A high-hardness wear-resistant hand tool and a preparation method thereof

Abstract

The application discloses a kind of high-hardness wear-resistant hand tools and preparation method thereof, it is related to alloy plating technical field, with alloy tool steel as matrix, sequentially complete pre-quenching and tempering, surface sand blasting, powder wet ball milling, prepare nickel-chromium intermediate layer using supersonic speed flame spraying, prepare graphene reinforced chromium carbide-nickel-chromium surface layer in combination with plasma spraying, finally carry out low-temperature stress relief treatment.The application sets two kinds of reinforcing phase and different powder ratio, can be adapted to blade, clamping impact type hand tools respectively.Two-layer gradient coating structure effectively relieves interface stress, avoids chromium carbide high-temperature phase change problem;Graphene and modified graphene can optimize coating density, wear resistance and corrosion resistance.The process flow is simple, controllable, and the tool coating prepared is firmly combined, with excellent comprehensive performance.

Description

Technical Field

[0001] This invention relates to the field of alloy coating technology, specifically to a high-hardness, wear-resistant hand tool and its preparation method. Background Technology

[0002] Hand tools are widely used in civilian, industrial, automotive repair, and outdoor operations. Chromium carbide-nickel-chromium cermet coatings, with their excellent wear resistance, have become the mainstream protective coating for hand tool surfaces. However, this type of coating still faces several common problems in practical applications: traditional processes often employ a single coating structure, and the significant difference in thermal expansion coefficients between the alloy substrate and the ceramic coating makes the coating prone to cracking and peeling due to internal stress generated during spraying; simultaneously, the numerous pores created by thermal spraying allow corrosive media such as water vapor and salt spray to easily penetrate along these pores, resulting in insufficient corrosion resistance. When conventional graphene is used as a reinforcing material, it is prone to agglomeration and can also cause galvanic corrosion with the metal substrate, significantly shortening the protective lifespan. Furthermore, most production processes have unreasonable heat treatment sequence designs, and high-temperature processes can easily cause chromium carbide decarburization and grain coarsening, resulting in a significant decrease in coating hardness and toughness. Moreover, existing coating formulations are too homogeneous to meet the differentiated usage requirements of high-hardness cutting tools and high-toughness impact tools, ultimately leading to poor overall service performance and a short service life for hand tools. Summary of the Invention

[0003] The purpose of this invention is to provide a high-hardness, wear-resistant hand tool and its preparation method, so as to solve the problems raised in the prior art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a high-hardness and wear-resistant hand tool includes the following steps: S1: The alloy tool steel substrate is subjected to quenching and tempering heat treatment in sequence to obtain a heat-treated tool blank; S2: The surface of the heat-treated tool blank is sandblasted. After sandblasting, it is cleaned and dried for later use to obtain a roughened tool blank. S3: The chromium carbide-nickel-chromium matrix powder is wet ball-milled and then vacuum-dried to obtain the composite spray powder; S4: Using nickel-chromium powder as raw material, a supersonic flame spraying process is used to spray the roughened tool blank surface, cool it, and form a nickel-chromium intermediate layer to obtain a transition layer tool blank; S5: Using composite spray powder as raw material, plasma spraying process is adopted to spray on the surface of the transition layer tool blank, and then cooled to form a composite chromium carbide-nickel chromium surface layer, thus obtaining a double-layer gradient coating tool blank. S6: Low-temperature heat treatment is performed on the double-layer gradient coated tool blank to obtain a high-hardness and wear-resistant manual tool.

[0005] Furthermore, the composite spray powder also includes a reinforcing phase; the reinforcing phase is either graphene nanosheets or alumina-coated modified graphene nanosheets. The preparation method of composite spray powder includes the following steps: chromium carbide-nickel-chromium matrix powder and alumina-coated modified nano-graphene sheets are mixed evenly in proportion, wet ball milling is performed, and vacuum drying is performed after ball milling to obtain composite spray powder.

[0006] Furthermore, the graphene nanosheets account for 1-2 wt% of the total mass of the composite spray powder; the alumina-coated modified graphene nanosheets account for 0.05-0.2 wt% of the total mass of the composite spray powder.

[0007] Furthermore, the preparation method of the alumina-coated modified graphene nanosheets includes the following steps: adding graphene nanosheets and aluminum nitrate nonahydrate to anhydrous ethanol, heating to 65-70℃ and stirring until the anhydrous ethanol is completely evaporated, calcining and grinding to obtain alumina-coated modified graphene nanosheets.

