阅读说明：本技术 一种应用于阀体表面的高硬度、高耐磨复合涂层、制备方法及阀体 (High-hardness and high-wear-resistance composite coating applied to surface of valve body, preparation method and valve body ) 是由 郑刚 唐华 付永忠 叶兴海 潘天红 滕成龙 杨龙祥 刘振 朱鑫达 赵荣河 邵玲 于 2020-12-08 设计创作，主要内容包括：本发明提供了一种应用于阀体表面的高硬度、高耐磨复合涂层、制备方法及阀体,在阀体表面引入Si掺杂W-2N层或Si掺杂的Mo-2N层,以及WC和新型的高熵合金AlMoCrFeNi的多层复合涂层,结合了高温陶瓷与高熵合金的优点,通过Si掺杂和WC的颗粒强化分别增强了W-2N层或Mo-2N层、高熵合金AlMoCrFeNi的硬度和韧性,具有高硬度和高耐磨性。本发明所制备的涂层结构致密、均匀且具有高的硬度、高强度、高韧性、高耐磨性以及好的耐腐蚀性能,适用于阀体表面。(The invention provides a high-hardness and high-wear-resistance composite coating applied to the surface of a valve body, a preparation method and the valve body, wherein Si-doped W is introduced into the surface of the valve body 2 N-layer or Si-doped Mo 2 The N layer and the WC and the novel high-entropy alloy AlMoCrFeNi multilayer composite coating combine the advantages of high-temperature ceramics and high-entropy alloy, and the W is respectively enhanced by doping Si and strengthening WC particles 2 N layer or Mo 2 The N layer and the high-entropy alloy AlMoCrFeNi have the hardness and toughness and have high hardness and high wear resistance. The coating prepared by the invention has compact and uniform structure, high hardness, high strength, high toughness, high wear resistance and good corrosion resistance, and is suitable for useA valve body surface.)

1. The high-hardness and high-wear-resistance composite coating applied to the surface of the valve body is characterized by comprising Si-doped W which is adhered to the surface of the valve body and is alternately laminated₂N-layer or Si-doped Mo₂The composite material comprises an N layer and a WC-AlMoCrFeNi composite layer, wherein the WC-AlMoCrFeNi composite layer is an AlMoCrFeNi layer dispersed with WC particles, the mass percentage of the WC particles is 5-10%, the particle size of the WC particles is 100-200 meshes, and the balance is AlMoCrFeNi.

2. The high-hardness and high-wear-resistance composite coating applied to the surface of the valve body according to claim 1, wherein the content of each element in the high-entropy alloy AlMoCrFeNi is calculated by atomic percent: 18-22% of Al, 18-22% of Cr, 18-22% of Mo, 18-22% of Fe and 18-22% of Ni, and the grain diameter of the alloy is 50-100 meshes.

3. The method for preparing the high-hardness and high-wear-resistance composite coating applied to the surface of the valve body according to claim 1, characterized by comprising the following steps:

(1) polishing, degreasing, pickling and sand blasting the valve body base material;

(2) cladding the mixed powder of W and Si or the mixed powder of Mo and Si on the surface of the valve body base material treated in the step (1) by adopting a laser cladding technology, placing the clad material in a muffle furnace, preserving the heat for 15-30min at the temperature of 700-850 ℃ under the protection of inert gas, and naturally cooling to room temperature; then transferring the mixture into a tube furnace at the temperature of 1000 ℃ and 1200 ℃ and N₂And NH₃Keeping the temperature for 1 to 3 hours under the atmosphere of the mixed gas to obtain Si-doped W₂N-layer or Si-doped Mo₂N layers;

(3) mixing Al, Cr, Mo, Fe and Ni in a nearly equimolar ratio to obtain multi-component mixed powder, adding the multi-component mixed powder into WC particles, and carrying out ball-milling mixing to obtain multi-component mixed powder containing WC;

(4) by atmospheric plasma sprayingThe technique is to spray the multi-element mixed powder prepared in the step (3) on Si-doped W₂N-layer or Si-doped Mo₂Preparing a WC-AlMoCrFeNi composite layer on the surface of the N layer; after ion spraying, placing the mixture in a muffle furnace, preserving the heat for 15-30min at the temperature of 350-500 ℃ under the protection of inert gas, and naturally cooling to room temperature.

