Special wear-resistant steel surface treatment process

Abstract

The invention relates to the technical field of metal material surface treatment, in particular to a special wear-resistant steel surface treatment process which comprises the following steps: surface pretreatment of alkaline degreasing, hydrochloric acid rust removal, neutralization and sand blasting roughening; mixing under the protection of argon to prepare composite functional powder; depositing the composite functional powder on the surface of the pretreated wear-resistant steel by adopting a supersonic plasma spraying process to form a coating; and finally performing diffusion heat treatment. NiTi-H shape memory alloy particles are added into the composite functional powder, so that the coating can induce martensite phase transformation by means of stress to absorb impact energy when being impacted, meanwhile, a graphene sheet layer is in bridge connection with microcracks and disperses stress concentration, the impact toughness of the coating is synergistically improved to be larger than or equal to 30 J / cm < 2 >, in addition, an HEA-B high-entropy alloy matrix provides a high-hardness framework, and the impact strength of the coating is improved. And in cooperation with the lubricating effect of graphene, the service life of the wear-resistant steel under the high-impact and high-wear working conditions is remarkably prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal material surface treatment, in particular to a surface treatment process of special wear-resistant steel. BACKGROUND

[0002] Special wear-resistant steel is widely used in the fields of mining, metallurgy, engineering machinery, etc., and its service environment is usually accompanied by severe impact, friction and wear.

[0003] In the prior art, in order to improve the wear resistance of special wear-resistant steel, surface coating technology (such as plasma spraying, surfacing, etc.) is often used, but these processes often result in insufficient bonding force between the coating and the substrate, or the overall toughness of the material is reduced due to the high brittleness of the coating, which is prone to cracks under impact load, seriously affecting the service life and safety. Based on this, the present application provides a surface treatment process of special wear-resistant steel. SUMMARY

[0004] The purpose of the present application is to provide a surface treatment process of special wear-resistant steel. The present application prepares a surface strengthening layer with high wear resistance and high toughness by surface pretreatment, composite powder design, optimization of spraying process and heat treatment parameters, and realizes the synergistic improvement of the comprehensive performance of special wear-resistant steel.

[0005] To achieve the above purpose, the present application provides the following technical scheme: A surface treatment process of special wear-resistant steel, comprising the following steps in sequence: S1: surface pretreatment, sequentially performing alkaline degreasing, hydrochloric acid rust removal, neutralization treatment and sand blasting roughening; S2: preparing a composite functional powder, the composite functional powder is mixed by the first powder, the second powder and the graphene sheet layer in a V-type mixer under argon protection, and the mass percentage is 50-55:32-34:3-5; S3: using supersonic plasma spraying process to deposit the composite functional powder on the surface of the wear-resistant steel treated by S1 to form a coating; S4: performing diffusion heat treatment on the sprayed sample to form an Fe, Ni, Cr, Co element interdiffusion layer; The impact toughness of the surface coating of the special wear-resistant steel treated by the process is ≥30 J / cm 2 , the volume wear rate is ≤9×10 -5 mm 3 / (N·m), and the porosity is ≤2.5%.

[0006] Further, the surface treatment process of the special wear-resistant steel, the alkaline degreasing in S1 is specifically: using an aqueous solution composed of 25-35 g / L sodium hydroxide, 12-18 g / L sodium carbonate and 1 g / L non-ionic surfactant OP-10, treating at 50-65℃ for 12-18 minutes.

[0007] Further, the surface treatment process of the special wear-resistant steel, the hydrochloric acid rust removal in S1 is specifically: using a 12-16% hydrochloric acid solution for 8-12 minutes, then immersing in a 5% sodium hydroxide solution for 4 minutes, and then washing with deionized water until pH=7.

[0008] Further, the surface treatment process of the special wear-resistant steel, the sand blasting in S1 is specifically: using 80-100 mesh alumina sand particles, treating under 0.38-0.42 MPa compressed air pressure, so that the surface roughness reaches Ra 3.5-4.5 µm, and then blowing the surface with compressed air to remove residual sand particles, so that the surface cleanliness reaches Sa3 level.

