Fan mill wear-resistant striking plate as well as preparation method and application thereof

Abstract

The invention relates to a fan mill wear-resistant striking plate and a preparation method and application thereof. The fan mill wear-resistant striking plate is particularly suitable for the working condition environment of high-speed rotation (larger than or equal to 490 r / min). The striking plate with a three-layer composite structure is prepared by combining the high-chromium cast iron, the ceramic particle reinforced phase and the carbon steel or alloy steel matrix and adopting a vacuum brazing process, and the striking plate has high wear resistance, sufficient strength and toughness, good heat resistance and excellent corrosion resistance, and can be used for manufacturing the high-strength and high-toughness striking plate. The high-manganese steel can stably work under the extreme working condition of high-speed rotation of the fan mill, and the service life is prolonged by 2-3 times compared with common high-manganese steel.

Description

Technical Field

[0001] The invention relates to the technical field of fan coal mills, in particular to a wear-resistant impact plate of a fan mill and a preparation method and application thereof. Background Art

[0002] Coal pulverization is a critical component of energy utilization in thermal power generation, industrial boilers, and other applications. As a key pulverizing device, fan mills efficiently grind raw materials like coal into pulverized coal, meeting combustion requirements and improving energy efficiency. During fan mill operation, the impact plate endures constant high-speed impact and friction from the raw material, operating at high temperatures. This critical component is the most susceptible to wear, and its service life directly impacts the equipment's operating efficiency and maintenance costs.

[0003] The particularity of the fan mill's working environment lies in its extremely high rotation speed (up to 490 r / min, peripheral linear speed up to 92.32 m / s or 332.3 km / h) and the high operating temperature generated by friction. This high-speed rotation and high-temperature environment places extremely high demands on the strike plate material, which needs to have high wear resistance, high toughness and good heat resistance.

[0004] At present, the commonly used materials for fan grinding plates mainly include the following:

[0005] 1) Austenitic manganese steel (such as ZGMn13-1) has good strength, toughness and wear resistance. When subjected to material impact and friction, a work-hardened layer will form on its surface, improving the surface hardness and wear resistance. However, it is only suitable for working conditions with moderate impact loads and abrasive wear. In the high-speed rotation environment of fan mill, its hardened layer is easily peeled off, resulting in accelerated wear;

[0006] 2) Ultra-high manganese steel has better work hardening ability and sufficient toughness than ordinary high manganese steel and alloyed high manganese steel under the erosion and wear conditions of high-speed moving coal blocks. The service life of the impact plate of large fan mill made of ultra-high manganese steel is 0.5 times longer than that of ordinary ZGMn13 high manganese steel impact plate. However, its mechanical properties will gradually deteriorate under long-term high temperature environment.

[0007] 3) Medium carbon medium chromium steel contains an appropriate amount of chromium, which can improve the material's wear resistance and corrosion resistance. It also has good mechanical properties and heat treatment properties. It can be improved through heat treatment processes such as quenching and tempering to increase hardness and strength to meet the use requirements of the strike plate. However, it has moderate wear resistance and performs poorly in the high-speed impact environment of fan grinding.

[0008] 4) High chromium cast iron has a high chromium content and good wear resistance and impact resistance. It can withstand large impact and friction forces and is often used to manufacture high-performance wear-resistant parts. However, its disadvantage is that it is brittle and prone to breakage when subjected to strong impact. In particular, the risk of cracking is higher under the violent vibration generated by the high-speed rotation of fan mills.

[0009] 5) Alloy steel + cladding is suitable for high-wear, medium-impact conditions (such as lignite mills). While moderately expensive, it offers moderate wear resistance and requires regular cladding repairs. This not only increases maintenance costs but also leads to frequent equipment downtime, severely impacting production efficiency. Each downtime typically takes 8-16 hours, and the bond strength between the cladding layer and the substrate gradually degrades in high-temperature environments, leading to flaking and sudden equipment failure.

