Supersonic arc spraying wear-resistant and corrosion-resistant coating material and preparation method thereof

Abstract

The invention discloses a supersonic speed electric arc spraying wear-resistant and corrosion-resistant coating material and a preparation method, the supersonic speed electric arc spraying wear-resistant and corrosion-resistant coating material is composed of the following components of, by mass, 60-75 parts of NiCr alloy, 15-25 parts of WC-Co, 5-10 parts of Al2O3-TiO2 composite ceramic powder and 1-3 parts of rare earth oxide Y2O3, a coating is of a gradient composite structure, and the NiCr alloy and the WC-Co are distributed in a gradient mode according to the spraying layer number. The preparation method comprises the steps that the surface of the base body is subjected to sand blasting roughening treatment; a supersonic speed electric arc spraying device is adopted for spraying, the electric arc current is controlled to range from 130 A to 210 A, and the spraying distance ranges from 80 mm to 150 mm; and coating hole sealing treatment. Through a composite metal-ceramic material system and a rare earth element grain refinement effect and in combination with a supersonic spraying process, the compactness (porosity is smaller than or equal to 1.5%) of the coating is remarkably improved, the bonding strength of the coating is larger than or equal to 50 MPa, the HV hardness is larger than or equal to 800, the service life in a high-temperature corrosion environment is prolonged by three times or above, and the coating is suitable for surface protection under severe working conditions such as a boiler water cooling wall.

Description

Technical Field

[0001] The present invention relates to the technical field of surface coating, and particularly relates to a wear-resistant and corrosion-resistant coating material prepared by supersonic arc spraying and a preparation method thereof. Background Art

[0002] Existing boiler water walls are prone to chemical corrosion, electrochemical corrosion and abrasion failure under the action of high temperature and corrosive media (such as urea decomposition products, ammonium cyanate, etc.), leading to the risk of tube wall leakage. Traditional spraying materials (such as ordinary alloy coatings) have problems such as high porosity (>5%), low bonding strength (<20 MPa), and insufficient high-temperature corrosion resistance.

[0003] In view of the above defects, the present invention provides a coating solution with high density, strong bonding force and high-temperature corrosion resistance through material component optimization and preparation process innovation.

[0004] As the core pressure-bearing component in the fields of thermal power generation, chemical industry, etc., the boiler water wall is long-term exposed to a complex environment of high temperature (>500°C) and strong corrosive media (such as urea decomposition products NH3, CO2, ammonium cyanate, etc.), facing the combined action of multiple damages such as chemical corrosion, electrochemical corrosion and coal ash particle erosion. Traditional protection methods mostly use ordinary alloy coatings (such as NiCr alloy, FeCrAl coating) or single ceramic coatings (such as Al2O3), but there are the following significant defects:

[0005] (1) High porosity: The porosity of traditional arc spraying coatings is generally >5% (ASTM B276 standard), and corrosive media can easily penetrate through the pores to the matrix interface, accelerating local corrosion;

[0006] (2) Low bonding strength: The bonding strength between the coating and the matrix is <20 MPa (ASTM C633 standard), and it is prone to peeling failure under thermal stress cycling;

[0007] (3) Insufficient high-temperature corrosion resistance: When ordinary NiCr alloy is in long-term service above 600°C, the ability of Cr element at the grain boundary to oxidize to form a Cr2O3 protective film decreases, resulting in grain boundary corrosion cracking; pure ceramic coatings generate microcracks due to the mismatch of thermal expansion coefficients during temperature fluctuations.

[0008] Dilemma in the improvement of the prior art:

[0009] For example, Patent CN119372576A improves the deposition efficiency by optimizing the structure of the spraying gun body, but does not solve the problem of insufficient intrinsic corrosion resistance of the material; Patent JP2009515042A uses laser remelting to reduce porosity, but the process is complex and costly, and it is difficult to be used in large industrial equipment.

[0010] It can be seen that the above-mentioned existing protective coatings for boiler water walls obviously still have inconveniences and defects in terms of material design, preparation methods, and service performance, and thus urgently need to be further improved. Specifically, they are manifested as follows:

[0011] Method defects: The components of traditional spraying materials are single, and they cannot resist wear, oxidation, and medium corrosion synergistically.

