A wear-resistant coating with adjustable hardness and high bonding strength, a preparation method and application thereof

Abstract

The application discloses a wear-resistant coating with adjustable hardness and high bonding strength, and a preparation method and application thereof, and belongs to the technical field of surface engineering. The wear-resistant coating is obtained by stacking and rolling metal cloth I and metal cloth II into a gradient metal cloth, placing the gradient metal cloth on the surface of a 45 steel pipe, and adopting a vacuum brazing process. The metal cloth I and the metal cloth II are prepared through a powder mixing, ball milling and rolling process, and the raw materials include WC powder, NiCrBSi powder and an organic additive. The hardness of the wear-resistant coating is adjusted and controlled, and the bonding strength between the wear-resistant coating and the base material is improved by adjusting the weight ratio of the WC powder and the NiCrBSi powder in the metal cloth. After the gradient metal cloth is coated on the surface of the 45 steel pipe and is subjected to the vacuum brazing, the wear-resistant coating is uniform, smooth, well-shaped, crack-free, controllable in hardness, and high in bonding strength between the coating and the 45 steel pipe base.

Description

Technical Field

[0001] This invention belongs to the field of surface engineering technology, and particularly relates to a wear-resistant coating with adjustable hardness and high bonding strength, its preparation method and application. Background Technology

[0002] WC, with its good wettability, high melting point, and high hardness, is commonly used as a reinforcing phase in metal coatings. WC-reinforced NiCrBSi alloy coatings combine the excellent properties of both, ensuring strong adhesion between the coating and the base material while exhibiting high hardness and wear resistance. Common industrial processes for introducing WC reinforcement into metal coatings include thermal spraying and welding. However, due to increasing demands on the working environment and surface properties of workpieces, these wear-resistant treatment methods are gradually becoming inadequate for practical production needs. For example, thermal spraying results in low bonding strength between the coating and the substrate, inconsistent coating thickness, and low powder utilization; welding processes suffer from uneven heating, large temperature gradients, and easy burn-off of WC, leading to cracks in high-quality WC-containing coatings. Therefore, existing WC coating preparation methods still require improvement.

[0003] Vacuum brazing is an advanced welding method that is pollution-free, light-free, heat-free, and smoke-free. While ensuring the utilization rate of WC particles, it uses an electronic system to precisely control the formation of a metallurgical bond between the matrix phase and the metal matrix. The matrix phase encapsulates the reinforcing phase, thereby producing a wear-resistant coating with high hardness and wear resistance.

[0004] Therefore, how to use vacuum brazing technology to process WC coating materials and prepare a coating composite material with high hardness and high bonding strength has become a problem that needs to be solved. Summary of the Invention

[0005] The primary objective of this invention is to provide a wear-resistant coating with adjustable hardness and high bonding strength, which has good forming effect and a smooth surface.

[0006] The second objective of this invention is to provide a method for preparing a wear-resistant coating, which can obtain a wear-resistant coating with a high percentage of WC by changing the mass ratio of WC and NiCrBSi.

[0007] The third objective of this invention is to propose an application of a wear-resistant coating with adjustable hardness and high bonding strength. The gradient metal cloth prepared by the above method is used to coat the surface of a metal substrate, and the wear-resistant coating obtained by vacuum brazing has high bonding strength with the substrate.

[0008] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0009] A wear-resistant coating with adjustable hardness and high bonding strength is disclosed. The wear-resistant coating is obtained by stacking and rolling metal cloth I and metal cloth II into a gradient metal cloth, placing it on the surface of a 45 steel pipe, and then using a vacuum brazing process. Metal cloth I and metal cloth II are both prepared by mixing WC powder, NiCrBSi powder, and organic additives through a powder mixing, ball milling, and rolling process. The hardness of the wear-resistant coating is controlled by adjusting the ratio of WC powder to NiCrBSi powder in the metal cloth, thereby improving the bonding strength between the wear-resistant coating and the substrate.

[0010] Furthermore, by mass percentage, in the metal cloth I, WC powder:NiCrBSi powder = 10%: 90%~50%: 50%; in the metal cloth II, WC powder:NiCrBSi powder = 90%: 10%~50%: 50%; the mass ratio of the mixed powder composed of WC powder and NiCrBSi powder to the organic additive in both metal cloth I and metal cloth II is 30:1.

[0011] Furthermore, by mass percentage, in the metal cloth I, WC powder:NiCrBSi powder = 10%: 90%; in the metal cloth II, WC powder:NiCrBSi powder = 90%: 10%.

[0012] Furthermore, the organic additive consists of 2.4 wt.% dispersant, 9.6 wt.% binder, 4 wt.% plasticizer and 84 wt.% solvent; the dispersant is Hypermer KD-1; the binder is PVB; the plasticizer is selected from PEG and glycerol; and the solvent is selected from anhydrous ethanol and methyl ethyl ketone.