[0010] All of the aforementioned materials have limitations in practical fan mill applications. They cannot simultaneously meet the comprehensive requirements for high wear resistance, high strength and toughness, good heat resistance, and corrosion resistance. This is particularly true under the extreme high-speed rotation conditions of fan mills, where existing materials struggle to provide long-term stable performance. Therefore, there is an urgent need to develop a new composite strike plate that can withstand the challenging operating conditions of fan mills. Summary of the Invention

[0011] To address the aforementioned issues, the present invention aims to provide a wear-resistant strike plate for a fan mill, its preparation method, and its application. By combining high-chromium cast iron, ceramic particle reinforcement, and a carbon steel matrix, and employing a vacuum brazing process, the resulting plate combines the advantages of multiple materials while overcoming the drawbacks of a single material. The plate is particularly well-suited for the extreme high-speed rotation conditions of fan mills. The strike plate of the present invention offers the following technical advantages:

[0012] 1) High wear resistance: The high chromium cast iron wear-resistant layer reinforced with ceramic particles significantly reduces the wear rate. Under the same working conditions, the wear rate is only 28-36% of that of traditional high manganese steel, extending the service life by 2-3 times;

[0013] 2) Sufficient strength and toughness: The three-layer composite structure design is adopted, and the carbon steel matrix provides overall strong and tough support, effectively resisting the impact of high-speed materials and preventing breakage and deformation;

[0014] 3) Good heat resistance: Maintains stable performance in high temperature environment (up to 350°C), and the hardness decreases by no more than 5% after 500 hours of continuous working;

[0015] 4) Excellent corrosion resistance: The high chromium cast iron layer can effectively resist the erosion of corrosive components such as moisture and sulfur in coal powder;

[0016] 5) Lightweight structure: Using ceramic materials with lower density (1.8-3.6g / cm3 ) replaces part of the metal materials, and the overall weight is 15-20% lighter than the high-chromium cast iron striking plate of the same size, reducing the energy consumption of the equipment.

[0017] The present invention provides a fan wear-resistant impact plate, which has a three-layer composite structure, comprising a base layer, a transition layer, and a wear-resistant layer from bottom to top.

[0018] The base layer is made of carbon steel or alloy steel plate with a thickness of 5-10 mm, providing overall strength and toughness support; the transition layer is made of high chromium cast iron B with a chromium content of 18-28% and a thickness of 20-50 mm, providing good wear resistance and certain impact toughness; the wear-resistant layer is made of high chromium cast iron A reinforced with ceramic particles and a thickness of 10-30 mm, providing extremely high surface hardness and wear resistance.

[0019] The transition layer is metallurgically bonded to the base layer and the wear-resistant layer through vacuum brazing; the ceramic particles are ZTA or TiC ceramic materials with a particle size of 0.5-3 mm; the vacuum degree of vacuum brazing is not less than 10^-3 Pa.

[0020] The ceramic particles in the wear-resistant layer are distributed in a flat plate or honeycomb pattern. The flat plate pattern is that the ceramic particles are evenly distributed to form a continuous wear-resistant layer; the honeycomb pattern is that the ceramic particles are distributed in a regular honeycomb shape, which improves the impact resistance while maintaining the wear resistance.

[0021] The solder between the transition layer and the base layer and the wear-resistant layer is nickel-based solder or copper-based solder.

[0022] The surface hardness of the fan wear-resistant impact plate is HRC60-65.

[0023] The present invention also provides a method for preparing the above-mentioned fan wear-resistant impact plate, which specifically comprises the following steps:

[0024] (1) High chromium ceramic casting and infiltration process

[0025] a. First, the ceramic particles and the binder are mixed in a weight ratio of 100: (1-7) and then pressurized and then heated at 120-150°C for 2-4 hours to obtain a preform;

[0026] The preform is placed in a casting mold and preheated, and then high chromium cast iron A is melted to 1400-1500° C. to obtain a high chromium cast iron A melt, and the high chromium cast iron A melt is poured onto the surface of the preform. After the pouring is completed, the preform is cooled to room temperature to obtain a metal-ceramic composite plate;

[0027] (2) Surface treatment and vacuum brazing

[0028] The surface of the metal-ceramic composite plate is machined and sandblasted; a carbon steel plate or alloy steel plate, a high chromium cast iron B plate, and the machined and sandblasted metal-ceramic composite plate are placed in order from bottom to top, and brazing filler metal is placed between two adjacent plates. A vacuum brazing process is used to form a metallurgical bond, and then the plate is cooled to room temperature to obtain a composite strike plate;

[0029] (3) Heat treatment process

[0030] The composite impact plate is kept in an inert atmosphere at 1000-1050°C for 2-2.5 hours, then oil quenched, tempered and cooled to room temperature, and then kept in a -70°C environment for 4-6 hours. After naturally returning to room temperature, it is tempered again to obtain a fan wear-resistant impact plate.

