A cutting knife for a granulator and a manufacturing and testing method thereof

Abstract

The application provides a pelletizer cutting knife and a manufacturing detection method thereof. The pelletizer cutting knife comprises a long strip-shaped cutter body, a cutting edge part fixed to the cutting edge of the cutter body, and a mounting part for mounting. The cutting edge part forms a covered cutting edge profile in the width direction of the cutting knife, and sequentially comprises a covered blade base part, an outward convex blade edge part, and a downward extending side blade part, so that the cutting edge can consider the bearing stability, cutting sharpness, and lateral constraint ability during the cutting process. The cutting edge part adopts a gradient functional composite material structure, which sequentially sets a metal-ceramic interpenetrating network composite layer and a transition gradient layer from inside to outside. The metal-ceramic interpenetrating network composite layer forms a continuous interpenetrating structure through hot-pressing sintering to improve the impact resistance and wear resistance. The transition gradient layer realizes the continuous change of composition and performance through laser cladding to buffer stress and reduce the risk of interface failure. The cutting knife can effectively reduce the stress concentration and wear of the cutting edge, and improve the cutting efficiency and service life.

Description

Technical Field

[0001] This invention belongs to the field of preparation materials and preparation and testing technology of pelletizing blades for granulators, specifically relating to a pelletizing blade for granulators and its manufacturing and testing method. Background Technology

[0002] In the processing of plastics, rubber, and related polymer materials, pelletizers typically use pelletizing blades to cut molten or semi-molten materials at high speeds. These blades must withstand frequent impacts, significant shearing forces, and continuous friction and wear over extended periods. Existing pelletizing blades often employ a single metal material or a simple coated structure, leading to stress concentration at corners and cutting edges. With increased use, this results in accelerated wear, chipping, and even breakage, affecting pellet quality and consistency, necessitating frequent blade replacements, and increasing equipment maintenance costs and downtime. Therefore, improving the structural reliability and service life of pelletizing blades for pelletizers while maintaining cutting sharpness has become a pressing technical challenge in the field of pelletizing blades. Summary of the Invention

[0003] To address the aforementioned technical problems, the present invention provides the following technical solution: In a first aspect of this application, a pelletizing blade for a pelletizer is provided, comprising: a blade body, which is a long strip-shaped base; a cutting edge portion, which is fixedly connected to the cutting edge of the blade body; and a mounting portion, located on the blade body, for fixing the pelletizing blade to the rotating shaft of the pelletizer;

[0004] The blade portion forms a wrapping blade profile in the cross section of the width direction of the pelletizer; the blade portion includes: a wrapping blade base portion, which connects downward from the upper surface of the blade body and surrounds the first corner of the blade body; an outwardly protruding blade edge portion located outside the wrapping blade base portion and connected to it, which protrudes obliquely upward; and a lower extension side blade portion connected downward from the outwardly protruding blade edge portion, which extends downward and smoothly connects to the lower part of the blade body.

[0005] The material of the blade is a gradient functional composite material, which includes, from the inner layer to the outer layer: a metal-ceramic interpenetrating network composite layer bonded to the blade body, and a transition gradient layer with continuously changing composition and properties.

[0006] Furthermore, the raw materials for preparing the metal-ceramic interpenetrating network composite layer include, by mass percentage: 70%-85% iron-based alloy powder, 5%-15% nano-titanium carbide, 5%-10% micron-sized chromium powder, 0.5%-2% nano-Y2O3, with the balance being unavoidable impurities; the iron-based alloy powder is Fe-Cr-Mo-V alloy powder.

[0007] Furthermore, the Fe-Cr-Mo-V alloy powder is a micron-sized pre-alloyed atomized powder or a micron-sized gas atomized powder with a particle size of 150-300 mesh; the average particle size D50 of the nano-titanium carbide is 70nm-90nm; the particle size of the micron-sized metallic chromium powder is 300-500 mesh; and the average particle size D50 of the nano-Y2O3 is 50nm-80nm.

