Control method and application of wear-resistant particles distributed in stepped mode

Abstract

The control method comprises the following steps that a preset layer is sequentially cold-sprayed on the surface of a steel substrate for N times, and the preset layer comprises pure Cu powder, Cu3P eutectic powder and Sn powder; wear-resistant particles are further distributed in the Nth preset layer, the wear-resistant particles are evenly mixed with the pure Cu powder, the Cu3P eutectic powder and the Sn powder, cold spraying is conducted, and the wear-resistant particles are fixed in the preset layers along with deformation of the pure Cu powder particles; wear-resistant particles dispersed with pure Cu powder, Cu3P eutectic powder and Sn powder from the Nth preset layer to the first preset layer on the surface of the steel substrate are reduced layer by layer; the wear-resistant coating is prepared on the surface of the steel substrate through a control method for distributing the wear-resistant particles in a stepped manner; according to the invention, the wear-resistant particles in stepped distribution are distributed in the wear-resistant coating on the surface of the steel substrate, so that the wear resistance and corrosion resistance of the obtained coating are effectively improved while the bonding strength of the obtained wear-resistant coating and the steel substrate is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of composite metal wear-resistant coatings, and in particular to a control method and application of step-wise distributed wear-resistant particles. Background Art

[0002] There are many ways to improve the wear resistance of the steel substrate surface in the prior art. For example, the invention patent with the authorization announcement number CN106381474B discloses a method for preparing a composite wear-resistant coating on the surface of a stainless steel plate. The double-layer glow plasma gold permeation technology is used. The bonding strength between the coating and the stainless steel plate is high. The coating is rapidly cooled by hydrogen, and the grains are fine and the mechanical strength is high, so as to obtain a composite wear-resistant coating with good thermal conductivity and electrical conductivity. The invention patent with the authorization announcement number CN115537803B discloses a WC-Ni wear-resistant coating on the surface of 316L stainless steel and a preparation method thereof, which involves a laser cladding material. The wear-resistant coating includes a substrate and a WC-Ni wear-resistant coating located on the surface of the substrate. The WC-Ni wear-resistant coating includes a surface layer and a transition layer arranged in sequence from top to bottom; the surface layer is formed by laser cladding with WC powder, and the WC powder contains 57-63% WC by mass; the transition layer is formed by laser cladding with Ni625 powder. The WC-Ni wear-resistant coating of the present invention comprises a surface layer and a transition layer, the surface layer is prepared from WC powder, and the transition layer is prepared from Ni625 powder, WC powder and Ni625 powder by laser cladding to prepare the WC-Ni wear-resistant coating, and the composite coating organically combines the excellent properties of metal with the properties of ceramic materials, and can effectively improve the surface quality of 316L stainless steel, improve its wear resistance, hardness and strength, and make it suitable for more harsh working environments. However, the preparation of the surface coating of the stainless steel substrate uses laser and other equipment, which has high requirements on production equipment on the one hand, and is not conducive to obtaining a thick wear-resistant coating on the other hand, which limits the use of steel. Summary of the invention

[0003] The purpose of the present invention is to provide a control method for step-by-step distribution of wear-resistant particles. The present invention pre-places wear-resistant particles of different concentrations on the surface of a steel substrate that has been treated to remove the oxide film by cold spraying. The concentration of the wear-resistant particles increases stepwise from the surface of the steel substrate toward the environment, thereby enhancing the wear resistance of the coating while ensuring the bonding strength between the coating and the steel substrate.

[0004] To solve this technical problem, the technical solution of the present invention is: a control method for stepwise distribution of wear-resistant particles, comprising the following steps: A pre-deposited layer is cold-sprayed N times on the surface of the steel substrate, the pre-deposited layer comprising pure Cu powder, Cu3P eutectic powder and Sn powder; The Nth pre-deposited layer is also provided with wear-resistant particles, which are uniformly mixed with pure Cu powder, Cu3P eutectic powder and Sn powder, and cold sprayed, so that the wear-resistant particles are fixed in the pre-deposited layer as the pure Cu powder particles are deformed; The total mass of pure Cu powder, Cu3P eutectic powder and Sn powder in the pre-deposited layer at the surface Nth layer is M1, the mass of the wear-resistant particles is M2, and the mass ratio of M1 to M2 is 1:(1.2 to 1.3); From the Nth pre-layer to the first pre-layer on the surface of the steel substrate, the wear-resistant particles dispersed in the pure Cu powder, Cu3P eutectic powder and Sn powder are reduced layer by layer.

