Surface-strengthened wear-resistant composite board and preparation device and method thereof

Abstract

The invention belongs to the technical field of wear-resistant materials, and particularly relates to a surface-strengthened wear-resistant composite board and a preparation device and method thereof. In order to solve the problem that the hardness and the wear resistance of a conventional surfacing wear-resistant composite plate reach the upper limit under the current process conditions and enable the performance of the conventional surfacing wear-resistant composite plate to still meet the requirements under some extreme working conditions, the concept of surface strengthening is introduced into manufacturing of the wear-resistant composite plate, millimeter-level ceramic particles are selected and added when the surface layer of a surfacing layer is in a semi-solid state, and the surface layer of the surfacing layer is in a semi-solid state; and the interface bonding strength between the non-metal filler and the semi-solid metal is improved, and the interface metallurgical bonding has very high quality. Besides, after the millimeter-scale ceramic particles are added, a water mist spraying cooling mode is adopted, so that through type large cracks generated by direct quenching are avoided, and meanwhile, the problem of insufficient hardness caused by slow cooling is also solved. The wear resistance of ceramic particles and the mechanical property of metal are organically combined, so that the whole composite plate has enough wear resistance under extreme working conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of wear-resistant materials, and particularly relates to a surface-strengthened wear-resistant composite plate and its preparation device and method. Background Art

[0002] With the rapid development of industrial technology, the wear problem of mechanical equipment in various harsh environments has become increasingly prominent, seriously affecting the service life and production efficiency of the equipment. In the actual service process of mining machinery, it is not only in harsh working conditions such as high-temperature oxidation, corrosion, and high impact, but also subject to the wear of hard abrasives, resulting in the rapid failure of components due to wear. Severe wear causes a large amount of metal loss, and at the same time, the rapid failure of components due to wear requires a large amount of manpower and material resources to be frequently replaced, resulting in production stoppages and cost increases, which has a great adverse impact on the production efficiency and economic benefits of enterprises. Therefore, the development of a new wear-resistant material that not only has excellent wear resistance but also good processability and cost-effectiveness has become an urgent need in the current industrial field.

[0003] The surfacing wear-resistant composite plate is a wear-resistant material widely used in modern industrial production. It forms a composite material with high hardness and high wear resistance by surfacing one or more layers of wear-resistant alloy layers on the surface of ordinary steel plates. This material not only retains the strength and toughness of ordinary steel plates but also greatly improves the wear resistance of its surface, enabling it to maintain good wear resistance for a long time in harsh working environments, thereby extending the service life of the equipment. Its main application fields include mining, metallurgical industry, cement production, thermal power generation, etc., where high requirements for wear resistance are required. The wear-resistant composite plate has excellent wear resistance, and its surface wear-resistant layer is usually composed of high-hardness alloy materials, with a hardness of more than 60 HRC, and even up to 70 HRC. In addition, this material has good processability, such as weldability, cuttability, and formability, enabling enterprises to carry out various complex-shaped processing and manufacturing according to specific requirements, greatly improving its scope of application and flexibility.

[0004] At present, the surfacing wear-resistant technology is used in the processing of various important metal materials and key components of mining machinery to improve the service life of the equipment, reduce the frequency of maintenance and replacement, thereby reducing costs and improving production efficiency. At the present stage, the surfacing wear-resistant composite plate is represented by the high-chromium cast iron surfacing composite wear-resistant plate. This material has good wear resistance and heat resistance and is suitable for a wide range of industrial applications, especially in working conditions that require high temperature and wear resistance. However, the hardness and wear resistance of metal materials have reached the upper limit under the current process conditions, and in some extreme working conditions, such as extremely high temperatures or severe corrosion environments, its performance is difficult to meet the requirements. Summary of the Invention

[0005] To solve the problem that the hardness and wear resistance of conventional surfacing wear-resistant composite plates have reached their upper limits under current process conditions, and to enable their performance to still meet the requirements of key components of mining machinery under some extreme working conditions, the present invention provides a surface-strengthened wear-resistant composite plate and its preparation device and method.

[0006] As a ceramic particle with high hardness, the Vickers hardness of Al2O3 particles is much higher than that of metal materials. Therefore, the iron-based ceramic composite material prepared by adding Al2O3 particles to cast iron is expected to greatly improve the hardness of the wear-resistant composite plate, pointing out an effective way to solve this problem. However, directly adding ceramic particles into the flux-cored wire used in the surfacing process will reduce the bonding quality between the substrate and the surfacing layer, which will surely have an adverse effect on the wear resistance of the wear-resistant composite plate. In addition, excessive use of ceramic particles will also increase the cost of the wear-resistant composite plate.

