阅读说明：本技术 适用于氧-丙烷超音速火焰短距离喷涂的碳化钨/碳化硅基复合材料、涂层及其制备方法 (Tungsten carbide/silicon carbide-based composite material and coating suitable for oxygen-propane supersonic flame short-distance spraying and preparation method thereof ) 是由 陈小明 张磊 刘德有 方勇 赵坚 毛鹏展 刘伟 张凯 伏利 霍嘉翔 苏建灏 于 2021-08-10 设计创作，主要内容包括：本发明公开了一种适用于氧-丙烷超音速火焰短距离喷涂的碳化钨/碳化硅基复合材料、涂层及其制备方法。该复合材料粉末的组成及质量分数为：纳米WC：60～75wt％、纳米SiC：10～20wt％、Co：5～8wt％、Cr：6～10wt％、Nb：1～5wt％,Al：2～4wt％,Re：0.5～4wt％。涂层制备方法如下：以该配方为喷涂材料,通过氧-丙烷超音速火焰90°内孔喷枪喷涂到经过预处理的钢质基材表面,最终形成厚度为100～500μm的涂层,该涂层均匀致密,孔隙率＜0.5％；显微硬度＞1150HV-(0.2)；涂层与基材结合强度≥72Mpa；涂层粗糙度＜Ra 4μm。涂层具有优良的耐腐蚀、抗泥沙冲蚀磨损性能,可满足水轮机、水泵等工件的狭窄内表面的喷涂。(The invention discloses a tungsten carbide/silicon carbide-based composite material and a coating suitable for oxygen-propane supersonic flame short-distance spraying and a preparation method thereof. The composite material powder comprises the following components in percentage by mass: nano WC: 60-75 wt%, nano SiC: 10-20 wt%, Co: 5-8 wt%, Cr: 6-10 wt%, Nb: 1-5 wt%, Al: 2-4 wt%, Re: 0.5 to 4 wt%. The preparation method of the coating comprises the following steps: the formula is used as a spraying material, and the spraying material is sprayed to the surface of the pretreated steel base material through an oxygen-propane supersonic flame 90-degree inner hole spray gun to finally form a coating with the thickness of 100-500 mu m, wherein the coating is uniform and compact, and the porosity is less than 0.5%; microhardnessDegree > 1150HV 0.2 (ii) a The bonding strength of the coating and the base material is more than or equal to 72 Mpa; the roughness of the coating is less than Ra 4 mu m. The coating has excellent corrosion resistance and sand erosion and abrasion resistance, and can meet the requirement of spraying the narrow inner surfaces of workpieces such as water turbines, water pumps and the like.)

1. The tungsten carbide/silicon carbide-based composite material suitable for oxygen-propane supersonic flame short-distance spraying is characterized by comprising the following components in percentage by weight: nano WC powder: 60-75 wt%, nano SiC powder: 10-30 wt%, Co metal powder: 5-8 wt%, Cr metal powder: 6-10 wt%, Nb metal powder: 1-5 wt%, Al metal powder: 1.5-4 wt%, Re metal powder: 0.5 to 3 wt%.

2. The tungsten carbide/silicon carbide-based composite material suitable for oxygen-propane supersonic flame short-distance spraying according to claim 1, wherein the particle size of the nano WC powder is 50-100 nm, the particle size of the nano SiC powder is 50-900 nm, the particle size of the Co metal powder is 0.5-1 μm, the particle size of the Cr metal powder is 0.5-1 μm, the particle size of the Nb metal powder is 0.5-1 μm, the particle size of the Al metal powder is 0.5-1 μm, and the particle size of the Re metal powder is 50-100 nm.

3. The tungsten carbide/silicon carbide-based composite material suitable for oxygen-propane supersonic flame short-distance spraying according to claim 1, wherein the purity of the nano SiC powder is not less than 99.9%, the purity of the Nb metal powder is not less than 99.9%, and the purity of the Re metal powder is not less than 99.9%.

