Method for forming h13 hard metal coating on hydraulic support and h13 hard metal coating

Abstract

The application provides a method for forming an H13 hard alloy coating on a hydraulic support and the H13 hard alloy coating, wherein the method comprises the following steps: pretreating the hydraulic support; synchronously fusing H13 powder on the surface of the pretreated hydraulic support by super-high-speed laser cladding under an argon atmosphere to form an H13 hard alloy coating; and laser remelting the H13 hard alloy coating to form a modified H13 hard alloy coating. The H13 alloy powder is synchronously fused on the surface of the hydraulic support by super-high-speed laser cladding, and the laser remelting technology is used to further modify the coating, so that the problem of element segregation in the super-high-speed laser cladding coating can be eliminated, the roughness of the H13 hard alloy coating is reduced, the cracks are reduced, and the hardness and wear resistance of the H13 hard alloy coating are improved.

Description

Technical Field

[0001] This invention belongs to the field of cemented carbide coating preparation technology, specifically relating to a method for forming an H13 cemented carbide coating on a hydraulic support and the H13 cemented carbide coating itself. Background Technology

[0002] Most hydraulic cylinder columns in domestic coal mines are made of 27SiMn steel. Under harsh service environments such as high-intensity mechanical impact or erosion with mud and sand particles, these columns are prone to failure characteristics such as scratches, grooves, cracks, pitting, and peeling. To improve their service life, industrial manufacturers typically use hard chrome plating. For example, a copper-tin alloy is used as a base plating layer (approximately 20–35 μm thick), and then hard chrome (30–45 μm thick) is electroplated onto the base plating surface to enhance the microhardness of the hard chrome layer.

[0003] However, when preparing a hard chrome coating on the surface of 27SiMn alloy columns, the electroplating process often results in numerous porosities and cracks. This leads to frequent pitting, peeling, and blistering of the hard chrome layer during actual use, posing significant safety hazards. Furthermore, the high price of chromium increases industrial application costs, and the electroplating process itself causes environmental pollution. Therefore, there is an urgent need to develop a coating technology and materials for use on hydraulic supports. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art, and provides a method for forming an H13 cemented carbide coating on a hydraulic support and the H13 cemented carbide coating formed on the hydraulic support.

[0005] In one aspect, the present invention provides a method for forming an H13 cemented carbide coating on a hydraulic support, the method comprising:

[0006] Pre-treatment of hydraulic supports;

[0007] Under an argon atmosphere, H13 powder is simultaneously melted onto the pretreated surface of a hydraulic support by ultra-high-speed laser cladding to form an H13 hard carbide coating.

[0008] The H13 cemented carbide coating is laser remelted to form a modified H13 cemented carbide coating.

[0009] Optionally, the H13 powder includes Cr, C, Mn, Ni, Si, Mo, Fe, and V.

[0010] Optionally, the Cr content is 4 wt.% to 5.5 wt.%;

[0011] The content of C is 0.3 wt.% to 0.4 wt.%.

[0012] The content of Mn is 0.3 wt.% to 0.5 wt.%.

[0013] The Ni content is 0.1 wt.% to 0.2 wt.%.

[0014] The Si content is 1 wt.% to 1.2 wt.%.

[0015] The content of V is 0.8 wt.% to 1 wt.%.

[0016] The Fe content is 91 wt.% to 93 wt.%.

[0017] Optionally, the diameter of the H13 alloy powder is 35–160 μm.

[0018] Optionally, the power range of the ultra-high-speed laser cladding is 1800-3400W, the linear velocity range is 15-30m / min, the powder feeding rate range is 22.1-35.7g / min, and the overlap rate range is 50%-85%.

[0019] Optionally, the ultra-high-speed laser cladding has a power of 2200W, a linear speed of 30m / min, a powder feeding rate of 32.3g / min, and an overlap rate of 85%.

[0020] Optionally, the linear velocity of the laser remelting is 0–30 m / min, the power is 2200–3400 W, and the heat input range is 4.4–6.8 kJ / m.

[0021] Optionally, the heat input of the laser remelting is less than the heat input of the ultra-high-speed laser cladding.

[0022] Optionally, the surface roughness of the modified H13 cemented carbide coating is 40% to 50% lower than that of the original H13 cemented carbide coating; and / or,

[0023] The modified H13 carbide coating has a wear loss weight that is 60% to 70% lower than that of the H13 carbide coating.

[0024] This invention proposes an H13 hard alloy coating on a hydraulic support, which is formed using the method described above.

