Surface coating of plunger or shaft workpiece and preparation method and application thereof

Abstract

The present application relates to the technical field of mechanical equipment, and specifically to a surface coating for a plunger or shaft workpiece, and a preparation method and application thereof. The preparation method comprises the following steps: spraying a metal spray coating onto the surface of a substrate, and then performing a remelting treatment and a heat preservation cooling treatment to obtain a surface coating. The preparation method improves the bonding strength between the surface coating and the substrate, prevents the surface coating from falling off, and at the same time reduces the porosity of the surface coating, improves the hardness and wear resistance of the surface coating, and effectively delays the spread of pitting corrosion. The Vickers hardness HV of the surface coating is 940 to 1300, and the Rockwell hardness HRC is 68 to 74.

Description

Technical Field

[0001] The present application relates to the technical field of mechanical equipment, and in particular to a surface coating of a plunger or shaft workpiece, a preparation method thereof, and an application thereof. Background Art

[0002] The plunger usually works in a corrosive fluid medium. Because the fluid contains solid particles, it is necessary to spray wear-resistant and corrosion-resistant materials on the plunger surface to improve the wear resistance, hardness, corrosion resistance and other properties of the plunger.

[0003] At present, the main spraying processes for spraying materials on the plunger surface include: (1) oxyacetylene spray welding process; (2) supersonic flame spraying process; (3) plasma flame spraying. However, these spraying processes all have disadvantages such as low coating hardness and insufficient bonding strength between the coating and the plunger substrate. For example, in the oxyacetylene spray welding process (1), the coating is mostly made of nickel-based alloy. The powder is first sprayed onto the substrate with oxyacetylene and then remelted. In this process, the coating and the substrate material achieve metallurgical bonding and high bonding strength, but the coating has high porosity and a hardness of only 58 to 62 HRC. It is easily scratched and worn by hard particles in the medium, resulting in coating failure and inability to cope with the operating conditions of the plunger. The service life of the plunger is short, resulting in a high frequency of replacement of the plunger and the seals that match it, reducing the working efficiency of the pump and increasing the production and use costs. In the supersonic flame spraying process (2), tungsten carbide alloy powder is sprayed onto the surface of the substrate material at high temperature and high speed. Although the hardness is high, the bonding between the coating and the substrate is mechanical, and the bonding strength is 70MPa. Under the high temperature, high pressure, and high corrosion conditions of the plunger, the coating is prone to pitting, shedding and other failure problems. Summary of the invention

[0004] In order to solve the above problems, the present application proposes a surface coating for a plunger or shaft workpiece, a preparation method and an application thereof. The hardness of the surface coating is as high as HRC 68 to 74, and it has a self-repairing function, which increases the service life of the plunger or shaft workpiece. The surface coating prepared by the preparation method has a high bonding strength with the plunger or shaft substrate, and the surface coating is not easy to fall off after long-term use and has excellent wear resistance and corrosion resistance.

[0005] This application is implemented through the following technical solutions:

[0006] One of the purposes of the present application is to provide a method for preparing a surface coating of a plunger or shaft workpiece, comprising the following steps:

[0007] The metal spray coating is sprayed onto the surface of the substrate, and then subjected to a remelting treatment and a heat preservation cooling treatment to obtain a surface coating;

[0008] Wherein, the spraying includes at least one of plasma spraying and supersonic spraying;

[0009] The substrate is at least one of a plunger substrate and a shaft workpiece substrate;

[0010] The metal spray coating comprises a raw material of a high entropy alloy; the raw material of the high entropy alloy comprises the following materials by mass fraction: 16.5% to 26% Ni, 18% to 25% Co, 20% to 28% Cr, 16.5% to 25% W, 16.5% to 22.5% Mo, 0.1% to 3% Cu, 0.1% to 3% Si and 0.1% to 3% B;

[0011] In the remelting step, the remelting temperature is 1000°C to 1150°C.

[0012] In some possible implementations, the flame velocity of the plasma spraying is 300 m / s to 400 m / s.

[0013] In some possible implementations, the flame velocity of the supersonic spraying is 1500m / s~2000m / s.

[0014] In some possible implementations, the impact velocity of the plasma sprayed powder is 150 m / s to 300 m / s.

[0015] In some possible implementations, the powder impact velocity of the supersonic spraying is 500 m / s to 1100 m / s.

[0016] In some possible implementations, the spraying distance of the plasma spraying is 100 mm to 150 mm.

[0017] In some possible implementations, the spraying distance of the supersonic spraying is 300 mm to 360 mm.

[0018] In some possible implementations, the metal spray coating further includes at least one of nano nickel-based alloy and metal microcapsules.

[0019] In some possible implementations, in the metal microcapsule, the wall material is graphene, and the core material is a nickel-based alloy.

[0020] The second object of the present application is to provide a surface coating obtained by the preparation method of the surface coating of a plunger or shaft workpiece provided in the present application;

[0021] The surface coating has a thickness of 300 μm to 800 μm.

[0022] In some possible implementations, the surface coating includes an integrally formed penetration transition layer and a wear-resistant layer; the penetration transition layer is located between the substrate surface and the wear-resistant layer.

[0023] In some possible implementations, the thickness of the penetration transition layer is 20 μm to 100 μm.