[0005] Preferably, the wear-resistant particles are WC-Co composite powders, wherein the mass ratio of WC to Co is (8.5 to 9.5): 1. The WC-Co composite powders in the present invention take into account the high hardness of WC and the toughness of Co, and the wear resistance and corrosion resistance of the wear-resistant coating are ensured while the interface bonding strength is further improved, and the compactness of the obtained wear-resistant coating is improved, and the distribution of the wear-resistant particles is controlled in a step-by-step manner to ensure the bonding strength between the wear-resistant coating and the steel substrate while concentrating the wear-resistant particles in the shallow surface layer of the wear-resistant coating, thereby enhancing the wear resistance of the wear-resistant coating.

[0006] Preferably, the WC-Co composite powder is nano-sized particles. The nano-sized WC-Co composite powder used in the present invention is evenly mixed with micron-sized pure Cu metal powder, and as the cold spraying is filled in the preset layer, the pure Cu powder is deformed during the cold spraying process to effectively cover the particle size of the WC-Co composite powder, and the WC-Co composite powder is dispersed and fixed by the pure Cu powder, Cu3P eutectic powder and Sn powder.

[0007] The mass fractions of Cu powder, Cu3P eutectic powder and Sn powder in the pre-deposited layer preferably used for dispersing wear-resistant particles are as follows: 35 to 40 parts of pure Cu powder; 5 to 8 parts of Cu3P eutectic powder; Sn powder 2 to 4 parts.

[0008] The pure Cu powder used in the present invention has a mass fraction of 35 to 40 parts, and the obtained Cu-based solder has excellent plasticity, thermal conductivity, electrical conductivity and corrosion resistance, and is very suitable as a low melting point component of the solder coating. In order to save costs and further reduce the melting point of the Cu-based solder, Sn and P are added to the Cu-based solder. P is added in the form of Cu3P master alloy as a copper-phosphorus eutectic component, and its melting point is 714°C, which can further reduce the melting temperature of the Cu-based solder. When the phosphorus is heated in the air furnace for solder coating, it can also play the role of a self-soldering agent.

[0009] Preferably, the process parameters of the pre-layer cold spraying are as follows: The working pressure of supersonic compressed gas is 0.6MPa to 0.8Mpa; Powder feeding rate 15g / min to 25g / min; Spray distance 15mm to 30mm; Spray angle 20° to 30°.

[0010] The cold spraying used in the present invention is supersonic cold spraying, which is a process at room temperature where a 20μm to 50μm mixed powder is shot onto a substrate by a supersonic gas-solid two-phase gas flow to form a dense layer. The supersonic cold spraying equipment uses compressed gas to generate a supersonic gas flow through a zoom-in type Lava tube, and feeds the brazing powder and WC-Co composite powder that are proportioned and evenly mixed into the supersonic gas flow axially to form a gas-solid two-phase flow. After acceleration, the flow hits the steel substrate to be coated in a completely solid state, causing a large plastic deformation and depositing on the surface of the substrate to form a coating layer with a certain bonding strength. Therefore, there is no high-temperature heating in the cold spraying technology, and there is no high-temperature oxidation, gasification, melting, crystallization, and other effects that affect the performance of the brazing coating.

[0011] Preferably, the amount of wear-resistant particles is reduced by 20% to 30% layer by layer. The present invention firmly combines the wear-resistant coating with the steel substrate by controlling the amount of wear-resistant particles in a step-by-step manner, while ensuring the wear resistance. The amount of wear-resistant particles increases in a step-by-step manner away from the steel substrate. Therefore, in the process of cold spraying the pre-set layer layer by layer, the cold sprayed pre-set layer is continuously further compacted, effectively ensuring the aggregation and enrichment of the wear-resistant particles.

[0012] Another object of the present invention is to provide an application of a method for controlling step-distributed wear-resistant particles. The present invention distributes step-distributed wear-resistant particles in a wear-resistant coating on the surface of a steel substrate, thereby effectively improving the wear resistance and corrosion resistance of the resulting coating while ensuring the bonding strength between the resulting wear-resistant coating and the steel substrate.