[0025] This invention proposes a method for forming an H13 cemented carbide coating on a hydraulic support, and the H13 cemented carbide coating formed on the hydraulic support. The method includes: pre-treating the hydraulic support; simultaneously melting H13 powder onto the surface of the pre-treated hydraulic support using ultra-high-speed laser cladding under an argon atmosphere to form an H13 cemented carbide coating; and laser remelting the H13 cemented carbide coating to form a modified H13 cemented carbide coating. This invention utilizes ultra-high-speed laser cladding to simultaneously melt H13 alloy powder onto the surface of the hydraulic support, and combines this with laser remelting technology to further modify the coating, eliminating elemental segregation problems in the ultra-high-speed laser cladding coating, reducing the roughness of the H13 cemented carbide coating, reducing cracks, and improving its hardness and wear resistance. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating a method for forming an H13 hard alloy coating on a hydraulic support according to an embodiment of the present invention.

[0027] Figure 2 These are three-dimensional morphology images of H13 cemented carbide coatings formed by ultra-high-speed laser cladding at different powder feeding rates according to Example 1 of the present invention; wherein, Figure 2 In the figure, (a) represents the powder feeding rate of 22.1 g / min; Figure 2 In (b), the powder feeding rate is 25.5 g / min; Figure 2 In the figure, (c) represents the powder feeding rate of 28.9 g / min; Figure 2 In this context, (d) represents the powder feeding rate of 32.3 g / min; Figure 2 In this context, (e) represents the powder feeding rate of 35.7 g / min; Figure 2 (f) in the figure represents the roughness variation law of the H13 cemented carbide coating;

[0028] Figure 3 This is a comparison of cross-sectional defect images of H13 cemented carbide coatings formed by ultra-high-speed laser cladding at different powder feeding rates according to Example 1 of the present invention; wherein, Figure 2 In the figure, (a) represents the powder feeding rate of 22.1 g / min; Figure 2 In (b), the powder feeding rate is 25.5 g / min; Figure 2 In the figure, (c) represents the powder feeding rate of 28.9 g / min; Figure 2 In this context, (d) represents the powder feeding rate of 32.3 g / min; Figure 2 In this context, (e) represents the powder feeding rate of 35.7 g / min;

[0029] Figure 4 The microhardness distribution of H13 cemented carbide coatings formed by ultra-high-speed laser cladding at different powder feeding rates in Example 1 of the present invention;

[0030] Figure 5 These are three-dimensional morphology images of the H13 cemented carbide coatings formed by ultra-high-speed laser cladding under different laser powers in Embodiment 2 of the present invention; wherein, Figure 5 In the example, (a) represents a laser power of 1800W; Figure 5 In (b), the laser power is 2200W; Figure 5 (c) in the figure represents a laser power of 2600W; Figure 5 In this context, (d) represents a laser power of 3000W; Figure 5 In this context, (e) represents the laser power of 3400W; Figure 5 (f) in the figure represents the roughness variation law of the H13 cemented carbide coating;

[0031] Figure 6 This is a comparison of cross-sectional defect images of H13 cemented carbide coatings formed by ultra-high-speed laser cladding under different laser powers in Embodiment 2 of the present invention; wherein, Figure 6 In the example, (a) represents a laser power of 1800W; Figure 6 In (b), the laser power is 2200W; Figure 6 (c) in the figure represents a laser power of 2600W; Figure 6 In this context, (d) represents a laser power of 3000W; Figure 6 In this context, (e) represents the laser power of 3400W;

[0032] Figure 7 The microhardness distribution of H13 cemented carbide coatings formed by ultra-high-speed laser cladding under different laser powers in Embodiment 2 of the present invention;

[0033] Figure 8 These are three-dimensional morphology images of the H13 cemented carbide coatings formed by ultra-high-speed laser cladding at different cladding linear velocities in Embodiment 3 of the present invention; wherein, Figure 8 In the figure, (a) represents the cladding linear velocity of 15 m / min; Figure 8 (b) in the figure represents a cladding linear velocity of 20 m / min; Figure 8 (c) in the figure represents the cladding linear velocity of 25 m / min; Figure 8 In this context, (d) represents the cladding linear velocity of 30 m / min. Figure 8 (e) in the figure represents the roughness variation law;

[0034] Figure 9 These are cross-sectional defect images of H13 cemented carbide coatings formed by ultra-high-speed laser cladding at different cladding linear speeds according to Embodiment 3 of the present invention; wherein, Figure 9 In the figure, (a) represents the cladding linear velocity of 15 m / min; Figure 9 (b) in the figure represents a cladding linear velocity of 20 m / min; Figure 9 (c) in the figure represents the cladding linear velocity of 25 m / min; Figure 9In this context, (d) represents the cladding linear velocity of 30 m / min.

[0035] Figure 10 The microhardness distribution of H13 cemented carbide coatings formed by ultra-high-speed laser cladding at different cladding linear speeds in Example 3 of the present invention is shown.