[0024] The third object of the present application is to provide a plunger, comprising a plunger base and a coating attached to the surface of the plunger base; the coating comprises the surface coating provided in the present application.

[0025] The fourth purpose of the present application is to provide a method for preparing a surface coating of a plunger or shaft workpiece provided in the present application, and the application of the surface coating or the plunger in the field of mechanical equipment.

[0026] The surface coating of the plunger or shaft workpiece and the preparation method thereof provided in the present application have at least the following beneficial technical effects:

[0027] (1) The method for preparing the surface coating of a plunger or shaft workpiece provided in the present application is to spray the metal spray coating to form a mechanical bond with the substrate; then remelt the metal spray coating to form an alloy in situ on the substrate surface, and diffuse atoms with the substrate interface. The metal spray coating and the substrate are metallurgically bonded to obtain a surface coating, thereby improving the bonding strength between the surface coating and the substrate, preventing the surface coating from falling off, and reducing the porosity of the surface coating, improving the hardness and wear resistance of the surface coating, and effectively delaying the spread of pitting corrosion. Cooling after heat preservation can effectively prevent the surface coating from cracking;

[0028] (2) The Vickers hardness HV of the surface coating provided in this application is 940~1300, and the Rockwell hardness HRC is 68~74;

[0029] (3) The plunger provided in the present application comprises a surface coating with high hardness and wear resistance provided in the present application, thereby making the plunger have high wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present drawings or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present drawings. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0031] Figure 1 This is a schematic diagram of the structure of a plunger in an embodiment of the present application.

[0032] Figure 2 This is an electron microscope image of a coating sprayed in a method for preparing a surface coating of a plunger or shaft workpiece in Example 1 of the present application.

[0033] Figure 3This is an electron microscope image of a surface coating obtained after remelting treatment in a method for preparing a surface coating of a plunger or shaft workpiece in Example 1 of the present application.

[0034] Explanation of reference numerals: 1- plunger substrate; 2- coating; PaR1- coating before remelting; PaR2- wear-resistant layer; Pa1- penetration transition layer.

[0035] The purpose, features and advantages of this figure will be further described in conjunction with the embodiments with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0037] Obviously, the following descriptions are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in the field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0038] However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the following description is provided for those skilled in the art to fully understand the present application and is not intended to limit the subject matter described in the claims.

[0039] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution, and all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0040] Due to the high failure rate of high-pressure plunger pumps (one or two months), short average trouble-free operation time (less than 2,000 hours), and short service life (about 500 hours), one of the main reasons for the failure of high-pressure plunger pumps is that the plunger surface is worn and corroded due to long-term operation and immersion in corrosive fluid media, which causes the plunger pump to fail. An effective way to improve the wear and corrosion resistance of the plunger surface is to set a coating on the surface. However, the current spray-coated tungsten carbide alloy coating has poor bonding strength and wear resistance with the substrate, and cannot significantly extend the service life of the plunger.

[0041] In order to improve the bonding strength, wear resistance and corrosion resistance of the coating of the plunger and the substrate, and thus significantly extend the service life of the plunger, the embodiment of the present application proposes a surface coating of a plunger or a shaft workpiece, and a preparation method and application thereof. Among them, the preparation method of the surface coating of the plunger or shaft workpiece significantly improves the bonding strength between the surface coating and the substrate, prevents the surface coating from falling off, and at the same time reduces the porosity of the surface coating, improves the hardness and wear resistance of the surface coating, and effectively delays the spread of pitting corrosion. The Vickers hardness HV of the surface coating is 940~1300, and the Rockwell hardness HRC is 68~74.

[0042] The following is a detailed description of a surface coating for a plunger or shaft workpiece, a preparation method, and an application thereof in an embodiment of the present application.

[0043] The first aspect of the embodiment of the present application provides a method for preparing a surface coating of a plunger or a shaft workpiece, comprising the following steps:

[0044] S1. The metal spray coating is sprayed onto the substrate surface, and then remelted and cooled to obtain a surface coating;

[0045] Wherein, the spraying includes at least one of plasma spraying and supersonic spraying;

[0046] The substrate is at least one of a plunger substrate and a shaft workpiece substrate;

[0047] The metal spray coating includes a raw material of a high entropy alloy; the raw material of the high entropy alloy includes the following materials by mass fraction: 16.5%~26% Ni, 18%~25% Co, 20%~28% Cr, 16.5%~25% W, 16.5%~22.5% Mo, 0.1%~3% Cu, 0.1%~3% Si and 0.1%~3% B;

[0048] In the remelting process step, the remelting temperature is 1000°C to 1150°C.

[0049] The preparation method of the surface coating of the plunger or shaft workpiece provided in the embodiment of the present application, spraying makes the metal spray coating form a mechanical bond with the substrate; remelting treatment, the metal spray coating is remelted in situ on the surface of the substrate into an alloy, and the atoms diffuse mutually with the substrate interface, the metal spray coating and the substrate are metallurgically bonded to obtain a surface coating, the bonding strength between the surface coating and the substrate is improved, the surface coating is prevented from falling off, and the porosity of the surface coating is reduced, the hardness and wear resistance of the surface coating are improved, and the diffusion of pitting corrosion is effectively delayed. In addition, the surface coating formed after the raw material of the high entropy alloy is remelted has the advantages of high corrosion resistance, high temperature strength, high hardness, higher thermal stability, high temperature mechanical properties and high degree of design freedom. Cooling after heat preservation can effectively prevent cracks from forming in the surface coating.