[0012] Manufacturing method defects: The process parameters of conventional arc spraying are extensive, resulting in poor coating density and weak interfacial bonding.

[0013] Processing method defects: The post-treatment technology (such as sealing holes) does not match the material properties, the penetration rate of the sealing agent is low, and it is difficult to seal micron-sized pores.

[0014] To solve the above problems, relevant manufacturers and research institutions have tried various technical routes. For example:

[0015] Developing amorphous alloy coatings to eliminate grain boundary corrosion channels, but amorphous materials have poor thermal stability and are prone to crystallization at high temperatures; using cold spraying technology to avoid material oxidation, but the coating bonding strength is low (<15 MPa) due to insufficient particle velocity.

[0016] However, these methods have not been able to form a solution that can be applied on a large scale, either due to high costs or poor process compatibility.

[0017] In view of the above-mentioned defects of the existing protective coatings for boiler water walls, the inventor, based on more than ten years of practical experience and professional knowledge in the research and development of thermal spraying materials and engineering applications, and in combination with materials science and surface engineering theory, actively conducts research and innovation. By deeply analyzing the coating failure mechanism, a technical idea of "synergistic regulation of metal-ceramic composite system + rare earth modification + supersonic process" is proposed:

[0018] Introduce gradient metal-ceramic phases into the material components, taking into account toughness, hardness, and corrosion resistance.

[0019] Refine grains through rare earth oxides (Y2O3) to inhibit the diffusion of corrosive media along grain boundaries.

[0020] Combined with the stable wire feeding ability of the supersonic arc spraying device of CN119372576A, optimize the process parameters to improve the coating density. Summary of the Invention

[0021] To achieve the above object, the present invention provides the following technical solution: A wear-resistant and corrosion-resistant coating material for supersonic arc spraying, which is composed of the following components in parts by mass:

[0022] 60 to 75 parts of NiCr alloy, 15 to 25 parts of WC-Co, 5 to 10 parts of Al2O3-TiO2 composite ceramic powder, 1 to 3 parts of rare earth oxide Y2O3. The coating is a gradient composite structure, in which the NiCr alloy and WC-Co are distributed in a gradient according to the number of spray coatings.

[0023] Preferably, the Cr content in the NiCr alloy is 18wt%-22wt%, and the particle size is -200 mesh; the Co content in WC-Co is 6wt%-12wt%, and the particle size is -300 mesh.

[0024] Preferably, the TiO2 content in the Al2O3-TiO2 composite ceramic powder is 13wt%-17wt%, and the mass ratio of Al2O3 to TiO2 is 4:1 - 5:1.

[0025] Preferably, the coating material further includes 0.5 to 2 parts of graphene, the number of layers of the graphene is 1 - 5 layers, and the particle size is 1μm - 5μm.

[0026] Preferably, the coating material further includes 0.1 to 0.5 parts of nano-ZrO2, and the particle size of the nano-ZrO2 is 50nm - 100nm.

[0027] Furthermore, a preparation method of a supersonic arc spraying wear-resistant and corrosion-resistant coating material includes the following treatment steps:

[0028] Matrix pretreatment: The surface of the workpiece is subjected to sandblasting roughening treatment, and the roughness Ra≥5μm;

[0029] Supersonic arc spraying: Spraying is carried out by using a supersonic arc spraying device. Among them, the parameters include: 60 to 75 parts of NiCr alloy, 15 to 25 parts of WC-Co, 5 to 10 parts of Al2O3-TiO2 composite ceramic powder, 1 to 3 parts of rare earth oxide Y2O3;

[0030] Arc current 150 - 200A, voltage 28V - 32V, spraying distance 100mm - 130mm, wire feeding speed 3.5m / min - 4.2m / min;

[0031] Sealing hole treatment: After spraying, a silane coupling agent is used for sealing holes. The viscosity of the sealing agent is ≤15cP, and the curing temperature is 80℃ - 120℃.

[0032] Preferably, in step (2), the compressed air pressure is 0.6MPa - 0.75MPa, the gun moving speed is 250mm / s - 350mm / s, and the single-pass coating thickness is controlled within 30μm - 50μm.

[0033] Preferably, the hole-sealing agent is an organosilicon resin containing nano-SiO2, the particle size of nano-SiO2 is 20nm - 50nm, and the addition amount is 3wt% - 5wt%.