[0031] Furthermore, the particle size of the ceramic particles in step (1) is 0.5-3 mm.

[0032] Furthermore, the binder in step (1) is one or more of phenolic resin, epoxy resin, and sodium silicate-based inorganic binder.

[0033] Furthermore, the pressure molding in step (1) is specifically to mix the ceramic particles and the binder, fill them into a mold, and perform pressure molding under a pressure of 0.1-0.2 MPa.

[0034] Furthermore, the preform is a flat plate preform or a honeycomb preform.

[0035] Furthermore, in step (1), the high chromium cast iron A is preheated to 250-300° C. and has a chromium content of 22-28%;

[0036] Furthermore, in step (1), the pouring temperature is controlled to be 1400-1500°C and the pouring pressure is controlled to be 0.1-0.3 MPa; during cooling, the cooling rate needs to be controlled to be 5-12°C / min;

[0037] Furthermore, the metal-ceramic composite plate that has been machined and sandblasted in step (2) is used as the wear-resistant layer of the fan wear-resistant impact plate.

[0038] Furthermore, the sandblasting treatment in step (2) specifically refers to using 60-100 mesh Al2O3 sand and sandblasting the surface of the metal-ceramic composite plate at a sandblasting pressure of 0.5-0.7 MPa; before vacuum brazing, using anhydrous ethanol to clean the carbon steel plate or alloy steel plate, high chromium cast iron B plate;

[0039] Furthermore, the solder in step (2) is nickel-based solder or copper-based solder, and the solder thickness is controlled to be 0.1-0.3 mm;

[0040] Furthermore, the nickel-based solder is BNi-2 or BNi-5 nickel-based solder, and the copper-based solder is BCu-1a copper-based solder.

[0041] Furthermore, in the vacuum brazing process described in step (2), the vacuum brazing furnace is first evacuated to a vacuum degree of not less than 10^-3Pa, and then heated according to the following heating program: heating to 400-500℃ at a rate of 5-10℃ / min, keeping warm for 20-30 minutes to eliminate stress, and then heating to the melting point of the solder at a rate of 10-15℃ / min, keeping warm at the melting point of the solder for 15-30 minutes to ensure that the solder is fully melted and forms a metallurgical bond, and then slowly cooling to below 400℃ with the furnace.

[0042] Furthermore, in step (3), the inert atmosphere is at least one of argon and nitrogen, the oil is quenched to 60-80°C, and tempered at 200-250°C for 2-2.5 hours, and cooling refers to air cooling; and re-tempering refers to tempering at 180-200°C for 1 hour.

[0043] The present invention also provides the application of the fan grinder wear-resistant impact plate described above in coal powder preparation systems of thermal power plants, coal powder preparation of industrial boilers, raw material grinding in cement plants, crushing equipment in the metallurgical industry and other wear environments requiring high wear resistance and high toughness.

[0044] The fan wear-resistant impact plate is suitable for extreme working conditions with high-speed rotation (rotation speed up to 490r / min, peripheral linear speed up to 92.32m / s or 332.3km / h), that is, suitable for working conditions with rotation speed ≤490r / min and peripheral linear speed ≤92.32m / s or 332.3km / h.