4. The method for preparing a high-hardness and high-wear-resistance composite coating according to claim 3, further comprising the step (5): repeating the steps (2) - (4) one or more times until a plurality of layers of laminated composite coatings are obtained.

5. The method for preparing the high-hardness and high-wear-resistance composite coating according to claim 3, wherein the specific process of the step (1) is as follows:

polishing: polishing the sample by using 100-2000-mesh abrasive paper step by step until the surface of the sample is bright and flat;

oil removal: placing the valve body substrate in alcohol or acetone for ultrasonic cleaning and oil removal;

acid washing: removing scratches and a hardened layer on the surface of the substrate by using a solution containing 5% of hydrofluoric acid, 40% of nitric acid and 55% of deionized water;

sand blasting: the abrasive material for sand blasting is brown corundum, the granularity is 60-100 meshes, the sand blasting time is 5-10s, the sand blasting distance is 30-60mm, and the air pressure is 0.5-1 MPa.

6. The method for preparing the high-hardness and high-wear-resistance composite coating according to claim 3, wherein the valve body material is 20Cr, 45 steel or GCr 15; the ball milling parameters of the multi-element mixed powder in the step (3) are as follows: mixing for 1-2h at the rotating speed of 60-120 rpm; the protective gas is nitrogen or argon.

7. The method for preparing a high-hardness and high-wear-resistance composite coating according to claim 3, wherein the Si-doped W prepared in the step (2)₂N-layer or Si-doped Mo₂The thickness of the N layer is 50-150 mu m; the thickness of the WC-AlMoCrFeNi composite layer prepared in the step (4) is 40-100 mu m.

8. The method for preparing the high-hardness and high-wear-resistance composite coating according to claim 3, wherein the laser cladding conditions in the step (2) are as follows: the laser power is 1.5-2kW, the protective gas is argon, the flow rate is 100-150mL/min, the powder feeding mode is coaxial powder feeding, the defocusing amount is 45-50mm, the spot size is 4-5mm, the scanning speed is 15-20mm/s, the lap joint rate is 50-75%, and the powder feeding amount is 20 g/min; the heat preservation temperature of the tubular furnace is 1000-1200 ℃, and the heat preservation time is 3-5 h.

9. The preparation method of the high-hardness and high-wear-resistance composite coating according to claim 3, wherein in the step (4), during the atmospheric plasma spraying, the used fuel gas is propane, the combustion-supporting gas is oxygen, the powder feeding gas is nitrogen, the gas flow rate of the fuel gas is 20-80mL/min, the gas flow rate of the combustion-supporting gas is 200-400mL/min, and the gas flow rate of the powder feeding gas is 20-80 mL/min.

10. A valve body having the high-hardness, high-abrasion resistant composite coating applied to the surface of the valve body as claimed in claim 1 or 2.

Technical Field

The invention relates to the technical field of surface engineering, in particular to a high-hardness and high-wear-resistance composite coating applied to the surface of a valve body, a preparation method and the valve body, belonging to the technical field of surface strengthening treatment.

Background

The valve body is used as a main part of the valve, and the pressure resistance, the wear resistance, the corrosion resistance and other properties of the valve body play an important role in the quality of the valve. The existing valve body is made of various materials, wherein high-quality tool steel, stainless steel and aluminum alloy are widely applied due to wear resistance and corrosion resistance, and the valve body made of the stainless steel is a mainstream product of the valve sold in the market at present. The common valve has poor sealing performance, easy leakage, easy perforation of a shell and short service life under the process conditions of strong corrosion, toxicity and harm, and can not meet the special requirement of effectively conveying toxic media for a long time. Therefore, the exploration and development of high-wear-resistance and corrosion-resistance valve body materials and processes are important guarantees for obtaining high-quality or special requirements of valves.