[0008] Furthermore, in the preparation process of alumina-coated modified graphene nanosheets, the mass ratio of graphene nanosheets to aluminum nitrate nonahydrate is 1:(2-4); the mass-volume ratio of graphene nanosheets to anhydrous ethanol is 1:5.

[0009] Furthermore, the quenching temperature is 820-860℃, and the holding time is 20-40 min; the tempering temperature is 200-280℃, and the holding time is 60-120 min. Furthermore, the low-temperature heat treatment temperature is 220-300℃, and the holding time is 1.5-2h.

[0010] Furthermore, the sandblasting parameters are as follows: using alumina sand as raw material, sandblasting pressure is 0.4-0.6MPa, sandblasting distance is 150-250mm, and the surface roughness of the roughened tool blank after treatment is 6-8μm; Furthermore, the wet ball milling medium is anhydrous ethanol, the mass ratio of milling balls to powder is 8:1, the ball milling speed is 200-220 r / min, and the ball milling is carried out in an intermittent mode of grinding for 20 min and stopping for 10 min, with a ball milling time of 2-2.5 h. Furthermore, the supersonic flame spraying process parameters are as follows: aviation kerosene is used as fuel, oxygen as combustion-supporting gas, and nitrogen as carrier gas; the aviation kerosene flow rate is 1.8-2 gal / h, the oxygen flow rate is 360-390 scfm, the spraying distance is 230-350 mm, and the shaft speed is 1800-1900 r / min.

[0011] Furthermore, the plasma spraying parameters are as follows: argon is the main gas, hydrogen is the auxiliary gas, and argon is the carrier gas; when graphene nanosheets are used as the reinforcing phase, the working current is 500A, the working voltage is 38V, the argon flow rate is 47L / min, the hydrogen flow rate is 14L / min, the argon flow rate is 6L / min, the spraying distance is 100mm, the powder feeding rate is 45g / min, and the spray gun moving speed is 450mm / s. When using alumina-coated modified nano-graphene sheets as the reinforcing phase, the operating current is 600A, the operating voltage is 40V, the argon flow rate is 80L / min, the hydrogen flow rate is 18L / min, the argon flow rate is 5L / min, the spraying distance is 90mm, the powder feeding rate is 30g / min, and the spray gun moving speed is 400mm / s.

[0012] Furthermore, the mass ratio of chromium carbide to nickel chromium in the chromium carbide-nickel chromium matrix powder is (65-75):(25-35).

[0013] Furthermore, the thickness of the nickel-chromium intermediate layer is 80-120 μm; the thickness of the composite chromium carbide-nickel-chromium surface layer is 200-250 μm.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention optimizes and improves existing hand tool coatings by addressing their common defects, such as numerous pores, susceptibility to cracking and peeling, and the tendency for improper high-temperature processes to cause degradation of the chromium carbide phase. It adopts an overall process scheme that combines pre-heat treatment of the substrate with composite spraying to prepare a double-layer gradient coating, thereby comprehensively improving the mechanical properties, wear resistance, corrosion resistance, and long-term stability of hand tools.

[0015] 2. This invention designs a dual-layer gradient composite coating structure, using a supersonic flame spraying process to prepare a nickel-chromium intermediate layer. The thermal expansion characteristics of nickel effectively connect the alloy substrate and the hard surface layer, mitigating the difference in thermal expansion between them, dispersing the internal stress caused by spraying and operating loads, and significantly reducing stress concentration at the coating interface. Simultaneously, the high density of the nickel-chromium intermediate layer prevents the penetration of corrosive media such as water vapor and salt spray, forming a dual corrosion protection system with the outer functional coating. This invention achieves adaptability to operating conditions by adjusting the component ratio of chromium carbide and nickel-chromium. The coating with a high proportion of chromium carbide exhibits higher hardness and excellent resistance to abrasive wear, making it suitable for bladed hand tools such as files and carving knives. The coating with a high proportion of nickel possesses superior toughness and resistance to adhesive wear, making it suitable for clamping and impact-type hand tools such as wrenches and pliers, effectively solving the problem that traditional coatings struggle to balance hardness and toughness and have limited applicability.