[0013] Furthermore, the steps of any of the above-described gradient metal cloth preparation methods are as follows:

[0014] (1) Weigh WC powder and NiCrBSi alloy powder by mass percentage, mix them, and obtain mixed powder;

[0015] (2) The mixed powder obtained in step (1) and the organic additive are added to a ball mill at a mass ratio of 30:1. After ball milling, a uniform mixture is obtained.

[0016] (3) Place the uniform mixture obtained in step (2) into the mold, and after demolding, obtain a rectangular block with a thickness of 4~6mm; roll the rectangular block, initially adjust the distance between the rollers to 4~5mm, the rolling temperature to 30~40℃, the rolling speed to 0.2m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and this step is repeated 4~5 times to obtain a rectangular block with a thickness of 4~5mm;

[0017] (4) Adjust the distance between the rollers to 1.2 mm, the rolling speed to 2 m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and the rolling is repeated 4 to 5 times to obtain a metal cloth I with a thickness of 1.2 mm; adjust the distance between the rollers to 0.8 mm, the rolling speed to 2 m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and the rolling is repeated 4 to 5 times to obtain a metal cloth II with a thickness of 0.8 mm;

[0018] (5) Stack the metal cloth I obtained in step (4) with the metal cloth II, adjust the roller spacing to 1.5 mm, and roll to form a gradient metal cloth.

[0019] Furthermore, in step (2), the ball-to-material ratio of the ball mill is 5:1, the rotation speed is 230 rpm, and the time is 1 hour; the ball milling method is alternating forward and reverse rotation.

[0020] Furthermore, in step (5), the metal cloth is stacked and rolled in such a way that metal cloth II is placed on top as a layer away from the substrate, and metal cloth I is placed on the bottom as a layer close to the substrate.

[0021] Furthermore, the application of gradient metal cloth in metal surface processing is as follows: the gradient metal cloth is coated onto the surface of a metal substrate, and a wear-resistant coating is prepared by vacuum brazing. The steps are as follows:

[0022] (1) Apply silicone epoxy resin AB glue evenly to the surface of DN50×10×50 45 steel pipe; cut the wear-resistant coating into 160×50×1.5mm metal cloth, wrap the cut gradient metal cloth around the surface of 45 steel pipe, then cover the surface of the metal cloth with high temperature resistant ceramic fiber pad, and wrap and fasten it with wire mesh.

[0023] (2) Place the assembled sample upright in a vacuum brazing furnace, raise the temperature to 350°C at a rate of 10°C / min, hold for 30 min, then raise the temperature to 1050°C, hold for 20 min, then cool to 700°C at a rate of 5°C / min, and cool to room temperature with the furnace. Remove the sample to complete the surface processing of the 45 steel pipe.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1) The gradient metal cloth prepared by this invention has a uniform and dense composition. The final thickness of the gradient metal cloth can be controlled by adjusting the distance between the rollers of the roller press.

[0026] 2) The gradient metal cloth prepared by this invention has a certain toughness and can be used to create coatings on the surface of workpieces with shapes such as plane, vertical, curved, and zigzag after cutting.

[0027] 3) The gradient metal cloth prepared by this invention can change the hardness and wear resistance of the obtained coating by changing the mass ratio of WC and NiCrBSi.

[0028] 4) After vacuum brazing, the gradient metal cloth produces a coating with good forming effect and a smooth surface. The high NiCrBSi content near the substrate results in high bonding strength between the coating and the substrate. The high WC content near the surface leads to a crack-free, highly wear-resistant coating with a WC content greater than 90%. The surface exhibits high hardness and high wear resistance.

[0029] 5) Vacuum brazing precisely controls welding temperature and vacuum level, resulting in excellent temperature uniformity within the furnace. The vacuum brazing process is free of light, heat, smoke, and pollution. Attached Figure Description

[0030] Figure 1 The images show the coatings obtained by vacuum brazing metal cloths with the same metal powder content but different amounts of organic additives. From left to right, these correspond to Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 6, Comparative Example 4, and Comparative Example 5, respectively.

[0031] Figure 2 This is a microstructure diagram of the coating in Example 6;

[0032] Figure 3 This is a microstructure diagram of the coating in Example 7;

[0033] Figure 4 This is a microstructure diagram of the coating in Example 8;

[0034] Figure 5 This is a microstructure diagram of the coating in Example 9;

[0035] Figure 6 This is a microstructure diagram of the coating in Example 10. Detailed Implementation

[0036] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0037] Unless otherwise specified, all raw materials used in the following embodiments are commercially available products.

[0038] The formulations of the organic additives used in the following embodiments of the present invention are shown in the table below:

[0039]

[0040] Note: Anhydrous ethanol and butanone are miscible. Anhydrous ethanol is a polar molecule containing hydrogen bonds, while butanone is a molecule containing a carbonyl group (C=O) and exhibiting polar properties. Both have polar molecular structures, and therefore can dissolve through intermolecular interactions (such as hydrogen bonds and dipole-dipole interactions). Ethanol and butanone are both relatively polar organic solvents, and their solubility in each other is high. Ethanol, in particular, is highly polar and can interact with the polar portion of the butanone molecule.