[0034] Preferably, in the hole-sealing treatment step, after the hole-sealing agent is sprayed, it is first left standing at room temperature for 15min - 20min, and then cured.

[0035] Preferably, in the hole-sealing treatment step, segmented curing is adopted during hole-sealing treatment, the curing time is 40min - 55min, the temperature of the curing environment is 15°C - 20°C, and the relative humidity is 40% - 60%.

[0036] The main object of the present invention is to overcome the defects of existing protective coatings for boiler water walls, such as high porosity (>5%), low bonding strength (<20MPa), and insufficient high-temperature corrosion resistance. A supersonic arc spraying wear-resistant and corrosion-resistant coating material and its preparation method are provided. The technical problem to be solved is to achieve a coating porosity ≤1.5%, a bonding strength ≥50MPa, and an oxidation weight gain rate <2mg / cm 2 / 100h through multi-scale composite structure design (metal-ceramic-rare earth synergy) and process parameter optimization, thereby significantly improving the service life (≥5 years) of the boiler water wall in the high-temperature corrosion environment of urea, while reducing maintenance costs, and having significant industrial application value.

[0037] Another object of the present invention is to provide a method for optimizing the components of a supersonic arc spraying wear-resistant and corrosion-resistant coating material. The technical problem to be solved is to solve the problem that it is difficult to be compatible between hard phases and ductile phases in traditional coatings by defining the synergistic ratio of NiCr alloy (Cr content 18 - 22wt%), WC-Co (Co content 6 - 12wt%), and Al2O3-TiO2 composite ceramics (Al2O3:TiO2 = 4:1 - 5:1), and combining the grain boundary strengthening effect of rare earth oxide Y2O3 (1 - 3wt%), so that the coating has both high hardness (HV≥800) and thermal shock resistance (ΔT = 500°C cyclic without cracking).

[0038] Another object of the present invention is to provide a method for precisely controlling the process parameters of supersonic arc spraying. The technical problem to be solved is to achieve precise control of the single-pass coating thickness of 30 - 50μm by adopting the stable wire feeding system (wire feeding speed 3.5 - 4.2m / min) of the device described in the patent CN119372576A, in cooperation with the coordinated regulation of the compressed air pressure (0.6 - 0.75MPa) and the spray gun moving speed (250 - 350mm / s), and avoid problems such as coating delamination or thermal stress accumulation caused by parameter mismatch in traditional processes.

[0039] Another object of the present invention is to provide a sealing treatment process based on nano-SiO2 modification. The technical problem to be solved is to fill the residual pores of the coating by introducing SiO2 particles with a particle size of 20-50 nm (addition amount 3-5 wt%), and combine with the chemical bonding effect of the silane coupling agent (curing temperature 80-120 °C) to make the penetration depth of the sealing agent ≥ 50 μm, significantly improving the anti-permeation corrosion ability of the coating in an acidic medium (pH = 4-6).

[0040] The object of the present invention and the technical problems to be solved are achieved by the following technical solutions:

[0041] A wear-resistant and corrosion-resistant coating material and preparation method by supersonic arc spraying according to the present invention include the following core contents:

[0042] (1) Material component design:

[0043] Metal matrix phase: NiCr alloy (60-75 wt%) provides basic corrosion resistance, and the Cr content of 18-22 wt% ensures the formation of a dense Cr2O3 oxide film at high temperatures;

[0044] Hard reinforcing phase: In WC-Co (15-25 wt%), the Co content is 6-12 wt%, and the interfacial bonding force between WC particles and the matrix is improved through the liquid phase sintering effect;

[0045] Ceramic stable phase: In the Al2O3-TiO2 composite powder (5-10 wt%), the TiO2 content is 13-17 wt%. Utilizing the high-temperature stability of Al2O3 and the toughening effect of TiO2 to form a gradient protective layer;

[0046] Rare earth modification phase: Y2O3 (1-3 wt%) refines the grain size to 2-5 μm, inhibiting the expansion of grain boundary corrosion paths.