4. A preparation method of a tungsten carbide/silicon carbide-based composite coating suitable for oxygen-propane supersonic flame short-distance spraying is characterized by comprising the following steps:

the method comprises the following steps: alloy powder formulation preparation

(1) Mixing the tungsten carbide/silicon carbide-based composite material according to any one of claims 1 to 3 in a ball mill for 15 to 35 hours, and performing spray drying to obtain composite powder with the particle size of 15 to 35 μm;

(2) placing the composite powder obtained in the last step in a drying oven, and drying for 3-5 hours at 100-150 ℃ for later use;

step two: pretreatment of substrate surfaces

(1) Removing oil and dirt of the base material to be clean through absolute ethyl alcohol or acetone, and drying;

(2) the surface of the base material is roughened by adopting a compressed air power sand blasting method, and the roughening treatment mode is as follows: selecting 20-40 meshes of white corundum, using compressed air for sand blasting at 0.5-0.6 Mpa, wherein the sand blasting distance is 80-150 mm, and the sand blasting angle is 60-90 degrees;

step three: oxy-propane supersonic flame internal hole spraying

And (3) spraying by using oxygen-propane supersonic flame spraying equipment and an inner hole spray gun to obtain the tungsten carbide/silicon carbide-based composite coating on the surface of the base material.

5. The method for preparing the tungsten carbide/silicon carbide-based composite coating according to claim 4, wherein the parameters of the spraying process in the third step are as follows: the flow rate of propane is 60-70L/min, the flow rate of oxygen is 220-240L/min, the flow rate of compressed air is 350-375L/min, the powder feeding rate is 35-100 g/min, the flow rate of powder-carrying nitrogen is 10-15L/min, the spraying distance is 100-300 mm, the spraying angle is 45-90 degrees, and the traveling speed of a spray gun is 300-500 mm/s.

6. The method for preparing the tungsten carbide/silicon carbide-based composite coating according to claim 4, wherein the spraying distance is less than or equal to 150 mm.

7. The method for preparing the tungsten carbide/silicon carbide-based composite coating according to claim 4, wherein the thickness of the obtained composite coating is 100-500 μm, the porosity is less than 0.5%, and the microhardness is more than 1150HV_0.2The bonding strength of the coating and the base material is more than or equal to 72Mpa, the roughness of the coating is less than Ra 4 mu m, and the coating has no bubble and corrosion and the silt erosion resistance is more than 7.5 times of that of 0Cr13Ni5Mo stainless steel through a 1000-hour neutral salt spray test.

Technical Field

The invention belongs to the field of wear resistance, corrosion resistance, cavitation erosion resistance and silt erosion protection of the surface of a mechanical part, and particularly relates to a wear-resistant and corrosion-resistant tungsten carbide/silicon carbide-based composite material and a coating which are suitable for an oxygen-propane supersonic flame process and are sprayed in a short distance (particularly, the spraying distance is less than or equal to 150mm), and a preparation method thereof.