[0016] 3. The present invention can flexibly select two reinforcing phases according to the usage environment: when ordinary graphene is used as the reinforcing phase, the unique two-dimensional sheet structure of graphene can fill the micropores inside the coating, bridge and block the crack propagation path, refine the coating grains, promote the formation of a dense passivation layer on the surface, and achieve a self-lubricating effect by relying on the interlayer slip characteristics, effectively reducing the degree of wear and corrosion, and meeting the usage needs of manual tools under normal indoor working conditions. For applications involving strong corrosion and heavy loads, such as outdoor, automotive repair, marine, and high-temperature environments, alumina-coated modified graphene is selected as the reinforcing phase. This reinforcing phase uses aluminum nitrate nonahydrate as a precursor, which, after water bath treatment and calcination, forms a complete alumina coating layer on the graphene surface. This not only further improves the interfacial bonding between graphene and the coating substrate and completely solves the agglomeration problem, but also relies on the insulating properties of alumina to block galvanic corrosion between graphene and the metal substrate. At the same time, it protects the graphene structure from oxidation and damage in high-temperature environments. Alumina itself can also act as a hard phase to further enhance the wear resistance of the coating. The reasonable design of the material ratio also ensures the integrity and uniformity of the coating layer, giving full play to the comprehensive reinforcing effect of modified graphene.

[0017] 4. This invention combines the advantages of two types of thermal spraying processes, utilizing supersonic flame spraying to prepare a dense transition layer and plasma spraying to complete the preparation of the functional surface layer. The high-temperature characteristics of the plasma flame enable in-situ exfoliation of multilayer graphene, fully releasing the reinforcing effect of graphene. The different heat resistance properties of the two reinforcing phases are matched with corresponding spraying conditions: ordinary graphene has relatively weak heat resistance, so a mild flame condition can be used to prevent graphene from burning off at high temperatures; alumina-coated modified graphene has stronger high-temperature resistance, and a high-temperature flame can be used to enhance the powder melting and graphene exfoliation effect. Both spraying methods ensure the coating formation quality and the integrity of the reinforcing phase structure.

[0018] 5. In summary, the various raw material components and preparation processes in this invention work together synergistically to enhance each other's effectiveness. The matrix, nickel-chromium intermediate layer, and reinforced functional surface layer constitute a gradient mechanical load-bearing and corrosion protection system. Powder modification, composite spraying, and low-temperature post-treatment form a complete closed-loop process. The resulting hand tool coating has a dense structure and strong adhesion. Under combined working conditions such as friction, impact, and corrosion, it is less prone to problems such as peeling, flaking, edge dulling, and surface corrosion, significantly improving the overall service life of the product. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the following examples, the preparation method of alumina-coated modified graphene nanosheets includes the following steps: 1g of graphene nanosheets and 3g of aluminum nitrate nonahydrate are added to 5mL of anhydrous ethanol, heated to 65°C and stirred until the anhydrous ethanol is completely evaporated, calcined and ground to obtain alumina-coated modified graphene nanosheets.

[0021] Example 1: A method for preparing a high-hardness, wear-resistant hand tool, comprising the following steps: S1: The 9SiCr steel matrix is ​​quenched at 840℃ and held for 30 min, then water cooled and tempered at 240℃ for 80 min to obtain the heat-treated tool blank. S2: The surface of the heat-treated tool blank is sandblasted with alumina sand as abrasive, with a sandblasting pressure of 0.5MPa and a sandblasting distance of 200mm. After sandblasting, it is cleaned and dried for later use to obtain a roughened tool blank. S3: 75:25 chromium carbide-nickel chromium matrix powder and graphene nanosheets were wet-milled intermittently for 2 hours with anhydrous ethanol as the medium, grinding balls to powder mass ratio of 8:1, ball milling speed of 200 r / min, and vacuum drying after ball milling to obtain composite spray powder. S4: Using nickel-chromium powder as raw material, a supersonic flame spraying process is used to spray the roughened tool blank surface, cool it, and form a nickel-chromium intermediate layer to obtain a transition layer tool blank; The supersonic flame spraying process parameters are as follows: aviation kerosene is used as fuel, oxygen is used as combustion-supporting gas, and nitrogen is used as carrier gas; the aviation kerosene flow rate is 1.8 gal / h, the oxygen flow rate is 360 scfm, the spraying distance is 230 mm, and the shaft speed is 1800 r / min. S5: Using composite spray powder as raw material, plasma spraying process is adopted to spray on the surface of the transition layer tool blank, and then cooled to form a composite chromium carbide-nickel chromium surface layer, thus obtaining a double-layer gradient coating tool blank. The composite spray powder contains 1.5 wt% graphene nanosheets. The thickness of the nickel-chromium intermediate layer shown is 80 μm, and the thickness of the chromium carbide-nickel-chromium surface layer is 200 μm; S6: The double-layer gradient coated tool blank is subjected to low-temperature heat treatment at 260℃ for 1.5h to obtain a high-hardness and wear-resistant manual tool.