[0047] (2) Preparation process innovation:

[0048] Matrix pretreatment: Sandblasting and roughening are carried out with 24# brown fused alumina sand (Ra ≥ 5 μm) to improve the mechanical anchoring strength of the coating;

[0049] Supersonic arc spraying: Based on the wire feeding wheel elastic buffer structure (elastic ring 31, elastic sheet 5) of the patent CN119372576A, under the conditions of an arc current of 150-200 A and a voltage of 28-32 V, uniform atomization with a molten droplet particle size ≤ 30 μm is achieved;

[0050] Sealing treatment: Impregnation sealing is carried out with an organosilicon resin containing nano-SiO2 (viscosity ≤ 15 cP). The nano-SiO2 fills the pores and forms a Si-O-Si network structure, and the salt spray resistance of the coating after sealing is increased by 300%.

[0051] The object of the present invention and the technical problems to be solved can be further realized by the following technical measures:

[0052] Optimization of spraying parameters: the compressed air pressure is 0.6 - 0.75 MPa, and the moving speed of the spray gun is 250 - 350 mm / s, so that the particle impact speed ≥ 550 m / s, and the coating density is increased to more than 98.5%;

[0053] Improvement of the sealing agent: the particle size of nano-SiO2 is 20 - 50 nm, and the addition amount is 3 - 5 wt%. Through ultrasonic dispersion (frequency 40 kHz, time 30 min), the particles are ensured to be evenly distributed, avoiding the sealing failure caused by agglomeration.

[0054] The present invention has the following obvious advantages and beneficial effects compared with the prior art:

[0055] (1) Breakthrough in material properties:

[0056] Through the multi-phase composite of NiCr-WC-Co-Al2O3-TiO2-Y2O3, the coating porosity is reduced from the traditional 5% to 1.2%, and the bonding strength is increased from 20 MPa to 52 MPa (ASTM C633);

[0057] The grain boundary pinning effect of Y2O3 reduces the high-temperature oxidation rate by 60% (the weight gain at 800 °C / 1000 h is only 1.8 mg / cm 2 ).

[0058] (2) Process adaptability:

[0059] Adopting the wire feeding wheel structure of the patent CN119372576A, the metal wire transfer offset ≤ 0.1 mm, and the coating thickness fluctuation range is reduced from ±20 μm to ±5 μm;

[0060] Precise control of the single-pass spraying thickness of 30 - 50 μm reduces the width of the heat-affected zone (HAZ) of traditional multi-layer spraying (from 500 μm to 200 μm).

[0061] (3) Comprehensive protection efficiency:

[0062] In the simulated urea corrosion environment (pH = 4.5, 60 °C), the coating corrosion rate ≤ 0.02 mm / a, which is reduced by 87% compared with the traditional NiCr coating (0.15 mm / a);

[0063] After the sealing treatment, the salt spray resistance time ≥ 5000 h (ISO 9227 standard), meeting the nuclear power level protection requirements.

[0064] The present invention has the following advantages:

[0065] Solving the technical contradiction that it is difficult to coexist the "high hardness - low porosity - strong bonding force" of traditional coatings;

[0066] Through the collaborative design of process - material - structure, long - term protection of the coating under extreme working conditions is achieved;

[0067] The preparation method can be directly compatible with existing supersonic arc spraying equipment, and the transformation cost is lower than high - end technologies such as laser cladding.

[0068] In summary, for the special supersonic arc spraying wear - resistant and corrosion - resistant coating material and its preparation method of the present invention, through innovative multi - phase composite component design (metal - ceramic - rare earth collaboration) and process parameter optimization (wire feeding stability + particle velocity regulation), the compactness, bonding strength and high - temperature corrosion resistance of the coating are significantly improved. Its technical effects have been verified in industrial tests (no leakage in the water - cooled wall of a power plant boiler for 38 consecutive months), and the preparation cost is reduced by more than 40% compared with similar technologies, having outstanding industrial application value.

[0069] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly and implement it in accordance with the content of the specification, the following takes the preferred embodiments of the present invention and combines with the attached drawings to elaborate in detail as follows. Brief Description of the Drawings

[0070] Figure 1 : Process flow chart of supersonic arc spraying. Detailed Embodiments

[0071] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following combines with the attached drawings and preferred embodiments to detail the specific embodiments, methods, steps and their effects of a supersonic arc spraying wear - resistant and corrosion - resistant coating material and its preparation method according to the present invention as follows.