[0045] As the energy industry's requirements for equipment reliability and economy continue to increase, the fan wear-resistant impact plate provided by the present invention has broad application prospects and market value, and can bring significant economic benefits to industries such as electricity, cement, and metallurgy.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) Material combination: By rationally combining ceramic particles, high chromium alloy and carbon steel or alloy steel, the advantages of material properties are complementary, solving the contradiction that a single material is difficult to meet both wear resistance and toughness;

[0048] Structural design: adopts a three-layer composite structure and two ceramic distribution methods (flat plate or honeycomb), which can be flexibly adjusted according to different working conditions to improve adaptability;

[0049] In terms of technology: the manufacturing process of combining cast infiltration with vacuum brazing solves the problem of high brittleness of traditional high-chromium cast iron and improves the overall performance and reliability of the strike plate.

[0050] (2) Performance advantages: Wear resistance is significantly improved, 2-3 times higher than that of ordinary high manganese steel; impact toughness is guaranteed, effectively preventing the risk of fracture; service life is extended by 50-100%; maintenance cycle is extended, reducing maintenance costs; reliable welding of the strike plate and the base can be achieved, making it easy to fix and replace. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a schematic diagram of the structure of a conventional striking wheel and striking plate;

[0052] Figure 2 Schematic diagram of the structure of the composite striking plate obtained in step (2) of Example 1, wherein the preform in this embodiment is a flat plate;

[0053] Figure 3 Schematic diagram of the structure of the composite striking plate obtained in step (2) of Example 3, in which the preform is a honeycomb type;

[0054] Figure 4 1 is a schematic cross-sectional view of the composite striking plate obtained in step (2) of Example 1, wherein the preform in this embodiment is a flat plate;

[0055] Figure 5 3 is a schematic cross-sectional view of the composite striking plate obtained in step (2) of Example 3. In this example, the preform is honeycomb-shaped.

[0056] Reference numerals

[0057] 1-protective baffle, 2-front disc, 3-connecting frame, 4-guard plate, 5-rear disc, 6-strike plate. DETAILED DESCRIPTION

[0058] In order to better understand the content of the present invention, the present invention will be further described below in conjunction with specific examples and drawings. The following examples are implemented based on the technology of the present invention and provide detailed implementation methods and operating steps, but the scope of protection of the present invention is not limited to the following examples.

[0059] Figure 1 It is a structural diagram of a conventional striking wheel and striking plate, wherein the striking wheel includes a protective baffle 1, a front disc 2, a connecting frame 3, a guard plate 4, a rear disc 5, and a striking plate 6.

[0060] Example 1:

[0061] (1) High chromium ceramic casting and infiltration process

[0062] a. Material preparation

[0063] Ceramic particles: ZTA (zirconia toughened alumina) ceramic material is selected with a particle size of 1.5-2.5 mm; metal matrix: high chromium cast iron A melt with a chromium content of 25% is used; binder: phenolic resin binder is selected for preform molding.

[0064] b. Preform Preparation

[0065] ZTA ceramic particles and phenolic resin binder are mixed uniformly in a weight ratio of 95:5 to obtain a mixture. A mold is designed according to the size of the striking plate. The mixture is filled into the mold and formed under a pressure of 0.1 MPa. The mold is then kept at 140°C for 3 hours to solidify the binder and form a flat preform. The ceramic particles are evenly distributed on the surface, forming a continuous wear-resistant layer.

[0066] c. Casting and infiltration molding

[0067] The preform is placed in a casting mold, which is then preheated to 250°C to reduce thermal shock. High chromium cast iron A with a chromium content of 25% is melted to 1450°C to obtain a high chromium cast iron A melt. The pouring temperature is controlled to be 1450±50°C, the pouring pressure is controlled to be 0.2MPa, and the pouring speed is controlled to be 6kg / min. The high chromium cast iron A melt is poured onto the surface of the preform so that the molten metal fully penetrates the pores of the flat preform. After the pouring is completed, the cooling speed is controlled to be 10°C / min to avoid cracking caused by thermal stress. After cooling to room temperature, a metal-ceramic composite plate is obtained.

[0068] (2) Surface treatment and vacuum brazing of carbon steel plates

[0069] d.Surface treatment

[0070] The above-mentioned metal-ceramic composite plate was machined to ensure dimensional accuracy, and then the surface of the metal-ceramic composite plate was sandblasted using 60-mesh Al2O3 sand at a sandblasting pressure of 0.6 MPa to improve its surface roughness (so that the Ra of the metal-ceramic composite plate after sandblasting is Ra = 3.2 μm) and enhance the brazing joint strength. In addition, the base layer is Q235 carbon steel plate, and the transition layer is high-chromium cast iron B plate with a chromium content of 23%. The surfaces of the high-chromium cast iron B plate and the carbon steel plate are thoroughly cleaned with anhydrous ethanol to remove oil stains and oxides.