[0022] Example 2: A method for preparing a high-hardness, wear-resistant hand tool, comprising the following steps: S1: The 9SiCr steel matrix is ​​quenched at 840℃ and held for 30 min, then water cooled and tempered at 240℃ for 80 min to obtain the heat-treated tool blank. S2: The surface of the heat-treated tool blank is sandblasted with alumina sand as abrasive, with a sandblasting pressure of 0.5MPa and a sandblasting distance of 200mm. After sandblasting, it is cleaned and dried for later use to obtain a roughened tool blank. S3: A 75:25 chromium carbide-nickel chromium matrix powder and alumina-coated modified nano-graphene sheets were subjected to wet ball milling for 2 hours with anhydrous ethanol as the medium, a ball-to-powder mass ratio of 8:1, a ball milling speed of 200 r / min, and vacuum drying after ball milling to obtain composite spray powder. S4: Using nickel-chromium powder as raw material, a supersonic flame spraying process is used to spray the roughened tool blank surface, cool it, and form a nickel-chromium intermediate layer to obtain a transition layer tool blank; The supersonic flame spraying process parameters are as follows: aviation kerosene is used as fuel, oxygen is used as combustion-supporting gas, and nitrogen is used as carrier gas; the aviation kerosene flow rate is 1.8 gal / h, the oxygen flow rate is 360 scfm, the spraying distance is 230 mm, and the shaft speed is 1800 r / min. S5: Using composite spray powder as raw material, plasma spraying process is adopted to spray on the surface of the transition layer tool blank, and then cooled to form a composite chromium carbide-nickel chromium surface layer, thus obtaining a double-layer gradient coating tool blank. The alumina-coated modified nano-graphene sheets in the composite spray powder account for 0.1 wt%; The thickness of the nickel-chromium intermediate layer shown is 80 μm, and the thickness of the chromium carbide-nickel-chromium surface layer is 200 μm; S6: The double-layer gradient coated tool blank is subjected to low-temperature heat treatment at 260℃ for 1.5h to obtain a high-hardness and wear-resistant manual tool.

[0023] Example 3: A method for preparing a high-hardness, wear-resistant hand tool, comprising the following steps: S1: The 4Cr5MoSiV steel matrix was quenched at 840℃ and held for 30 minutes, then water-cooled and tempered at 240℃ for 80 minutes to obtain the heat-treated tool blank. S2: The surface of the heat-treated tool blank is sandblasted with alumina sand as abrasive, with a sandblasting pressure of 0.5MPa and a sandblasting distance of 200mm. After sandblasting, it is cleaned and dried for later use to obtain a roughened tool blank. S3: 65:35 chromium carbide-nickel chromium matrix powder and graphene nanosheets were wet-milled intermittently for 2 hours with anhydrous ethanol as the medium, grinding balls to powder mass ratio of 8:1, ball milling speed of 200 r / min, and vacuum drying after ball milling to obtain composite spray powder. S4: Using nickel-chromium powder as raw material, a supersonic flame spraying process is used to spray the roughened tool blank surface, cool it, and form a nickel-chromium intermediate layer to obtain a transition layer tool blank; The supersonic flame spraying process parameters are as follows: aviation kerosene is used as fuel, oxygen is used as combustion-supporting gas, and nitrogen is used as carrier gas; the aviation kerosene flow rate is 1.8 gal / h, the oxygen flow rate is 360 scfm, the spraying distance is 230 mm, and the shaft speed is 1800 r / min. S5: Using composite spray powder as raw material, plasma spraying process is adopted to spray on the surface of the transition layer tool blank, and then cooled to form a composite chromium carbide-nickel chromium surface layer, thus obtaining a double-layer gradient coating tool blank. The composite spray powder contains 1.5 wt% graphene nanosheets. The thickness of the nickel-chromium intermediate layer shown is 80 μm, and the thickness of the chromium carbide-nickel-chromium surface layer is 200 μm; S6: The double-layer gradient coated tool blank is subjected to low-temperature heat treatment at 260℃ for 1.5h to obtain a high-hardness and wear-resistant manual tool.