[0008] Furthermore, the method for preparing the metal-ceramic interpenetrating network composite layer includes the following steps:

[0009] S11: Weigh each raw material powder according to the types and corresponding proportions of the raw materials to be prepared, place them in a planetary ball mill, and mill them under argon protection. The ball-to-material ratio of the planetary ball mill is 5:1–15:1, the spindle speed is 200–400 rpm, and the milling time is 4–8 hours to obtain a uniformly mixed composite powder; S12: Load the composite powder into a graphite mold and place it in a vacuum hot pressing sintering furnace;

[0010] S13: When the vacuum degree is ≤10 -2 Under Pa conditions, the temperature is increased to 1000℃-1150℃ at a rate of 15℃ / min-20℃ / min, and a pressure of 25MPa-35MPa is applied. The temperature and pressure are maintained for 30 minutes-60 minutes, which allows the metal matrix to flow plastically and encapsulate ceramic particles. At the same time, chromium diffuses to the interface to form a strong metallurgical bond.

[0011] S14: Cool to room temperature in the furnace and demold to obtain the blank of the metal-ceramic interpenetrating network composite layer.

[0012] Furthermore, the raw material composition of the transition gradient layer includes a first metal powder, a second metal powder, and a ceramic powder. From the innermost side closest to the metal-ceramic interpenetrating network composite layer outwards, the mass fraction of the first metal powder decreases from a first gradient percentage to a second gradient percentage, and the sum of the mass fractions of the second metal powder and the ceramic powder increases from a third gradient percentage to a fourth gradient percentage. The first metal powder is an Fe-Cr-Mo-V alloy powder compatible with the metal-ceramic interpenetrating network composite layer, the second metal powder is a WC-Co alloy powder, and the ceramic powder is nano-TiB2 or nano-Cr3C2 powder.

[0013] Furthermore, the first gradient percentage and the fourth gradient percentage both range from 75% to 80%, and the second gradient percentage and the third gradient percentage both range from 20% to 25%.

[0014] Furthermore, the method for preparing the transition gradient layer includes the following steps:

[0015] S21: Set the raw materials required for the transition gradient layer to be loaded into at least two powder feeders respectively. The first powder feeder is filled with Fe-Cr-Mo-V alloy powder, and the second powder feeder is filled with WC-Co alloy powder and ceramic powder.

[0016] S22: Synchronously control the powder feeding rate of each powder feeder, and further prepare a transition gradient layer using laser cladding method, controlling the powder feeding rate of the first powder feeder from the first initial value V. A1 Linearly decreasing to the final value, first final value V A2 Simultaneously, control the powder feeding rate of the second powder feeder from the second initial value V. D1 Linearly increasing to the second final value V D2 And the linear increase rate or linear decrease rate of the powder feeding rate is constant;

[0017] S23: During the laser cladding process, an alloy melt with continuously changing composition is formed in the molten pool under the irradiation of the laser beam. After the laser beam is removed, the molten pool solidifies, thus obtaining a transition gradient layer with continuously changing composition and properties.

[0018] Furthermore, in step S23, the laser power used for laser cladding is 800W-2000W, the laser scanning speed is 5mm / s-20mm / s, the laser spot diameter is controlled to be 1.0mm-3.0mm, and the cladding layer thickness is 0.3mm-1.2mm.

[0019] Furthermore, the first initial value V A1 The first final value V is 15 g / min–21 g / min. A2 The flow rate is 3g / min–8g / min, and the second initial value V D1 The second final value V is 3g / min–8g / min. D2 The total powder feeding rate is 15 g / min–21 g / min, and the total real-time powder feeding rate is kept constant during the laser cladding process; the total real-time powder feeding rate is maintained at 22 g / min–24 g / min.

[0020] In another aspect of this application, a manufacturing inspection method for inspecting the pelletizing blade for a pelletizer as described above is also provided. The inspection method is applied during and after the manufacturing process of the pelletizing blade, and includes the following steps:

[0021] D1: After the metal-ceramic interpenetrating network composite layer is prepared, its cross-section is examined by microstructure detection. The metal continuous phase and the ceramic reinforcing phase are observed by scanning electron microscopy to see whether an interpenetrating network structure is formed and whether there are obvious pores or unbonded areas at the interface.

[0022] D2: During or after the laser cladding of the transition gradient layer, the composition distribution at different thickness locations is detected, and the continuous variation characteristics of the corresponding elements of the first metal powder, the second metal powder, and the ceramic powder along the thickness direction are verified by energy dispersive spectroscopy and line scanning.