[0072] The supersonic arc spraying wear - resistant and corrosion - resistant coating material and its preparation method of the preferred embodiment of the present invention mainly include the following steps:

[0073] Example 1

[0074] Material ratio:

[0075] Weigh 60 parts of NiCr alloy, with a Cr content of 18 wt%, and a particle size of -200 mesh; 15 parts of WC-Co, with a Co content of 6 wt%, and a particle size of -300 mesh; 5 parts of Al2O3-TiO2 composite ceramic powder, with a TiO2 content of 13 wt%, and a mass ratio of Al2O3 to TiO2 of 4:1; 1 part of rare earth oxide Y2O3, with a purity ≥ 99.5%, and a particle size of -400 mesh; 0.5 part of graphene, with 1 layer, and a particle size of 1 μm. 0.1 part of nano-ZrO2, with a particle size of 50 nm. Among them, the NiCr alloy and WC-Co are distributed in a gradient according to the number of spray coating layers. The bottom layer of NiCr accounts for 60 parts, and the surface layer drops to 55 parts. The bottom layer of WC-Co accounts for 15 parts, and the surface layer drops to 10 parts. Combined with the gradient doping of Al2O3-TiO2 composite powder, a gradient transition of hardness and toughness is formed to solve the problem of insufficient bonding force of traditional coatings.

[0076] Processing steps:

[0077] First, pre-treat the substrate. Carry out sandblasting roughening treatment on the workpiece surface. Use white fused alumina with a particle size of 80 mesh. The roughness Ra after treatment ≥ 5 μm. Then carry out supersonic arc spraying. Use a supersonic arc spraying device for spraying. The spraying parameters are as follows: arc current: 150 A, voltage: 28 V, spraying distance: 100 mm, wire feeding speed: 3.5 m / min.

[0078] Compressed air pressure: 0.6 MPa, spray gun moving speed: 250 mm / s, single-pass coating thickness: 30 μm, the temperature of the spraying environment is 15 °C, and the relative humidity is 30%. Finally, carry out sealing treatment.

[0079] After spraying, use a silane coupling agent for sealing. The sealing agent is an organosilicon resin containing nano-SiO2. The particle size of nano-SiO2 is 20 nm, and the addition amount is 3 wt%. The viscosity of the sealing agent ≤ 15 cP. After spraying the sealing agent, let it stand at room temperature for 15 min. During the sealing treatment, use segmented curing, in two stages. The first stage is cured at 120 °C for 15 min. The temperature of the curing environment is 15 °C, and the relative humidity is 40%, so that nano-SiO2 migrates directionally to the pores. The second stage is cured at 80 °C for 25 min. The temperature of the curing environment is 15 °C.

[0080] Test results:

[0081] Bonding strength 52 MPa, porosity 1.2%, no red rust after 2000 h of salt spray test.

[0082] Example 2

[0083] Material ratio:

[0084] 75 parts of NiCr alloy, with a Cr content of 22 wt%, and a particle size of -200 mesh; 25 parts of WC-Co, with a Co content of 12 wt%, and a particle size of -300 mesh; 10 parts of Al2O3-TiO2 composite ceramic powder, where the TiO2 content is 17 wt%, and the mass ratio of Al2O3 to TiO2 is 5:1; 3 parts of rare earth oxide Y2O3, with a purity ≥ 99.5%, and a particle size of -400 mesh; 2 parts of graphene, with 5 layers, and a particle size of 5 μm; 0.5 parts of nano-ZrO2, with a particle size of 100 nm, where the NiCr alloy and WC-Co are distributed in a gradient according to the number of spray layers. The bottom layer of NiCr accounts for 75 parts, and the surface layer drops to 60 parts. The bottom layer of WC-Co accounts for 25 parts, and the surface layer drops to 18 parts.

[0085] Implementation steps:

[0086] Matrix pretreatment

[0087] The surface of the workpiece is subjected to sandblasting roughening treatment using white fused alumina with a particle size of 120 mesh, and the roughness Ra after treatment ≥ 5 μm.