[0009] Further, the surface treatment process of the special wear-resistant steel, the preparation step of the first powder in S2 is: (1) Raw material mixing: mixing Al, Co, Cr, Cu, Fe and Ni pure metal powders in an atomic ratio of 1:1:1:1:1:1, and adding 0.35-0.45 at% B; (2) Planetary ball milling: ball-to-material ratio of 12:1, rotation speed of 300 rpm, ball milling time of 7-8 hours, ball milling medium is WC-Co hard alloy ball with a diameter of 5 mm and Co content of 6%, and pure argon gas with a purity of ≥99.99% is introduced for protection throughout the process; (3) Sieving: sieving through a 200 mesh standard sieve to obtain the first powder with a D50 of 12-18 µm.

[0010] Further, the surface treatment process of the special wear-resistant steel, the preparation step of the second powder in S2 is: a: Raw material pretreatment: crushing NiTi alloy scrap with an atomic ratio of Ni:Ti of 50.8:49.2 to a particle size of ≤3 mm; b: Hydrogenation treatment: heating at 300℃ in an atmosphere of 0.2 MPa hydrogen gas with a purity of ≥99.999% for 1 hour; c: Ball milling: after cooling to room temperature, ball milling at a rotation speed of 200 rpm for 30 minutes, with a ball-to-material ratio of 8:1; d: Dehydrogenation and strengthening phase precipitation: heating to 600℃ under argon protection for 1.2 hours, and then sieving through a 200 mesh sieve after cooling to obtain the second powder with a D50 of 8-12 µm.

[0011] Further, the surface treatment process of the special wear-resistant steel, the graphene sheet layer in S2 is prepared by an oxidation-reduction method, specifically: taking natural flake graphite as raw material, oxidizing by Hummers method to obtain graphene oxide, and then reducing by vitamin C, and ultrasonic peeling in anhydrous ethanol for 30 minutes at a power of 300 W to obtain graphene sheet layers with a thickness of 1-5 nm and a diameter of 1-5 microns.

[0012] Further, the surface treatment process of the special wear-resistant steel, the mixing of the composite powder in S2 is specifically: adding 0.5% of silane coupling agent KH550 to the mixture of the first powder, the second powder and the graphene sheet layer, mixing in a V-type mixer at a speed of 30 rpm for 8 minutes, and the argon gas flow is 0.5 L / min.

[0013] Further, the surface treatment process of the special wear-resistant steel, the parameters of the supersonic plasma spraying in S3 are: a spraying power of 35-38 kW, a spraying distance of 120-140 mm, a plasma gas being a mixed gas of 90-92% by volume of argon and 8-10% by volume of hydrogen, and a powder feeding rate of 22-26 g / min.

[0014] Further, the surface treatment process of the special wear-resistant steel, the parameters of the diffusion heat treatment in S4 are: increasing the temperature to 850-900 DEG C at a rate of 8 DEG C / min, keeping the temperature for 2 hours, introducing Ar gas with a purity of greater than or equal to 99.99% as a protective atmosphere, controlling the oxygen content in the furnace to be less than or equal to 50 ppm, and taking out the furnace after furnace cooling to 200 DEG C.

[0015] Compared with the prior art, the beneficial effects of the present application are: 1、In the surface supersonic plasma spraying process of the special wear-resistant steel, the second powder is added in the composite functional powder, the nickel-titanium alloy is generated by Ni and Ti in the second powder, the shape memory function of the nickel-titanium alloy is utilized, the coating can absorb impact energy by stress-induced martensitic phase transformation when impacted, the graphene sheet layer bridges micro-cracks and disperses stress concentration, so that the impact toughness of the coating is improved to 30 J / cm 2 In addition, the combination of metal powders in the first powder can provide a high-hardness skeleton, and the lubricating effect of the graphene sheet layer can reduce the volume wear rate, thereby significantly enhancing the service life of the wear-resistant steel under high-impact and high-wear working conditions.

[0016] 2、In the application, by diffusing heat treatment of 850-900 DEG C to the sprayed special wear-resistant steel, the mutual diffusion layer of Fe, Ni, Cr, Co elements is formed between the coating and the matrix, effectively filling and healing the pores generated in the spraying process, the porosity is controlled to be ≤2.5%, so that the coating density is significantly improved, the dense mutual diffusion layer not only prevents the penetration of corrosive medium, but also further strengthens the metallurgical bonding of the coating and the matrix, so that the special wear-resistant steel is not easy to peel off and crack in long-term use, and the overall reliability and durability are greatly improved. DETAILED DESCRIPTION