[0024] Example 4: A method for preparing a high-hardness, wear-resistant hand tool, comprising the following steps: S1: The 4Cr5MoSiV steel matrix was quenched at 840℃ and held for 30 minutes, then water-cooled and tempered at 240℃ for 80 minutes to obtain the heat-treated tool blank. S2: The surface of the heat-treated tool blank is sandblasted with alumina sand as abrasive, with a sandblasting pressure of 0.5MPa and a sandblasting distance of 200mm. After sandblasting, it is cleaned and dried for later use to obtain a roughened tool blank. S3: A 65:35 chromium carbide-nickel chromium matrix powder and alumina-coated modified nano-graphene sheets were subjected to wet ball milling for 2 hours with anhydrous ethanol as the medium, a ball-to-powder mass ratio of 8:1, a ball milling speed of 200 r / min, and vacuum drying after ball milling to obtain composite spray powder. S4: Using nickel-chromium powder as raw material, a supersonic flame spraying process is used to spray the roughened tool blank surface, cool it, and form a nickel-chromium intermediate layer to obtain a transition layer tool blank; The supersonic flame spraying process parameters are as follows: aviation kerosene is used as fuel, oxygen is used as combustion-supporting gas, and nitrogen is used as carrier gas; the aviation kerosene flow rate is 1.8 gal / h, the oxygen flow rate is 360 scfm, the spraying distance is 230 mm, and the shaft speed is 1800 r / min. S5: Using composite spray powder as raw material, plasma spraying process is adopted to spray on the surface of the transition layer tool blank, and then cooled to form a composite chromium carbide-nickel chromium surface layer, thus obtaining a double-layer gradient coating tool blank. The alumina-coated modified nano-graphene sheets in the composite spray powder account for 0.1 wt%; The thickness of the nickel-chromium intermediate layer shown is 80 μm, and the thickness of the chromium carbide-nickel-chromium surface layer is 200 μm; S6: The double-layer gradient coated tool blank is subjected to low-temperature heat treatment at 260℃ for 1.5h to obtain a high-hardness and wear-resistant manual tool.

[0025] Example 5: A method for preparing a high-hardness, wear-resistant hand tool, comprising the following steps: S1: The 9SiCr steel matrix is ​​quenched at 840℃ and held for 30 min, then water cooled and tempered at 240℃ for 80 min to obtain the heat-treated tool blank. S2: The surface of the heat-treated tool blank is sandblasted with alumina sand as abrasive, with a sandblasting pressure of 0.5MPa and a sandblasting distance of 200mm. After sandblasting, it is cleaned and dried for later use to obtain a roughened tool blank. S3: 75:25 chromium carbide-nickel chromium matrix powder and graphene nanosheets were wet-milled intermittently for 2 hours with anhydrous ethanol as the medium, grinding balls to powder mass ratio of 8:1, ball milling speed of 200 r / min, and vacuum drying after ball milling to obtain composite spray powder. S4: Using nickel-chromium powder as raw material, a supersonic flame spraying process is used to spray the roughened tool blank surface, cool it, and form a nickel-chromium intermediate layer to obtain a transition layer tool blank; The supersonic flame spraying process parameters are as follows: aviation kerosene is used as fuel, oxygen is used as combustion-supporting gas, and nitrogen is used as carrier gas; the aviation kerosene flow rate is 1.8 gal / h, the oxygen flow rate is 360 scfm, the spraying distance is 230 mm, and the shaft speed is 1800 r / min. S5: Using composite spray powder as raw material, plasma spraying process is adopted to spray on the surface of the transition layer tool blank, and then cooled to form a composite chromium carbide-nickel chromium surface layer, thus obtaining a double-layer gradient coating tool blank. The graphene nanosheets in the composite spray powder account for 2 wt%; The thickness of the nickel-chromium intermediate layer shown is 80 μm, and the thickness of the chromium carbide-nickel-chromium surface layer is 200 μm; S6: The double-layer gradient coated tool blank is subjected to low-temperature heat treatment at 260℃ for 1.5h to obtain a high-hardness and wear-resistant manual tool.