Background

In the fields of water conservancy and hydropower, mechanical manufacturing, aerospace, chemical engineering and petroleum and the like, many key and important parts have narrow inner hole structures, such as an inner flow passage of a mixed-flow turbine, an engine cylinder hole, a hydraulic mechanism pump shell and the like, and the inner structures of the parts are in service under severe working conditions of high-speed overflow, high temperature and high pressure, corrosive wear and the like, so that the parts are easy to lose effectiveness such as serious wear, corrosion, fatigue and the like. At present, the service life of the part is improved mainly by preparing an anti-wear and anti-corrosion coating on the inner wall of the part. Including electroplating/electroless plating, anodization, thermal spraying, physical/chemical vapor deposition, and the like. Wherein, the use of electroplating is gradually limited due to the problems of complex process, environmental pollution of electroplating solution and the like; the anodic oxidation has specific requirements on the material of the base material and cannot be widely applied; physical/chemical vapor deposition processes have disadvantages such as high cost, limited coating thickness, and the like, which are difficult to apply on a large scale. The hot spraying technology represented by spraying WC coatings by using the supersonic flame technology (HVOF) has small limitation on the material and size of workpieces, the coating has good wear resistance and corrosion resistance, the coating material is wide, the production efficiency is high, the production cost is low, and the hot spraying technology has the remarkable advantages of universality, practicability, economy and the like. However, due to the technical characteristics of thermal spraying, the conventional HVOF spray gun is difficult to penetrate into the inner space of a workpiece, and cannot realize ideal spraying distance, vertical angle, and the freedom of movement and running speed of the spray gun which are accurately controlled, so that the problem of inner hole spraying is difficult to effectively solve by the conventional thermal spraying technology. In recent years, the development of the inner-hole supersonic flame spray gun provides convenience for solving the problem, and the design of the spray gun with multiple spraying angles can realize near-vertical spraying to the maximum extent by lengthening and extending a miniaturized spray gun into a workpiece.

However, the spraying distance of the current inner bore spraying spray gun is still large, when the conventional WC-CoCr powder is adopted for spraying, when the spraying distance is reduced to be less than 150mm, the heating and acceleration time of powder particles in flame flow jetted from a bore combustion chamber is short under the condition of extremely short spraying distance, particles with low melting degree cannot be fully spread and flow after impacting the surface due to poor fluidity, and gaps among deposited particles cannot be filled, so that the larger porosity is caused; meanwhile, the particles on the surface layer of the coating keep the original shape due to poor fluidity to form densely distributed large raised particles, which causes the severe roughness phenomenon on the surface of the coating. Furthermore, the coating is exposed to high temperature impacts of the flame stream at short spray distances, and the susceptibility to cracking increases due to thermal shock.

Therefore, innovative improvement on powder feeding is needed, and the spraying distance is further reduced on the premise of ensuring the performance and quality of the coating, so that the method is suitable for spraying the carbide coating by using the oxygen-propane supersonic flame in a narrower space.

Disclosure of Invention

Aiming at the defects of the existing technology for spraying a carbide coating in an inner hole of an oxygen-propane supersonic flame, the invention provides an anti-wear and anti-corrosion tungsten carbide/silicon carbide-based composite material and a coating which are suitable for oxygen-propane supersonic flame short-distance spraying (particularly when the spraying distance is less than or equal to 150mm), and a preparation method thereof. The technical scheme adopted by the invention is as follows:

the invention relates to a tungsten carbide/silicon carbide-based composite material suitable for oxygen-propane supersonic flame short-distance spraying, which comprises the following components in percentage by weight: 60-75 wt%, SiC: 10-30 wt%, Co: 5-8 wt%, Cr: 6-10 wt%, Nb: 1-5 wt%, Al: 1.5-4 wt%, Re: 0.5 to 3 wt%.

The particle size of the tungsten carbide/silicon carbide-based composite material is 50-100 nm of the particle size of nano WC powder, 50-900 nm of the particle size of nano SiC powder, 0.5-1 mu m of the particle size of Co metal powder, 0.5-1 mu m of the particle size of Cr metal powder, 0.5-1 mu m of the particle size of Nb metal powder, 0.5-1 mu m of the particle size of Al metal powder and 50-100 nm of the particle size of Re metal powder. The composite powder is prepared in a spray drying mode, and the particle size is 15-35 mu m.

The tungsten carbide/silicon carbide-based composite material has the component purity that the purity of the nano SiC powder is not less than 99.9 percent, the purity of the Nb metal powder is not less than 99.9 percent, and the purity of the Re metal powder is not less than 99.9 percent.