[0013] To solve this technical problem, the technical solution of the present invention is: an application of a step-wise distributed wear-resistant particle control method, comprising the following steps: S1. One-time sandblasting treatment of the steel substrate surface to remove the oxide film on the steel substrate surface; S2, cold spraying the preset layers layer by layer; S3, shot peening impacts a steel substrate with multiple pre-set layers to construct a rough hydrophobic surface; S4, placing the steel substrate / multi-layer pre-prepared layer after S3 in a heating furnace for brazing to obtain a wear-resistant coating with wear-resistant particles distributed in a stepped manner.

[0014] Preferably, the brazing heating temperature in S4 is 695° C. to 705° C., and the brazing time is 10 min to 20 min. The present invention utilizes heating brazing to improve the bonding strength between the wear-resistant coating and the steel substrate.

[0015] The preferred process conditions for shot peening are as follows: The particle size of shot peening is 0.10mm to 0.15mm; The air flow pressure of shot peening is 0.3MPa to 0.4Mpa.

[0016] The present invention utilizes shot peening to form a micro-nano surface by impacting the surface of the enriched nanoparticles, further reducing the spreading of water or aqueous solution on the surface of the wear-resistant coating, thereby further improving the corrosion resistance of the obtained wear-resistant coating.

[0017] The thickness of the wear-resistant coating is preferably 8 mm to 13 mm. The present invention further improves the stability of the combination between the wear-resistant coating and the steel body by distributing the wear-resistant particles in a stepped manner, so that even if the thickness of the obtained wear-resistant coating is relatively thick, it can be stably combined with the steel substrate.

[0018] By adopting the above technical solution, the beneficial effects of the present invention are: The present invention utilizes cold spraying in combination with a low-melting-point copper solder to combine with a base material. The wear-resistant particles are arranged in a stepped concentration in the base and are evenly dispersed in each concentration. The wear-resistant solder coating is further formed by furnace brazing to form a soft-hard combination wear-resistant coating. The thickness of the obtained wear-resistant coating is continuously controllable, and a centimeter-level wear-resistant coating can be prepared.

[0019] In the brazing process of the present invention, the brazing material is heated to a temperature exceeding the melting temperature of its low-melting-point brazing component and wets the base material and the cemented carbide. The liquid brazing material first passes through the gaps of the cemented carbide under the capillary action, wets the workpiece surface and fills the space between the entire cemented carbide particles. The brazing coating after cooling is composed of the brazing material and the cemented carbide dispersed in the brazing material, so as to achieve a brazing coating that can be well bonded to the substrate and has good wear resistance. The brazing method of heating in the furnace melts the low-melting-point copper-based brazing material and wets the high-melting-point WC-Co wear-resistant particles. The wear-resistant particles do not melt during the brazing process, and finally form a brazing coating that is wear-resistant and corrosion-resistant and has a tight bond between the coating and the substrate; The wear-resistant particles in the pre-deposited layer on the surface of the wear-resistant coating of the present invention have the largest content. Further in combination with the effect of shot peening, different degrees of deformation are formed due to the difference in hardness between the wear-resistant particles and the pure copper powder, that is, the wear-resistant particles protrude from the surface of the pre-deposited layer, thereby obtaining a hydrophobic surface with a micro-nano structure, thereby further improving the anti-corrosion performance of the obtained wear-resistant coating. DETAILED DESCRIPTION

[0020] In order to further explain the technical solution of the present invention, the present invention is described in detail below through specific embodiments.

[0021] Example 1

[0022] This embodiment discloses a control method for stepwise distribution of wear-resistant particles, comprising the following steps: A pre-deposited layer is cold-sprayed N times on the surface of the steel substrate, the pre-deposited layer comprising pure Cu powder, Cu3P eutectic powder and Sn powder; The Nth pre-deposited layer is also provided with wear-resistant particles, which are uniformly mixed with pure Cu powder, Cu3P eutectic powder and Sn powder, and cold sprayed, so that the wear-resistant particles are fixed in the pre-deposited layer as the pure Cu powder particles are deformed; The total mass of pure Cu powder, Cu3P eutectic powder and Sn powder in the pre-deposited layer at the surface Nth layer is M1, the mass of the wear-resistant particles is M2, and the mass ratio of M1 to M2 is 1:(1.2 to 1.3), as shown in Table 1; From the Nth pre-layer to the first pre-layer on the surface of the steel substrate, the wear-resistant particles dispersed in the pure Cu powder, Cu3P eutectic powder and Sn powder are reduced layer by layer.