[0017] The technical solutions in the experiments of the application will be described clearly and completely in combination with the experiments of the application. Obviously, the described experiments are only a part of the experiments of the application, rather than all the experiments. Based on the experiments in the application, all other experiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0018] The embodiment provides a special wear-resistant steel surface treatment process, which comprises the following steps in sequence: S1: surface pretreatment, which is performed in sequence of alkaline degreasing, hydrochloric acid rust removal, neutralization treatment and sand blasting roughening; S2: preparing a composite functional powder, the composite functional powder is mixed by the first powder, the second powder and the graphene sheet layer in a V-type mixer under argon protection, and the mass percentage is 50-55:32-34:3-5; S3: the composite functional powder is deposited on the wear-resistant steel surface treated in S1 by using the supersonic plasma spraying process to form a coating; S4: diffusing heat treatment is performed on the sprayed test piece to form a mutual diffusion layer of Fe, Ni, Cr and Co elements; In some embodiments, the alkaline degreasing in the surface pretreatment is: using an aqueous solution composed of 25-35 g / L sodium hydroxide, 12-18 g / L sodium carbonate and 1 g / L non-ionic surfactant OP-10, and treating at 50-65 DEG C for 12-18 minutes.

[0019] In some embodiments, the hydrochloric acid rust removal in the surface pretreatment is: using a hydrochloric acid solution with a mass fraction of 12-16% to treat for 8-12 minutes, after the hydrochloric acid rust removal, immersing in a sodium hydroxide solution with a mass fraction of 5% for 4 minutes, and then washing with deionized water until pH=7.

[0020] In some embodiments, the sand blasting roughening in the surface pretreatment is: using 80-100 mesh alumina sand particles, and treating under the pressure of 0.38-0.42 MPa compressed air, so that the surface roughness reaches Ra3.5-4.5 µm, after the sand blasting, the surface residual sand particles are blown off by using compressed air, and the surface cleanliness reaches Sa3 level.

[0021] In some embodiments, the preparation step of the first powder in the composite functional powder is as follows: (1) Raw material mixing: Al, Co, Cr, Cu, Fe and Ni pure metal powders are mixed in an atomic ratio of 1:1:1:1:1:1, and 0.35-0.45 at% B is added; (2) Planetary ball mill: ball-to-material ratio 12:1, rotation speed 300 rpm, ball milling time 7-8 hours, ball milling media are WC-Co hard alloy balls with a diameter of 5 mm and a Co content of 6%, and argon gas with a purity of ≥99.99% is introduced throughout the process for protection. (3) Sieving: Pass through a 200-mesh standard sieve to obtain the first powder with a D50 of 12-18μm.

[0022] In some embodiments, the preparation step of the second powder in the composite functional powder is as follows: a: Raw material pretreatment: NiTi alloy scrap with an atomic ratio of 50.8:49.2 is crushed to a particle size ≤3mm; b: Hydrogenation treatment: Keep warm for 1 hour at 300℃ and 0.2MPa in an atmosphere with hydrogen purity ≥99.999%; c: Ball milling: After cooling to room temperature, ball mill at 200 rpm for 30 minutes with a ball-to-material ratio of 8:1; d: Dehydrogenation and enhanced phase precipitation: Under argon protection, the temperature was raised to 600℃ and held for 1.2 hours. After cooling, the mixture was passed through a 200-mesh sieve to obtain a second powder with a D50 of 8-12μm.

[0023] In some embodiments, the graphene sheets in the composite functional powder are prepared by a redox method, specifically: using natural flake graphite as raw material, oxidizing it by the Hummers method to obtain graphene oxide, then reducing it with vitamin C, and ultrasonically exfoliating it in anhydrous ethanol at 300W power for 30 minutes to obtain graphene sheets with a thickness of 1-5nm and a diameter of 1-5μm.

[0024] In some embodiments, the composite powder mixing specifically involves adding 0.5% by mass of silane coupling agent KH550 to a mixture of the first powder, the second powder, and the graphene sheets, mixing for 8 minutes at 30 rpm in a V-type mixer, with an argon flow rate of 0.5 L / min.

[0025] In some embodiments, the parameters for supersonic plasma spraying are: spraying power 35-38kW, spraying distance 120-140mm, plasma gas is a mixture of 90-92% volume fraction argon and 8-10% volume fraction hydrogen, and powder feeding rate 22-26g / min.