[0007] Therefore, surface strengthening is a new idea to solve this problem. During welding, the flux-cored wire melts first and then solidifies again on the substrate to form a surfacing layer. When the surface layer of the surfacing layer is liquid, the added ceramic particles are likely to aggregate; when the surface layer of the surfacing layer is solid, the ceramic particles cannot be directly added. Therefore, adding ceramic particles when the surface layer of the surfacing layer is semi-solid has become a new solution. During the service process of the wear-resistant composite plate, the surface-strengthened wear-resistant composite plate can directly bear the load, and at the same time, the existence of the intermediate metal transition layer can reduce stress and provide good toughness support.

[0008] To achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a preparation device for a surface-strengthened wear-resistant composite plate, including a workbench. A carbon steel substrate is arranged on the workbench. Above the carbon steel substrate, there is a ceramic particle spray head for spraying millimeter-sized ceramic particles. An infrared temperature gun is arranged on one side of the ceramic particle spray head. Above the carbon steel substrate, there are also a preheating flame spray head, a welding torch, and a water mist spray head, and the preheating flame spray head, the welding torch, and the water mist spray head are fixed on a bracket. An acetylene input pipe and an oxygen input pipe are connected to the preheating flame spray head.

[0009] In the second aspect, the present invention also provides a preparation method for a surface-strengthened wear-resistant composite plate. Based on the above preparation device for a surface-strengthened wear-resistant composite plate, it includes the following steps: Step 1, clean the welding area of the carbon steel substrate, and use the preheating flame spray head to preheat the welding area of the carbon steel substrate. Cleaning the welding area is used to remove oil stains, rust, moisture, etc., and the purpose is to ensure the welding quality; Step 2: Use a welding torch to weld the flux-cored wire within the welding area of the carbon steel substrate. The surfacing alloy process is adopted for the welding process. During welding, use an infrared temperature gun to measure the temperature of the surfacing layer surface in real time. When the temperature of the surfacing layer surface reaches the semi-solid state, use a ceramic particle spray head to evenly spray millimeter-sized ceramic particles onto the surfacing layer surface; Step 3: After spraying the millimeter-sized ceramic particles, use a water mist spray head to spray water mist onto the surfacing layer; Step 4: After welding, cut, grind, and clean the obtained composite plate to obtain the surface-strengthened wear-resistant composite plate.

[0010] Furthermore, in Step 1, the preheating temperature is 300 - 350 °C and the time is 10 - 15 min.

[0011] Furthermore, the parameters of the surfacing alloy process in Step 2 are: welding voltage 25 - 28 V, welding current 170 - 220 A, welding speed 120 mm·min -1 。

[0012] Furthermore, the elemental composition of the flux-cored wire in Step 2 is as follows: Cr: 18.6 - 26.8 wt.%, B: 0.1 - 0.6 wt.%, C: 5.0 - 5.5 wt.%, Si: 2.0 - 2.6 wt.%; Mn: 0.1 - 0.6 wt.%.

[0013] Furthermore, the temperature of the surfacing layer surface in the semi-solid state in Step 2 is between 1000 - 1200 °C, which can ensure that the millimeter-sized ceramic particles are added when the surfacing layer surface is in the semi-solid state.

[0014] Furthermore, the distance between the water mist spray head and the welding torch is 5 - 15 cm.

[0015] Furthermore, in Step 2, the millimeter-sized ceramic particles are Al2O3 particles with a particle size of 1 mm. These Al2O3 particles need to be cleaned and dried before spraying. Ultrasonic vibration cleaning is used for cleaning, and the cleaning duration is 3 min to wash off the impurities and oil on the surface of the Al2O3 particles. Drying is natural drying.

[0016] Thirdly, the present invention also provides a surface-strengthened wear-resistant composite plate prepared by the preparation method of the above-mentioned surface-strengthened wear-resistant composite plate.

[0017] Compared with the prior art, the present invention has the following advantages: 1. Based on the high hardness and high wear resistance of millimeter-sized ceramic particles, the millimeter-sized ceramic particle-reinforced iron-based wear-resistant material has more excellent hardness and wear resistance than high-chromium cast iron. Moreover, the ceramic particles directly rub against the working part on the surfacing layer surface, greatly increasing the wear resistance of the wear-resistant composite plate.

[0018] 2. The millimeter-sized ceramic particles of the present invention are added when the surface layer of the surfacing layer is in a semi-solid state. The semi-solid metal forming process is the optimal method for adding ceramic particles. This method is easy to add non-metallic fillers, and as long as the appropriate addition temperature is selected, it is beneficial to improve the interfacial bonding strength between the non-metallic filler and the semi-solid metal, and has a high interfacial metallurgical bonding quality.

