceramic composite coating has a thickness of 0.28 mm, a porosity of 0.43%, and a microhardness of 1217 HV. 0.2 The bonding strength between the substrate and the coating is 85 MPa. Under the same cavitation erosion conditions, the cavitation erosion resistance of the coating is 5.27 times that of the substrate ZG06Cr13Ni5Mo stainless steel (cavitation erosion weight loss of the coating is 0.00101 g, and cavitation erosion weight loss of the substrate ZG06Cr13Ni5Mo stainless steel is 0.00532 g); the erosion resistance is 12.4 times that of the substrate ZG06Cr13Ni5Mo stainless steel (erosion erosion weight loss of the coating is 0.01447 g, and erosion erosion weight loss of the substrate ZG06Cr13Ni5Mo stainless steel is 0.17948 g).

[0034] Example 3

[0035] (1) Take the following components by mass percentage: WC powder: balance, Fe powder: 6.5%, Cr powder: 6.0%, Ni powder: 4.2%, Al powder: 1.2%, Ti powder: 1.0%, and prepare high-entropy alloy / ceramic composite powder;

[0036] (2) The high-entropy alloy / ceramic composite powder is laid out separately and placed in a heat preservation box for drying. The heat preservation temperature is 100℃ and the drying time is 2 hours.

[0037] (3) Clean the surface of the substrate with acetone or alcohol and dry it in an insulated box at 60°C to remove oil stains and dirt from its surface.

[0038] (4) The above-mentioned substrate surface is derusted and roughened by pneumatic sandblasting. 20~30 mesh white corundum or brown corundum is selected for sandblasting. The pressure of compressed air during sandblasting is 0.4~0.6MPa, the sandblasting distance is 100~150mm, and the sandblasting angle is 65°~90°.

[0039] (5) Atmospheric supersonic spraying process parameters: compressed air: 88 PSI, propane: 80 PSI, nitrogen flow rate: 25 slpm, hydrogen flow rate: 35 slpm, powder feeding rate: 65 g / min, spraying distance: 210 mm;

[0040] (6) The prepared high-entropy alloy / ceramic composite coating has a thickness of 0.38 mm, a porosity of 0.33%, and a microhardness of 1282 HV. 0.2The bonding strength between the substrate and the coating is 88 MPa. Under the same cavitation erosion conditions, the cavitation erosion resistance of the coating is 4.09 times that of the substrate ZG06Cr13Ni5Mo stainless steel (cavitation erosion weight loss of the coating is 0.00130 g, and cavitation erosion weight loss of the substrate ZG06Cr13Ni5Mo stainless steel is 0.00532 g); the erosion resistance is 13.02 times that of the substrate ZG06Cr13Ni5Mo stainless steel (erosion erosion weight loss of the coating is 0.01379 g, and erosion erosion weight loss of the substrate ZG06Cr13Ni5Mo stainless steel is 0.17948 g).

[0041] The above description is only a partial embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-entropy alloy / ceramic composite anti-erosion and anti-abrasion coating, characterized in that, The coating is prepared by an atmospheric supersonic spraying device with a powder formula as raw material, and the powder formula comprises the following components in mass percentage: WC powder: the balance, Fe powder: 6.5-10.4%, Cr powder: 4.1-6.2%, Ni powder: 2.6-5.0%, Al powder: 0.8-1.7%, and Ti powder: 0.8-1.7%.

2. A method of producing a high-entropy alloy / ceramic composite anti-erosion anti-abrasion coating as claimed in claim 1, characterized in that, The method comprises the following steps: Step 1: proportionally configuring Fe powder, Cr powder, Ni powder, Al powder, Ti powder and WC powder to prepare high-entropy alloy / ceramic composite powder with a particle size of 5-35 μm; Step 2: separately placing and laying the high-entropy alloy / ceramic composite powder, drying at a temperature of 100-120 ℃ for 2-4 hours; Step 3: cleaning the surface of a spraying substrate with acetone or alcohol and drying at 50-60 ℃ to remove surface oil stains and dirt; Step 4: adopting an air power sandblasting method to perform rust removal and roughening treatment on the surface of the spraying substrate, and selecting 20-30 mesh white or brown corundum for sandblasting treatment, the pressure of compressed air is 0.4-0.6 MPa, the sandblasting distance is 100-150 mm, and the sandblasting angle is 65°-90°; Step 5: setting an atmospheric supersonic spraying process to prepare a high-entropy alloy / ceramic composite coating.

3. The method for preparing the high-entropy alloy / ceramic composite anti-cavitation and anti-wear coating according to claim 2, characterized in that, The thickness of the high-entropy alloy / ceramic composite coating prepared by the atmospheric supersonic spraying is 0.10-0.4 mm.

4. The method for preparing the high-entropy alloy / ceramic composite anti-cavitation and anti-wear coating according to claim 2, characterized in that, The atmospheric supersonic spraying process parameters in Step 5 are as follows: compressed air: 85-92 PSI, propane: 75-86 PSI, nitrogen flow: 20-30 slpm, hydrogen flow: 30-40 slpm, powder feeding rate: 40-80 g / min, and spraying distance: 170-250 mm.