[0026] In some embodiments, the parameters of the diffusion heat treatment are as follows: the temperature is raised to 850-900°C at a rate of 8°C / min, the temperature is kept for 2 hours, Ar gas with a purity of ≥99.99% is introduced as a protective atmosphere, the oxygen content in the furnace is controlled to be ≤50 ppm, and the furnace is cooled to 200°C before being taken out of the furnace.

[0027] Based on the foregoing embodiments, the following groups of experiments are carried out: It should be noted that the raw materials used in the following experiments are all commercially available.

[0028] Experiment 1: S1: Surface pretreatment Alkaline degreasing: A water solution composed of 30 g / L sodium hydroxide, 15 g / L sodium carbonate and 1 g / L OP-10 is used, and the treatment is carried out at 60°C for 15 minutes.

[0029] Hydrochloric acid rust removal: A 14% (mass fraction) hydrochloric acid solution is used for treatment for 10 minutes, followed by neutralization with a 5% sodium hydroxide solution for 4 minutes and washing with deionized water until pH=7.

[0030] Sand blasting roughening: 90-mesh aluminum oxide sand particles are used, and the treatment is carried out under a compressed air pressure of 0.40 MPa, so that the surface roughness reaches Ra4.0 µm. After sand blasting, the surface is cleaned by blowing compressed air, and the surface cleanliness reaches Sa3 level.

[0031] S2: Preparation of composite functional powder Formulation: First powder (52 parts), second powder (33 parts), graphene sheet layer (4 parts).

[0032] First powder preparation: Al, Co, Cr, Cu, Fe, Ni pure metal powders are mixed in an atomic ratio of 1:1:1:1:1:1, and 0.40 at% B is added. Planetary ball milling (ball-to-material ratio of 12:1, rotation speed of 300 rpm, time of 7.5 hours). Sieved through a 200-mesh sieve to obtain a D50=15 µm powder.

[0033] Second powder preparation: Ni:Ti=50.8:49.2 alloy scrap is hydriding treated (300°C, 0.2 MPa hydrogen, 1 hour). After ball milling (200 rpm, 30 min, ball-to-material ratio of 8:1), dehydrogenation and precipitation of strengthening phases are carried out under argon protection at 600°C for 1.2 hours. Sieved through a 200-mesh sieve to obtain a D50=10 µm powder.

[0034] Graphene sheet layer: Graphene oxide prepared by the Hummers method is reduced by vitamin C, and obtained after ultrasonic exfoliation.

[0035] Mixing: 0.45 parts of silane coupling agent KH550 was added to the above three powder mixtures, and mixed in a V-type mixer at a speed of 30 rpm for 8 minutes (argon flow rate 0.5 L / min).

[0036] S3: Supersonic plasma spraying Parameters: spraying power 36 kW, spraying distance 130 mm, plasma gas (91% Ar + 9% hydrogen), powder feeding rate 24 g / min.

[0037] S4: Diffusion heat treatment Parameters: temperature rise to 875°C at a rate of 8°C / min, holding for 2 hours (Ar protection, oxygen content ≤ 50 ppm), furnace cooling to 200°C before discharging.

[0038] Experiment two: S1: Surface pretreatment Alkaline degreasing: using an aqueous solution composed of 35 g / L sodium hydroxide, 18 g / L sodium carbonate and 1 g / L OP-10, treating at 65°C for 12 minutes.

[0039] Hydrochloric acid rust removal: using a 16% (mass fraction) hydrochloric acid solution for 8 minutes, followed by neutralization with a 5% sodium hydroxide solution for 4 minutes and washing with deionized water to pH = 7.

[0040] Sand blasting roughening: using 100 mesh alumina sand particles, treating under a compressed air pressure of 0.38 MPa to achieve a surface roughness of Ra 3.8 μm. After sand blasting, the surface was cleaned by blowing compressed air to achieve a surface cleanliness of Sa level 3.

[0041] S2: Preparation of composite functional powder Formulation: first powder (50 parts), second powder (34 parts), graphene sheet (5 parts).

[0042] First powder preparation: Al, Co, Cr, Cu, Fe, Ni pure metal powders were mixed in an atomic ratio of 1:1:1:1:1:1, with the addition of 0.35 at% B. Planetary ball milling (ball-to-material ratio 12:1, rotation speed 300 rpm, time 8 hours). Sieved through a 200 mesh sieve to obtain a D50 = 12 μm powder.