In recent years, high-hardness and high-wear-resistance coating materials are widely applied to coating of substrate materials so as to further enhance the performance of the substrate, for example, two-dimensional materials, ceramics, high-entropy alloys and the like form composite coatings on the surfaces of substrates by the technologies of thermal spraying, ion spraying, laser cladding and the like. Hong et al reported a layered 2D structured MoSi₂N₄The preparation method of the film (Science369, 670-674 (2020)) has better mechanical property and stability than the traditional two-dimensional ceramic material, and provides a brand new idea for designing the ultrahigh-hardness and high-wear-resistance composite coating. In addition, the high-entropy alloy is widely applied to metal coatings and films due to high strength, high hardness, high wear resistance and high corrosion resistance, the preparation method and the spraying technology of the high-entropy alloy are greatly developed, Chinese invention patent applications CN111593248A, CN111549344A, CN111364040A and CN111593339A provide a high-entropy alloy synthesis method and a multilayer coating preparation process, theoretical basis and technical guarantee are provided for designing and developing composite coatings of two-dimensional ceramic materials and high-entropy alloys, and the high-entropy alloy has great potential for improving the performance of valve body materials.

Disclosure of Invention

Based on the prior art, the invention provides the high-hardness and high-wear-resistance composite coating applied to the surface of the valve body, which is low in cost, simple in process and high in yield, the preparation method thereof and the valve body with the composite coating. Introducing Si-doped W on the surface of the valve body₂N-layer or Si-doped Mo₂The multilayer composite coating of the N layer, WC and high-entropy alloy AlMoCrFeNi is used for improving the hardness and the wear resistance of the surface of the coating.

The present invention achieves the above-described object by the following technical means.

The high-hardness and high-wear-resistance composite coating applied to the surface of the valve body is characterized by comprising Si-doped W which is adhered to the surface of the valve body and is alternately laminated₂N-layer or Si-doped Mo₂The composite material comprises an N layer and a WC-AlMoCrFeNi composite layer, wherein the WC-AlMoCrFeNi composite layer is an AlMoCrFeNi layer dispersed with WC particles, the mass percentage of the WC particles is 5-10%, the particle size of the WC particles is 100-200 meshes, and the balance is AlMoCrFeNi.

Further, the content of each element in the high-entropy alloy AlMoCrFeNi is calculated by the atomic percentage: 18-22% of Al, 18-22% of Cr, 18-22% of Mo, 18-22% of Fe and 18-22% of Ni, and the grain diameter of the alloy is 50-100 meshes.

Further, the method comprises the following steps:

(1) polishing, degreasing, pickling and sand blasting the valve body base material;

(2) cladding W, Si powder or mixed powder of Mo and Si on the surface of the valve body substrate treated in the step (1) by adopting a laser cladding technology, placing the clad material in a muffle furnace, preserving heat for 15-30min at the temperature of 700-850 ℃ under the protection of inert gas, and naturally cooling to room temperature; then transferring the mixture into a tube furnace at the temperature of 1000 ℃ and 1200 ℃ and N₂And NH₃Keeping the temperature for 1 to 3 hours under the atmosphere of the mixed gas to obtain Si-doped W₂N-layer or Si-doped Mo₂N layers;

(3) mixing Al, Cr, Mo, Fe and Ni in a nearly equimolar ratio to obtain multi-component mixed powder, adding the multi-component mixed powder into WC particles, and carrying out ball-milling mixing to obtain multi-component mixed powder containing WC;

(4) spraying the multi-element mixed powder prepared in the step (3) on Si-doped W by adopting an atmospheric plasma spraying technology₂N-layer or Si-doped Mo₂Preparing a WC-AlMoCrFeNi composite layer on the surface of the N layer; after ion spraying, placing the mixture in a muffle furnace, preserving the heat for 15-30min at the temperature of 350-500 ℃ under the protection of inert gas, and naturally cooling to room temperature.