[0050] In an embodiment, the raw materials of the high entropy alloy include the following materials by mass fraction: 16.5%~26% Ni, 18%~25% Co, 20%~28% Cr, 16.5%~25% W, 16.5%~22.5% Mo, 0.1%~3% Cu, 0.1%~3% Si and 0.1%~3% B; it can be 18% Ni, 19% Co, 21% Cr, 20% W, 20% Mo, 1.5% Cu, 0.2% Si and 0.3% B, 19% Ni, 20% Co, 20% Cr, 20% W, 19% Mo, 1% Cu, 0.5% Si and 0.5% B and other typical but non-limiting mass fractions or a range between any two mass fractions.

[0051] In the embodiment, in the remelting step, the remelting temperature is 1000° C. to 1150° C., which can be a typical but non-limiting remelting temperature such as 1000° C., 1100° C., 1150° C., or a range between any two remelting temperatures. At this remelting temperature, a deep melting transition layer can be formed between the surface coating and the substrate, thereby improving the bonding strength between the surface coating and the substrate.

[0052] In some embodiments, in the above step S1, the powder particle size of the raw material of the high entropy alloy is 15 μm to 45 μm. In the exemplary embodiment, it can be a typical but non-limiting powder particle size such as 15 μm, 25 μm, 30 μm, 40 μm, 45 μm, or a range between any two powder particle sizes. In this powder particle size range, the raw material of the high entropy alloy can quickly absorb heat to form a molten or semi-molten state, and sprayed onto the surface of the substrate to form a uniform preformed coating.

[0053] In some embodiments, in the above step S1, the metal spray coating further includes at least one of nano nickel-based alloy and metal microcapsules. In this case, the surface coating made of the metal spray coating has a self-repairing function, and the surface coating of the plunger or shaft workpiece will produce cracks and other damage after long-term work. The nano nickel-based alloy and metal microcapsules in the surface coating repair the damage by changing their own structure or releasing repair materials.

[0054] In some embodiments, the average particle size of the nano nickel-based alloy is 10nm to 100nm. In the exemplary embodiment, the average particle size may be 10nm, 30nm, 60nm, 100nm, etc., which are typical but non-limiting average particle sizes, or a range between any two average particle sizes. In this case, the nano nickel-based alloy repairs damage such as cracks in the surface coating of a plunger or shaft workpiece by changing its own structure.

[0055] In some specific embodiments, the nano nickel-based alloy is a component of the following mass fractions: W 18.5%~20%, Cr 1%~5%, and the balance is Ni and inevitable impurities. In this case, the melting point of the nano nickel-based alloy is to change its own structure to repair the damage such as cracks in the surface coating of the plunger or shaft workpiece based on its own volume effect and surface effect characteristics. Exemplarily, the mass fraction of W in the nano nickel-based alloy can be: 18.5%, 19%, 19.5%, 20% and other typical but non-restrictive mass fractions or the range between any two mass fractions; the mass fraction of Cr can be: 1%, 2%, 3%, 4%, 5% and other typical but non-restrictive mass fractions or the range between any two mass fractions.

[0056] In other specific embodiments, the nano nickel-based alloy is a nickel-chromium-tungsten-molybdenum alloy (Inconel 230), and the component contents (mass fraction) are: Ni 75%-76%, Cr 12%-19%, W 10%-13%, Mo 1%-3%, and the remainder is a metal or non-metal element with a mass fraction of less than 1%. In this case, the nickel-chromium-tungsten-molybdenum alloy has excellent high temperature performance, corrosion resistance and mechanical properties.

[0057] In some specific embodiments, in the metal microcapsule, the wall material is graphene and the core material is a nickel-based alloy; wherein the material of the nickel-based alloy is the nickel-based alloy provided in the embodiments of the present application. In this case, after the graphene as the wall material is worn, the metal microcapsule can release the repair material (nickel-based alloy) to repair the damage.

[0058] In some embodiments, the average particle size of the metal microcapsules is 200 μm to 300 μm. In exemplary embodiments, the average particle size may be 200 μm, 250 μm, 300 μm, or other typical but non-limiting average particle sizes, or a range between any two average particle sizes.

[0059] In some embodiments, the thickness of the wall material of the metal microcapsule is 10 μm to 100 μm, and in exemplary embodiments, it can be a typical but non-limiting thickness of 10 μm, 30 μm, 60 μm, 100 μm, or a range between any two thicknesses. In this case, when preparing the surface coating of a plunger or shaft workpiece, the metal microcapsule can always maintain its structure without being destroyed.

[0060] In some embodiments, preparing metal microcapsules comprises the following steps:

[0061] Step 1. Obtain the powder ratio of nickel-based alloy raw materials (Ni, Cr, W, Mo).

[0062] Step 2. Under an inert atmosphere, ball milling the nickel-based alloy raw material to obtain a nickel-based alloy.

[0063] Step 3. Use chemical vapor deposition to coat the graphene with a nickel-based alloy to obtain metal microcapsules.