[0043] Second powder preparation: Ni:Ti = 50.8:49.2 alloy scrap hydrogenation treatment (300°C, 0.2 MPa hydrogen, 1 hour). After ball milling (200 rpm, 30 min, ball-to-material ratio 8:1), dehydrogenation and precipitation of strengthening phase under argon protection at 600°C for 1.2 hours. Sieved through a 200 mesh sieve to obtain a D50 = 8 μm powder.

[0044] Graphene sheets: The graphene oxide prepared by Hummers method was reduced by vitamin C, and then ultrasonically exfoliated in anhydrous ethanol for 30 minutes at a power of 300 W to obtain graphene sheets with a thickness of 1-5 nm and a diameter of 1-5 μm.

[0045] Mixing: 0.45 parts of silane coupling agent KH550 was added to the above three powder mixtures, and mixed in a V-type mixer at a speed of 30 rpm for 8 minutes (argon flow rate 0.5 L / min).

[0046] S3: Supersonic plasma spraying Parameters: spraying power 35 kW, spraying distance 140 mm, plasma gas mixture of 90% by volume argon and 10% by volume hydrogen, powder feeding rate 22 g / min.

[0047] S4: Diffusion heat treatment Parameters: heating rate 8 ℃ / min to 850 ℃, holding for 2 hours, pure Ar gas with a purity of ≥99.99% as protective atmosphere, oxygen content in the furnace controlled at ≤50 ppm, furnace cooling to 200 ℃ before discharging.

[0048] Experiment three: S1: Surface pretreatment Alkaline degreasing: using an aqueous solution composed of 25 g / L sodium hydroxide, 12 g / L sodium carbonate and 1 g / L OP-10, treated at 55 ℃ for 18 minutes.

[0049] Hydrochloric acid rust removal: using a 12% (mass fraction) hydrochloric acid solution for 12 minutes, followed by neutralization with a 5% sodium hydroxide solution for 4 minutes, and washing with deionized water to pH=7.

[0050] Sand blasting roughening: using 80 mesh alumina grits, treated under a compressed air pressure of 0.42 MPa to achieve a surface roughness of Ra4.3 μm. After sand blasting, the surface was cleaned by blowing compressed air to achieve a surface cleanliness of Sa3 level.

[0051] S2: Preparation of composite functional powder Formulation: first powder (55 parts), second powder (32 parts), graphene sheets (3 parts).

[0052] First powder preparation: Al, Co, Cr, Cu, Fe, Ni pure metal powders were mixed according to the atomic ratio of 1:1:1:1:1:1, and 0.45 at% B was added. Planetary ball milling (ball-to-material ratio 12:1, rotation speed 300 rpm, time 7 hours). Sieved through a 200 mesh sieve to obtain a powder with D50=18 μm.

[0053] Second powder preparation: hydrogenation treatment of alloy scrap with Ni:Ti=50.8:49.2 (300℃, 0.2MPa hydrogen, 1 hour). After ball milling (200rpm, 30min, ball-to-powder ratio 8:1), dehydrogenation and strengthening phase precipitation were carried out at 600℃ for 1.2 hours under argon protection. The powder was sieved through a 200-mesh sieve, and the D50=12μm powder was obtained.

[0054] Graphene sheets: graphene oxide prepared by Hummers method was reduced by vitamin C and ultrasonically exfoliated in anhydrous ethanol for 30 minutes at a power of 300W to obtain graphene sheets with a thickness of 1-5nm and a diameter of 1-5μm.

[0055] Mixing: 0.45 parts of silane coupling agent KH550 were added to the above-mentioned three powder mixtures, and mixed in a V-type mixer at a speed of 30rpm for 8 minutes (argon flow rate 0.5L / min).

[0056] S3: supersonic plasma spraying Parameters: spraying power 38kW, spraying distance 120mm, plasma gas mixture of 92% by volume argon and 8% by volume hydrogen, powder feeding rate 26g / min.

[0057] S4: diffusion heat treatment Parameters: temperature increased to 900℃ at a rate of 8℃ / min, held for 2 hours, pure Ar gas with a purity of ≥99.99% was used as the protective atmosphere, the oxygen content in the furnace was controlled to be ≤50ppm, and the furnace was cooled to 200℃ before the furnace was discharged.

[0058] Comparative Example 1: In the S2 step, the composition of the composite functional powder was changed to: second powder (85 parts), graphene sheets (5 parts), and the first powder was omitted, and the same proportion of the second powder was added to make up (i.e. the total composition was 85 parts of NiTi-H, 5 parts of graphene). All other steps were exactly the same as in Example 1.