[0071] e. Solder selection and preparation

[0072] BNi-2 nickel-based brazing filler metal (i.e. Ni-7Cr-4.5Si-3.1B) was selected, the thickness of the brazing filler metal was controlled at 0.2 mm, and the brazing filler metal sheets were evenly placed on the connection interface.

[0073] f. Vacuum brazing process

[0074] Place the surface-treated carbon steel plate, high chromium cast iron plate B, and metal-ceramic composite plate from bottom to top. The thickness of each plate is as follows: the carbon steel plate: 10 mm, the high chromium cast iron plate: 30 mm, and the metal-ceramic composite plate: 15 mm. Then, use a precision fixture to fix the workpiece to ensure that the contact surfaces to be brazed are tightly fitted. Place the assembled workpiece in a vacuum brazing furnace and evacuate to 5×10 -4 Pa, create an oxidation-free environment, and heat according to the following heating program: heat to 500℃ at a rate of 8℃ / min, keep warm for 30 minutes to eliminate stress, then heat to the melting point of the solder (specifically 980℃) at a rate of 12℃ / min, keep warm at the melting point of the solder for 25 minutes to ensure that the solder is fully melted and forms a metallurgical bond, then slowly cool to 400℃ with the furnace (cooling rate 5℃ / min), then take out and naturally cool to room temperature to obtain a composite strike plate.

[0075] (3) Final heat treatment process

[0076] g.Heat treatment process

[0077] The composite strike plate obtained by vacuum brazing was kept at 1030°C for 2 hours (using argon protective atmosphere), then oil quenched to 70°C with a cooling rate of 70°C / s, then tempered at 220°C for 2 hours, and then air-cooled to room temperature.

[0078] h. Cold treatment

[0079] The tempered striking plate was placed in a -70°C environment (specifically, liquid nitrogen indirect cooling) for 5 hours, naturally returned to room temperature, and tempered again at 190°C for 1 hour to obtain a fan wear-resistant striking plate.

[0080] After the aforementioned processing and testing, the wear-resistant strike plate of the fan mill produced in this embodiment achieved a surface hardness of HRC63, a flexural strength of 980 MPa, and a fracture toughness of 28 MPa·m^(1 / 2). During continuous operation under actual fan mill operating conditions, the wear rate was 0.08 g / h, compared to 0.25 g / h for a conventional high-manganese steel strike plate under the same test conditions, representing a 3.1-fold improvement in wear resistance.

[0081] Example 2:

[0082] (1) High chromium ceramic casting and infiltration process

[0083] a. Material preparation

[0084] Ceramic particles: TiC (titanium carbide) ceramic material with a particle size of 2.0-3.0 mm; Metal matrix: High chromium cast iron A melt with a chromium content of 22%; Binder: Sodium silicate-based inorganic binder is used for preform molding.

[0085] b. Preform Preparation

[0086] TiC ceramic particles and sodium silicate-based inorganic binder are uniformly mixed in a weight ratio of 100:6 to obtain a mixture. A mold is designed according to the size of the striking plate. The mixture is filled into the mold and press-formed under a pressure of 0.15 MPa. The mold is then kept warm at 150°C for 4 hours to solidify the binder and form a flat preform.

[0087] c. Casting and infiltration molding

[0088] The preform is placed in a casting mold, which is then preheated to 280°C. High chromium cast iron A with a chromium content of 22% is melted to 1480°C to obtain a high chromium cast iron A melt. The pouring temperature is controlled to be 1480±50°C, the pouring pressure is controlled to be 0.3 MPa, and the pouring speed is controlled to be 8 kg / min. The high chromium cast iron A melt is poured onto the surface of the flat preform. After the pouring is completed, the cooling speed is controlled to be 8°C / min. After cooling to room temperature, a metal-ceramic composite plate is obtained.