Further, the method also comprises the step (5): repeating the steps (2) - (4) one or more times until a plurality of layers of laminated composite coatings are obtained.

Further, the specific process of the step (1) is as follows:

polishing: polishing the sample by using 100-2000-mesh abrasive paper step by step until the surface of the sample is bright and flat;

oil removal: placing the valve body substrate in alcohol or acetone for ultrasonic cleaning and oil removal;

acid washing: removing scratches and a hardened layer on the surface of the substrate by using a solution containing 5% of hydrofluoric acid, 40% of nitric acid and 55% of deionized water;

sand blasting: the abrasive material for sand blasting is brown corundum, the granularity is 60-100 meshes, the sand blasting time is 5-10s, the sand blasting distance is 30-60mm, and the air pressure is 0.5-1 MPa.

Further, the valve body is made of 20Cr, 45 steel or GCr 15; the ball milling parameters of the multi-element mixed powder in the step (3) are as follows: mixing for 1-2h at the rotating speed of 60-120 rpm; the protective gas is nitrogen or argon.

Further, the Si-doped W prepared in the step (2)₂N-coating or Si-doped Mo₂The thickness of the N layer is 50-150 mu m; the thickness of the WC-AlMoCrFeNi composite layer prepared in the step (4) is 40-100 mu m.

Further, the laser cladding conditions in the step (2) are as follows: the laser power is 1.5-2kW, the protective gas is argon, the flow rate is 100-150mL/min, the tungsten source is metal tungsten, the silicon source is simple substance silicon, the powder feeding mode is coaxial powder feeding, the defocusing amount is 45-50mm, the spot size is 4-5mm, the scanning speed is 15-20mm/s, the lap joint rate is 50-75%, and the powder feeding amount is 20 g/min; the heat preservation temperature of the tubular furnace is 1000-1200 ℃, and the heat preservation time is 3-5 h.

Further, in the step (4), during the atmospheric plasma spraying, the used fuel gas is propane, the combustion-supporting gas is oxygen, the powder feeding gas is nitrogen, the flow rate of the fuel gas is 20-80mL/min, the flow rate of the combustion-supporting gas is 200-400mL/min, and the flow rate of the powder feeding gas is 20-80 mL/min.

The valve body is provided with the high-hardness and high-wear-resistance composite coating applied to the surface of the valve body.

The high-hardness and high-wear-resistance composite coating prepared by the invention utilizes the high strength, high hardness, high wear resistance and high corrosion resistance of the two-dimensional ceramic material and the high-entropy alloy, introduces the Si-doped W2N, WC and a novel high-entropy alloy AlMoCrFeNi multilayer composite coating on the surface of the valve body, and adopts the traditional W-doped W2N, WC and AlMoCrFeNi multilayer composite coating₂Si and WC are respectively doped in the N coating and the high-entropy alloy coating, and the hardness and toughness of the two coatings are further improved in a doping mode, so that the wear resistance is improved. Meanwhile, the preparation method of the coating comprises the steps of cladding the mixed powder of simple substance silicon and tungsten on the surface of the matrix in a laser cladding mode, and then cladding the mixed powder of simple substance silicon and tungsten on the surface of the matrix by NH₃Reacting W in the mixed layer as a nitrogen source and cladding to generate W₂N, the preparation process makes silicon in W₂More uniform dispersion in NThe conditions of segregation and uneven distribution do not exist, and the doping strengthening effect is improved. In the preparation process of the WC-AlMoCrFeNi composite layer, the mixed micro powder of the WC and the AlMoCrFeNi composite layer is sprayed on the silicon-doped W in a plasma spraying mode₂On the N layer, the bonding strength of the two coatings is improved, and the distribution of WC in the high-entropy alloy is more uniform. The composite coating combines the advantages of high-temperature ceramics and high-entropy alloy, thereby having high hardness and high wear resistance, and being suitable for preparing the coating which has compact and uniform structure, high hardness, high strength, high toughness, high wear resistance and good corrosion resistance. According to the invention, a multilayer film structure is formed on the surface of the valve body through a simple coating process, the hardness and the friction performance of the valve body are effectively improved by about 10% compared with the traditional valve body, and the valve body has a wide practical application prospect.