[0041] Polyvinyl butyral (PVB) is soluble in anhydrous ethanol, and Hypermer KD-1 is soluble in methyl ethyl ketone (MEK). Anhydrous ethanol, MEK, and dispersant (HYKD-1) are first mixed evenly, and then binder (PVB) and plasticizer (PEG and glycerol) are added and mixed to prepare an organic additive.

[0042] The WC powder particles used in this invention have three specifications: 80-100 mesh, 180-200 mesh, and 250-300 mesh, in a ratio of 1:2:2.

[0043] The NiCrBSi powder used in this invention has a grain size of 200 mesh.

[0044] The rolling process used in this invention is carried out at room temperature; the vacuum brazing equipment used is a VB-8812MD vacuum brazing furnace.

[0045] Hardness testing method: A 10mm × 10mm × 10mm coating sample was cut by wire cutting. Both sides were ground parallel, and the test surface was water-ground and then polished. The surface hardness of the wear-resistant coating was measured using an HRS-150 Rockwell hardness tester with a diamond indenter, a load of 150 kg, and a holding time of 10 seconds. According to the standard, the distance from the test point to the edge of the sample should be no less than 2 mm, and the distance between test points should be 2 mm. Each measurement was taken 6 times, and the average value was calculated.

[0046] Test method for bonding strength: Using a CMT5205 electronic universal testing machine and a self-made shear fixture, the coating was peeled off from the substrate. Three shear specimens were taken for each type of coating. The size of the specimens was 5mm×5mm×10mm. The displacement rate of the indenter was 0.3mm / min. The average value of the measurement results was taken as the bonding strength of the coating interface.

[0047] Example 1

[0048] A gradient metal cloth includes metal cloth I and metal cloth II; wherein metal cloth I comprises a mixed powder (by mass percentage, 10% WC powder and 90% NiCrBSi powder) and an organic additive; metal cloth II comprises a mixed powder (by mass percentage, 90% WC powder and 10% NiCrBSi powder) and an organic additive. In both metal cloth I and metal cloth II, the mass ratio of the mixed powder to the organic additive is 30:1.

[0049] The method for preparing the above-mentioned metal coating includes the following steps:

[0050] (1) Weigh WC powder and NiCrBSi alloy powder by mass percentage, mix them, and obtain mixed powder;

[0051] (2) The mixed powder obtained in step (1) and the organic additive are added to the ball mill at a mass ratio of 30:1. The ball-to-material ratio is 5:1 and the rotation speed is 230 rpm. The mill is run alternately in forward and reverse directions for 1 hour to obtain a uniform mixture.

[0052] (3) Place the uniform mixture obtained in step (2) into a rectangular mold frame and compact it. After demolding, a rectangular block with a thickness of 4~6mm is obtained. Place the rectangular block into an automatic rolling equipment for rolling. First, adjust the distance between the rollers to 4~5mm, the rolling temperature to 30~40℃, and the rolling speed to 0.2m / min. The rectangular block passes through the rollers, is folded, rotated 90°, and rolled repeatedly. Repeat this step 4~5 times to obtain a rectangular block with a thickness of 4~5mm.

[0053] (4) Adjust the distance between the rollers to 1.2 mm, the rolling speed to 2 m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and the rolling is repeated. Repeat this step 4 to 5 times to obtain a metal cloth I with a thickness of 1.2 mm; adjust the distance between the rollers to 0.8 mm, the rolling speed to 2 m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and the rolling is repeated. Repeat this step 4 to 5 times to obtain a metal cloth II with a thickness of 0.8 mm.

[0054] (5) Stack the metal cloth I obtained in step (4) with the metal cloth II, adjust the roller spacing to 1.5 mm, and roll to form a gradient metal cloth.

[0055] Example 2

[0056] A gradient metal cloth includes metal cloth I and metal cloth II; wherein metal cloth I comprises a mixed powder (by mass percentage, 20% WC powder and 80% NiCrBSi powder) and an organic additive; metal cloth II comprises a mixed powder (by mass percentage, 80% WC powder and 20% NiCrBSi powder) and an organic additive. In both metal cloth I and metal cloth II, the mass ratio of the mixed powder to the organic additive is 30:1.

[0057] The method for preparing the above-mentioned metal coating includes the following steps:

[0058] (1) Weigh WC powder and NiCrBSi alloy powder by mass percentage, mix them, and obtain mixed powder;

[0059] (2) The mixed powder obtained in step (1) and the organic additive are added to the ball mill at a mass ratio of 30:1. The ball-to-material ratio is 5:1 and the rotation speed is 230 rpm. The mill is run alternately in forward and reverse directions for 1 hour to obtain a uniform mixture.