[0059] Comparative Example 2: In the S2 step, the composition of the composite functional powder was changed to: first powder (85 parts), graphene sheets (5 parts), and the second powder was omitted, and the same proportion of the first powder was added to make up (i.e. the total composition was 85 parts of HEA-B, 5 parts of graphene). All other steps were exactly the same as in Example 1.

[0060] Comparative Example 3: Scheme: in the S2 step, the composition of the composite functional powder was changed to: first powder (55 parts), second powder (42 parts), and the graphene sheets were omitted. All other steps were exactly the same as in Example 1.

[0061] Comparative Example 4: After the completion of S3 supersonic plasma spraying, the performance test is directly performed on the test piece, and the S4 diffusion heat treatment step is omitted. The rest of the steps are exactly the same as in Example 1.

[0062] Performance test: the performance of the treated special wear-resistant steel in Experiment 1, Experiment 2, Experiment 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 is tested, The test data obtained are recorded in the following table:

[0063] In the performance test, the impact toughness, volume wear rate and porosity of the treated special wear-resistant steel in Experiment 1, Experiment 2, Experiment 3, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 are tested, the impact toughness is tested according to GB / T1732-2020, the volume wear rate is tested according to GB / T 12444-2006, and the porosity is tested according to GB / T 226-2015.

[0064] The process (Examples 1-3) of the present application can stably obtain excellent comprehensive performance of high impact toughness (≥30 J / cm 2 ), low wear rate (≤9×10 -5 mm 3 / (N·m) and low porosity (≤2.5%) for the surface coating of the special wear-resistant steel. As can be seen from the comparative examples, the absence of HEA-B high-entropy alloy, NiTi-H shape memory alloy, graphene sheet layer and diffusion heat treatment will affect the performance of the material. The NiTi-H shape memory alloy particles can absorb impact energy by stress-induced martensitic phase transformation when the coating is impacted, and the graphene sheet layer can bridge micro-cracks and disperse stress concentration, thereby synergistically improving the impact toughness of the coating. The HEA-B high-entropy alloy matrix provides a high-hardness skeleton, which, together with the lubricating effect of graphene, reduces the volume wear rate and significantly enhances the service life of the wear-resistant steel under high-impact and high-wear conditions.

[0065] By performing diffusion heat treatment at 850-900℃ on the sprayed special wear-resistant steel, a mutual diffusion layer of Fe, Ni, Cr and Co elements is formed between the coating and the matrix, effectively filling and healing the pores generated during the spraying process, and the porosity is controlled to be below 2.5%, thereby significantly improving the density of the coating. The dense mutual diffusion layer not only prevents the penetration of corrosive media, but also further strengthens the metallurgical bonding between the coating and the matrix, so that the special wear-resistant steel is not easy to peel off and crack during long-term use, and the overall reliability and durability are greatly improved.

[0066] Through comparison and analysis of the related data in the table, it can be known that the special wear-resistant steel processed by the special wear-resistant steel surface treatment process has not only good wear resistance, but also excellent impact toughness, so that the special wear-resistant steel surface treatment process has wider market prospect and is more suitable for promotion.

[0067] In the description of the present specification, the description referring to the terms "one experiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the experiment or example are contained in at least one experiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same experiment or example. Furthermore, the specific features, structures, materials or characteristics described can be combined in any one or more experiments or examples in a suitable manner.

[0068] The preferred experiments of the present application disclosed above are only used to help explain the present application. The preferred experiments do not describe all the details and limit the present application to the specific embodiments described. Obviously, according to the content of the present specification, many modifications and changes can be made. The present specification selects and specifically describes these experiments in order to better explain the principles and practical applications of the present application, so that the persons skilled in the art can well understand and utilize the present application. The present application is limited only by the claims and the entire scope and equivalents thereof.