[0023] The wear-resistant particles are WC-Co composite powders, wherein the mass ratio of WC to Co is (8.5 to 9.5):1.

[0024] The WC-Co composite powder is nano-scale particles.

[0025] The specific mass fractions of Cu powder, Cu3P eutectic powder and Sn powder in the pre-layer for dispersing wear-resistant particles are shown in Table 1, and the process parameters of cold spraying of the pre-layer are shown in Table 2.

[0026] The amount of wear-resistant particles is reduced by 20% layer by layer.

[0027] This embodiment also discloses an application of a stepwise distributed wear-resistant particle control method, comprising the following steps: S1. One-time sandblasting treatment of the steel substrate surface to remove the oxide film on the steel substrate surface; S2, cold spraying the preset layers layer by layer; S3, shot peening impacts a steel substrate with multiple pre-set layers to construct a rough hydrophobic surface; S4, placing the steel substrate / multi-layer pre-prepared layer after S3 in a heating furnace for brazing to obtain a wear-resistant coating with step-wise distribution of wear-resistant particles. Specific process parameters are shown in Table 2.

[0028] Example 2

[0029] The differences between this embodiment and embodiment 1 are shown in Table 1 and Table 2.

[0030] Example 3

[0031] The differences between this embodiment and embodiment 1 are shown in Table 1 and Table 2.

[0032] Example 4

[0033] The differences between this embodiment and embodiment 1 are shown in Table 1 and Table 2.

[0034] Example 5

[0035] The differences between this embodiment and embodiment 1 are shown in Table 1 and Table 2.

[0036] Comparative Example This comparative example discloses a preparation method for uniformly distributing wear-resistant particles in a wear-resistant coating, comprising the following steps: A pre-deposited layer is cold sprayed on the surface of the steel substrate, and the pre-deposited layer includes pure Cu powder, Cu3P eutectic powder and Sn powder; Wear-resistant particles are also distributed in the pre-deposited layer. The wear-resistant particles are uniformly mixed with pure Cu powder, Cu3P eutectic powder and Sn powder, and cold sprayed. The wear-resistant particles are fixed in the pre-deposited layer as the pure Cu powder particles are deformed. The total mass of pure Cu powder, Cu3P eutectic powder and Sn powder in the pre-deposited layer is M1, the mass of wear-resistant particles is M2, and the specific amount and proportion of each substance are shown in Table 1; the process parameters of the pre-deposited layer cold spraying are shown in Table 2.

[0037] The preparation method of the wear-resistant coating in this comparative example comprises the following steps: S1. One-time sandblasting treatment of the steel substrate surface to remove the oxide film on the steel substrate surface; S2, cold spraying the preset layers layer by layer; S3, shot peening impacts a steel substrate with multiple pre-set layers to construct a rough hydrophobic surface; S4. Place the steel substrate / pre-layer after S3 in a heating furnace for brazing to obtain a wear-resistant coating with wear-resistant particles distributed thereon. The specific process parameters are shown in Table 2.

[0038] Table 1 Composition and dosage of wear-resistant coating (mass fraction)

[0039] Table 2 Process parameters for preparing wear-resistant coatings in Examples 1 to 5

[0040] Table 3 Performance indicators of the wear-resistant coatings obtained in Examples 1 to 5 and Comparative Examples

[0041] Combining the data of Table 1, Table 2 and Table 3, it can be seen that the present invention ensures the bonding strength between the wear-resistant coating and the steel substrate while effectively ensuring the hardness of the wear-resistant coating through the control method of step-by-step distribution of wear-resistant particles. The present invention utilizes the preset layer obtained by cold spraying, heats the brazing coating, and the brazing coating material is heated to a melting temperature exceeding its low-melting point brazing component and wets the parent material and the cemented carbide. The liquid brazing material first passes through the gap of the cemented carbide under the capillary action, wets the workpiece surface and fills the space between the entire cemented carbide particles. The brazing coating after cooling is composed of the brazing material and the cemented carbide dispersed in the brazing material, so as to achieve a brazing coating that can be well bonded to the substrate and has good wear resistance of the coating. Therefore, the wear-resistant coating in the comparative example has insufficient bonding strength compared to the wear-resistant coating obtained in Examples 1 to 5 due to the excessively high content of wear-resistant particles.