[0036] Figure 11 The images show SEM and three-dimensional morphology images of the modified H13 cemented carbide coatings formed by high-speed laser remelting under different laser powers in Example 4 of this invention; wherein, Figure 11 In the diagram, (a) represents a laser power of 0W; Figure 11 In (b), the laser power is 2200W; Figure 11 (c) in the figure represents a laser power of 2800W; Figure 11 In this context, (d) represents the laser power of 3400W;

[0037] Figure 12 The images show cross-sectional views of the modified H13 cemented carbide coatings formed by high-speed laser remelting under different laser powers in Embodiment 4 of the present invention; wherein, Figure 12 In the diagram, (a) represents a laser power of 0W; Figure 12 In (b), the laser power is 2200W; Figure 12 (c) in the figure represents a laser power of 2800W; Figure 12 In this context, (d) represents the laser power of 3400W;

[0038] Figure 13 The microhardness distribution of the cross-section of the modified H13 cemented carbide coating formed by high-speed laser remelting under different laser powers in Example 4 of the present invention is shown.

[0039] Figure 14 Friction curves of the modified H13 cemented carbide coating formed by high-speed laser remelting under different laser powers in Example 4 of the present invention;

[0040] Figure 15 The wear loss results of the modified H13 cemented carbide coating formed by high-speed laser remelting under different laser powers in Example 4 of the present invention are shown.

[0041] Figure 16 The wear morphology of the modified H13 cemented carbide coating formed by high-speed laser remelting at different remelting powers in Example 4 of the present invention is shown; wherein, Figure 16 In the diagram, (a) represents a laser power of 0W; Figure 16 In (b), the laser power is 2200W; Figure 16 (c) in the figure represents a laser power of 2800W; Figure 16 In the figure, (d) represents the laser power of 3400W. Detailed Implementation

[0042] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0043] like Figure 1 As shown, one aspect of the present invention provides a method S100 for forming an H13 hard alloy coating on a hydraulic support, specifically including the following steps S110 to S130:

[0044] S110. Pre-treat the hydraulic support.

[0045] Specifically, 27SiMn steel was used as the matrix of the hydraulic support. This matrix is ​​mainly composed of martensite and ferrite, and its chemical composition includes less than 0.3 wt.% Cr, 0.24-0.32 wt.% C, 1.01 wt.% Mn, less than 0.3 wt.% Ni, 0.96 wt.% Si, and the balance Fe. Subsequently, the oxide scale on the surface of the hydraulic support was removed by machining, and the surface dust and oil were removed with anhydrous ethanol to ensure the accuracy and reliability of the test.

[0046] S120. Under an argon atmosphere, H13 is synchronously melted onto the pretreated hydraulic support surface by ultra-high-speed laser cladding to form an H13 hard carbide coating.

[0047] Specifically, H13 powder is fed into the ultra-high-speed laser cladding system by a powder feeder in a coaxial manner. Under an argon atmosphere, the H13 cemented carbide coating is laser-clad onto a 27SiMn hydraulic support that is rotating at high speed on a machine tool through a laser head, solidified, and formed into a modified H13 cemented carbide coating.

[0048] In step S120, the H13 powder includes Cr, C, Mn, Ni, Si, Mo, Fe and V. This composition matches the matrix, and the diameter of the H13 alloy powder is preferably 35 to 160 μm. This particle size distribution is beneficial for obtaining a dense coating with few defects.

[0049] In some preferred embodiments, the Cr content is 4 wt.% to 5.5 wt.%; the C content is 0.3 wt.% to 0.4 wt.%; the Mn content is 0.3 wt.% to 0.5 wt.%; the Ni content is 0.1 wt.% to 0.2 wt.%; the Si content is 1 wt.% to 1.2 wt.%; the V content is 0.8 wt.% to 1 wt.%; and the Fe content is 91 wt.% to 93 wt.%.

[0050] In some other preferred embodiments, the H13 powder comprises 5.02 wt.% Cr, 0.39 wt.% C, 0.37 wt.% Mn, 0.17 wt.% Ni, 1.02 wt.% Si, 0.97 wt.% V, with the balance being Fe, and the diameter of the H13 alloy powder is 97 μm.

[0051] In this embodiment, H13 alloy powder is used as the coating material, which is low in cost and can meet the coating hardness requirements. At the same time, it can improve the coating's resistance to thermal cracking, so that the hydraulic support can be used in service environments with large impact and vibration loads.

[0052] Furthermore, in step S120, the power range of the ultra-high-speed laser cladding is 1800–3400 W, the linear velocity range is 15–30 m / min, the powder feeding rate range is 22.1–35.7 g / min, the overlap rate is 50%–85%, and the heat input range is 4.4–6.8 kJ / m. Under the above preferred parameters, the obtained H13 cemented carbide coating has high hardness, good wear resistance, and few voids and cracks. At the same time, the coating surface has less powder adhering to it, resulting in a low surface roughness.