[0064] In some specific embodiments, in the above step 2, the grinding balls used in the ball mill are stainless steel balls, and the sizes of the stainless steel balls are selected from large balls, medium balls and small balls for mixed grinding, and the number ratio of large balls, medium balls and small balls is 1:20:100, and the diameter D of the large balls is 大 10mm<D 大 ≤20mm, diameter of the middle ball D 中 5mm≤D 中 ≤10mm, ball diameter D 小 0.5mm≤D 小 <5mm. In some specific embodiments, in the above step 2, the rotation speed of the ball mill is 90r / min~150r / min. In the exemplary example, it can be 90r / min, 100r / min, 120r / min, 150r / min and other typical but non-limiting rotation speeds or the range between any two rotation speeds. In some specific embodiments, in the above step 2, during the ball milling process, the rotation direction is changed every 20min; each ball milling is 3min~5min, and then stopped for 5min to prevent the ball mill from overheating and powder agglomeration. The ball milling time is 3h~12h. In some specific embodiments, in the above step 2, the ball-to-material ratio (mass ratio of the ball-to-material) of the ball milling is (1~20):1. In some specific embodiments, in the above step 2, anhydrous ethanol is added during ball milling to improve the ball milling effect, and the amount of anhydrous ethanol used depends on the specific ball milling situation, which belongs to conventional technology and is not limited here. In this case, the nickel-based alloy obtained by ball milling is uniformly alloyed and has a refined particle size, and the particle size of the prepared nickel-based alloy is 100μm~290μm.

[0065] In some specific embodiments, in the above step 3, the carbon source and temperature can be adjusted according to the actual preparation process without limitation. In the exemplary embodiment, the carbon source can be methane, ethylene, ethane, etc.; the temperature of the carbon source pyrolysis can be 900°C to 1000°C.

[0066] In some other embodiments, the preparation of metal microcapsules comprises the following steps:

[0067] X1. Mechanically crush the nickel-based alloy and screen the nickel-based alloy powder with a particle size of 100μm~290μm.

[0068] X2. Use chemical vapor deposition to coat graphene with nickel-based alloy to obtain metal microcapsules.

[0069] In some specific embodiments, in the above step X2, the carbon source and temperature can be adjusted according to the actual preparation process without limitation. In the exemplary embodiment, the carbon source can be methane, ethylene, ethane, etc.; the temperature of the carbon source pyrolysis can be 900°C to 1000°C.

[0070] In some embodiments, the substrate is a plunger substrate or a shaft-type substrate.

[0071] In some embodiments, before preparing the surface coating on the substrate surface, the substrate surface is pretreated, and the pretreatment includes substrate surface cleaning and sandblasting. In this case, substrate cleaning can remove organic matter and other impurities on the substrate surface, and sandblasting can coarsen the substrate surface and help improve the bonding strength between the substrate surface and the surface coating. It should be noted that surface cleaning and sandblasting are both conventional in the art, and the materials and conditions of the treatment are not particularly limited in the embodiments of the present application. As an example, alcohol or ultrasonic cleaning can be used to clean the substrate surface; a sandblaster is used to sandblast the substrate surface to coarsen the substrate surface so that the metal spray coating is easily attached to the substrate.

[0072] In some embodiments, in the above step S1, before spraying, the substrate is preheated at a temperature of 80°C to 90°C. In an exemplary embodiment, the preheating temperature may be 80°C, 85°C, 90°C, or any other typical but non-limiting preheating temperature or a range between any two preheating temperatures. In this case, preheating the substrate may improve the mechanical bonding between the metal spray coating and the substrate surface.

[0073] In some embodiments, in the above step S1, the flame velocity of plasma spraying is 300m / s~400m / s, and in the exemplary example, it can be a typical but non-limiting flame velocity such as 300m / s, 350m / s, 400m / s, or a range between any two flame velocity. In some embodiments, in the above step S1, the flame velocity of supersonic spraying is 1500m / s~2000m / s, and in the exemplary example, it can be a typical but non-limiting flame velocity such as 1500m / s, 1800m / s, 2000m / s, or a range between any two flame velocity. At this flame velocity, the metal spray coating is heated in the flame to form a molten or semi-molten state, and is sprayed onto the substrate surface to form a denser coating, thereby improving the quality of the surface coating.

[0074] In some embodiments, in the above step S1, the impact velocity of the powder of plasma spraying is 150m / s~300m / s, and in the exemplary embodiment, it can be a typical but non-limiting powder impact velocity such as 150m / s, 200m / s, 300m / s, or a range between any two powder impact velocities. In some embodiments, in the above step S1, the impact velocity of the powder of supersonic spraying is 500m / s~1100m / s, and in the exemplary embodiment, it can be a typical but non-limiting powder impact velocity such as 500m / s, 800m / s, 1100m / s, or a range between any two powder impact velocities. At this powder impact velocity, the energy size and distribution of the metal spray coating when it impacts the substrate surface are uniform, thereby improving the bonding strength, density and wear resistance of the surface coating.

[0075] In some embodiments, in the above step S1, the spraying distance of plasma spraying is 100mm~150mm, and in the exemplary example, it can be a typical but non-restrictive spraying distance such as 100mm, 130mm, 150mm, or a range between any two spraying distances. In some embodiments, in the above step S1, the spraying distance of supersonic spraying is 300mm~360mm, and in the exemplary example, it can be a typical but non-restrictive spraying distance such as 300mm, 330mm, 360mm, or a range between any two spraying distances. At this spraying distance, the degree of mechanical bonding between the coating and the substrate is high, thereby improving the quality of the surface coating.