[0026] Example 6: A method for preparing a high-hardness, wear-resistant hand tool, comprising the following steps: S1: The 4Cr5MoSiV steel matrix was quenched at 840℃ and held for 30 minutes, then water-cooled and tempered at 240℃ for 80 minutes to obtain the heat-treated tool blank. S2: The surface of the heat-treated tool blank is sandblasted with alumina sand as abrasive, with a sandblasting pressure of 0.5MPa and a sandblasting distance of 200mm. After sandblasting, it is cleaned and dried for later use to obtain a roughened tool blank. S3: A 65:35 chromium carbide-nickel chromium matrix powder and alumina-coated modified nano-graphene sheets were subjected to wet ball milling for 2 hours with anhydrous ethanol as the medium, a ball-to-powder mass ratio of 8:1, a ball milling speed of 200 r / min, and vacuum drying after ball milling to obtain composite spray powder. S4: Using nickel-chromium powder as raw material, a supersonic flame spraying process is used to spray the roughened tool blank surface, cool it, and form a nickel-chromium intermediate layer to obtain a transition layer tool blank; The supersonic flame spraying process parameters are as follows: aviation kerosene is used as fuel, oxygen is used as combustion-supporting gas, and nitrogen is used as carrier gas; the aviation kerosene flow rate is 1.8 gal / h, the oxygen flow rate is 360 scfm, the spraying distance is 230 mm, and the shaft speed is 1800 r / min. S5: Using composite spray powder as raw material, plasma spraying process is adopted to spray on the surface of the transition layer tool blank, and then cooled to form a composite chromium carbide-nickel chromium surface layer, thus obtaining a double-layer gradient coating tool blank. The alumina-coated modified nano-graphene sheets in the composite spray powder account for 0.2 wt%; The thickness of the nickel-chromium intermediate layer shown is 80 μm, and the thickness of the chromium carbide-nickel-chromium surface layer is 200 μm; S6: The double-layer gradient coated tool blank is subjected to low-temperature heat treatment at 260℃ for 1.5h to obtain a high-hardness and wear-resistant manual tool.

[0027] Example 7: A method for preparing a high-hardness, wear-resistant hand tool, comprising the following steps: S1: The 9SiCr steel matrix is ​​quenched at 840℃ and held for 30 min, then water cooled and tempered at 240℃ for 80 min to obtain the heat-treated tool blank. S2: The surface of the heat-treated tool blank is sandblasted with alumina sand as abrasive, with a sandblasting pressure of 0.5MPa and a sandblasting distance of 200mm. After sandblasting, it is cleaned and dried for later use to obtain a roughened tool blank. S3: The 75:25 chromium carbide-nickel chromium matrix powder was wet-milled for 2 hours with anhydrous ethanol as the medium, the mass ratio of grinding balls to powder was 8:1, the ball milling speed was 200 r / min, and the powder was vacuum-dried after ball milling to obtain the composite spraying powder. S4: Using nickel-chromium powder as raw material, a supersonic flame spraying process is used to spray the roughened tool blank surface, cool it, and form a nickel-chromium intermediate layer to obtain a transition layer tool blank; The supersonic flame spraying process parameters are as follows: aviation kerosene is used as fuel, oxygen is used as combustion-supporting gas, and nitrogen is used as carrier gas; the aviation kerosene flow rate is 1.8 gal / h, the oxygen flow rate is 360 scfm, the spraying distance is 230 mm, and the shaft speed is 1800 r / min. S5: Using composite spray powder as raw material, plasma spraying process is adopted to spray on the surface of the transition layer tool blank, and then cooled to form a composite chromium carbide-nickel chromium surface layer, thus obtaining a double-layer gradient coating tool blank. The thickness of the nickel-chromium intermediate layer shown is 80 μm, and the thickness of the chromium carbide-nickel-chromium surface layer is 200 μm; S6: The double-layer gradient coated tool blank is subjected to low-temperature heat treatment at 260℃ for 1.5h to obtain a high-hardness and wear-resistant manual tool.

[0028] Comparative Example 1: A method for preparing a high-hardness, wear-resistant hand tool, comprising the following steps: S1: The 9SiCr steel matrix is ​​quenched at 840℃ and held for 30 min, then water cooled and tempered at 240℃ for 80 min to obtain the heat-treated tool blank. S2: The surface of the heat-treated tool blank is sandblasted with alumina sand as abrasive, with a sandblasting pressure of 0.5MPa and a sandblasting distance of 200mm. After sandblasting, it is cleaned and dried for later use to obtain a roughened tool blank. S3: 75:25 chromium carbide-nickel chromium matrix powder and graphene nanosheets were wet-milled intermittently for 2 hours with anhydrous ethanol as the medium, grinding balls to powder mass ratio of 8:1, ball milling speed of 200 r / min, and vacuum drying after ball milling to obtain composite spray powder. S4: Using composite spray powder as raw material, plasma spraying process is adopted to spray on the surface of roughened tool blank, and then cooled to form a composite chromium carbide-nickel chromium surface layer, thus obtaining a double-layer gradient coating tool blank; The composite spray powder contains 1.5 wt% graphene nanosheets. The thickness of the chromium carbide-nickel-chromium surface layer shown is 200 μm; S5: The double-layer gradient coated tool blank is subjected to low-temperature heat treatment at 260℃ for 1.5h to obtain a high-hardness and wear-resistant manual tool.