In addition, in the preparation process, all reagents are commercial products, the re-preparation is not needed, the process is simple, the cost is low, the production process is simple and easy to control, the product difference rate is high, and the method is suitable for large-scale industrial production. The hardness and the wear resistance of the prepared composite coating are greatly improved.

Drawings

FIG. 1 is Si-doped W prepared in example 1₂TEM image of N.

FIG. 2 is a gold phase diagram of the WC-AlMoCrFeNi composite layer prepared in example 1.

FIG. 3 is an SEM image of the wear scar of the substrate after the rubbing test with example 1.

Detailed Description

The present invention will be further described with reference to the following specific examples, but the scope of the present invention is not limited thereto.

Example 1:

a20 Cr valve body is used as a base material, and a high-hardness and high-wear-resistance composite coating is prepared on the surface of the valve body, and the method comprises the following specific steps:

(1) using 20Cr as a base material, and gradually polishing the surface of a sample by using 100-mesh, 200-mesh, 500-mesh and 1500-mesh sand paper until the surface of the sample is bright and flat; then, the 20Cr substrate is placed in alcohol or acetone for ultrasonic cleaning and oil removal, a solution containing 5% hydrofluoric acid, 40% nitric acid and 55% deionized water is adopted to remove scratches and a hardened layer on the surface of the substrate, and then surface sand blasting treatment is carried out, wherein the sand blasting abrasive is brown corundum, the granularity is 60 meshes, the sand blasting time is 5s, the sand blasting distance is 30mm, and the air pressure is 0.5 MPa; the 20Cr substrate with smooth surface is obtained.

(2) And (2) cladding W, Si mixed powder on the surface of the 20Cr substrate treated in the step (1) by adopting a laser cladding technology, wherein the laser power is 1.7kW, the protective gas is argon, the flow is 100mL/min, the powder feeding mode is coaxial powder feeding, the diameter of a light spot is 2.5mm, the positive defocusing amount is 5mm, the scanning speed is 15mm/s, the lap joint rate is 50%, and the powder feeding amount is 15 g/min. After laser cladding, the mixture is placed in a muffle furnace at 1000 ℃ and N₂And NH₃Keeping the temperature for 1h in the mixed gas atmosphere, and naturally cooling to room temperature to obtain Si-doped W₂And (4) coating N. Prepared Si-doped W₂The thickness of the N coating was 70 μm. A TEM image of the above sample subjected to TEM test is shown in fig. 1, and a distinct layered structure can be observed.

(3) Mixing Cr, Mo, Fe, Co and Ni with the purity of more than or equal to 99.0 percent and the granularity of less than 100 meshes in nearly equal molar ratio, wherein the atomic number content is 18-22 percent of Cr, 18-22 percent of Mo, 18-22 percent of Fe, 18-22 percent of Co and 18-22 percent of Ni, simultaneously adding WC particles with the purity of more than or equal to 99.0 percent and the granularity of less than 200 meshes, wherein the adding amount of the WC particles is 5 percent of the total mass of the mixed powder of Cr, Mo, Fe, Co and Ni, placing the mixture in a grinding tank, and carrying out ball milling and mixing for 1h to obtain the multi-component mixed powder containing WC.