[0076] In some embodiments, in the above step S1, in the remelting step, the coating is subjected to secondary melting treatment by high frequency remelting or flame remelting. In this case, the remelting treatment can achieve metallurgical bonding between the substrate and the coating, and the surface hardness of the coating reaches HRC 68-74.

[0077] In some embodiments, in the above step S1, perlite is used for heat preservation and cooling treatment. In this case, the perlite heat preservation and cooling treatment can promote the formation of fine grains in the alloy, improve the wear resistance and corrosion resistance of the surface coating, and effectively prevent cracks in the surface coating.

[0078] In some embodiments, in the above step S1, the melting point of the surface coating is 1050°C to 1280°C. In the exemplary embodiment, it can be a typical but non-limiting melting point such as 1050°C, 1100°C, 1200°C, 1280°C, or a range between any two melting points. In this case, the surface coating can still work normally in a high temperature environment and has high wear resistance.

[0079] A second aspect of the embodiments of the present application provides a surface coating obtained by the method for preparing a surface coating of a plunger or shaft workpiece provided in the embodiments of the present application;

[0080] The thickness of the surface coating is 300μm~800μm.

[0081] The surface coating provided in the present application has a Vickers hardness HV of 940 to 1300, a Rockwell hardness HRC of 68 to 74, and a melting point of 1050° C. to 1280° C.

[0082] In the exemplary embodiment, the thickness of the surface coating is 300 μm to 800 μm, which may be 300 μm, 400 μm, 636.4 μm, 800 μm, or other typical but non-limiting thicknesses or a range between any two thicknesses.

[0083] In some embodiments, please refer to Figure 3 , the surface coating includes an integrally formed penetration transition layer Pa1 and a wear-resistant layer PaR2; the penetration transition layer Pa1 is located between the substrate and the wear-resistant layer PaR2. In this case, the penetration transition layer is a transition layer produced by the metallurgical bonding between the surface coating and the substrate, which improves the bonding strength between the substrate and the surface coating and prevents the surface coating from falling off.

[0084] In some embodiments, the thickness of the penetration transition layer is 20 μm to 100 μm. In the exemplary embodiment, it can be a typical but non-limiting thickness of 20 μm, 48 μm, 80 μm, 100 μm, or a range between any two thicknesses. In some embodiments, the thickness of the wear-resistant layer is 200 μm to 780 μm. In the exemplary embodiment, it can be a typical but non-limiting thickness of 200 μm, 588 μm, 780 μm, or a range between any two thicknesses. In this case, the metallurgical bonding strength between the surface coating and the substrate is high, and the performance of the substrate and the surface coating itself is not affected.

[0085] A third aspect of the present application provides a plunger, such as Figure 1As shown, it includes a plunger base 1 and a coating 2 attached to the surface of the plunger base; the coating includes the surface coating provided in the embodiment of the present application.

[0086] The plunger of the embodiment of the present application needs to be provided with a surface coating to make it have high wear resistance and corrosion resistance in an environment of long-term wear and corrosion, thereby extending its service life. The plunger of the embodiment of the present application includes a surface coating with high hardness and wear resistance provided by the embodiment of the present application, thereby making the plunger have high wear resistance.

[0087] In some specific embodiments, the diameter of the plunger is 38 mm to 120 mm. In the exemplary examples, it can be a typical but non-restrictive diameter such as 38 mm, 50 mm, 80 mm, 120 mm, or a range between any two diameters. It should be noted that the length of the plunger varies according to different practical application fields, but as an example, the length of the plunger can be 300 mm, 449.7 mm, that is, the size of the plunger can be φ38 mm*300 mm, φ41 mm*300 mm, 120.65 mm*449.7 mm, etc.

[0088] A fourth aspect of an embodiment of the present application provides a shaft workpiece, comprising a shaft workpiece substrate and a coating attached to the surface of the shaft workpiece substrate; the coating comprises the surface coating provided in an embodiment of the present application.

[0089] The shaft workpiece provided in the embodiment of the present application needs to be provided with a surface coating to make it have high wear resistance and corrosion resistance in an environment of long-term wear and corrosion, thereby extending its service life. The shaft workpiece in the embodiment of the present application includes a surface coating with high hardness and wear resistance provided in the embodiment of the present application, thereby making the shaft workpiece have high wear resistance.

[0090] In some specific embodiments, the diameter of the shaft workpiece is 60 mm to 115 mm. In the exemplary examples, it can be a typical but non-restrictive diameter such as 60 mm, 90 mm, 114.3 mm, 115 mm, or a range between any two diameters. It should be noted that the length of the shaft workpiece varies according to the actual application field, but as an example, the length of the shaft workpiece can be 400 mm to 500 mm, that is, the size of the shaft workpiece can be φ114.3 mm*500 mm, φ60 mm*482 mm, etc.

[0091] A fifth aspect of the embodiments of the present application provides a method for preparing a surface coating of a plunger or shaft workpiece provided by the embodiments of the present application, and an application of the surface coating or the plunger in the field of mechanical equipment.

[0092] The following is further described in conjunction with specific embodiments.