[0019] 3. The present invention abandons the traditional welding idea of preheating + slow cooling to control welding deformation and cracks, and innovatively proposes the idea of preheating + rapid cooling, which has the following main advantages: 1) The cooling method of spraying water mist is adopted, reducing the tendency of cold cracks. It will neither produce a large number of cracks caused by direct quenching, allowing a certain time for the formation of the surfacing layer, nor make up for the problem of insufficient hardness caused by air cooling. 2) It not only controls welding deformation and cracks through preheating, but also adjusts the growth direction of hard carbides through the idea of rapid cooling by spraying water mist, greatly improving the wear resistance of the composite plate.

[0020] 4. The key technology for preparing the surface-strengthened wear-resistant composite plate proposed by the present invention is to uniformly add millimeter-sized ceramic particles when the surface layer of the surfacing layer is in a semi-solid state, enabling the millimeter-sized ceramic particles and the metal matrix to achieve uniform distribution and high-quality metallurgical bonding. The wear resistance of the ceramic particles and the mechanical properties of the casting alloy can be organically combined, so that the entire composite plate has sufficient anti-wear strength during operation, in order to extend the service life of mechanical parts and ultimately improve the practical effect and economic benefits of the enterprise. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the preparation device for a surface-strengthened wear-resistant composite plate of the present invention.

[0022] Figure 2 It is a schematic cross-sectional view of the surfacing layer of the surface-strengthened wear-resistant composite plate obtained in Example 2.

[0023] Figure 3 It is a metallographic diagram of the cross-section of the surfacing layer of the surface-strengthened wear-resistant composite plate obtained in Example 2.

[0024] Figure 4 It is a metallographic diagram of the surface of the surfacing layer of the surface-strengthened wear-resistant composite plate obtained in Example 2.

[0025] Figure 5 It is an internal structure diagram of the surface layer of the surfacing layer in Example 2.

[0026] Figure 6 It is an internal structure diagram of the surface layer of the surfacing layer in Example 3.

[0027] Figure 7 It is an internal structure diagram of the surface layer of the surfacing layer in Example 4.

[0028] Figure 8 Bar chart of friction and wear results of the surface-strengthened wear-resistant composite plates prepared in Example 2, Example 3, Example 4 and Comparative Example 1.

[0029] Figure 9 Bar chart of the hardness of the surfacing layer cross-section of the surface-strengthened wear-resistant composite plates prepared in Example 2, Example 3, Example 4 and Comparative Example 1.

[0030] Figure 10 Bar chart of the surface hardness of the surfacing layer of the surface-strengthened wear-resistant composite plates prepared in Example 2, Example 3, Example 4 and Comparative Example 1.

[0031] Among them, 1 - ceramic particle spray head, 2 - infrared temperature measuring gun, 3 - carbon steel substrate, 4 - workbench, 5 - preheating flame spray head, 6 - welding torch, 7 - water mist spray head, 8 - acetylene input pipe, 9 - oxygen input pipe, 10 - millimeter-level ceramic particles, 11 - surface layer of the surfacing layer, 12 - intermediate layer of the surfacing layer, 13 - bonding surface of the surfacing layer. Detailed implementation manners

[0032] In order to further elaborate the technical solution of the present invention, the present invention will be further described below through examples. Example 1

[0033] As Figure 1 shown, a preparation device for a surface-strengthened wear-resistant composite plate in this embodiment includes a workbench 4, on which a carbon steel substrate 3 is arranged. Above the carbon steel substrate 3, a ceramic particle spray head 1 is arranged for spraying millimeter-level ceramic particles 10. On one side of the ceramic particle spray head 1, an infrared temperature measuring gun 2 is arranged. Above the carbon steel substrate 3, a preheating flame spray head 5, a welding torch 6 and a water mist spray head 7 are also arranged, and the preheating flame spray head 5, the welding torch 6 and the water mist spray head 7 are fixed on a bracket. An acetylene input pipe 8 and an oxygen input pipe 9 are connected to the preheating flame spray head 5. Example 2