[0053] In some preferred embodiments, the power of the ultra-high-speed laser cladding is preferably 2200W, the linear speed is preferably 30m / min, the powder feeding rate is preferably 32.3g / min, the overlap rate is preferably 85%, and the heat input is preferably 5.6kJ / m.

[0054] In this embodiment, an H13 cemented carbide coating can be formed on a hydraulic support using ultra-high-speed laser cladding technology. Defects such as cracks in the coating can be eliminated by increasing the powder feeding rate or reducing the laser power. In addition, the thickness of the H13 cemented carbide coating can be made to reach 106.2 to 200 μm and the roughness to be 13 to 24 μm by adjusting the process.

[0055] In this embodiment, H13 alloy powder is melted and coated onto the hydraulic support using ultra-high-speed laser cladding. This allows the surface of the hydraulic support substrate and the coating powder to melt simultaneously, and the H13 alloy powder to coat the substrate surface simultaneously, effectively improving the bonding force between the two. The resulting coating has a high degree of density. At the same time, the heat input during ultra-high-speed laser cladding is relatively small, resulting in a faster cooling rate of the coating and less powder adhering to the surface. The surface of the resulting H13 cemented carbide coating has a small number of adhering single powder particles, and the overall coating surface is flat with low surface roughness and dilution rate. It also forms a finer and more uniform microstructure, resulting in higher hardness and wear resistance.

[0056] S130, laser remelting of H13 cemented carbide coating to form modified H13 cemented carbide coating with a thickness of 200-600μm.

[0057] Specifically, based on the ultra-high-speed laser cladding coating, a laser remelting process with the same speed and overlap rate is carried out without powder feeding. Under the protection of argon gas, an in-situ high-energy laser beam is used to rapidly melt and solidify the coating surface again, forming a modified H13 hard alloy coating.

[0058] In this embodiment, by using laser remelting to remelt the H13 cemented carbide coating, on the one hand, the powder on the surface of the H13 cemented carbide coating is melted, reducing surface roughness, eliminating coating defects, and improving hardness and wear resistance. On the other hand, part of the substrate is melted, increasing the coating thickness, thereby improving the overall performance of the coating. Furthermore, it can also eliminate element segregation, thereby improving the overall performance of the coating.

[0059] In some preferred embodiments, the linear velocity range during the laser remelting process is 1–30 m / min, the power range is 2200–3400 W, and the heat input range is 4.4–6.8 kJ / m.

[0060] In some other preferred embodiments, when the laser power for remelting is 2800W, the surface roughness of the H13 coating is further reduced. Compared with the H13 cemented carbide coating obtained in step S120, the surface roughness of the modified H13 cemented carbide coating can be reduced by 40% to 45%, which can effectively eliminate the protrusions on the surface of the H13 cemented carbide coating, especially the unmelted H13 powder, improve the coating smoothness, and reduce the amount of secondary machining.

[0061] In other preferred embodiments, when the laser power for remelting is 2200W, the microhardness and wear resistance of the H13 coating are further improved. Compared with the H13 cemented carbide coating obtained in step S120, the wear loss of the modified H13 cemented carbide coating is reduced by 60%-70% compared with the ultra-high-speed laser cladding coating, effectively improving the wear resistance of the coating. That is to say, when the heat input of remelting is less than the heat input of ultra-high-speed laser, the wear resistance of the H13 cemented carbide coating is enhanced.

[0062] In this embodiment, by laser remelting the H13 cemented carbide coating, the unmelted powder on the surface of the H13 cemented carbide coating is fully melted and recrystallized, forming a more uniform and dense microstructure. This can effectively eliminate defects and element segregation in the ultra-high-speed laser cladding coating, thereby eliminating powder adhering to the surface of the H13 cemented carbide coating, further reducing the surface roughness of the H13 cemented carbide coating, making the coating surface smoother, and effectively improving the microhardness and wear resistance of the coating.

[0063] The method for forming an H13 hard alloy coating on a hydraulic support according to the present invention is simple, has low material cost, and the preparation process is relatively environmentally friendly. Moreover, the coating formed reduces pitting, peeling, and bubbling in practical applications, thus meeting the needs of industrial applications.

[0064] In another aspect of the present invention, an H13 hard alloy coating is provided for forming on a hydraulic support. The coating is formed using the method described above, the specific process of which is described above and will not be repeated here.

[0065] The H13 cemented carbide coating of the present invention has a smooth surface, low roughness, no large number of pores and cracks, high hardness, good wear resistance, and low cost, and can be used to replace the current chromium coating.