Claims

1. A surface treatment process for a special wear-resistant steel, characterized in that, Comprise the following steps in sequence: S1: surface pretreatment, in turn, alkaline degreasing, hydrochloric acid rust removal, neutralization treatment and sand blasting roughening; S2: preparation of composite functional powder, the composite functional powder is prepared by mixing the first powder, the second powder and the graphene sheet in a V-type mixer under argon protection, and the mass percentage is 50-55:32-34:3-5; The preparation step of the first powder in S2 is: (1) raw material mixing: mix Al, Co, Cr, Cu, Fe and Ni pure metal powder in an atomic ratio of 1:1:1:1:1:1, and add 0.35-0.45at% B; (2) planetary ball milling: ball-to-material ratio of 12:1, rotation speed of 300 rpm, ball milling time of 7-8 hours, ball milling medium is WC-Co hard alloy ball with a diameter of 5 mm, Co content of 6%, pure argon gas with a purity of ≥99.99% is passed through the whole process for protection; (3) screening: pass through a 200-mesh standard screen to obtain a first powder with a D50 of 12-18 μm; The preparation step of the second powder in S2 is: a: raw material pretreatment: NiTi alloy scrap with an atomic ratio of Ni:Ti of 50.8:49.2 is broken to a particle size of ≤3 mm; b: hydrogenation treatment: heat preservation for 1 hour at 300℃ under an atmosphere of 0.2MPa hydrogen gas with a purity of ≥99.999%; c: ball milling: cool to room temperature, then ball mill at a speed of 200 rpm for 30 minutes, ball-to-material ratio of 8:1; d: dehydrogenation and strengthening phase precipitation: heat to 600℃ under argon protection for 1.2 hours, then pass through a 200-mesh screen after cooling to obtain a second powder with a D50 of 8-12 μm; S3: deposit the composite functional powder on the surface of the wear-resistant steel treated in S1 by using supersonic plasma spraying process to form a coating; S4: diffusion heat treatment is performed on the sprayed sample to form an interdiffusion layer of Fe, Ni, Cr and Co elements; The parameters of the diffusion heat treatment in S4 are: heat to 850-900℃ at a heating rate of 8℃ / min, heat preservation for 2 hours, pure Ar gas with a purity of ≥99.99% is used as the protective atmosphere, the oxygen content in the furnace is controlled to be ≤50ppm, and the furnace is cooled to 200℃ before being taken out of the furnace; The surface coating of the special wear-resistant steel treated by the process has impact toughness ≥ 30 J / cm 2 , volume wear rate ≤ 9 × 10 - 5 mm 3 / (N·m), and porosity ≤ 2.5%.

2. A process for surface treatment of a special wear resistant steel as claimed in claim 1, wherein, The alkaline degreasing in S1 is specifically: using an aqueous solution composed of 25-35g / L sodium hydroxide, 12-18g / L sodium carbonate and 1g / L non-ionic surfactant OP-10, treating at 50-65℃ for 12-18 minutes.

3. A process for surface treatment of a special wear resistant steel as claimed in claim 1, wherein, The hydrochloric acid rust removal in S1 is specifically: using a hydrochloric acid solution with a mass fraction of 12-16% to treat for 8-12 minutes, then immersing in a 5% sodium hydroxide solution for 4 minutes after hydrochloric acid rust removal, and then washing with deionized water until pH=7.

4. The process for surface treatment of a special wear-resistant steel according to claim 1, characterized in that, The sand blasting roughening in S1 is specifically: using 80-100 mesh alumina sand particles, treating under a compressed air pressure of 0.38-0.42 MPa to make the surface roughness reach Ra3.5-4.5µm, and then blowing the surface residual sand particles with compressed air to make the surface cleanliness reach Sa3 level.

5. A process for surface treatment of a special wear resistant steel as claimed in claim 1 wherein, The graphene sheet layers in S2 are prepared by a redox method, specifically: taking natural flake graphite as raw material, oxidizing to obtain graphene oxide by Hummers method, and then reducing with vitamin C, and ultrasonic peeling in anhydrous ethanol for 30 minutes at a power of 300W to obtain graphene sheet layers with a thickness of 1-5nm and a diameter of 1-5μm.

6. A process for surface treatment of a special wear resistant steel as claimed in claim 1 wherein, The composite powder mixing in S2 is specifically: adding 0.5% of silane coupling agent KH550 to the mixture of the first powder, the second powder and the graphene sheet layers, mixing in a V-type mixer at a speed of 30rpm for 8 minutes, and the argon flow rate is 0.5L / min.

7. A process for surface treatment of a special wear resistant steel as claimed in claim 1 wherein, The parameters of the supersonic plasma spraying in S3 are: spraying power 35-38kW, spraying distance 120-140mm, plasma gas is a mixed gas of 90-92% by volume of argon and 8-10% by volume of hydrogen, and the powder feeding rate is 22-26g / min.

Images