[0089] (2) Surface treatment and vacuum brazing of carbon steel plates

[0090] d.Surface treatment

[0091] The above-mentioned metal-ceramic composite plate was mechanically processed, and then the surface of the metal-ceramic composite plate was sandblasted with 80-mesh Al2O3 sand at a sandblasting pressure of 0.5 MPa; the base layer was a Q235 carbon steel plate, and the transition layer was a high-chromium cast iron B plate with a chromium content of 20%. The surfaces of the high-chromium cast iron B plate and the carbon steel plate were thoroughly cleaned with anhydrous ethanol to remove oil stains and oxides.

[0092] e. Solder selection and preparation

[0093] BCu-1a copper-based solder (Cu-7P-1Sn) is selected, and the solder thickness is controlled at 0.15mm.

[0094] f. Vacuum brazing process

[0095] This step is the same as step f of step (2) in Example 1, except that the vacuum is pumped to 8×10 -4 Pa was heated according to the following heating program: heating to 500°C at a rate of 10°C / min, keeping warm for 20 minutes, then heating to the melting point of the solder (specifically 850°C) at a rate of 15°C / min, keeping warm at the melting point of the solder for 20 minutes, slowly cooling to 400°C with the furnace, then taking out and naturally cooling to room temperature to obtain a composite strike plate.

[0096] (3) Final heat treatment process

[0097] g.Heat treatment process

[0098] The composite strike plate obtained by vacuum brazing was kept at 1000°C for 2.5 hours (using nitrogen protective atmosphere), then oil quenched to 60°C, tempered at 240°C for 2.5 hours, and air-cooled to room temperature.

[0099] h. Cold treatment

[0100] The tempered striking plate was placed in a -70°C environment for 4 hours, naturally returned to room temperature, and tempered again at 180°C for 1 hour to obtain a fan wear-resistant striking plate.

[0101] Testing showed that the strike plate produced in this example achieved a surface hardness of HRC61, a flexural strength of 920 MPa, and a fracture toughness of 26 MPa·m^(1 / 2). In a sulfur-containing, highly abrasive coal dust environment (sulfur content >0.5%, Hardening coefficient <50), the strike plate produced in this example exhibited excellent corrosion resistance, with a corrosion rate 15% lower than that of the fan wear-resistant strike plate produced in Example 1.

[0102] Example 3:

[0103] (1) High chromium ceramic casting and infiltration process

[0104] a. Material preparation

[0105] Ceramic particles: ZTA (zirconia toughened alumina) ceramic material is selected with a particle size of 1.0-2.0 mm; metal matrix: high chromium cast iron A melt with a chromium content of 28% is used; binder: epoxy resin binder is selected for preform molding.

[0106] b. Preform Preparation

[0107] ZTA ceramic particles and epoxy resin binder are evenly mixed in a weight ratio of 100:7 to obtain a mixture. A honeycomb mold (honeycomb unit diameter 8mm, spacing 3mm) is used to fill the mixture into the mold, vibrate it, and press it under a pressure of 0.2MPa. The mold is then kept at 120°C for 2 hours to solidify the binder and form a honeycomb preform. The ceramic particles are regularly distributed in a honeycomb shape, which improves the impact resistance while maintaining good wear resistance.

[0108] c. Casting and infiltration molding

[0109] The preform is placed in a casting mold, which is preheated to 300°C. High chromium cast iron A with a chromium content of 28% is melted to 1500°C to obtain a high chromium cast iron A melt. The high chromium cast iron A melt is poured onto the surface of the preform to allow the molten metal to fully penetrate the pores of the honeycomb preform. After the pouring is completed, the cooling rate is controlled by a program. The initial cooling rate is 5°C / min. After cooling to 800°C, the cooling rate is increased to 12°C / min. After cooling to room temperature, a metal-ceramic composite plate is obtained.