[0034] A preparation method for a surface-strengthened wear-resistant composite plate in this embodiment, based on the preparation device for a surface-strengthened wear-resistant composite plate described in Example 1, includes the following steps: Step 1, clean the welding area of the carbon steel substrate 3, and use the preheating flame spray head 5 to preheat the welding area of the carbon steel substrate 3. The preheating temperature is 300 °C and the time is 12 min. The carbon steel substrate 3 uses a Q235 substrate; Step 2: Use the welding torch 6 to weld the flux-cored wire within the welding area of the carbon steel substrate 3. The surfacing alloy process is adopted for the welding process. During the welding, use the infrared temperature measuring gun 2 to measure the temperature of the surface layer 11 of the surfacing layer in real time. When the temperature of the surface layer 11 of the surfacing layer reaches the semi-solid state temperature, use the ceramic particle spray head 1 to evenly spray millimeter-sized ceramic particles 10 onto the surface layer 11 of the surfacing layer. The semi-solid state temperature of the surface layer 11 of the surfacing layer is 1000 °C. The millimeter-sized ceramic particles 10 are Al2O3 particles with a particle size of 1 mm. The parameters of the surfacing alloy process are: welding voltage 25 V, welding current 200 A, welding speed 120 mm·min -1 , and the elemental composition of the flux-cored wire is as follows: Cr: 18.6 wt.%, B: 0.4 wt.%, C: 5.0 wt.%, Si: 2.0 wt.%; Mn: 0.1 wt.%; Step 3: After the spraying of the millimeter-sized ceramic particles 10 is completed, use the water mist spray head 7 to spray water mist onto the surfacing layer. The distance between the water mist spray head 7 and the welding torch 6 is 5 cm; Step 4: After the welding is completed, cut, grind, and clean the obtained composite plate to obtain the surface-strengthened wear-resistant composite plate. Use the DK7763F CNC wire-cut electric discharge machine to cut out wear-resistant specimens with dimensions of 75 mm × 25 mm × 10 mm and cubes with dimensions of 10 mm × 10 mm × 10 mm on the surface-strengthened wear-resistant composite plate; wipe the surface of the specimens with anhydrous ethanol to ensure that the surface of the specimens is clean, free of oil stains, and rust; Step 5: First, rough grind the prepared cubes with dimensions of 10 mm × 10 mm × 10 mm using 400# sandpaper to remove surface stains, oxide layers, etc., and then successively use 800#, 1200#, 1500#, and 2000# sandpaper for fine grinding until the surface is flat and free of scratches, presenting a mirror or near-mirror surface. Then, polish using a high-efficiency diamond metallographic polishing agent with a particle size of 2.5 μm until the surface of the cube becomes a reflective and shiny mirror surface. Then, corrode with a stainless steel etching agent for 70 s, wipe with alcohol, and dry with a hair dryer. Then, observe the metallographic structure through an HFX-IIA Nikon metallographic microscope; Step 6: Use an HR-150A Rockwell hardness tester to detect the macro hardness of the prepared wear-resistant specimens with dimensions of 75 mm × 25 mm × 10 mm. Take 10 test points at different positions as required to test the hardness. The test load is 1470 N, and the load lasts for 15 s. After removing the maximum and minimum values, calculate the average value. The hardness of the surface layer 11 of the surfacing layer in this example is 57.8 HRC, the hardness of the middle layer 12 of the surfacing layer is 56.9 HRC, and the hardness of the joint surface 13 of the surfacing layer is 56.3 HRC ( Figure 9 ); the hardness of the surface of the surfacing layer is 60.1 HRC ( Figure 10 ).

[0035] Figure 2 Schematic cross-sectional view of the surfacing layer of the surface-strengthened wear-resistant composite plate obtained in this embodiment, including millimeter-sized ceramic particles 10, and the surfacing layer surface 11, the surfacing layer intermediate layer 12, and the surfacing layer joint surface 13 from top to bottom. The surface of the surfacing layer is not marked.

[0036] Step 7, use the LGM-130 dry sand rubber wheel wear testing machine produced by Jinan Lianggong Testing Technology Co., Ltd. for testing. Its test parameters are: rubber wheel diameter 229 mm, hardness 60 HA, weight of the weight 2.5 kg, rubber wheel rotation speed 192 rad·min -1 . Before the test, weigh the wear-resistant specimen after grinding and cleaning as the initial weight M0. Then grind the wear-resistant specimen for 1 h, clean it, wipe it with alcohol and dry it. The weight of the wear-resistant specimen is M1. Calculate the absolute weight loss △M = M0 - M1 of the wear-resistant specimen, and take the average value of three wear-resistant specimens to obtain the wear amount of this embodiment as 198 mg ( Figure 8 ). Example 3