[0060] (3) Place the uniform mixture obtained in step (2) into a rectangular mold frame and compact it. After demolding, a rectangular block with a thickness of 4~6mm is obtained. Place the rectangular block into an automatic rolling equipment for rolling. First, adjust the distance between the rollers to 4~5mm, the rolling temperature to 30~40℃, and the rolling speed to 0.2m / min. The rectangular block passes through the rollers, is folded, rotated 90°, and rolled repeatedly. Repeat this step 4~5 times to obtain a rectangular block with a thickness of 4~5mm.

[0061] (4) Adjust the distance between the rollers to 1.2 mm, the rolling speed to 2 m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and the rolling is repeated. Repeat this step 4 to 5 times to obtain a metal cloth I with a thickness of 1.2 mm; adjust the distance between the rollers to 0.8 mm, the rolling speed to 2 m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and the rolling is repeated. Repeat this step 4 to 5 times to obtain a metal cloth II with a thickness of 0.8 mm.

[0062] (5) Stack the metal cloth I obtained in step (4) with the metal cloth II, adjust the roller spacing to 1.5 mm, and roll to form a gradient metal cloth.

[0063] Example 3

[0064] A gradient metal cloth includes metal cloth I and metal cloth II; wherein metal cloth I comprises a mixed powder (by mass percentage, 30% WC powder and 70% NiCrBSi powder) and an organic additive; metal cloth II comprises a mixed powder (by mass percentage, 70% WC powder and 30% NiCrBSi powder) and an organic additive. In both metal cloth I and metal cloth II, the mass ratio of the mixed powder to the organic additive is 30:1.

[0065] The method for preparing the above-mentioned metal coating includes the following steps:

[0066] (1) Weigh WC powder and NiCrBSi alloy powder by mass percentage, mix them, and obtain mixed powder;

[0067] (2) The mixed powder obtained in step (1) and the organic additive are added to the ball mill at a mass ratio of 30:1. The ball-to-material ratio is 5:1 and the rotation speed is 230 rpm. The mill is run alternately in forward and reverse directions for 1 hour to obtain a uniform mixture.

[0068] (3) Place the uniform mixture obtained in step (2) into a rectangular mold frame and compact it. After demolding, a rectangular block with a thickness of 4~6mm is obtained. Place the rectangular block into an automatic rolling equipment for rolling. First, adjust the distance between the rollers to 4~5mm, the rolling temperature to 30~40℃, and the rolling speed to 0.2m / min. The rectangular block passes through the rollers, is folded, rotated 90°, and rolled repeatedly. Repeat this step 4~5 times to obtain a rectangular block with a thickness of 4~5mm.

[0069] (4) Adjust the distance between the rollers to 1.2 mm, the rolling speed to 2 m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and the rolling is repeated. Repeat this step 4 to 5 times to obtain a metal cloth I with a thickness of 1.2 mm; adjust the distance between the rollers to 0.8 mm, the rolling speed to 2 m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and the rolling is repeated. Repeat this step 4 to 5 times to obtain a metal cloth II with a thickness of 0.8 mm.

[0070] (5) Stack the metal cloth I obtained in step (4) with the metal cloth II, adjust the roller spacing to 1.5 mm, and roll to form a gradient metal cloth.

[0071] Example 4

[0072] A gradient metal cloth includes metal cloth I and metal cloth II; wherein metal cloth I comprises a mixed powder (40% WC powder and 60% NiCrBSi powder by mass percentage) and an organic additive; metal cloth II comprises a mixed powder (60% WC powder and 40% NiCrBSi powder by mass percentage) and an organic additive. In both metal cloth I and metal cloth II, the mass ratio of the mixed powder to the organic additive is 30:1.

[0073] The method for preparing the above-mentioned metal coating includes the following steps:

[0074] (1) Weigh WC powder and NiCrBSi alloy powder by mass percentage, mix them, and obtain mixed powder;

[0075] (2) The mixed powder obtained in step (1) and the organic additive are added to the ball mill at a mass ratio of 30:1. The ball-to-material ratio is 5:1 and the rotation speed is 230 rpm. The mill is run alternately in forward and reverse directions for 1 hour to obtain a uniform mixture.

[0076] (3) Place the uniform mixture obtained in step (2) into a rectangular mold frame and compact it. After demolding, a rectangular block with a thickness of 4~6mm is obtained. Place the rectangular block into an automatic rolling equipment for rolling. First, adjust the distance between the rollers to 4~5mm, the rolling temperature to 30~40℃, and the rolling speed to 0.2m / min. The rectangular block passes through the rollers, is folded, rotated 90°, and rolled repeatedly. Repeat this step 4~5 times to obtain a rectangular block with a thickness of 4~5mm.