The tungsten carbide/silicon carbide-based composite coating is prepared by spraying the powder formula through an inner hole spray gun with a hydrogen-propane supersonic flame of 45 degrees or 90 degrees, the thickness of the obtained coating is 100-500 mu m, the porosity is less than 0.5%, and the microhardness is more than 1150HV_0.2The bonding strength between the coating and the base material is more than or equal to 72Mpa, and the roughness of the coating is less than Ra 4 mu m. Through a 1000h neutral salt spray test, the coating has no phenomena of bubbles, corrosion and the like. The silt scouring resistance is more than 7.5 times of that of 0Cr13Ni5Mo stainless steel.

The preparation method of the wear-resistant and corrosion-resistant tungsten carbide/silicon carbide-based composite coating comprises the following steps:

the method comprises the following steps: alloy powder formulation preparation

(1) Mixing nano WC powder, nano SiC powder, Co metal powder, Cr metal powder, Nb metal powder, Al metal powder and Re metal powder according to a ratio, mixing for 15-35 hours in a ball mill to realize homogenization of the composite material, and performing spray drying to obtain the composite material with the granularity of 15-35 mu m.

(2) And (3) placing the composite powder obtained in the last step into a drying oven, and drying for 3-5 hours at 100-150 ℃ for later use.

Step two: pretreatment of substrate surfaces

(1) Removing oil and dirt of the base material to be clean through absolute ethyl alcohol or acetone, and drying;

(2) and performing texturing treatment on the surface of the base material by adopting a compressed air power sand blasting method, wherein 20-40-mesh white corundum is selected, the compressed air used for sand blasting is 0.5-0.6 Mpa, the sand blasting distance is 80-150 mm, and the sand blasting angle is 60-90 degrees.

Step three: oxy-propane supersonic flame internal hole spraying

Adopting oxygen-propane supersonic flame spraying equipment and an inner hole spray gun to obtain the wear-resistant and corrosion-resistant tungsten carbide/silicon carbide-based composite coating on the surface of the base material. The parameters of the spraying process in the third step are as follows: the flow rate of propane is 60-70L/min, the flow rate of oxygen is 220-240L/min, the flow rate of compressed air is 350-375L/min, the powder feeding rate is 35-100 g/min, the flow rate of powder-carrying nitrogen is 10-15L/min, the spraying distance is 100-300 mm, the spraying angle is 45-90 degrees, and the traveling speed of a spray gun is 300-500 mm/s.

The invention has the following advantages: in the formula of the invention, the nano WC has the characteristics of high melting point, high hardness, high strength and the like, and the nano WC is uniformly distributed to play a role of an anti-wear network and a framework; the silicon carbide with lower melting point is partially melted in the high-temperature spraying flame flow and has good wettability with the metal-based binding phase, the crack sensitivity of the coating is reduced, and simultaneously, partial SiC is oxidized and decomposed to generate SiO₂The fused mass can fill the pores of the coating, and the compactness of the coating is improved. The metal Nb can inhibit thick Cr in the coating₇C₃And the growth of primary carbides is reduced, so that the brittleness and crack sensitivity of the coating are reduced. Tong (Chinese character of 'tong')The melting point of the composite metal matrix is reduced by adding Al, the particle melting property and the flattening degree can be improved under a shorter spraying distance, and the porosity of the coating is reduced. The rare-earth Re can improve the toughness and the thermal shock resistance of the metal matrix, so that the cracking sensitivity of the coating is reduced to be lower under a shorter spraying distance. The tungsten carbide/silicon carbide-based composite coating has the thickness of 100-500 mu m, the porosity of less than 0.5 percent and the microhardness of more than 1150HV_0.2The bonding strength between the coating and the base material is more than or equal to 72Mpa, and the roughness of the coating is less than Ra 4 mu m. The coating is uniform, compact and crack-free, has low porosity and has excellent wear resistance, corrosion resistance and sand erosion resistance.