[0037] A preparation method of a surface-strengthened wear-resistant composite plate in this embodiment, based on the preparation device of a surface-strengthened wear-resistant composite plate described in Example 1, includes the following steps: Step 1, clean the welding area of the carbon steel substrate 3, and use the preheating flame nozzle 5 to preheat the welding area of the carbon steel substrate 3. The preheating temperature is 350 °C and the time is 15 min. The carbon steel substrate 3 uses a Q235 substrate; Step 2, use the welding torch 6 to weld the flux-cored wire in the welding area of the carbon steel substrate 3. The welding process uses the surfacing alloy process. During welding, use the infrared temperature measuring gun 2 to measure the temperature of the surfacing layer surface 11 in real time. When the temperature of the surfacing layer surface 11 reaches the semi-solid state temperature, use the ceramic particle nozzle 1 to evenly spray millimeter-sized ceramic particles 10 onto the surfacing layer surface 11. The semi-solid state temperature of the surfacing layer surface 11 is 1100 °C. The millimeter-sized ceramic particles 10 select Al2O3 particles with a particle size of 1 mm. The parameters of the surfacing alloy process are: welding voltage 28 V, welding current 220 A, welding speed 120 mm·min -1 , and the element composition of the flux-cored wire is as follows: Cr: 26.5 wt.%, B: 0.1 wt.%, C: 5.2 wt.%, Si: 2.1 wt.%; Mn: 0.2 wt.%; Step 3, after spraying the millimeter-sized ceramic particles 10, use the water mist nozzle 7 to spray water mist onto the surfacing layer. The distance between the water mist nozzle 7 and the welding torch 6 is 10 cm; Step 4, after welding is completed, cut, grind, and clean the obtained composite plate to obtain the surface-strengthened wear-resistant composite plate. Use a DK7763F CNC wire-cut EDM machine to cut a wear-resistant specimen with dimensions of 75 mm × 25 mm × 10 mm and a cube with dimensions of 10 mm × 10 mm × 10 mm from the surface-strengthened wear-resistant composite plate; wipe the surface of the specimen with anhydrous ethanol to ensure that the surface of the specimen is clean, free of oil stains and rust; Step 5, first coarsely grind the prepared cube with dimensions of 10 mm × 10 mm × 10 mm using 400# sandpaper to remove surface stains, oxide layers, etc., and then sequentially finely grind it using 800#, 1200#, 1500#, and 2000# sandpapers until the surface is flat and has no scratches, presenting a mirror or near-mirror surface. Then polish it using a high-efficiency diamond metallographic polishing agent with a particle size of 2.5 μm until the surface of the cube becomes a reflective and shiny mirror surface. Then corrode it with a stainless steel etching agent for 70 s, wipe it with alcohol, and dry it with a hair dryer. Then observe the metallographic structure through an HFX-IIA Nikon metallographic microscope; Step 6, for the prepared wear-resistant specimen with dimensions of 75 mm × 25 mm × 10 mm, measure the macroscopic hardness using an HR-150A Rockwell hardness tester. Take 10 test points at different positions as needed to measure the hardness. The test load is 1470 N, and the load lasts for 15 s. Calculate the average value after removing the maximum and minimum values. The hardness of the surfacing layer surface 11 in this embodiment is 62.0 HRC, the hardness of the surfacing layer intermediate layer 12 is 60.4 HRC, and the hardness of the surfacing layer joint surface 13 is 59.4 HRC ( Figure 9 ); the hardness of the surfacing layer surface is 61.2 HRC ( Figure 10 ).

[0038] Step 7, use an LGM-130 dry sand rubber wheel wear testing machine produced by Jinan Lianggong Testing Technology Co., Ltd. for testing. Its test parameters are: the diameter of the rubber wheel is 229 mm, the hardness is 60 HA, the weight of the weight is 2.5 kg, and the rotational speed of the rubber wheel is 192 rad·min -1 . Before testing, weigh the wear-resistant specimen after grinding and cleaning as the initial weight M0. Then grind the wear-resistant specimen for 1 h, clean it, wipe it with alcohol, and dry it. The weight of the wear-resistant specimen is M1. Calculate the absolute weight loss of the wear-resistant specimen △M = M0 - M1. Take the average value of three specimens to obtain the wear amount of this embodiment as 190 mg ( Figure 8 ). Example 4