[0110] (2) Surface treatment and vacuum brazing of carbon steel plates

[0111] d.Surface treatment

[0112] The above-mentioned metal-ceramic composite plate was machined to ensure dimensional accuracy, and then the surface of the metal-ceramic composite plate was sandblasted with 100-mesh Al2O3 sand at a sandblasting pressure of 0.7 MPa; the base layer was a 42CrMo alloy steel plate, and the transition layer was a high-chromium cast iron B plate with a chromium content of 25%. The surfaces of the high-chromium cast iron B plate and the 42CrMo alloy steel plate were thoroughly cleaned with anhydrous ethanol to remove oil stains and oxides.

[0113] e. Solder selection and preparation

[0114] BNi-5 nickel-based brazing filler metal (specifically Ni-19Cr-10Si) was selected, the thickness of the brazing filler metal was controlled at 0.25 mm, and the brazing filler metal sheets were evenly placed on the connection interface.

[0115] f. Vacuum brazing process

[0116] This step is the same as step f of step (2) in Example 1, except that the vacuum is pumped to 3×10 -4 Pa was heated according to the following heating program: heating to 400°C at a rate of 5°C / min, keeping warm for 30 minutes, then heating to the melting point of the solder (specifically 1100°C) at a rate of 10°C / min, keeping warm at the melting point of the solder for 20 minutes, slowly cooling to 400°C with the furnace, then taking out and naturally cooling to room temperature to obtain a composite strike plate.

[0117] (3) Final heat treatment process

[0118] g.Heat treatment process

[0119] The composite strike plate obtained by vacuum brazing was kept at 1050°C for 2 hours (using argon protective atmosphere), then oil quenched to 80°C, tempered at 230°C for 2 hours, and air-cooled to room temperature.

[0120] h. Cold treatment

[0121] The tempered striking plate was placed in a -70°C environment for 6 hours, naturally returned to room temperature, and tempered again at 200°C for 1 hour to obtain a fan wear-resistant striking plate.

[0122] Testing showed that the strike plate produced in this embodiment achieved a surface hardness of HRC65, a flexural strength of 1050 MPa, and a fracture toughness of 32 MPa·m^(1 / 2). The honeycomb structure design ensures improved toughness and fracture resistance under high-speed impact loads. In impact wear tests simulating the extreme operating conditions of a fan mill (at a speed of 500 r / min), the strike plate demonstrated a 25% improvement in impact resistance compared to Example 1, making it particularly suitable for fan mills processing high-hardness, highly abrasive coals.

[0123] The above description is merely an embodiment of the present invention and does not constitute any form of limitation to the present invention. The present invention may also have other forms of embodiments based on the above structures and functions, which are not listed here one by one. Therefore, any simple modification, equivalent changes, and modifications made to the above embodiments by any person skilled in the art in accordance with the technical essence of the present invention without departing from the scope of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A wear-resistant impact plate for a fan, characterized in that: The striking plate is a three-layer composite structure, which includes a base layer, a transition layer, and a wear-resistant layer from bottom to top; The base layer is made of carbon steel or alloy steel plate with a thickness of 5-10 mm; the transition layer is made of high chromium cast iron B with a chromium content of 18-28% and a thickness of 20-50 mm; the wear-resistant layer is made of high chromium cast iron A reinforced with ceramic particles with a thickness of 10-30 mm. The ceramic particles are ZTA or TiC ceramic materials with a particle size of 0.5-3 mm. The transition layer is metallurgically bonded to the base layer and the wear-resistant layer through vacuum brazing, and the vacuum degree of the vacuum brazing is not less than 10^-3Pa.

2. The wear-resistant impact plate for a fan according to claim 1, characterized in that: The surface hardness of the striking plate is HRC60-65.

3. The wear-resistant impact plate for a fan according to claim 1, characterized in that: The ceramic particles in the wear-resistant layer are distributed in a flat plate or honeycomb type. The flat plate type is that the ceramic particles are evenly distributed to form a continuous wear-resistant layer; the honeycomb type is that the ceramic particles are distributed in a regular honeycomb shape; the brazing material between the transition layer and the base layer and the wear-resistant layer is nickel-based brazing material or copper-based brazing material.