The wear-resistant corrosion-resistant tungsten carbide/silicon carbide-based composite material and the coating which are suitable for spraying the inner hole of the oxygen-propane supersonic flame contain metal-based alloy components with excellent corrosion resistance, hard ceramic components with excellent wear resistance and components for improving the organizational structure and toughness of the coating, the excellent corrosion resistance, wear resistance and sand erosion resistance of the WC metal ceramic coating can be realized in a shorter spraying distance, and the tungsten carbide/silicon carbide-based composite material and the coating are suitable for spraying the inner space of engineering machinery, hydraulic machinery and the like.

Detailed Description

Example 1:

(1) composite powder

Mixing nano WC with the powder granularity of 50-100 nm, nano SiC with the granularity of 50-100 nm and the purity of not less than 99.9%, Co metal powder with the granularity of 0.5-1 mu m, Cr metal powder with the granularity of 0.5-1 mu m, Nb metal powder with the granularity of 0.5-1 mu m and the purity of not less than 99.9%, Al metal powder with the granularity of 0.5-1 mu m and Re metal powder with the granularity of 50-100 nm and the purity of not less than 99.9%.

Wherein the mass fraction of each component is as follows: 60 wt% of WC, SiC: 10 wt%, Co: 10 wt%, Cr: 8 wt%, Nb: 5 wt%, Al: 4 wt%, Re: 3 wt%. And mixing the mixed powder in a ball mill for 35 hours to realize homogenization of the composite material, and performing spray drying to obtain the composite material with the granularity of 15-35 microns. And placing the obtained composite powder in a drying oven, and drying for 3h at 100 ℃ for later use.

(2) Substrate pretreatment

Using absolute ethyl alcohol to remove oil and dirt on the 45 steel substrate until the substrate is clean, and drying the substrate; the surface of the base material is roughened by adopting a compressed air power sand blasting method, 40-mesh white corundum is selected, the compressed air used for sand blasting is 0.5 Mpa, the sand blasting distance is 120mm, and the sand blasting angle is 90 degrees.

(3) Oxy-propane supersonic flame internal hole spraying

And adopting oxygen-propane supersonic flame spraying equipment and a 90-degree inner hole spray gun to obtain the wear-resistant and corrosion-resistant tungsten carbide/silicon carbide-based composite coating on the surface of the base material. The parameters of the spraying process are as follows: the flow rate of propane is 60L/min, the flow rate of oxygen is 230L/min, the flow rate of compressed air is 375L/min, the powder feeding speed is 85g/min, the flow rate of powder-carrying nitrogen is 12.5L/min, the spraying distance is 150mm, the spraying angle is 90 degrees, and the walking speed of a spray gun is 500 mm/s.

The wear-resistant and corrosion-resistant nickel-based silicon carbide composite coating is uniform and crack-free, and the thickness of the coating is 300 mu m. Microhardness of the coating is 1150HV_0.2Average porosity 0.32%, roughness Ra 3.2 μm, and coating and substrate bonding strength 73 MPa. Through a 1000h neutral salt spray test, the coating has no phenomena of bubbles, corrosion and the like. The silt scouring resistance is 8.3 times of that of 0Cr13Ni5Mo stainless steel.

Example 2:

(1) composite powder

Mixing nano WC with the powder granularity of 50-100 nm, nano SiC with the granularity of 50-100 nm and the purity of not less than 99.9%, Co metal powder with the granularity of 0.5-1 mu m, Cr metal powder with the granularity of 0.5-1 mu m, Nb metal powder with the granularity of 0.5-1 mu m and the purity of not less than 99.9%, Al metal powder with the granularity of 0.5-1 mu m and Re metal powder with the granularity of 50-100 nm and the purity of not less than 99.9%.

Wherein the mass fraction of each component is as follows: 65 wt% of WC, SiC: 15 wt%, Co: 8 wt%, Cr: 6 wt%, Nb: 3 wt%, Al: 2 wt%, Re: 1 wt%. And mixing the mixed powder in a ball mill for 35 hours to realize homogenization of the composite material, and performing spray drying to obtain the composite material with the granularity of 15-35 microns. And placing the obtained composite powder in a drying oven, and drying for 3h at 100 ℃ for later use.