[0039] A preparation method of a surface-strengthened wear-resistant composite plate in this embodiment is based on the preparation device of a surface-strengthened wear-resistant composite plate described in Example 1 and includes the following steps: Step 1: Clean the welding area of the carbon steel substrate 3, and preheat the welding area of the carbon steel substrate 3 using a preheating flame spray head 5. The preheating temperature is 330°C and the time is 10 min. The carbon steel substrate 3 is a Q235 substrate; Step 2: Use a welding torch 6 to weld the flux-cored wire in the welding area of the carbon steel substrate 3. The surfacing alloy process is adopted for the welding process. During the welding, use an infrared temperature measuring gun 2 to measure the temperature of the surfacing layer surface 11 in real time. When the temperature of the surfacing layer surface 11 reaches the semi-solid state, use a ceramic particle spray head 1 to evenly spray millimeter-sized ceramic particles 10 onto the surfacing layer surface 11. The temperature of the surfacing layer surface 11 in the semi-solid state is 1200°C. The millimeter-sized ceramic particles 10 are Al2O3 particles with a particle size of 1 mm. The parameters of the surfacing alloy process are: welding voltage 26V, welding current 170A, welding speed 120 mm·min -1 , and the elemental composition of the flux-cored wire is as follows: Cr: 26.8 wt.%, B: 0.6 wt.%, C: 5.5 wt.%, Si: 2.6 wt.%; Mn: 0.6 wt.%; Step 3: After spraying the ceramic particles, use a water mist spray head 7 to spray water mist onto the surfacing layer. The water mist spray head 7 is 15 cm away from the welding torch 6; Step 4: After welding, cut, grind, and clean the obtained composite plate to obtain the surface-strengthened wear-resistant composite plate. Use a DK7763F CNC wire-cut electric discharge machine to cut out wear-resistant specimens with dimensions of 75 mm × 25 mm × 10 mm and cubes with dimensions of 10 mm × 10 mm × 10 mm on the surface-strengthened wear-resistant composite plate; wipe the surface of the specimens with anhydrous ethanol to ensure that the surface of the specimens is clean, free of oil stains, and rust; Step 5: First, coarsely grind the prepared cubes with dimensions of 10 mm × 10 mm × 10 mm using 400# sandpaper to remove surface stains, oxide layers, etc., and then finely grind them successively using 800#, 1200#, 1500#, and 2000# sandpapers until the surface is flat and free of scratches, presenting a mirror or near-mirror surface. Then, polish using a high-efficiency diamond metallographic polishing agent with a particle size of 2.5 μm until the surface of the cube becomes a reflective and shiny mirror surface. Then, corrode with a stainless steel etchant for 70 s, wipe with alcohol, and dry with a hair dryer. Then, observe the metallographic structure through an HFX-IIA Nikon metallographic microscope; Step 6: Use an HR-150A Rockwell hardness tester to detect the macro hardness of the prepared wear-resistant specimens with dimensions of 75 mm × 25 mm × 10 mm. Take 10 test points at different positions as needed to test the hardness. The test load is 1470 N, and the load lasts for 15 s. Calculate the average value after removing the maximum and minimum values. The hardness of the surface layer 11 of the surfacing layer in this example is 61.1 HRC, the hardness of the intermediate layer 12 of the surfacing layer is 60.8 HRC, and the hardness of the joint surface 13 of the surfacing layer is 60.2 HRC ( Figure 9 ); the hardness of the surface of the surfacing layer is 60.7 HRC ( Figure 10 ).

[0040] Step 7: Use an LGM-130 dry sand rubber wheel wear tester produced by Jinan Lianggong Testing Technology Co., Ltd. for detection. Its test parameters are: the diameter of the rubber wheel is 229 mm, the hardness is 60 HA, the weight of the weight is 2.5 kg, and the rotational speed of the rubber wheel is 192 rad·min -1 . Before the test, weigh the wear-resistant specimen after grinding and cleaning as the initial weight M0. Then grind the wear-resistant specimen for 1 h, clean it, wipe it with alcohol and dry it. The weight of the wear-resistant specimen is M1. Calculate the absolute weight loss of the specimen △M = M0 - M1. Take the average value of three wear-resistant specimens to obtain the wear amount of this example as 193 mg ( Figure 8 ).