[0077] (4) Adjust the distance between the rollers to 1.2 mm, the rolling speed to 2 m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and the rolling is repeated. Repeat this step 4 to 5 times to obtain a metal cloth I with a thickness of 1.2 mm; adjust the distance between the rollers to 0.8 mm, the rolling speed to 2 m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and the rolling is repeated. Repeat this step 4 to 5 times to obtain a metal cloth II with a thickness of 0.8 mm.

[0078] (5) Stack the metal cloth I obtained in step (4) with the metal cloth II, adjust the roller spacing to 1.5 mm, and roll to form a gradient metal cloth.

[0079] Example 5

[0080] A gradient metal cloth includes metal cloth I and metal cloth II; wherein metal cloth I comprises a mixed powder (by mass percentage, 50% WC powder and 50% NiCrBSi powder) and an organic additive; metal cloth II comprises a mixed powder (by mass percentage, 50% WC powder and 50% NiCrBSi powder) and an organic additive. In both metal cloth I and metal cloth II, the mass ratio of the mixed powder to the organic additive is 30:1.

[0081] The method for preparing the above-mentioned metal coating includes the following steps:

[0082] (1) Weigh WC powder and NiCrBSi alloy powder by mass percentage, mix them, and obtain mixed powder;

[0083] (2) The mixed powder obtained in step (1) and the organic additive are added to the ball mill at a mass ratio of 30:1. The ball-to-material ratio is 5:1 and the rotation speed is 230 rpm. The mill is run alternately in forward and reverse directions for 1 hour to obtain a uniform mixture.

[0084] (3) Place the uniform mixture obtained in step (2) into a rectangular mold frame and compact it. After demolding, a rectangular block with a thickness of 4~6mm is obtained. Place the rectangular block into an automatic rolling equipment for rolling. First, adjust the distance between the rollers to 4~5mm, the rolling temperature to 30~40℃, and the rolling speed to 0.2m / min. The rectangular block passes through the rollers, is folded, rotated 90°, and rolled repeatedly. Repeat this step 4~5 times to obtain a rectangular block with a thickness of 4~5mm.

[0085] (4) Adjust the distance between the rollers to 1.2 mm, the rolling speed to 2 m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and the rolling is repeated. Repeat this step 4 to 5 times to obtain a metal cloth I with a thickness of 1.2 mm; adjust the distance between the rollers to 0.8 mm, the rolling speed to 2 m / min, the rectangular block passes through the rollers, is folded, rotated 90°, and the rolling is repeated. Repeat this step 4 to 5 times to obtain a metal cloth II with a thickness of 0.8 mm.

[0086] (5) Stack the metal cloth I obtained in step (4) with the metal cloth II, adjust the roller spacing to 1.5 mm, and roll to form a gradient metal cloth.

[0087] The gradient metal cloth prepared in Examples 1 to 5 above is used to coat the surface of the metal substrate, and a wear-resistant coating on the metal surface is prepared by vacuum brazing technology.

[0088] Example 6

[0089] The preparation method of wear-resistant coating on the surface of 45 steel pipe is as follows:

[0090] (1) Prepare a DN50×10×50 45 steel pipe, sand the surface of the 45 steel pipe with sandpaper, put it in acetone for ultrasonic cleaning, blow dry, and then evenly apply organosilicon epoxy resin AB glue to the surface of the 45 steel pipe; cut the gradient metal cloth prepared in Example 1 into a size of 50×160×1.5mm, wrap the cut gradient metal cloth around the surface of the 45 steel pipe, then cover the surface of the metal cloth with a high temperature resistant ceramic fiber pad, and wrap and fasten it with wire mesh;

[0091] (2) Place the assembled sample upright in a vacuum of 7.0 × 10⁻⁶. -3 In a vacuum brazing furnace with a temperature of Pa, the temperature was increased to 350°C at a heating rate of 10°C / min, held for 30 min, then increased to 1050°C, held for 20 min, and then cooled to 700°C at a rate of 5°C / min. The sample was then cooled to room temperature with the furnace and removed.

[0092] Through observation, the coating on the surface of the 45 steel pipe is uniform and flat, well formed, and forms a dense interface bond. Multiple tests were conducted on the surface of the coating material, and the test results are shown in Table 1 below.

[0093] Example 7

[0094] The preparation method of wear-resistant coating on the surface of 45 steel pipe is as follows:

[0095] (1) Prepare a DN50×10×50 45 steel pipe, sand the surface of the 45 steel pipe with sandpaper, put it in acetone for ultrasonic cleaning, blow dry, and then evenly apply organosilicon epoxy resin AB glue to the surface of the 45 steel pipe; cut the gradient metal cloth prepared in Example 2 into a size of 50×160×1.5mm, wrap the cut gradient metal cloth around the surface of the 45 steel pipe, then cover the surface of the metal cloth with a high temperature resistant ceramic fiber pad, and wrap and fasten it with wire mesh;

[0096] (2) Place the assembled sample upright in a vacuum of 7.0 × 10⁻⁶. -3 In a vacuum brazing furnace with a temperature of Pa, the temperature was increased to 350°C at a heating rate of 10°C / min, held for 30 min, then increased to 1080°C, held for 15 min, and then cooled to 700°C at a rate of 5°C / min. The sample was then cooled to room temperature with the furnace and removed.