(2) Substrate pretreatment

Degreasing the 40CrMnMo alloy steel base material by using absolute ethyl alcohol, removing dirt until the base material is clean, and drying; the surface of the base material is roughened by adopting a compressed air power sand blasting method, 30-mesh white corundum is selected, the compressed air used for sand blasting is 0.6Mpa, the sand blasting distance is 100mm, and the sand blasting angle is 90 degrees.

(3) Oxy-propane supersonic flame internal hole spraying

And (3) obtaining the wear-resistant and corrosion-resistant tungsten carbide/silicon carbide-based composite coating on the surface of the base material by adopting oxygen-propane supersonic flame spraying equipment and a 45-degree inner hole spray gun. The parameters of the spraying process are as follows: the flow rate of propane is 65L/min, the flow rate of oxygen is 235L/min, the flow rate of compressed air is 375L/min, the powder feeding speed is 65g/min, the flow rate of powder-carrying nitrogen is 12.5L/min, the spraying distance is 125mm, the spraying angle is 90 degrees, and the walking speed of a spray gun is 400 mm/s.

The wear-resistant and corrosion-resistant nickel-based silicon carbide composite coating is uniform and crack-free, and the thickness of the coating is 350 mu m. Microhardness of the coating was 1252HV_0.2Average porosity of 0.42%, roughness of Ra 3.8 μm, and bonding strength of the coating layer and the substrate of 75 MPa. The coating has no phenomena of bubbles, corrosion and the like through a 1500-hour neutral salt spray test. Through a 1000h neutral salt spray test, the coating has no phenomena of bubbles, corrosion and the like. The silt scouring resistance is 7.7 times of that of 0Cr13Ni5Mo stainless steel.

Example 3:

(1) composite powder

Mixing nano WC with the powder granularity of 50-100 nm, nano SiC with the granularity of 50-100 nm and the purity of not less than 99.9%, Co metal powder with the granularity of 0.5-1 mu m, Cr metal powder with the granularity of 0.5-1 mu m, Nb metal powder with the granularity of 0.5-1 mu m and the purity of not less than 99.9%, Al metal powder with the granularity of 0.5-1 mu m and Re metal powder with the granularity of 50-100 nm and the purity of not less than 99.9%.

Wherein the mass fraction of each component is as follows: 68 wt% of WC, SiC: 18 wt%, Co: 6 wt%, Cr: 4 wt%, Nb: 1.5 wt%, Al: 1.5 wt%, Re: 1 wt%. And mixing the mixed powder in a ball mill for 35 hours to realize homogenization of the composite material, and performing spray drying to obtain the composite material with the granularity of 15-35 microns. And placing the obtained composite powder in a drying oven, and drying for 3h at 100 ℃ for later use.

(2) Substrate pretreatment

Removing oil and dirt of a 0Cr13Ni5Mo stainless steel substrate by using acetone until the substrate is clean, and drying; the surface of the base material is roughened by adopting a compressed air power sand blasting method, 20-mesh white corundum is selected, the compressed air used for sand blasting is 0.6Mpa, the sand blasting distance is 80mm, and the sand blasting angle is 90 degrees.

(3) Oxy-propane supersonic flame internal hole spraying

And adopting oxygen-propane supersonic flame spraying equipment and a 90-degree inner hole spray gun to obtain the wear-resistant and corrosion-resistant tungsten carbide/silicon carbide-based composite coating on the surface of the base material. The parameters of the spraying process are as follows: the flow rate of propane is 70L/min, the flow rate of oxygen is 240L/min, the flow rate of compressed air is 375L/min, the powder feeding speed is 45g/min, the flow rate of powder-carrying nitrogen is 12.5L/min, the spraying distance is 150mm, the spraying angle is 90 degrees, and the walking speed of a spray gun is 350 mm/s.