[0041] Comparative Example 1 A preparation method of a wear-resistant composite plate used in this comparative example includes the following steps: Step 1: Clean the welding area of the carbon steel substrate 3, and use a preheating flame spray gun 5 to preheat the welding area of the carbon steel substrate 3. The preheating temperature is 300 °C, and the time is 10 min. The carbon steel substrate 3 uses a Q235 substrate; Step 2: Use a welding torch 6 to weld the flux-cored wire in the welding area of the carbon steel substrate 3. The welding process uses a surfacing alloy process. The parameters of the surfacing alloy process are: welding voltage 25 V, welding current 170 A, welding speed 120 mm·min -1 , and the elemental composition of the flux-cored wire is as follows: Cr: 26.5 wt.%, B: 0.1 wt.%, C: 5.2 wt.%, Si: 2.1 wt.%; Mn: 0.2 wt.%; Step 3: After welding, cool the welded composite plate in the air to room temperature, and cut, grind and clean the obtained composite plate to obtain the wear-resistant composite plate. Use a DK7763F CNC wire-cut EDM machine to cut a wear-resistant specimen with dimensions of 75 mm × 25 mm × 10 mm and a cube with dimensions of 10 mm × 10 mm × 10 mm on the wear-resistant composite plate; wipe the surface of the specimen with anhydrous ethanol to ensure that the surface of the test block is clean, free of oil stains and rust; Step 4: First, coarsely grind the prepared cube with a size of 10 mm × 10 mm × 10 mm using 400# sandpaper to remove surface stains, oxide layers, etc. Then, successively use 800#, 1200#, 1500#, and 2000# sandpapers for fine grinding until the surface is smooth and free of scratches, presenting a mirror or near-mirror surface. Subsequently, polish it with a high-efficiency diamond metallographic polishing agent with a particle size of 2.5 μm until the surface of the cube becomes a reflective and shiny mirror. Then, corrode it with a stainless steel etchant for 70 s, wipe it with alcohol, and dry it with a hair dryer. Then, observe the metallographic structure through an HFX-IIA Nikon metallographic microscope; Step 5: For the prepared wear-resistant specimen with a size of 75 mm × 25 mm × 10 mm, measure the macrohardness with an HR-150A Rockwell hardness tester. Take 10 test points at different positions as needed to measure the hardness. The test load is 1470 N, and the load lasts for 15 s. Calculate the average value after removing the maximum and minimum values. The hardness of the surface layer 11 of the surfacing layer in this example is 56.5 HRC, the hardness of the intermediate layer 12 of the surfacing layer is 54.9 HRC, and the hardness of the joint surface 13 of the surfacing layer is 52.1 HRC ( Figure 9 ); the hardness of the surface of the surfacing layer is 59.5 HRC ( Figure 10 ).

[0042] Step 6: Use an LGM-130 dry sand rubber wheel wear testing machine produced by Jinan Lianggong Testing Technology Co., Ltd. for testing. Its test parameters are: the diameter of the rubber wheel is 229 mm, the hardness is 60 HA, the weight of the weight is 2.5 kg, and the rotational speed of the rubber wheel is 192 rad·min -1 . Before the test, weigh the wear-resistant specimen after grinding and cleaning as the initial weight M0. Then, grind the wear-resistant specimen for 1 h, clean it, wipe it with alcohol, and dry it. The weight of the wear-resistant specimen is M1. Calculate the absolute weight loss of the specimen △M = M0 - M1. Take the average value of three wear-resistant specimens to obtain the wear amount of this example as 233 mg ( Figure 8 ).

[0043] The influence of welding voltage and welding current on the wear-resistant composite plate is mainly reflected in the width of the formed weld bead and the depth of the molten pool. At the same time, during the actual welding process, the welding voltage and welding current are in dynamic fluctuation. The hardness and wear resistance of the wear-resistant composite plate prepared in the above examples are mainly determined jointly by whether ceramic particles are added, the cooling rate, the cooling method, the content of hard carbides, and the growth direction of hard carbides.

[0044] According to the test data, metallographic diagrams ( Figure 3 and Figure 4 ) and the internal structure diagrams of the surface layer of the surfacing layer ( Figures 5 - 7), it is found that the idea of rapid cooling by spraying water mist makes the growth direction of hard carbide perpendicular to the surface of the surfacing layer, and the hardness of the surface layer 11 of the surfacing layer of the composite plate after slow cooling after welding is improved, thereby improving the wear resistance of the composite plate. In Example 2, the water mist nozzle 7 is 5 cm away from the welding torch 6. Due to the relatively intense cooling, a large number of cracks and pores and other defects appear in the surface layer 11 of the surfacing layer, resulting in a decrease in the quality of the surfacing layer; since the flux-cored wire used in Example 2 reduces the addition amount of Cr and C elements, the content of hard carbide in the surfacing layer decreases, but after spraying ceramic particles, forced water mist cooling is carried out, thereby regulating the growth direction of hard carbide in the surfacing layer. Therefore, its hardness is even slightly higher than that of Comparative Example 1. It can be seen that the regulation of the growth direction of hard carbide has a crucial impact on the hardness of the surfacing layer. In Example 4, the water mist nozzle 7 is 15 cm away from the welding torch 6. Due to the relatively long distance, the surfacing layer is forced to cool by water mist after cooling in the air for a long time, and the growth direction of hard carbide is not effectively regulated. Although the content of Cr and C elements increases, the hardness of the surface of the surfacing layer and the surface layer 11 of the surfacing layer also decreases compared with Example 3, thereby resulting in a decrease in the performance of the composite plate. In Example 3, the water mist nozzle 7 is 10 cm away from the welding torch 6. Since the cooling is milder than that in Example 2, only a small amount of cracks appear in the surface layer 11 of the surfacing layer; moreover, Example 3 ensures a relatively high addition of Cr and C elements, thereby ensuring the content of hard carbide; in addition, due to the appropriate distance between the water mist nozzle 7 and the welding torch 6, both the cooling effect and the large generation of cracks are avoided. In summary, the process parameters of Example 3 are considered to be relatively excellent process parameters. In addition, due to the addition of millimeter-sized ceramic particles 10, the wear amounts in the friction and wear tests of Examples 2, 3, and 4 are all the wear loss amounts of the millimeter-sized ceramic particles 10. Therefore, the wear amounts of these groups are relatively close, but compared with Comparative Example 1 without the addition of millimeter-sized ceramic particles 10, the wear amount has decreased significantly.