4. A method for preparing a wear-resistant impact plate for a fan according to any one of claims 1 to 3, characterized in that: The specific steps include: (1) High chromium ceramic casting and infiltration process First, ceramic particles and a binder are mixed in a weight ratio of 100:(1-7) and then press-formed, and then kept at 120-150°C for 2-4 hours to obtain a preform; The preform is placed in a casting mold and preheated, and then high chromium cast iron A is melted to 1400-1500° C. to obtain a high chromium cast iron A melt, and the high chromium cast iron A melt is poured onto the surface of the preform. After the pouring is completed, the preform is cooled to room temperature to obtain a metal-ceramic composite plate; (2) Surface treatment and vacuum brazing The surface of the metal-ceramic composite plate is machined and sandblasted; a carbon steel plate or alloy steel plate, a high chromium cast iron B plate, and the machined and sandblasted metal-ceramic composite plate are placed in order from bottom to top, and brazing filler metal is placed between two adjacent plates. A vacuum brazing process is used to form a metallurgical bond, and then the plate is cooled to room temperature to obtain a composite strike plate; (3) Heat treatment process The composite impact plate is kept in an inert atmosphere at 1000-1050°C for 2-2.5 hours, then oil quenched, tempered and cooled to room temperature, and then kept in a -70°C environment for 4-6 hours. After naturally returning to room temperature, it is tempered again to obtain a fan wear-resistant impact plate.

5. The method for preparing the wear-resistant striking plate of a fan grinder according to claim 4, characterized in that: The binder in step (1) is one or more of phenolic resin, epoxy resin, and sodium silicate-based inorganic binder, the chromium content of high chromium cast iron A is 22-28%, and the preform is a flat preform or a honeycomb preform; the solder in step (2) is a nickel-based solder or a copper-based solder, and the solder thickness is controlled to be 0.1-0.3 mm.

6. The method for preparing the wear-resistant striking plate of a fan according to claim 4, characterized in that: The pressure molding in step (1) is specifically to mix the ceramic particles and the binder, fill them into a mold and pressurize them under a pressure of 0.1-0.2 MPa; the preheating is to preheat to 250-300°C; the pouring temperature is controlled to 1400-1500°C and the pouring pressure is controlled to 0.1-0.3 MPa; the cooling rate needs to be controlled during cooling, and the cooling rate is 5-12°C / min.

7. The method for preparing the wear-resistant striking plate of a fan according to claim 5, characterized in that: The sandblasting treatment in step (2) specifically refers to using 60-100 mesh Al2O3 sand and sandblasting the surface of the metal-ceramic composite plate at a sandblasting pressure of 0.5-0.7 MPa; before vacuum brazing, using anhydrous ethanol to clean the carbon steel plate or alloy steel plate, high chromium cast iron B plate; the nickel-based brazing filler metal is BNi-2 or BNi-5 nickel-based brazing filler metal, and the copper-based brazing filler metal is BCu-1a copper-based brazing filler metal.

8. The method for preparing a wear-resistant striking plate for a fan according to claim 4, characterized in that: The vacuum brazing process described in step (2) is to first evacuate the vacuum brazing furnace so that the vacuum degree is not less than 10^-3Pa, and then heat it according to the following heating program: heat it to 400-500℃ at a rate of 5-10℃ / min, keep it warm for 20-30 minutes, then heat it to the melting point of the solder at a rate of 10-15℃ / min, keep it warm at the melting point of the solder for 15-30 minutes, and then slowly cool it to below 400℃ with the furnace.

9. The method for preparing a wear-resistant striking plate for a fan according to claim 4, wherein: In step (3), the inert atmosphere is at least one of argon and nitrogen, the oil is quenched to 60-80°C, and tempered at 200-250°C for 2-2.5 hours. Cooling refers to air cooling; and re-tempering refers to tempering at 180-200°C for 1 hour.

10. The fan grinder wear-resistant impact plate according to any one of claims 1 to 3 is used in coal powder preparation systems in thermal power plants, coal powder preparation in industrial boilers, raw material grinding in cement plants, crushing equipment in the metallurgical industry, and wear environments requiring high wear resistance and high toughness, and in working conditions with a rotation speed of ≤490 r / min and a peripheral linear speed of ≤92.32 m / s or 332.3 km / h.

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