[0023] D3: The phase analysis of the transition gradient layer material of the blade after the pelletizer is prepared is carried out. The presence of iron matrix phase, hard phase and ceramic phase is confirmed by X-ray diffraction, and the correspondence between the hard phase types in the transition gradient layer in different embodiments is verified.

[0024] D4: Based on the results of microhardness testing or wear performance testing, comprehensively determine the structural integrity and gradient effectiveness of the metal-ceramic interpenetrating network composite layer and the transition gradient layer to confirm whether the pelletizer meets the performance requirements for use.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. The cutting edge of this application includes a covered cutting edge base, an outwardly convex cutting edge, and a downwardly extending side cutting edge. The covered cutting edge base is used to stably cover and support the blade body rotation during pelleting, so as to achieve smooth transmission of cutting load, thereby reducing root stress concentration and improving connection reliability. The outwardly convex cutting edge is used to form a cutting edge with preferential contact, which facilitates the concentration of cutting force and reduces instantaneous cutting resistance, thereby improving pelleting efficiency and reducing impact. The downwardly extending side cutting edge is used to form lateral constraints on the material and maintain the continuity of the cutting edge shape, reducing material slippage or escape, thereby helping to obtain more regular and more uniformly sized particles and reducing the risk of chipping and wear.

[0027] 2. The blade of this application is made of a gradient functional composite material composed of a metal-ceramic interpenetrating network composite layer and a transition gradient layer. This allows the blade to achieve a continuous transition from high toughness to high wear resistance in the thickness direction. This ensures that the blade has load-bearing strength, impact resistance and wear resistance during pelletizing, avoids interface failure caused by abrupt changes in material properties, improves the performance of the blade under high-frequency cutting conditions, and effectively extends the service life of the pelletizing blade.

[0028] 3. In the gradient functional composite material for preparing the cutting edge provided in this application, the metal-ceramic interpenetrating network composite layer forms a three-dimensional continuous structure through the mutual penetration of the metal phase and the ceramic phase. During the preparation process, the two phases support each other in space and work together to bear the force. Thus, during the pelletizing process, the metal phase can absorb and buffer the impact load, while the ceramic phase can provide high hardness and wear resistance, effectively preventing plastic deformation or early wear at the root of the cutting edge.

[0029] 4. In the gradient functional composite material for preparing the cutting edge provided in this application, the transition gradient layer continuously controls the composition ratio and microstructure during the preparation process, so that its performance is between that of the metal-ceramic interpenetrating network composite layer and the outer cutting edge region. This plays a role in stress buffering and performance transition during pellet cutting, reduces mechanical mismatch between different material layers, reduces the risk of interface peeling and crack propagation, and further improves the bending resistance and wear resistance of the overall structure of the cutting edge. Attached Figure Description

[0030] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0031] Figure 1 The diagram illustrates the different types of pelletizing blades commonly used in existing pelletizers.

[0033] Figure 2 for Figure 1 The cross-sectional view of the pelletizer along the AA direction is shown below;

[0034] Figure 3 SEM images of the metal-ceramic interpenetrating network composite layers prepared in Examples 1, 2 and Comparative Example 1 of this application;

[0035] Figure 4 The images show the scanning electron microscope (SEM) morphology of the interface region of the metal-ceramic interpenetrating network composite layer synthesized in Examples 1, 2, and Comparative Example 1 of this application, along with a comparison of the corresponding EDS elemental surface distribution and line scan results.

[0036] Figure 5 The images show XRD patterns of the transition metal layers synthesized in Examples 3-5 and Comparative Example 2 of this application. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] like Figure 1As shown, existing pelletizing blades for pelletizers typically employ a solid metal blade structure or a single wear-resistant layer formed on the surface of the metal blade. The blades are mostly elongated or sheet-like in shape and are used in conjunction with the pelletizer's rotating shaft via mounting holes. In practical use, these pelletizing blades primarily rely on the metal substrate or a single surface-hardened layer to withstand cutting loads and wear. While simple in structure and easy to manufacture, under high-load, high-frequency pelletizing, or long-term continuous operation conditions, they are prone to problems such as accelerated wear, chipping, or interface failure of the cutting edge, thus affecting pelletizing accuracy and service life. Based on the shortcomings of the existing technology, this application focuses on the material structure of the cutting edge and makes targeted improvements to the cutting edge 2. It introduces a composite material structure with gradient functions, constructing a metal-ceramic interpenetrating network composite layer and a transition gradient layer between the blade body and the wear-resistant surface layer to achieve a synergistic improvement in the cutting edge's toughness, wear resistance, and structural stability. This proposes an improved pelletizing blade technology solution for pelletizers.