Claims

1. A preparation device for a surface-strengthened wear-resistant composite plate, characterized in that, It includes a workbench (4), on which a carbon steel substrate (3) is arranged. Above the carbon steel substrate (3), a ceramic particle spray head (1) is provided for spraying millimeter-sized ceramic particles (10). On one side of the ceramic particle spray head (1), an infrared temperature gun (2) is arranged. Above the carbon steel substrate (3), a preheating flame spray head (5), a welding torch (6) and a water mist spray head (7) are also arranged. And the preheating flame spray head (5), the welding torch (6) and the water mist spray head (7) are fixed on a bracket. An acetylene input pipe (8) and an oxygen input pipe (9) are connected to the preheating flame spray head (5).

2. A preparation method of a surface-strengthened wear-resistant composite plate, characterized in that, A preparation device for a surface-strengthened wear-resistant composite plate according to claim 1, comprising the following steps: Step 1: Clean the welding area of the carbon steel substrate (3), and use the preheating flame spray head (5) to preheat the welding area of the carbon steel substrate (3); Step 2: Use the welding torch (6) to weld the flux-cored wire in the welding area of the carbon steel substrate (3). The surfacing alloy process is adopted for the welding process. During the welding, use the infrared temperature gun (2) to measure the temperature of the surfacing layer surface in real time. When the temperature of the surfacing layer surface reaches the semi-solid state temperature, use the ceramic particle spray head (1) to evenly spray millimeter-sized ceramic particles (10) onto the surfacing layer surface; Step 3: After spraying the millimeter-sized ceramic particles (10) is completed, use the water mist spray head (7) to spray water mist onto the surfacing layer; Step 4: After the welding is completed, cut, grind and clean the obtained composite plate to obtain the surface-strengthened wear-resistant composite plate.

3. The preparation method of a surface-strengthened wear-resistant composite plate according to claim 2, characterized in that, In step 1, the preheating temperature is 300 - 350 °C and the time is 10 - 15 min.

4. The preparation method of a surface-strengthened wear-resistant composite plate according to claim 2, characterized in that, The parameters of the surfacing alloy process in Step 2 are as follows: welding voltage 25 - 28V, welding current 170 - 220A, welding speed 120mm·min -1 .

5. The preparation method of a surface-strengthened wear-resistant composite plate according to claim 2 or 4, characterized in that, The element composition of the flux-cored wire in step 2 is as follows: Cr: 18.6 - 26.8 wt.%, B: 0.1 - 0.6 wt.%, C: 5.0 - 5.5 wt.%, Si: 2.0 - 2.6 wt.%; Mn: 0.1 - 0.6 wt.%.

6. The preparation method of a surface-strengthened wear-resistant composite plate according to claim 5, characterized in that, In step 2, the temperature of the surfacing layer surface in the semi-solid state is between 1000 - 1200 °C.

7. The preparation method of a surface-strengthened wear-resistant composite plate according to claim 2, characterized in that The distance between the water mist spray head (7) and the welding torch (6) is 5 - 15 cm.

8. The preparation method of a surface-strengthened wear-resistant composite plate according to claim 2, characterized in that, In step 2, the millimeter-sized ceramic particles (10) are Al2O3 particles with a particle size of 1 mm.

9. A surface-strengthened wear-resistant composite plate prepared by the preparation method of a surface-strengthened wear-resistant composite plate according to any one of claims 2 - 8.

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