[0093] Example 1

[0094] Example 1 A method for preparing a plunger surface coating is proposed, using a raw material of a high entropy alloy as a metal spray coating, wherein the mass fraction of each material in the raw material of the high entropy alloy is 18% Ni, 19% Co, 21% Cr, 20% W, 20% Mo, 1.5% Cu, 0.2% Si and 0.3% B; the steps are as follows:

[0095] (1) Select a plunger base with a size of φ37.4 mm*300 mm; clean the surface of the plunger base with alcohol or ultrasonic cleaning, and then use a sandblasting machine to sandblast the surface of the plunger base to roughen the base surface; the sandblasting pressure is set at 0.6 MPa and the sandblasting time is 4 min.

[0096] (2) Spraying: The raw material of the high entropy alloy was baked at a temperature of 120°C for 90 minutes; the plunger substrate was preheated to 80°C and the metal spray coating was evenly sprayed onto the plunger substrate by supersonic spraying. The conditions for supersonic spraying were as follows: the gun distance was set to 320 mm (spraying distance), the oxygen was set to 1850 SCHF, the kerosene was set to 5.8 GPH, the Mach node was 7, and a 4-inch barrel was used for spraying; the flame velocity was 1700 m / s, and the powder impact velocity was 700 m / s.

[0097] (3) Remelting treatment: After spraying, the plunger substrate with coating is remelted at a temperature of 1100°C by high-frequency remelting or flame remelting.

[0098] (4) After remelting, the product is cooled to room temperature in perlite to obtain a surface coating of the plunger.

[0099] The surface coating is subsequently ground and polished to achieve the required accuracy to obtain the plunger.

[0100] This embodiment also proposes a surface coating of the plunger, which is prepared by the preparation method of the plunger surface coating of this embodiment, and includes an integrally formed penetration transition layer and a wear-resistant layer; wherein the thickness of the penetration transition layer is 48μm, and the thickness of the wear-resistant layer is 588μm.

[0101] Example 2

[0102] Example 2 proposes a method for preparing a plunger surface coating, and the steps are basically the same as those of Example 1, except that:

[0103] The flame velocity of step (2) is 1500 m / s and the powder impact velocity is 500 m / s.

[0104] Example 3

[0105] Example 3 proposes a method for preparing a plunger surface coating, and the steps are basically the same as those of Example 1, except that:

[0106] The flame velocity of step (2) is 2000 m / s and the powder impact velocity is 900 m / s.

[0107] Example 4

[0108] Example 4 proposes a method for preparing a plunger surface coating, and the steps are basically the same as those of Example 1, except that:

[0109] The remelting temperature of step (3) is 1000°C.

[0110] Example 5

[0111] Example 5 proposes a method for preparing a plunger surface coating, and the steps are basically the same as those of Example 1, except that:

[0112] The remelting temperature of step (3) is 1150°C.

[0113] Example 6

[0114] Example 6 proposes a method for preparing a plunger surface coating. The steps are basically the same as those in Example 1, except that the mass fractions of each material in the raw material of the high entropy alloy are 19% Ni, 20% Co, 20% Cr, 20% W, 19% Mo, 1% Cu, 0.5% Si and 0.5% B.

[0115] This embodiment also proposes a plunger surface coating, which is prepared by the plunger surface coating preparation method of this embodiment, and includes an integrally formed penetration transition layer and a wear-resistant layer; wherein the thickness of the penetration transition layer is 50 μm, and the thickness of the wear-resistant layer is 580 μm.

[0116] Example 7

[0117] Example 7 proposes a method for preparing a plunger surface coating. The steps are the same as those in Example 1, except that the mass fractions of each material in the raw material of the high entropy alloy are 18% Ni, 18% Co, 20% Cr, 17% W, 18% Mo, 3% Cu, 3% Si and 3% B.

[0118] This embodiment also proposes a plunger surface coating, which is prepared by the plunger surface coating preparation method of this embodiment, and includes an integrally formed penetration transition layer and a wear-resistant layer; wherein the thickness of the penetration transition layer is 80μm and the thickness of the wear-resistant layer is 600μm.

[0119] Example 8

[0120] Example 8 proposes a method for preparing a plunger surface coating. The steps are the same as those of Example 1, except that the mass fractions of the materials in the raw materials of the high entropy alloy are 16.5% Ni, 23% Co, 25% Cr, 16.5% W, 16.5% Mo, 2% Cu, 0.4% Si and 0.1% B.

[0121] This embodiment also proposes a plunger surface coating, which is prepared by the plunger surface coating preparation method of this embodiment, and includes an integrally formed penetration transition layer and a wear-resistant layer; wherein the thickness of the penetration transition layer is 25μm, and the thickness of the wear-resistant layer is 710μm.

[0122] Example 9

[0123] Example 9 proposes a method for preparing a plunger surface coating, and the steps are basically the same as those of Example 1, except that: the metal spray coating is the raw material of the high entropy alloy and the nano nickel-based alloy of Example 1;

[0124] The nano nickel-based alloy has the following components by mass fraction: W 18.5%, Cr 5%, and the balance is Ni and inevitable impurities; the average particle size of the nano nickel-based alloy is 60nm.

[0125] This embodiment also proposes a plunger surface coating, which is prepared by the plunger surface coating preparation method of this embodiment, and includes an integrally formed penetration transition layer and a wear-resistant layer; wherein the thickness of the penetration transition layer is 73μm, and the thickness of the wear-resistant layer is 693μm.