[0066] The method of forming an H13 cemented carbide coating on a hydraulic support will be further illustrated below with reference to several specific embodiments:

[0067] Example 1

[0068] The method for forming an H13 hard alloy coating on a hydraulic support in this example includes the following steps:

[0069] S1. The oxide scale on the surface of the 27SiMn hydraulic support is removed by machining, and the surface dust and oil are removed by anhydrous ethanol.

[0070] S2. Under an argon atmosphere, H13 powder is simultaneously melted onto the pretreated surface of the hydraulic support using ultra-high-speed laser cladding technology to form an H13 hard alloy coating. The parameters of the ultra-high-speed laser cladding are as follows: laser power of 3200W, cladding linear speed of 30m / min, overlap rate of 85%, and powder feeding rates of 22.1, 25.5, 28.9, 32.3, and 35.7 g / min, respectively.

[0071] like Figure 2 As shown, with the increase of powder feeding rate, the surface roughness of the H13 cemented carbide coating formed by ultra-high-speed laser cladding first increases slightly and then decreases. Among them, as... Figure 2 As shown in (d, f), the H13 coating exhibits the lowest roughness (17.09 μm) at a powder feeding rate of 35.7 g / min; Figure 2 As shown in (c, f), the H13 cemented carbide coating exhibits the highest roughness (21.6 μm) at a powder feeding rate of 28.9 g / min.

[0072] like Figure 3 As shown, with the increase of powder feeding rate, the thermal stress in the coating decreases, resulting in a reduction in the number of cracks in the coating. Please refer to [reference needed]. Figure 3 In (e), when the powder feeding rate is 35.7 g / min, almost no obvious cracks appear in the H13 cemented carbide coating.

[0073] like Figure 4 As shown, the microhardness of the coating does not change significantly under different powder feeding rates. When the powder feeding rate increases sequentially from 22.1 g / min to 25.5 g / min, 28.9 g / min, and 32.3 g / min, the hardness at the interface does not change much (500–528 HV). 0.3 However, when the powder feeding rate reached 35.7 g / min, the hardness at the joint rapidly decreased to 391 HV. 0.3 This indicates that the powder absorbs a significant amount of energy during the coating formation process. Furthermore, this result further demonstrates that increasing the powder feed rate can effectively reduce the thermal stress in the coating, which is beneficial for eliminating cracks in the H13 cemented carbide coating clad by ultra-high-speed laser welding.

[0074] Therefore, considering the surface roughness, hardness, and crack condition of the H13 cemented carbide coating, the powder feeding rate is preferably 32.3 g / min, resulting in an H13 cemented carbide coating with lower roughness, fewer cracks, and higher microhardness.

[0075] Example 2

[0076] The method for forming an H13 hard alloy coating on a hydraulic support in this example includes the following steps:

[0077] S1. The oxide scale on the surface of the 27SiMn hydraulic support is removed by machining, and the surface dust and oil are removed by anhydrous ethanol.

[0078] S2. Under an argon atmosphere, H13 powder is synchronously melted onto the pretreated surface of the hydraulic support using ultra-high-speed laser cladding technology to form an H13 hard alloy coating. The parameters of the ultra-high-speed laser cladding are as follows: cladding linear speed of 30 m / min, overlap rate of 85%, powder feed rate of 32.3 g / min, and laser power of 1800 W, 2200 W, 2600 W, 3000 W, and 3400 W.

[0079] like Figure 5 As shown in (a, f), when the laser power is 1800W, the H13 cemented carbide coating has exposed substrate on its surface, meaning the H13 cemented carbide coating is not continuously formed, resulting in a large surface roughness; as Figure 5 As shown in (b, f), when the laser power reaches 2200W, the surface of the H13 cemented carbide coating is continuously formed, and the surface roughness is minimal at 13μm; Figure 5 As shown in (cf), when the laser power reaches 2600W, 3000W, and 3400W, the surface roughness of the H13 cemented carbide coating is 14.13μm, 16.86μm, and 20.27μm, respectively. This indicates that with the increase of laser power, the overall heat input of the H13 cemented carbide coating increases during the cladding process. The heat accumulation causes the surface temperature of the coating to continuously increase, further increasing the amount of unmelted powder adhering to the surface of the H13 cemented carbide coating, resulting in a gradual increase in the surface roughness of the H13 cemented carbide coating.