[0029] Comparative Example 2: A method for preparing a high-hardness, wear-resistant hand tool, comprising the following steps: S1: The surface of the 9SiCr blank is sandblasted with alumina sand as abrasive, with a sandblasting pressure of 0.5MPa and a sandblasting distance of 200mm. After sandblasting, it is cleaned and dried for later use to obtain a roughened tool blank. S2: 75:25 chromium carbide-nickel-chromium matrix powder and graphene nanosheets were wet-milled intermittently for 2 hours with anhydrous ethanol as the medium, grinding balls to powder mass ratio of 8:1, ball milling speed of 200 r / min, and vacuum drying after ball milling to obtain composite spray powder. S3: Using nickel-chromium powder as raw material, a supersonic flame spraying process is used to spray the roughened tool blank surface, cool it, and form a nickel-chromium intermediate layer to obtain a transition layer tool blank; The supersonic flame spraying process parameters are as follows: aviation kerosene is used as fuel, oxygen is used as combustion-supporting gas, and nitrogen is used as carrier gas; the aviation kerosene flow rate is 1.8 gal / h, the oxygen flow rate is 360 scfm, the spraying distance is 230 mm, and the shaft speed is 1800 r / min. S4: Using composite spray powder as raw material, plasma spraying process is adopted to spray on the surface of the transition layer tool blank, and then cooled to form a composite chromium carbide-nickel chromium surface layer, thus obtaining a double-layer gradient coating tool blank. The composite spray powder contains 1.5 wt% graphene nanosheets. The thickness of the nickel-chromium intermediate layer shown is 80 μm, and the thickness of the chromium carbide-nickel-chromium surface layer is 200 μm; S5: The double-layer gradient coated tool blank is subjected to low-temperature heat treatment at 260℃ for 1.5h to obtain a high-hardness and wear-resistant manual tool.

[0030] Comparative Example 3: A method for preparing a high-hardness, wear-resistant hand tool, comprising the following steps: S1: The 9SiCr steel matrix is ​​quenched at 840℃ and held for 30 min, then water cooled and tempered at 240℃ for 80 min to obtain the heat-treated tool blank. S2: The surface of the heat-treated tool blank is sandblasted with alumina sand as abrasive, with a sandblasting pressure of 0.5MPa and a sandblasting distance of 200mm. After sandblasting, it is cleaned and dried for later use to obtain a roughened tool blank. S3: 75:25 chromium carbide-nickel chromium matrix powder and graphene nanosheets were wet-milled intermittently for 2 hours with anhydrous ethanol as the medium, grinding balls to powder mass ratio of 8:1, ball milling speed of 200 r / min, and vacuum drying after ball milling to obtain composite spray powder. S4: Using nickel-chromium powder as raw material, a supersonic flame spraying process is used to spray the roughened tool blank surface, cool it, and form a nickel-chromium intermediate layer to obtain a transition layer tool blank; The supersonic flame spraying process parameters are as follows: aviation kerosene is used as fuel, oxygen is used as combustion-supporting gas, and nitrogen is used as carrier gas; the aviation kerosene flow rate is 1.8 gal / h, the oxygen flow rate is 360 scfm, the spraying distance is 230 mm, and the shaft speed is 1800 r / min. S5: Using composite spray powder as raw material, plasma spraying process is adopted to spray on the surface of the transition layer tool blank, and then cooled to form a composite chromium carbide-nickel chromium surface layer, resulting in a high-hardness and wear-resistant manual tool. The composite spray powder contains 1.5 wt% graphene nanosheets.

[0031] The thickness of the nickel-chromium intermediate layer shown is 80 μm, and the thickness of the chromium carbide-nickel-chromium surface layer is 200 μm.

[0032] Experimental test: Micro Vickers hardness: According to ASTM E384, parameters: Vickers microhardness tester, load 200gf, holding load 30s; Reciprocating friction and wear performance: According to ASTM G133, parameters: friction and wear test machine, paired grinding balls are silicon nitride balls, load 10N, frequency 4Hz, test duration 15min; Electrochemical polarization test: According to ASTM G59, parameters: electrochemical workstation, three-electrode system (working electrode: sample; reference electrode: silver-silver chloride electrode; counter electrode: platinum sheet), electrolyte is 3.5wt% sodium chloride solution; Neutral salt spray test: According to GB / T 10125, parameters: salt spray test chamber, 5wt% sodium chloride solution, continuous spraying.