[0126] Example 10

[0127] Example 10 proposes a method for preparing a plunger surface coating, and the steps are basically the same as those of Example 9, except that the average particle size of the nano nickel-based alloy is 10 nm.

[0128] This embodiment also proposes a plunger surface coating, which is prepared by the plunger surface coating preparation method of this embodiment, and includes an integrally formed penetration transition layer and a wear-resistant layer; wherein the thickness of the penetration transition layer is 30 μm, and the thickness of the wear-resistant layer is 571 μm.

[0129] Embodiment 11

[0130] Example 11 proposes a method for preparing a plunger surface coating, and the steps are basically the same as those of Example 9, except that the average particle size of the nano nickel-based alloy is 50 nm.

[0131] This embodiment also proposes a plunger surface coating, which is prepared by the plunger surface coating preparation method of this embodiment, and includes an integrally formed penetration transition layer and a wear-resistant layer; wherein the thickness of the penetration transition layer is 78μm and the thickness of the wear-resistant layer is 601μm.

[0132] Example 12

[0133] Example 12 proposes a method for preparing a plunger surface coating, and the steps are basically the same as those of Example 9, except that the average particle size of the nano nickel-based alloy is 100 nm.

[0134] This embodiment also proposes a plunger surface coating, which is prepared by the plunger surface coating preparation method of this embodiment, and includes an integrally formed penetration transition layer and a wear-resistant layer; wherein the thickness of the penetration transition layer is 57μm, and the thickness of the wear-resistant layer is 621μm.

[0135] Example 13

[0136] Example 13 proposes a method for preparing a plunger surface coating, and the steps are basically the same as those of Example 1, except that: the metal spray coating is the raw material of the high entropy alloy and metal microcapsules of Example 1;

[0137] Among them, in the metal microcapsule, the wall material is graphene, the core material is nickel-based alloy, and the nickel-based alloy has the following mass fractions: W 18.5%, Cr 5%, and the remainder is Ni and unavoidable impurities; the average particle size of the nano nickel-based alloy is 60nm.

[0138] This embodiment also proposes a plunger surface coating, which is prepared by the plunger surface coating preparation method of this embodiment, and includes an integrally formed penetration transition layer and a wear-resistant layer; wherein the thickness of the penetration transition layer is 91 μm, and the thickness of the wear-resistant layer is 753 μm.

[0139] Embodiment 14

[0140] Example 14 proposes a method for preparing a plunger surface coating, and the steps are basically the same as those in Example 1, except that:

[0141] Step (2) uses plasma spraying, specifically: baking the raw material of the high entropy alloy at a temperature of 120°C for 90 minutes; preheating the plunger substrate to 100°C and then using plasma spraying to evenly spray the metal spray coating onto the plunger substrate. The conditions of plasma spraying are: the gun distance is set to 120 mm (spraying distance), the current is set to 750A, the argon gas is set to 50L / min, and the hydrogen gas is set to 1L / min; the flame flow velocity is 400m / s, and the powder impact velocity is 240m / s.

[0142] This embodiment also proposes a surface coating of a plunger, which is prepared by the preparation method of the plunger surface coating of this embodiment, and includes an integrally formed penetration transition layer and a wear-resistant layer; wherein the thickness of the penetration transition layer is 40μm, and the thickness of the wear-resistant layer is 604μm.

[0143] Embodiment 15

[0144] Example 15 provides a method for preparing a plunger surface coating, and the steps are basically the same as those in Example 1, except that:

[0145] Step (2) uses plasma spraying, specifically: baking the raw material of the high entropy alloy at a temperature of 120°C for 90 minutes; preheating the plunger substrate to 100°C and then using plasma spraying to evenly spray the metal spray coating onto the plunger substrate. The conditions for plasma spraying are: the gun distance is set to 140 mm (spraying distance), the current is set to 720A, the argon is set to 45L / min, and the hydrogen is set to 1L / min; the flame velocity is 350m / s, and the powder impact velocity is 170m / s.

[0146] This embodiment also proposes a surface coating of a plunger, which is prepared by the preparation method of the plunger surface coating of this embodiment, and includes an integrally formed penetration transition layer and a wear-resistant layer; wherein the thickness of the penetration transition layer is 44μm, and the thickness of the wear-resistant layer is 590μm.

[0147] Comparative Example 1

[0148] Comparative Example 1 proposes a method for preparing a plunger surface coating, using tungsten carbide alloy as a metal spray coating, the raw material composition of the tungsten carbide alloy is: by mass percentage, graphite powder 2%, chromium powder 15%, nickel powder 6%, manganese powder 1.2%, molybdenum powder 2.5%, boron powder 1.8%, silicon powder 1%, rare earth oxide powder 4%, nickel-coated graphite powder 8%, and the balance is tungsten carbide powder; the steps are as follows:

[0149] The alloy powder is clad on the surface of the plunger substrate after sandblasting by laser cladding process; then it is rough-machined by turning, and then the surface of the plunger substrate is fine-machined by ultrasonic calendering process, and finally a layer with a thickness of 0.3mm~2.5mm and a hardness of 45HRC~65HRC is obtained on the surface of the plunger substrate.