[0042] The present invention combines cold spraying with the stepped distribution of wear-resistant particles, effectively reducing the amount of wear-resistant particles, improving the bonding strength between the wear-resistant coating and the steel substrate while ensuring the hardness of the coating, and being able to obtain a centimeter-level thick, dense, and hydrophobic wear-resistant coating. Even if the resulting steel substrate with the wear-resistant coating is applied to a relatively humid and harsh environment, since the wear-resistant coating of the steel substrate itself has sufficient thickness and a hydrophobic surface, it can effectively alleviate the interaction between the steel substrate and oxygen and water in the environment, thereby inhibiting the occurrence of corrosion.

Claims

1. A method for controlling stepwise distribution of wear-resistant particles, characterized in that: The following steps are involved: A pre-deposited layer is cold-sprayed N times on the surface of the steel substrate, the pre-deposited layer comprising pure Cu powder, Cu3P eutectic powder and Sn powder; The Nth pre-deposited layer is also provided with wear-resistant particles, which are uniformly mixed with pure Cu powder, Cu3P eutectic powder and Sn powder, and cold sprayed, so that the wear-resistant particles are fixed in the pre-deposited layer as the pure Cu powder particles are deformed; The total mass of pure Cu powder, Cu3P eutectic powder and Sn powder in the pre-deposited layer at the surface Nth layer is M1, the mass of the wear-resistant particles is M2, and the mass ratio of M1 to M2 is 1:(1.2 to 1.3); From the Nth pre-layer to the first pre-layer on the surface of the steel substrate, the wear-resistant particles dispersed in the pure Cu powder, Cu3P eutectic powder and Sn powder are reduced layer by layer.

2. A method for controlling stepwise distribution of wear-resistant particles according to claim 1, characterized in that: The wear-resistant particles are WC-Co composite powders, wherein the mass ratio of WC to Co is (8.5 to 9.5):

1.

3. A method for controlling stepwise distribution of wear-resistant particles according to claim 2, characterized in that: The WC-Co composite powder is nano-scale particles.

4. The control method of stepwise distribution of wear-resistant particles according to claim 1, characterized in that: The mass fractions of Cu powder, Cu3P eutectic powder and Sn powder in the pre-layer for dispersing wear-resistant particles are as follows: 35 to 40 parts of pure Cu powder; 5 to 8 parts of Cu3P eutectic powder; Sn powder 2 to 4 parts.

5. The control method of stepwise distribution of wear-resistant particles according to claim 1, characterized in that: The process parameters of the pre-layer cold spraying are as follows: The working pressure of supersonic compressed gas is 0.6MPa to 0.8Mpa; Powder feeding rate 15g / min to 25g / min; Spray distance 15mm to 30mm; Spray angle 20° to 30°.

6. The control method of stepwise distribution of wear-resistant particles according to claim 1, characterized in that: The amount of wear-resistant particles is reduced by 20% to 30% layer by layer.

7. An application of a stepwise distribution wear-resistant particle control method, characterized in that: The following steps are involved: S1. One-time sandblasting treatment of the steel substrate surface to remove the oxide film on the steel substrate surface; S2, cold spraying the preset layers layer by layer; S3, shot peening impacts a steel substrate with multiple pre-set layers to construct a rough hydrophobic surface; S4, placing the steel substrate / multi-layer pre-prepared layer after S3 in a heating furnace for brazing to obtain a wear-resistant coating with wear-resistant particles distributed in a stepped manner.

8. Application of the stepwise distribution wear-resistant particle control method according to claim 7, characterized in that: The brazing heating temperature is 695°C to 705°C, and the brazing time is 10min to 20min.

9. Application of the stepwise distribution wear-resistant particle control method according to claim 7, characterized in that: The process conditions of shot peening are as follows: The particle size of shot peening is 0.10mm to 0.15mm; The air flow pressure of shot peening is 0.3MPa to 0.4Mpa.

10. Application of the stepwise distribution wear-resistant particle control method according to claim 7, characterized in that: The thickness of the wear-resistant coating is 8mm to 13mm.

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