[0097] Through observation, the coating on the surface of the 45 steel pipe is uniform and flat, well formed, and forms a dense interface bond. Multiple tests were conducted on the surface of the coating material, and the test results are shown in Table 1 below.

[0098] Example 8

[0099] The preparation method of wear-resistant coating on the surface of 45 steel pipe is as follows:

[0100] (1) Prepare a DN50×10×50 45 steel pipe, sand the surface of the 45 steel pipe with sandpaper, put it in acetone for ultrasonic cleaning, blow dry, and then evenly apply silicone epoxy resin AB glue to the surface of the 45 steel pipe; cut the gradient metal cloth prepared in Example 3 into a size of 50×160×1.5mm, wrap the cut gradient metal cloth around the surface of the 45 steel pipe, then cover the surface of the metal cloth with a high temperature resistant ceramic fiber pad, and wrap and fasten it with wire mesh;

[0101] (2) Place the assembled sample upright in a vacuum of 7.0 × 10⁻⁶. -3 In a vacuum brazing furnace with a temperature of Pa, the temperature was increased to 350°C at a heating rate of 10°C / min, held for 30 min, then increased to 1080°C, held for 15 min, and then cooled to 700°C at a rate of 5°C / min. The sample was then cooled to room temperature with the furnace and removed.

[0102] Through observation, the coating on the surface of the 45 steel pipe is uniform and flat, well formed, and forms a dense interface bond. Multiple tests were conducted on the surface of the coating material, and the test results are shown in Table 1 below.

[0103] Example 9

[0104] The preparation method of wear-resistant coating on the surface of 45 steel pipe is as follows:

[0105] (1) Prepare a DN50×10×50 45 steel pipe, sand the surface of the 45 steel pipe with sandpaper, put it in acetone for ultrasonic cleaning, blow dry, and then evenly apply organosilicon epoxy resin AB glue to the surface of the 45 steel pipe; cut the gradient metal cloth prepared in Example 4 into a size of 50×160×1.5mm, wrap the cut gradient metal cloth around the surface of the 45 steel pipe, then cover the surface of the metal cloth with a high temperature resistant ceramic fiber pad, and wrap and fasten it with wire mesh;

[0106] (2) Place the assembled sample upright in a vacuum of 7.0 × 10⁻⁶. -3 In a vacuum brazing furnace with a temperature of Pa, the temperature was increased to 350°C at a heating rate of 10°C / min, held for 30 min, then increased to 1080°C, held for 15 min, and then cooled to 700°C at a rate of 5°C / min. The sample was then cooled to room temperature with the furnace and removed.

[0107] Through observation, the coating on the surface of the 45 steel pipe is uniform and flat, well formed, and forms a dense interface bond. Multiple tests were conducted on the surface of the coating material, and the test results are shown in Table 1 below.

[0108] Example 10

[0109] The preparation method of wear-resistant coating on the surface of 45 steel pipe is as follows:

[0110] (1) Prepare a DN50×10×50 45 steel pipe, sand the surface of the 45 steel pipe with sandpaper, put it in acetone for ultrasonic cleaning, blow dry, and then evenly apply silicone epoxy resin AB glue to the surface of the 45 steel pipe; cut the gradient metal cloth prepared in Example 5 into a size of 50×160×1.5mm, wrap the cut gradient metal cloth around the surface of the 45 steel pipe, then cover the surface of the metal cloth with a high temperature resistant ceramic fiber pad, and wrap and fasten it with wire mesh;

[0111] (2) Place the assembled sample upright in a vacuum of 7.0 × 10⁻⁶. -3 In a vacuum brazing furnace with a temperature of Pa, the temperature was increased to 350°C at a heating rate of 10°C / min, held for 30 min, then increased to 1080°C, held for 15 min, and then cooled to 700°C at a rate of 5°C / min. The sample was then cooled to room temperature with the furnace and removed.

[0112] Through observation, the coating on the surface of the 45 steel pipe is uniform and flat, well formed, and forms a dense interface bond. Multiple tests were conducted on the surface of the coating material, and the test results are shown in Table 1 below.

[0113] Comparative Example 1

[0114] The technical solution is the same as in Example 1, except that the ratio of the mixed powder to the organic additive is changed to 5:1, while other parts remain unchanged. The prepared wear-resistant coating is welded onto the surface of a 45 steel pipe according to the method in Example 6. Multiple tests were performed on the surface of the coating material, and the test results are shown in Table 1 below.

[0115] Comparative Example 2

[0116] The technical solution is the same as in Example 1, except that the ratio of the mixed powder to the organic additive is changed to 10:1, while other parts remain unchanged. The prepared wear-resistant coating is welded onto the surface of a 45 steel pipe according to the method in Example 6. Multiple tests were performed on the surface of the coating material, and the test results are shown in Table 1 below.