[0080] like Figure 6 As shown in (a), when the laser power is 1800W, the H13 cemented carbide coating does not form a continuous shape, but rather exhibits regular discontinuous forming regions. This is because the laser energy distribution is Gaussian, with lower energy at the edge of the spot. Consequently, the energy is too low near the overlap area, preventing the unmelted powder from forming a good metallurgical bond with the substrate that has not formed an effective molten pool. Figure 6 As shown in (be), by sequentially increasing the laser power to 2200W, 2600W, 3000W, and 3400W, the H13 cemented carbide coating was consistently formed well. Furthermore, refer to... Figure 6Further observation of the formed coating revealed cracks of varying sizes within the H13 cemented carbide coating, and the number of cracks gradually increased with increasing laser power. The primary cause of these cracks is that the total energy input during coating formation increases with increasing laser power. Beyond the minimum energy required to melt the powder and molten pool, the remaining energy increases, leading to increased thermal stress within the coating and consequently, cracking. Furthermore, when the laser power increased to 3000W and 3400W, due to energy concentration in the central region of the laser spot, a distinctly regular melting depth appeared at the bottom of the H13 cemented carbide coating, indicating an increased coating dilution rate.

[0081] like Figure 7 As shown, with the increase of laser power and laser energy, the temperature of the molten pool also increases, and the number of dislocations introduced into the H13 cemented carbide coating also increases. The dislocations play a certain strengthening role in improving the hardness of the coating, thus leading to an increase in the hardness of the coating.

[0082] Therefore, considering the surface roughness, hardness, and crack condition of the H13 cemented carbide coating, the laser power is preferably 2200W, resulting in an H13 cemented carbide coating with lower roughness, fewer cracks, and higher microhardness.

[0083] Example 3

[0084] The method for forming an H13 hard alloy coating on a hydraulic support in this example includes the following steps:

[0085] S1. The oxide scale on the surface of the 27SiMn hydraulic support is removed by machining, and the surface dust and oil are removed by anhydrous ethanol.

[0086] S2. Under an argon atmosphere, H13 powder is synchronously melted onto the pretreated hydraulic support surface using ultra-high-speed laser cladding to form an H13 hard alloy coating. The parameters of the ultra-high-speed laser cladding are as follows: laser power of 2200W, overlap rate of 85%, powder feed rate of 32.3g / min, and cladding linear speeds of 15m / min, 20m / min, 25m / min, and 30m / min.

[0087] like Figure 8As shown, the amount of powder adhering to the H13 cemented carbide coating surface decreases with increasing cladding linear velocity. This is because during ultra-high-speed laser cladding, the ratio of laser energy to velocity decreases with increasing cladding linear velocity, i.e., the heat input decreases. Consequently, the surface temperature of the coating after formation is lower, making it less likely for unmelted powder to adhere to the coating surface, thus reducing roughness. When the cladding linear velocity increases sequentially from 15 m / min to 20 m / min, 25 m / min, and 30 m / min, the surface roughness of the H13 cemented carbide coating becomes 12.26 μm, 11.79 μm, 10.82 μm, and 10.73 μm, respectively.

[0088] like Figure 9 As shown, with the increase of cladding linear velocity, virtually no defects appeared in the H13 cemented carbide coating, and the thickness of the H13 cemented carbide coating decreased. When the cladding linear velocity increased from 15 m / min to 20 m / min, 25 m / min, and 30 m / min, the thickness of the H13 cemented carbide coating decreased from 234.27 μm to 164.49 μm, 140.50 μm, and 110.90 μm, respectively. This is because with the increase of cladding linear velocity, the laser energy per unit time and given volume decreases, resulting in less energy that the substrate and powder can absorb. Consequently, the amount of powder that can be melted gradually decreases, and the thickness of the H13 cemented carbide coating decreases accordingly.

[0089] like Figure 10 As shown, the microhardness of the H13 cemented carbide coating increases with increasing cladding speed. The highest hardness (755.33 HV) is achieved when the cladding speed is 30 m / min. 0.3 This is because as the cladding line speed increases, the solidification rate of the coating gradually increases. Rapid heating and cooling leads to finer grains in the coating structure, resulting in a grain-refining effect and further improving the hardness of the coating.

[0090] Therefore, considering the surface roughness, hardness, and crack condition of the H13 cemented carbide coating, the preferred cladding speed is 30 m / min, resulting in an H13 cemented carbide coating with lower roughness, fewer cracks, and higher microhardness.

[0091] Example 4

[0092] The method for forming an H13 hard alloy coating on a hydraulic support in this example includes the following steps:

[0093] S1. The oxide scale on the surface of the 27SiMn hydraulic support is removed by machining, and the surface dust and oil are removed by anhydrous ethanol.

[0094] S2. Under an argon atmosphere, H13 powder is synchronously melted onto the pretreated hydraulic support surface by ultra-high-speed laser cladding to form an H13 hard alloy coating. The parameters of the ultra-high-speed laser cladding are as follows: laser power of 2200W, overlap rate of 85%, powder feed rate of 32.3g / min, and cladding linear speed of 30m / min.