(4) Spraying the WC-containing multi-component mixed powder prepared in the step (3) on Si-doped W by adopting an atmospheric plasma spraying technology₂Preparing a WC-AlMoCrFeNi composite layer with the thickness of 80 mu m on the surface of the N coating. Spraying conditions are as follows: the used fuel gas is propane, the gas flow of the fuel gas is 35mL/min, the combustion-supporting gas is oxygen, the gas flow of the combustion-supporting gas is 150mL/min, the powder feeding gas is nitrogen, the gas flow of the powder feeding gas is 40mL/min, the spraying distance is 80mm, and the length of the spraying pipe is 60 mm.

And (3) performing a metallographic experiment on the WC-AlMoCrFeNi composite layer prepared in the step (4), wherein the composite layer is composed of an irregular latticed structure and has good quality and no defects such as holes and cracks, as shown in figure 2.

Example 2:

(1) taking 45 steel as a base material, and gradually polishing the surface of a sample by adopting 150-mesh, 400-mesh, 1200-mesh and 2000-mesh sand paper until the surface of the sample is bright and flat; and then placing the 45 steel substrate in alcohol or acetone for ultrasonic cleaning and oil removal, removing scratches and a hardened layer on the surface of the substrate by adopting a solution containing 5% hydrofluoric acid, 40% nitric acid and 55% deionized water, and then carrying out surface sand blasting treatment to obtain the 45 steel substrate. The abrasive material for sand blasting is brown corundum, the granularity is 80 meshes, the sand blasting time is 70s, the sand blasting distance is 50mm, and the air pressure is 0.7 MPa.

(2) And cladding the W, Si mixed powder on the surface of the 45 steel matrix by a laser cladding method. The laser power is 1.5kW, the protective gas is argon, the flow is 120mL/min, the powder feeding mode is coaxial powder feeding, the spot diameter is 2.5mm, the positive defocusing amount is 5mmL/min, the scanning speed is 18mm/s, the lap joint rate is 60%, and the powder feeding amount is 15 g/min. After cladding, the workpiece is placed in a muffle furnace at 800 ℃ and N₂And NH₃Keeping the temperature for 2h in the mixed gas atmosphere, and naturally cooling to room temperature to obtain Si-doped W₂And (4) coating N. Prepared Si-doped W₂The thickness of the N coating was 120. mu.m.

(3) Mixing Cr, Mo, Fe, Co and Ni with the purity of more than or equal to 99.0 percent and the granularity of less than 100 meshes in nearly equal molar ratio, wherein the atomic number content is 18-22 percent of Cr, 18-22 percent of Mo, 18-22 percent of Fe, 18-22 percent of Co and 18-22 percent of Ni, simultaneously adding WC particles with the purity of more than or equal to 99.0 percent and the granularity of less than 200 meshes, wherein the adding amount of the WC particles is 8 percent of the total mass of the mixed powder of Cr, Mo, Fe, Co and Ni, placing the mixture in a grinding tank for ball milling and mixing for 1h, and placing the mixture in the grinding tank for ball milling and mixing for 1h to obtain the multi-component mixed powder containing WC.

(4) Spraying the WC-containing multi-component mixed powder prepared in the step (3) on Si-doped W by adopting an atmospheric plasma spraying technology₂Preparing a WC-AlMoCrFeNi composite layer with the thickness of 50 mu m on the surface of the N coating. Spraying conditions are as follows: the used fuel gas is propane, the gas flow of the fuel gas is 20mL/min, the combustion-supporting gas is oxygen, the gas flow of the combustion-supporting gas is 300mL/min, the powder feeding gas is nitrogen, the gas flow of the powder feeding gas is 20mL/min, the spraying distance is 40mm, and the length of the spraying pipe is 120 mm.

Example 3:

(1) using GCr15 as a base material, and gradually polishing by using 100-mesh, 200-mesh, 600-mesh, 1200-mesh and 2000-mesh sand paper until the surface of a sample is bright and flat; and then placing the GCr15 substrate in alcohol or acetone for ultrasonic cleaning and oil removal, removing scratches and a hardened layer on the surface of the substrate by using a solution containing 5% hydrofluoric acid, 40% nitric acid and 55% deionized water, and then performing surface sand blasting treatment to obtain the GCr15 substrate. The abrasive material for sand blasting is brown corundum, the granularity is 100 meshes, the sand blasting time is 10s, the sand blasting distance is 60mm, and the air pressure is 1 MPa.