[0033] The experimental data are shown in Table 1 below.

[0034] Table 1 Performance test data of high-hardness and wear-resistant hand tools

[0035] Conclusion: The synergistic cooperation of each process and component in this invention produces a dense, firm coating for hand tools that is resistant to passivation and corrosion, resulting in a significantly improved overall service life.

[0036] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a high-hardness, wear-resistant hand tool, characterized in that: Includes the following steps: S1: The alloy tool steel matrix is ​​subjected to quenching and tempering heat treatment in sequence to obtain a heat-treated tool blank; S2: The surface of the heat-treated tool blank is sandblasted. After sandblasting, it is cleaned and dried for later use to obtain a roughened tool blank. S3: The chromium carbide-nickel-chromium matrix powder is wet ball-milled and then vacuum-dried to obtain the composite spray powder; S4: Using nickel-chromium powder as raw material, a supersonic flame spraying process is used to spray the roughened tool blank surface, cool it, and form a nickel-chromium intermediate layer to obtain a transition layer tool blank; S5: Using composite spray powder as raw material, plasma spraying process is adopted to spray on the surface of the transition layer tool blank, and then cooled to form a composite chromium carbide-nickel chromium surface layer, thus obtaining a double-layer gradient coating tool blank. S6: Low-temperature heat treatment is performed on the double-layer gradient coated tool blank to obtain a high-hardness and wear-resistant manual tool.

2. The method for preparing a high-hardness, wear-resistant hand tool according to claim 1, characterized in that: The composite spraying powder also includes a reinforcing phase; the reinforcing phase is either graphene nanosheets or alumina-coated modified graphene nanosheets; the preparation method of the composite spraying powder includes the following steps: mixing chromium carbide-nickel-chromium matrix powder and alumina-coated modified graphene nanosheets evenly in proportion, performing wet ball milling, and vacuum drying after ball milling to obtain the composite spraying powder.

3. The method for preparing a high-hardness, wear-resistant hand tool according to claim 2, characterized in that: The graphene nanosheets account for 1-2 wt% of the total mass of the composite spray powder; the alumina-coated modified graphene nanosheets account for 0.05-0.2 wt% of the total mass of the composite spray powder.

4. The method for preparing a high-hardness, wear-resistant hand tool according to claim 3, characterized in that: The preparation method of the alumina-coated modified graphene nanosheets includes the following steps: adding graphene nanosheets and aluminum nitrate nonahydrate to anhydrous ethanol, heating to 65-70℃ and stirring until the anhydrous ethanol is completely evaporated, calcining and grinding to obtain alumina-coated modified graphene nanosheets.

5. The method for preparing a high-hardness, wear-resistant hand tool according to claim 4, characterized in that: In the preparation of alumina-coated modified graphene nanosheets, the mass ratio of graphene nanosheets to aluminum nitrate nonahydrate is 1:(2-4); the mass-volume ratio of graphene nanosheets to anhydrous ethanol is 1:

5.

6. The method for preparing a high-hardness, wear-resistant hand tool according to claim 1, characterized in that: The quenching temperature is 820-860℃, and the holding time is 20-40 min; the tempering temperature is 200-280℃, and the holding time is 60-120 min; the low-temperature heat treatment temperature is 220-300℃, and the holding time is 1.5-2 h.

7. The method for preparing a high-hardness, wear-resistant hand tool according to claim 1, characterized in that: The supersonic flame spraying process parameters are as follows: aviation kerosene is used as fuel, oxygen as combustion-supporting gas, and nitrogen as carrier gas; the aviation kerosene flow rate is 1.8-2 gal / h, the oxygen flow rate is 360-390 scfm, the spraying distance is 230-350 mm, and the shaft speed is 1800-1900 r / min.

8. The method for preparing a high-hardness, wear-resistant hand tool according to claim 1, characterized in that: The mass ratio of chromium carbide to nickel chromium in the chromium carbide-nickel chromium matrix powder is (65-75):(25-35).

9. The method for preparing a high-hardness, wear-resistant hand tool according to claim 1, characterized in that: The thickness of the nickel-chromium intermediate layer is 80-120 μm; the thickness of the composite chromium carbide-nickel-chromium surface layer is 200-250 μm.

10. A high-hardness, wear-resistant hand tool prepared by the method for preparing a high-hardness, wear-resistant hand tool according to any one of claims 1-9.

Images