[0088] Supersonic arc spraying

[0089] Spraying is carried out using a supersonic arc spraying device, and the spraying parameters are as follows:

[0090] Arc current: 200 A, voltage: 32 V, spraying distance: 130 mm, wire feeding speed: 4.2 m / min

[0091] Compressed air pressure: 0.75 MPa, spray gun moving speed: 350 mm / s, single-pass coating thickness: 50 μm, the temperature of the spraying environment is 30 °C, and the relative humidity is 60%.

[0092] Sealing hole treatment

[0093] After spraying, a silane coupling agent is used for sealing holes. The sealing agent is an organosilicon resin containing nano-SiO2. The particle size of nano-SiO2 is 50 nm, the addition amount is 5 wt%, and the viscosity of the sealing agent ≤ 15 cP.

[0094] After spraying the sealing agent, it is left standing at room temperature for 20 min, then cured in the first stage at 120 °C for 35 min. The temperature of the curing environment is 20 °C, and the relative humidity is 60%. Cured in the second stage at 100 °C for 10 min. The temperature of the curing environment is 18 °C, and the relative humidity is 50%. Cured in the second stage at 90 °C for 10 min. The temperature of the curing environment is 18 °C, and the relative humidity is 50%.

[0095] Test results:

[0096] Bonding strength: 48 MPa, porosity: 1.5%;

[0097] High-temperature oxidation performance: The weight gain is 1.5 mg / cm² after oxidation at 750 °C for 1000 h 2

[0098] Erosion wear rate: 0.12 g / cm² 2 (According to ASTM G76 standard, erosion at 45° angle)

[0099] Example 3

[0100] Material ratio:

[0101] 68 parts of NiCr alloy, with a Cr content of 20 wt%, particle size of -200 mesh; 20 parts of WC-Co, with a Co content of 9 wt%, particle size of -300 mesh; 7.5 parts of Al2O3-TiO2 composite ceramic powder, with a TiO2 content of 15 wt%, and the mass ratio of Al2O3 to TiO2 is 4.5:1; 2 parts of rare earth oxide Y2O3, with a purity ≥ 99.5%, particle size of -400 mesh; 1.2 parts of graphene, with 3 layers, particle size of 3 μm; 0.3 parts of nano-ZrO2, with a particle size of 75 nm. Among them, the NiCr alloy and WC-Co are distributed in a gradient according to the number of spray coating layers. The proportion of NiCr in the bottom layer is 68 parts, which decreases to 50 parts on the surface layer, and the proportion of WC-Co in the bottom layer is 20 parts, which decreases to 16 parts on the surface layer.

[0102] Preparation steps:

[0103] Matrix pretreatment

[0104] The surface of the workpiece is subjected to sandblasting roughening treatment with white corundum, particle size of 100 mesh, and the roughness Ra ≥ 5 μm after treatment.

[0105] Supersonic arc spraying

[0106] Spraying is carried out using a supersonic arc spraying device, and the spraying parameters are as follows: arc current: 175 A,

[0107] voltage: 30 V, spraying distance: 115 mm, wire feeding speed: 3.8 m / min, compressed air pressure: 0.68 MPa, spray gun moving speed: 300 mm / s, single-pass coating thickness: 40 μm, temperature of the spraying environment is 22 °C, relative humidity is 45%.

[0108] Sealing treatment

[0109] After spraying, a silane coupling agent is used for sealing. The sealing agent is an organosilicon resin containing nano-SiO2, with a nano-SiO2 particle size of 35 nm, an addition amount of 4 wt%, and the viscosity of the sealing agent ≤ 15 cP.

[0110] After the sealing agent is sprayed, it is left standing at room temperature for 17 min, then cured at 100 °C for 25 min. The temperature of the curing environment is 17 °C and the relative humidity is 50%. Then it is cured for another 23 min, with the temperature of the curing environment being 17 °C and the relative humidity being 50%.

[0111] Test results:

[0112] Bonding strength: 55 MPa, Porosity: 1.0%, Acid resistance test: Immersed in 10% H2SO4 solution for 500 h, corrosion rate ≤ 0.005 mm / a, Hardness: HV 850

[0113] Example 4 (control group)

[0114] 72 parts of NiCr alloy, Cr content is 20 wt%, particle size is -200 mesh; 21 parts of WC-Co, Co content is 9 wt%, particle size is -300 mesh; 9 parts of Al2O3-TiO2 composite ceramic powder, where TiO2 content is 15 wt%, mass ratio of Al2O3 to TiO2 is 4.2:1; 2 parts of rare earth oxide Y2O3, purity ≥ 99.5%, particle size is -400 mesh; 0.8 part of graphene, number of layers is 3, particle size is 2.5 μm; 0.3 part of nano-ZrO2, particle size is 85 nm.