[0117] Comparative Example 3

[0118] The technical solution is the same as in Example 1, except that the ratio of the mixed powder to the organic additive is changed to 20:1, while other parts remain unchanged. The prepared wear-resistant coating is welded onto the surface of a 45 steel pipe according to the method in Example 6. Multiple tests were performed on the surface of the coating material, and the test results are shown in Table 1 below.

[0119] Comparative Example 4

[0120] The technical solution is the same as in Example 1, except that the ratio of the mixed powder to the organic additive is changed to 40:1, while other parts remain unchanged. The prepared wear-resistant coating is welded onto the surface of a 45 steel pipe according to the method in Example 6. Multiple tests were performed on the surface of the coating material, and the test results are shown in Table 1 below.

[0121] Comparative Example 5

[0122] The technical solution is the same as in Example 1, except that the ratio of the mixed powder to the organic additive is changed to 50:1, while other parts remain unchanged. The prepared wear-resistant coating is welded onto the surface of a 45 steel pipe according to the method in Example 6. Multiple tests were performed on the surface of the coating material, and the test results are shown in Table 1 below.

[0123] Table 1. Comparison of surface coating test results for 45 steel welded in Examples 6-10 and Comparative Examples 1-5

[0124]

[0125] Comparing the data in Table 1 above, it can be seen that in Examples 6 to 9, the higher the NiCrBSi powder content in metal cloth I, the higher the bonding strength between the coating and the substrate; and the higher the WC particle content in metal cloth II, the greater the hardness of the coating.

[0126] Organic additives primarily act as a binder, integrating nickel-based powder and tungsten carbide powder into an organic whole, facilitating the rolling into fabric. During vacuum brazing, the organic additives volatilize completely at 350℃, not participating in the metallurgical reaction between the nickel-based tungsten carbide and the metal matrix, nor becoming trapped within the metal coating. Therefore, they do not affect the coating's hardness or shear strength. Organic additives mainly influence the forming of the metal fabric, thus affecting the macroscopic morphology of the coating. The amount of binder added affects the macroscopic morphology of the coating surface. For example... Figure 1As shown, the ratios of the mixed powder to the organic additive from left to right are 5:1, 10:1, 20:1, 30:1, 40:1, and 50:1, with the proportion of organic additive gradually decreasing. When the content of organic additive is 5:1, 10:1, and 20:1, the rolled metal cloth does not disperse, is relatively hard, and has poor toughness. During the vacuum brazing process, all the organic additives volatilize, leaving a small amount of nickel-based tungsten carbide powder, resulting in obvious cracks and grooves in the prepared coating. The higher the proportion of organic additive, the more obvious the cracks and grooves become. The coating with obvious defects is insufficient for mechanical property testing, leading to missing hardness and bonding strength data for Comparative Examples 1 and 2. When the ratio is 30:1, the rolled metal cloth has a beautiful shape, good toughness, and can be folded. The coating obtained in Example 6 has the best macroscopic morphology, with a metallic luster, a smooth surface, and dense formation. When the content of organic additive is 40:1 and 50:1, the rolled metal cloth has poor toughness and is easily dispersed. The low content of organic additives affects the forming of the metal cloth, resulting in poor forming and consequently impacting the macroscopic morphology of the coating surface. Comparative Examples 4 and 5 show rough coating surfaces. While Comparative Examples 3-5 exhibit good mechanical test data, Comparative Example 3 shows some cracks and grooves, and Comparative Examples 4 and 5 show rough coating surfaces. These wear-resistant coatings have surface defects and poor practicality. Therefore, a metal powder to organic additive ratio of 30:1 produces a beautifully formed metal cloth with good toughness, and the prepared coating has the best macroscopic morphology, exhibiting metallic luster, a smooth surface, and dense formation, thus possessing practicality.

[0127] As the proportion of WC hard particles in the outer metal cloth II increases within a limited range, the hardness gradually increases. Further increases in WC content will lead to a decrease in the metallurgical bond between WC and the brazing filler metal. For example... Figures 2-6As shown, the supporting effect of the solder is weakened, and some gaps between WC particles are not filled by the liquid solder, forming pores in the coating and making the surface prone to cracking. The substrate surface lacks sufficient liquid solder wetting, resulting in low bonding strength between the coating and the metal substrate. Through the gradient metal cloth combination, the proportion of NiCrBSi in the inner metal cloth I increases, ensuring sufficient solder to wet the WC and metal substrate surfaces and fill the gaps between WC particles. During vacuum brazing, the outer metal cloth II is mainly composed of WC, while the inner metal cloth I is mainly composed of NiCrBSi. During vacuum brazing, WC remains solid, and the entire metal cloth II moves downwards within the NiCrBSi liquid phase of metal cloth I. This gradient metal cloth combination ensures that the coating surface possesses high hardness and wear resistance, as well as high bonding strength. The optimal gradient metal cloth combination is: metal cloth I includes a mixture of powders (10% WC powder, 90% NiCrBSi powder) and organic additives; metal cloth II includes a mixture of powders (90% WC powder, 10% NiCrBSi powder) and organic additives. In both Metal Cloth I and Metal Cloth II, the mass ratio of mixed powder to organic additives is 30:1. The surface coating test results show that the surface Rockwell hardness is 87HRC and the bonding strength is 425MPa.