[0095] S3. Laser remelting of the H13 cemented carbide coating to form a modified H13 cemented carbide coating. The laser remelting parameters are as follows: cladding line speed 30m / min, powder feeding rate 32.3g / min, overlap rate 85%, and laser power 2200W, 2800W, and 3400W respectively.

[0096] like Figure 11 As shown, during the ultra-high-speed laser cladding process, the H13 powder is heated and melted in an extremely short time and then rapidly solidifies. The surface of the unremelted H13 cemented carbide coating contains some unmelted particles, and the surface of the H13 cemented carbide coating has irregular, uneven undulations, such as... Figure 11 As shown in (a), the surface roughness of the H13 cemented carbide coating formed by ultra-high-speed laser cladding is 15.56 μm. The surface of the coating after high-speed laser remelting is as follows: Figure 11 As shown in (bd), when the laser remelting power is 2200W, 2800W and 3400W respectively, the roughness of the modified H13 cemented carbide coating is 10.76μm, 9.11μm and 9.21μm, respectively, which is 30.85%, 41.45% and 40.8% lower than that of the ultra-high speed laser cladding coating. This indicates that the unmelted powder on the surface of the H13 cemented carbide coating was fully melted by laser remelting. Moreover, the surface of the H13 cemented carbide coating formed by ultra-high speed laser cladding shows regular undulations. As the remelting laser power increases, the surface undulations of the modified H13 cemented carbide coating gradually decrease. The reason for this phenomenon is that in the laser remelting process, higher laser power can provide more sufficient heat, resulting in better melting and recrystallization of the H13 cemented carbide coating.

[0097] like Figure 12 As shown, the H13 cemented carbide coating without laser remelting treatment is as follows: Figure 12 As shown in (a), cracks of similar size can be observed, and the bottom of the coating exhibits irregular undulations. Figure 12As shown in (bd), cracks in the modified H13 cemented carbide coatings formed after remelting with high-speed lasers of different powers were effectively eliminated, and the top of the modified H13 cemented carbide coating gradually became flatter with increasing remelting laser power. This is because the additional heat input during remelting promotes the recrystallization of the coating material, filling the internal defects of the modified H13 cemented carbide coating, thereby improving the quality and performance of the coating.

[0098] Please continue to refer to this. Figure 12 When the remelting heat input is less than the original heat input (remelting laser power is 2200W, corresponding to a remelting heat input of 4.4kJ / m, while the original heat input for ultra-high-speed laser cladding is 5.6kJ / m), the melting depth of the modified H13 cemented carbide coating does not change. When the remelting heat input is equal to the original heat input (remelting laser power is 2800W, corresponding to a remelting heat input of 5.6kJ / m, while the original heat input for ultra-high-speed laser cladding is 5.6kJ / m), a regular melting depth appears at the bottom of the modified H13 cemented carbide coating. When the remelting heat input is greater than the original heat input (remelting laser power is 3400W, corresponding to a remelting heat input of 6.8kJ / m, while the original heat input for ultra-high-speed laser cladding is 5.6kJ / m), the melting depth at the bottom of the modified H13 cemented carbide coating further widens.

[0099] Please continue to refer to this. Figure 12 The thickness of the H13 cemented carbide coating without remelting was 122.43 μm. During laser remelting, the thickness of the modified H13 cemented carbide coating was increased due to the additional heat input. For example, under high-speed laser remelting, as the laser power increased from 2200 W to 2800 W and then to 3400 W, the coating thicknesses were 132.09 μm, 146.62 μm, and 154.21 μm, respectively. In other words, when the heat input for remelting is less than the original heat input, the change in coating thickness is solely due to the melting of unmelted powder on the coating surface caused by the additional heat input. As the heat input for remelting increases to be equal to or greater than the original heat input, the molten pool temperature further rises under the action of the laser, further enhancing the Marangoni effect. The molten substrate is also drawn into the coating, thereby increasing the melting depth of the remelted coating.

[0100] like Figure 13As shown, the microhardness of the modified H13 cemented carbide coating increased after laser remelting. Furthermore, the microhardness of the modified H13 cemented carbide coating was highest at a remelting power of 2200W. This phenomenon is attributed to the recrystallization and refinement of the grains in the coating at this point. With increasing laser power, the microhardness of the modified H13 cemented carbide coating decreased. Simultaneously, due to the grain refinement and solid solution strengthening effects on the substrate in the heat-affected zone, the microhardness was higher than the average hardness of the substrate.