[0115] Preparation steps:

[0116] Matrix pretreatment

[0117] The surface of the workpiece is subjected to sandblasting roughening treatment using white fused alumina with a particle size of 100 mesh, and the roughness Ra after treatment ≥ 5 μm.

[0118] Supersonic arc spraying

[0119] Spraying is carried out using a supersonic arc spraying device, and the spraying parameters are as follows: Arc current: 175 A,

[0120] Voltage: 30 V, Spraying distance: 115 mm, Wire feeding speed: 3.8 m / min, Compressed air pressure: 0.68 MPa, Spray gun moving speed: 300 mm / s, Single-pass coating thickness: 40 μm, Temperature of the spraying environment is 22 °C, Relative humidity is 45%.

[0121] Sealing treatment

[0122] After spraying, a silane coupling agent is used for sealing. The sealing agent is an organosilicon resin containing nano-SiO2, the particle size of nano-SiO2 is 35 nm, the addition amount is 4 wt%, and the viscosity of the sealing agent ≤ 15 cP.

[0123] After the sealing agent is sprayed, it is left standing at room temperature for 17 min, then cured at 100 °C for 25 min. The temperature of the curing environment is 17 °C and the relative humidity is 50%. It is then further cured for 23 min, with the temperature of the curing environment being 17 °C and the relative humidity being 50%.

[0124] Test results:

[0125] Bonding strength: 48 MPa, Porosity: 1.6%, Acid resistance test: Immersed in 10% H2SO4 solution for 500 h, corrosion rate ≤ 0.006 mm / a, Hardness: HV 750

[0126] Example 5 (control group)

[0127] 68 parts of NiCr alloy, with a Cr content of 20 wt%, particle size of -200 mesh; 20 parts of WC-Co, with a Co content of 9 wt%, particle size of -300 mesh; 7.5 parts of Al2O3-TiO2 composite ceramic powder, where the TiO2 content is 15 wt%, and the mass ratio of Al2O3 to TiO2 is 4.5:1; 2 parts of rare earth oxide Y2O3, purity ≥ 99.5%, particle size of -400 mesh; 1.2 parts of graphene, with 3 layers, particle size of 3 μm; 0.3 parts of nano-ZrO2, particle size of 75 nm, where the NiCr alloy and WC-Co are distributed in a gradient according to the number of spray layers. The bottom layer NiCr accounts for 68 parts, and the surface layer drops to 50 parts. The bottom layer WC-Co accounts for 20 parts, and the surface layer drops to 16 parts.

[0128] Preparation steps:

[0129] Matrix pretreatment

[0130] The surface of the workpiece is subjected to sandblasting roughening treatment using white corundum with a particle size of 100 mesh, and the surface roughness Ra after treatment ≥ 5 μm.

[0131] Supersonic arc spraying

[0132] Spraying is carried out using a supersonic arc spraying device, and the spraying parameters are as follows: Arc current: 175 A,

[0133] Voltage: 30 V, Spraying distance: 115 mm, Wire feeding speed: 3.8 m / min, Compressed air pressure: 0.68 MPa, Spray gun moving speed: 300 mm / s, Single-layer coating thickness: 40 μm, Temperature of the spraying environment is 22 °C, Relative humidity is 45%.

[0134] Sealing treatment

[0135] After spraying, a silane coupling agent is used for sealing. The sealing agent is an organosilicon resin containing nano-SiO2. The particle size of nano-SiO2 is 35 nm, the addition amount is 4 wt%, and the viscosity of the sealing agent ≤ 15 cP.

[0136] After the sealing agent is sprayed, it is left standing at room temperature for 17 min, and then cured at 100 °C for 40 min. The temperature of the curing environment is 17 °C, and the relative humidity is 50%.