[0128] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. Application of gradient metal cloth in wear-resistant coating with adjustable hardness and high bonding strength in metal surface processing, the steps are as follows: (1) evenly apply silicone epoxy resin AB glue on the surface of DN50mm*10mm*50mm 45 steel pipe; cut the gradient metal cloth into 50mm*160mm*1.5mm size, cover the cut gradient metal cloth on the surface of the 45 steel pipe, cover the high-temperature ceramic fiber pad on the surface of the metal cloth, and use the steel wire mesh for packaging and fastening; (2) vertically place the assembled sample in the vacuum brazing furnace, increase the temperature to 350℃ at a rate of 10℃ / min, keep the temperature for 30min, then continue to increase the temperature to 1050℃, keep the temperature for 20min, then cool to 700℃ at a rate of 5℃ / min, and cool to room temperature with the furnace, take out the sample, and complete the surface processing of the 45 steel pipe; the metal cloth I and the metal cloth II are prepared by mixing powder, ball milling and rolling process, and the raw materials include WC powder, NiCrBSi powder and organic additives; wherein, by adjusting the ratio of WC powder and NiCrBSi powder in the metal cloth, the hardness of the wear-resistant coating is adjusted, and the bonding strength of the wear-resistant coating and the base material is improved; in the metal cloth I, the mass ratio of WC powder to NiCrBSi powder is 10%:90%; in the metal cloth II, the mass ratio of WC powder to NiCrBSi powder is 90%:10%; the mass ratio of the mixed powder composed of WC powder and NiCrBSi powder in the metal cloth I and the metal cloth II to the organic additive is 30:1; WC powder particles are composed of three specifications with particle size of 80-100 mesh, 180-200 mesh and 250-300 mesh; wherein, the mass ratio of WC powder particles with particle size of 80-100 mesh, WC powder particles with particle size of 180-200 mesh and WC powder particles with particle size of 250-300 mesh is 1:2:2; The organic additive is composed of 2.4wt.% dispersant, 9.6wt.% binder, 4wt.% plasticizer and 84wt.% solvent; the dispersant is Hypermer KD-1; the binder is PVB; the plasticizer is PEG and glycerol; the solvent is anhydrous ethanol and butanone; The wear-resistant coating is obtained by stacking and rolling the metal cloth I and the metal cloth II into a gradient metal cloth, placing the gradient metal cloth on the surface of a DN50mmx10mmx50mm 45 steel pipe, and using a vacuum brazing process; wherein, The preparation method of the gradient metal cloth in the wear-resistant coating with adjustable hardness and high bonding strength, the steps are as follows: (1) weigh the WC powder and the NiCrBSi alloy powder according to the mass percentage, mix them to obtain a mixed powder; (2) add the mixed powder obtained in step (1) and the organic additive into a ball mill according to a mass ratio of 30:1, and run alternately in forward and reverse directions, the ball-to-material ratio of ball milling is 5:1, the rotating speed is 230rpm, and the time is 1h, after ball milling, a uniform mixture is obtained; ​ ​ ​ ​ ​ ​ (3) Put the uniform mixture obtained in step (2) into a mold, and after demolding, a rectangular block with a thickness of 4-6 mm is obtained; roll the rectangular block, initially adjust the distance between the rollers to 4-5 mm, the rolling temperature is 30-40℃, the rolling rate is 0.2 m / min, the rectangular block passes through the rollers, is folded, is rotated by 90°, and this step is repeated 4-5 times to obtain a rectangular block with a thickness of 4-5 mm; (4) Then, the distance between the rollers is adjusted to 1.2 mm, the rolling rate is 2 m / min, the rectangular block passes through the rollers, is folded, is rotated by 90°, and the rolling is repeated 4-5 times to obtain a metal cloth I with a thickness of 1.2 mm; the distance between the rollers is adjusted to 0.8 mm, the rolling rate is 2 m / min, the rectangular block passes through the rollers, is folded, is rotated by 90°, and the rolling is repeated 4-5 times to obtain a metal cloth II with a thickness of 0.8 mm; (5) Stack the metal cloth I and the metal cloth II obtained in step (4), the metal cloth II is on the top as a layer far from the base material, and the metal cloth I is on the bottom as a layer close to the base material, the roller spacing is adjusted to 1.5 mm, and a gradient metal cloth is formed by rolling.

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