[0150] In order to verify the progressiveness of the surface coating of a plunger or shaft workpiece and its preparation method provided in the embodiment of the present application, the sliding friction and wear test of the coating was carried out using the reciprocating module of the UMT high-temperature friction and wear tester. The friction and wear sample size was 20×10×5mm, and the grinding pair selected a high-hardness silicon nitride ceramic ball of Ф6.35mm. Before the test, the coating surface was repeatedly ground and the coating sample was polished with a 1.2μm diamond polisher until the surface was glossy, and the surface roughness of the polished coating was controlled within the range of 0.2~0.5μm (Ra). The coating was ultrasonically cleaned in acetone before and after wear. The friction and wear test parameters are as follows: the friction environment is air / dry friction; the sliding load is 60N; the sliding time is 30min; the reciprocating frequency is 8.3Hz; the reciprocating stroke is 5mm; and the total sliding distance is 75m. According to GB / T10125-201, the coatings prepared in the embodiment and the comparative example were subjected to corrosion resistance tests, and the hardness was measured for comparison. The experimental results are shown in Table 1 below. Taking Example 1 as an example, the coating obtained by spraying (before remelting) was scanned by electron microscope to obtain the microstructure of the coating as shown in Figure 2 As shown, the surface coating after remelting treatment was scanned by electron microscope to obtain the microstructure of the coating as shown in Figure 3 shown.

[0151] Table 1

[0152]

[0153] According to Table 1 above and the instructions attached Figure 2~3 At least the following conclusions can be drawn:

[0154] (1) As can be seen from Table 1, the wear rate of the surface coating of the plunger in the embodiment of the present application is less than 2%, the hardness HRC is greater than 68, and the corrosion rate is less than 3.5%. That is, the surface coating of the embodiment of the present application has excellent wear resistance, hardness and corrosion rate, which can significantly improve the service life of the plunger;

[0155] (2) Attached to the instruction manual Figure 2 and 3 It can be seen that in the preparation method of the surface coating of the plunger in the embodiment of the present application, the thickness of the coating PaR1 before remelting is 636.4μm; after remelting, the surface coating includes a wear-resistant layer PaR2 and a fusion transition layer Pa1, and the thicknesses are PaR2 of 616μm and Pa1 of 48.01μm respectively; obviously, the sum of PaR2 and Pa1 is greater than PaR1, indicating that during remelting, the metal spray coating is metallurgically bonded to the substrate, and part of the metal spray coating is metallurgically bonded to the plunger substrate to form a fusion transition layer, so that the coating will not fall off from the substrate, further improving the service life of the plunger.

[0156] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing a surface coating of a plunger or shaft workpiece, characterized in that: The steps include: The metal spray coating is sprayed onto the surface of the substrate, and then subjected to a remelting treatment and a heat preservation cooling treatment to obtain a surface coating; Wherein, the spraying includes at least one of plasma spraying and supersonic spraying; The substrate is at least one of a plunger substrate and a shaft workpiece substrate; The metal spray coating comprises a raw material of a high entropy alloy; the raw material of the high entropy alloy comprises the following materials by mass fraction: 16.5% to 26% Ni, 18% to 25% Co, 20% to 28% Cr, 16.5% to 25% W, 16.5% to 22.5% Mo, 0.1% to 3% Cu, 0.1% to 3% Si and 0.1% to 3% B; In the remelting step, the coating is subjected to secondary melting treatment by high-frequency remelting or flame remelting, and the remelting temperature is 1000° C. to 1150° C.; The surface coating has a thickness of 300 μm to 800 μm; The surface coating comprises an integrally formed penetration transition layer and a wear-resistant layer; the penetration transition layer is located between the substrate and the wear-resistant layer; The thickness of the penetration transition layer is 20 μm to 100 μm.

2. The method for preparing the surface coating of a plunger or shaft workpiece according to claim 1, characterized in that: The metal spray coating also includes at least one of nano nickel-based alloy and metal microcapsule.

3. The method for preparing the surface coating of a plunger or shaft workpiece according to claim 2, characterized in that: In the metal microcapsule, the wall material is graphene and the core material is nickel-based alloy.

4. The method for preparing the surface coating of a plunger or shaft workpiece according to any one of claims 1 to 3, characterized in that: The spraying satisfies at least one of the following conditions (1) and (2): (1) The flame velocity of the plasma spraying is 300m / s~400m / s; (2) The flame velocity of the supersonic spraying is 1500m / s~2000m / s.

5. The method for preparing the surface coating of a plunger or shaft workpiece according to any one of claims 1 to 3, characterized in that: The spraying satisfies at least one of the following conditions (1) and (2): (1) The powder impact velocity of the plasma spraying is 150m / s~300m / s; (2) The impact velocity of the powder during supersonic spraying is 500 m / s to 1100 m / s.

6. The method for preparing the surface coating of a plunger or shaft workpiece according to any one of claims 1 to 3, characterized in that: The spraying satisfies at least one of the following conditions (1) and (2): (1) The spraying distance of the plasma spraying is 100 mm to 150 mm; (2) The spraying distance of the supersonic spraying is 300 mm to 360 mm.

7. Application of a method for preparing a surface coating of a plunger or shaft workpiece as claimed in any one of claims 1 to 6 in the field of mechanical equipment.

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