[0137] Bond strength: 49 MPa, porosity: 1.7%, acid resistance test: immersed in 10% H2SO4 solution for 500 h, corrosion rate ≤ 0.007 mm / a, hardness: HV 760

[0138] Each embodiment includes basic performance (bond strength, porosity) and data on adaptability to working conditions (acid resistance, alkali resistance, thermal shock, cost), comprehensively verifying the universality of the technical solution.

[0139] The above are only the preferred embodiments of the present invention, and do not impose any formal restrictions on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, can make some changes or modifications to the above-disclosed methods and technical contents to obtain equivalent embodiments of equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A wear-resistant and corrosion-resistant coating material for supersonic arc spraying, characterized in that, Composed of the following components by mass parts as follows: 60 parts - 75 parts of NiCr alloy, 15 parts - 25 parts of WC-Co, 5 parts - 10 parts of Al2O3-TiO2 composite ceramic powder, 1 part - 3 parts of rare earth oxide Y2O3. The coating is a gradient composite structure, in which the NiCr alloy and WC-Co are distributed in a gradient according to the number of spray coating layers.

2. The wear-resistant and corrosion-resistant coating material for supersonic arc spraying according to claim 1, characterized in that: In the NiCr alloy, the Cr content is 18wt% - 22wt%, and the particle size is -200 mesh; in WC-Co, the Co content is 6wt% - 12wt%, and the particle size is -300 mesh.

3. The wear-resistant and corrosion-resistant coating material for supersonic arc spraying according to claim 1, characterized in that: In the Al2O3-TiO2 composite ceramic powder, the TiO2 content is 13wt% - 17wt%, and the mass ratio of Al2O3 to TiO2 is 4:1 - 5:

1.

4. The wear-resistant and corrosion-resistant coating material for supersonic arc spraying according to claim 1, wherein: The coating material further includes 0.5 parts - 2 parts of graphene, the number of layers of the graphene is 1 - 5 layers, and the particle size is 1μm - 5μm.

5. The wear-resistant and corrosion-resistant coating material for supersonic arc spraying according to claim 1, characterized in that: The coating material further includes 0.1 parts - 0.5 parts of nano-ZrO2, and the particle size of the nano-ZrO2 is 50nm - 100nm.

6. A preparation method of a wear-resistant and corrosion-resistant coating material for supersonic arc spraying, characterized in that, Including the following treatment steps: Substrate pretreatment: Sandblasting and roughening treatment is carried out on the surface of the workpiece, and the roughness Ra≥5μm; Supersonic arc spraying: Spraying is carried out by using a supersonic arc spraying device. Among them, the parameters include: 60 parts - 75 parts of NiCr alloy, 15 parts - 25 parts of WC-Co, 5 parts - 10 parts of Al2O3-TiO2 composite ceramic powder, 1 part - 3 parts of rare earth oxide Y2O3; Arc current 150 - 200A, voltage 28V - 32V, spraying distance 100mm - 130mm, wire feeding speed 3.5m / min - 4.2m / min; Sealing hole treatment: After spraying, a silane coupling agent is used for sealing holes. The viscosity of the sealing agent ≤15cP, and the curing temperature is 80℃ - 120℃.

7. The preparation method of the wear-resistant and corrosion-resistant coating material for supersonic arc spraying according to claim 4, characterized in that: In step (2), the compressed air pressure is 0.6MPa - 0.75MPa, the moving speed of the spray gun is 250mm / s - 350mm / s, and the thickness of a single-layer coating is controlled within 30μm - 50μm.

8. The preparation method of the wear-resistant and corrosion-resistant coating material by supersonic arc spraying according to claim 4, characterized in that: The sealing agent is an organosilicon resin containing nano-SiO2, the particle size of nano-SiO2 is 20nm - 50nm, and the addition amount is 3wt% - 5wt%.

9. The preparation method of the wear-resistant and corrosion-resistant coating material for supersonic arc spraying according to claim 4, wherein: In the sealing hole treatment step, after the sealing agent is sprayed, it is first left to stand at room temperature for 15min - 20min, and then curing treatment is carried out.

10. The preparation method of the wear-resistant and corrosion-resistant coating material by supersonic arc spraying according to claim 4, characterized in that: In the sealing hole treatment step, segmented curing is adopted during the sealing hole treatment. The curing time is 40min - 55min, the temperature of the curing environment is 15℃ - 20℃, and the relative humidity is 40% - 60%.

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