(2) W, Si powder is cladded on the surface of the GCr15 base body by adopting a laser cladding technology. The laser power is 1.5kW, the protective gas is argon, the flow rate is 150mL/min, the powder feeding mode is coaxial powder feeding, the spot diameter is 2.5mm, the positive defocusing amount is 5mmL/min, the scanning speed is 20mm/s, the lap joint rate is 60%, and the powder feeding amount is 20 g/min. After cladding, the mixture is placed in a muffle furnace at 850 ℃ and N₂And NH₃Keeping the temperature for 3h in the mixed gas atmosphere, and naturally cooling to room temperature to obtain Si-doped W₂And (4) coating N. Prepared Si-doped W₂The thickness of the N coating was 140 μm.

(3) Mixing Cr, Mo, Fe, Co and Ni with the purity of more than or equal to 99.0 percent and the granularity of less than 100 meshes in nearly equal molar ratio, wherein the atomic number content of the Cr, the Mo, the Fe, the Co and the Ni is 18-22 percent, 18-22 percent and 18-22 percent respectively, simultaneously adding WC particles with the purity of more than or equal to 99.0 percent and the granularity of less than 200 meshes, wherein the adding amount of the WC particles is 5 percent of the total mass of the mixed powder of the Cr, the Mo, the Fe, the Co and the Ni, placing the mixture in a grinding tank for ball milling and mixing for 1 hour, placing the mixture in the grinding tank for ball milling and mixing for 2 hours, and obtaining the multi-component mixed powder containing WC.

(4) Spraying the WC-containing multi-component mixed powder prepared in (3) on Si-doped W by adopting an atmospheric plasma spraying technology₂Preparing a WC-AlMoCrFeNi composite layer with the thickness of 90 mu m on the surface of the N coating. Spraying conditions are as follows: the used fuel gas is propane, the gas flow of the fuel gas is 80mL/min, the combustion-supporting gas is oxygen, the gas flow of the combustion-supporting gas is 400mL/min, the powder feeding gas is nitrogen, the gas flow of the powder feeding gas is 80mL/min, the spraying distance is 120mm, and the length of the spraying pipe is 200 mm.

Table 1 shows the response of the composite coatings prepared in the three examples and the hardness of the base material, and the hardness of the composite coatings prepared by the present invention is improved to a great extent by comparison.

TABLE 1 hardness of each example and comparative example

The friction properties of the composite coatings prepared in the above examples were measured using a UMT-2 multipurpose Friction wear tester, from CETR, USA. The friction experiment process adopts a ball disc type friction mode, the upper sample adopts a 440C stainless steel ball with the diameter of 10mm, and the material hardness is HRC 62; the lower samples were made of the base materials having the high-hardness and high-abrasion-resistance composite coatings prepared in examples 1 to 3 of the present invention, respectivelyA disk. Friction test conditions: the load is 10-30N, the rotating speed is 100rpm, and the experimental time is 1 h. The test results are shown in table 2, and experiments prove that the composite coating prepared by the invention has lower friction coefficient, reduces the wear rate under the same conditions, and greatly improves the wear resistance of the matrix. In addition, the composite coating prepared in example 1 was subjected to SEM test for wear scar after friction test and compared with the wear scar of the 20Cr substrate, as shown in fig. 3, wherein (a) is the wear scar of the 20Cr substrate after friction test and (b) is the wear scar of the composite coating prepared in example 1 after friction test. It is clear that the composite coating prepared in example 1 has a shallower wear scar and less wear by the friction test, which is consistent with the wear rate data.

TABLE 2 Friction Properties of examples and comparative examples

The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.