[0101] like Figure 14 and Figure 15 As shown, the wear weight loss of four H13 cemented carbide coatings was compared and analyzed. The wear weight loss of the unremelted H13 cemented carbide coating was 1.1 mg. After laser remelting, with the remelting laser power increasing sequentially from 2200 W to 2800 W and 3400 W, the wear weight loss of the modified H13 cemented carbide coatings was 0.4 mg, 1.0 mg, and 1.3 mg, respectively. The results show that when the laser power is 2200 W (secondary heat input is less than the original heat input), the wear resistance of the modified H13 cemented carbide coating is significantly improved, and the wear weight loss decreases by 63.6%. When the remelting laser power is 2800 W (secondary heat input equals the original heat input), the wear amount of the modified H13 cemented carbide coating is close to that of the unremelted ultra-high-speed laser cladding coating. When the remelting laser power is 3400 W (secondary heat input is greater than the original heat input), the wear amount of the modified H13 cemented carbide coating is greater than that of the original coating. The main reason for the improved wear resistance is the increased microhardness of the coating, while the elements in the coating become more uniform due to the additional heat input.

[0102] like Figure 16 Figure (a) shows the wear morphology of the H13 cemented carbide coating without remelting. Several circular pits of varying contrasts are clearly visible within the scratch, indicating significant abrasive wear. Other areas show a smoother wear path, exhibiting slight ploughing and spalling wear characteristics. The main wear patterns are adhesive wear, oxidative wear, and a small amount of abrasive wear. After 2200W laser remelting, the wear morphology of the modified H13 cemented carbide coating is as follows: Figure 16 As shown in (b), it can be seen that there are almost no obvious pits in the wear trajectory, and the wear marks are mainly concentrated in the middle of the trajectory. At the same time, the content of dark oxides is also reduced, and the spalling pits are also reduced. The wear characteristics at this time are mainly adhesive wear and a small amount of oxidation wear. When the laser power of remelting reaches 2800W, the wear trajectory of the modified H13 cemented carbide coating is as follows. Figure 16As shown in (c), the wear trajectory further increases, and some flaking wear material appears, indicating that the coating's wear resistance has decreased at this point. The wear characteristics are mainly adhesive wear, oxidative wear, and abrasive wear. When the remelting power is further increased to 3400W, the wear condition of the modified H13 cemented carbide coating is as follows. Figure 16 As shown in (d), it can be seen that the number and area of ​​furrows caused by wear further increase, and the main characteristics of wear at this time are oxidative wear and adhesive wear.

[0103] Therefore, considering the surface roughness, hardness, and crack condition of the modified H13 cemented carbide coating, the surface roughness of the modified H13 cemented carbide coating is the smallest when the remelting power is preferably 2800W, which is 41.45% lower than that of the original H13 cemented carbide coating. When the remelting power is preferably 2200W, the wear weight loss of the modified H13 cemented carbide coating is the smallest, which is 63.6% lower than that of the original H13 cemented carbide coating, and its wear resistance is the best.

[0104] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for forming an H13 hard alloy coating on a hydraulic support, characterized in that, The method includes: Pre-treatment of hydraulic supports; Under an argon atmosphere, H13 powder is simultaneously melted onto the pretreated surface of a hydraulic support using ultra-high-speed laser cladding to form an H13 hard alloy coating. The H13 powder comprises Cr, C, Mn, Ni, Si, Mo, Fe, and V; wherein the Cr content is 4 wt.%–5.5 wt.%; the C content is 0.3 wt.%–0.4 wt.%; the Mn content is 0.3 wt.%–0.5 wt.%; the Ni content is 0.1 wt.%–0.2 wt.%; the Si content is 1 wt.%–1.2 wt.%; the V content is 0.8 wt.%–1 wt.%; and the Fe content is 91 wt.%–93 wt.%. The ultra-high-speed laser cladding uses a power range of 1800–3400 W, a linear velocity range of 15–30 m / min, a powder feed rate range of 22.1–35.7 g / min, and an overlap rate range of 50%–85%. The H13 cemented carbide coating is laser-remelted to form a modified H13 cemented carbide coating; the linear velocity of the laser remelting ranges from 1 to 30 m / min, the power ranges from 2200 to 3400 W, and the heat input ranges from 4.4 to 6.8 kJ / m; wherein the heat input of the laser remelting is less than that of the ultra-high-speed laser cladding.

2. The method according to claim 1, characterized in that, The diameter of the H13 powder is 35~160μm.

3. The method according to claim 1, characterized in that, The power of the ultra-high-speed laser cladding is 2200W, the linear speed is 30m / min, the powder feeding rate is 32.3g / min, and the overlap rate is 85%.

4. The method according to any one of claims 1 to 3, characterized in that, The modified H13 cemented carbide coating has a surface roughness that is 40%–45% lower than that of the original H13 cemented carbide coating; and / or, The wear loss weight of the modified H13 cemented carbide coating is 60% to 70% lower than that of the H13 cemented carbide coating.

5. An H13 hard alloy coating formed on a hydraulic support, characterized in that, The H13 cemented carbide coating is formed using the method described in any one of claims 1 to 4.

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