The wear-resistant and corrosion-resistant nickel-based silicon carbide composite coating is uniform and crack-free, and the thickness of the coating is 400 mu m. Microhardness of the coating is 1336HV_0.2Average porosity 0.61%, roughness Ra 3.8 μm, and coating and substrate bonding strength 75 MPa. Through a 1000h neutral salt spray test, the coating has no phenomena of bubbles, corrosion and the like. The silt scouring resistance is 9.5 times of that of 0Cr13Ni5Mo stainless steel.

Comparative example 1

(1) Powder of

Commercial WC-10Co-4Cr crushing type powder is adopted, and the mass fractions of the components are as follows: 86 wt% of WC, Co: 10 wt%, Cr: 4 wt%; the particle size is 15-45 μm. The powder is put in a drying oven and dried for 3 hours at 100 ℃ for standby.

(2) Substrate pretreatment

Removing oil and dirt of a 0Cr13Ni5Mo stainless steel substrate by using acetone until the substrate is clean, and drying; the surface of the base material is roughened by adopting a compressed air power sand blasting method, 20-mesh white corundum is selected, the compressed air used for sand blasting is 0.6Mpa, the sand blasting distance is 80mm, and the sand blasting angle is 90 degrees.

(3) Oxy-propane supersonic flame internal hole spraying

And adopting oxygen-propane supersonic flame spraying equipment and a 90-degree inner hole spray gun to obtain a WC-10Co-4Cr coating on the surface of the base material. The parameters of the spraying process are as follows: the flow rate of propane is 60L/min, the flow rate of oxygen is 230L/min, the flow rate of compressed air is 375L/min, the powder feeding speed is 85g/min, the flow rate of powder-carrying nitrogen is 12.5L/min, the spraying distance is 150mm, the spraying angle is 90 degrees, and the walking speed of a spray gun is 500 mm/s.

The coating has micro cracks and the thickness of the coating is 298 mu m. Microhardness of coating 1110HV_0.2Average porosity of 1.1%, roughness of Ra 5.2 μm, and bonding strength of the coating layer and the substrate of 62 MPa. And in a 120-hour neutral salt spray test, the coating has the phenomena of corrosion traces, partial falling and the like.

Comparative example 2

(1) Powder of

Commercial WC-10Co-4Cr agglomerated powder is adopted, and the mass fractions of the components are as follows: 86 wt% of WC, Co: 10 wt%, Cr: 4 wt%; the particle size is 15-45 μm. The powder is put in a drying oven and dried for 3 hours at 100 ℃ for standby.

(2) Substrate pretreatment

Removing oil and dirt of a 0Cr13Ni5Mo stainless steel substrate by using acetone until the substrate is clean, and drying; the surface of the base material is roughened by adopting a compressed air power sand blasting method, 20-mesh white corundum is selected, the compressed air used for sand blasting is 0.6Mpa, the sand blasting distance is 80mm, and the sand blasting angle is 90 degrees.

(3) Oxy-propane supersonic flame internal hole spraying

And adopting oxygen-propane supersonic flame spraying equipment and a 90-degree inner hole spray gun to obtain a WC-10Co-4Cr coating on the surface of the base material. The parameters of the spraying process are as follows: the flow rate of propane is 70L/min, the flow rate of oxygen is 240L/min, the flow rate of compressed air is 375L/min, the powder feeding speed is 45g/min, the flow rate of powder-carrying nitrogen is 12.5L/min, the spraying distance is 150mm, the spraying angle is 90 degrees, and the walking speed of a spray gun is 350 mm/s.

The coating has micro cracks and the thickness is 390 mu m. Microhardness of the coating is 1140HV_0.2Average porosity of 1.05%, roughness of Ra 4.9 μm, and bonding strength of the coating layer and the substrate of 59 MPa. And in 96h neutral salt spray test, the coating has the phenomena of corrosion trace, partial falling and the like.