[0039] Figure 1 This application illustrates a pelletizing blade for a pelletizer, as shown in an embodiment. Figure 1 As shown, the pelletizer cutter of this application has an overall elongated structure, including a cutter body 1, a cutting edge 2 located at the cutting edge of the cutter body, and a mounting part 3 located at one end of the cutter body. The cutter body 1, as the main load-bearing structure of the pelletizer, is typically made of a single piece of metal. It serves two purposes: firstly, it withstands the centrifugal force, bending load, and impact load transmitted by the pelletizer's rotating shaft during pelletizing; secondly, it provides stable structural support and a geometric positioning basis for the cutting edge 2, ensuring the cutting edge maintains shape stability and precise position under high-speed rotation and cyclic cutting conditions. The mounting part 3 is fixed to the pelletizer's rotating shaft or cutter head through mounting holes, allowing the pelletizer to move synchronously with the rotating mechanism during operation and reliably transmit the mechanical load generated during cutting to the cutter body 1, thereby ensuring the assembly reliability and operational safety of the entire pelletizer.

[0040] The cutting edge 2, located in the cutting edge area of ​​the blade body 1, is the functional part of the pelletizer that directly participates in the cutting operation during the pelletizing process. During operation, it periodically contacts the extruded strip material, cutting the continuous material into uniformly sized particles through shearing or splitting action. Because the cutting edge 2 directly bears the impact, friction, wear, and localized stress concentration of the material during pelletizing, its performance has a decisive influence on pelletizing efficiency, particle size consistency, and the service life of the pelletizer. This application, considering the characteristics of the cutting edge 2 during pelletizing, optimizes the material and structure of the cutting edge 2 while maintaining the overall mechanical strength and structural stability of the blade body 1. This design enables it to simultaneously possess good wear resistance, anti-chipping ability, and long-term stability under high-frequency cutting conditions, thereby improving the overall performance of the pelletizer.

[0041] Figure 2 Further shown Figure 1 A cross-sectional view of the pelletizer along the AA direction. (See diagram below.) Figure 1 and Figure 2 As shown, the cutting edge 2 forms a wrap-around cutting edge profile in the width direction cross-section of the pelletizer. It is continuously composed of a wrap-around cutting edge base 201, an outwardly convex cutting edge 202, and a downwardly extending side cutting edge 203. The wrap-around cutting edge base 201 extends continuously downwards from the upper surface of the blade body 1 and surrounds the area where the first corner 101 of the blade body 1 is located, forming a wrap-around joint structure between the cutting edge 2 and the blade body 1 at this corner, thus providing a stable load-bearing and support foundation in the root region of the cutting edge. The outer surface of the wrap-around cutting edge base 201 forms a continuous arc-shaped profile along the length of the cutting edge, providing a geometric transition for the outer cutting edge structure. Through the wrap-around arrangement of the cutting edge base 201 around the corner region of the blade body 1, the cutting edge 2 can effectively transfer the stress from the cutting edge region to the interior of the blade body 1 under cutting load, reducing the risk of stress concentration at the root of the cutting edge.

[0042] The convex cutting edge 202 is located outside the covering cutting edge base 201 and smoothly connected to it. It convexes obliquely upward at the corner of the blade body 1 to form a cutting edge structure that protrudes beyond the blade body contour. This is used to concentrate cutting stress and guide the material into the cutting zone. At the same time, the protruding cutting edge formed by the convex shape allows the cutting edge 2 to form point or line preferential contact with the material in the initial stage of pelleting. This is beneficial to concentrate cutting force and reduce instantaneous cutting resistance, thereby improving pelleting efficiency and reducing the impact on the drive system.

[0043] The lower extension side cutting edge 203 continuously connects downwards from the outwardly protruding cutting edge 202 and extends downwards along the vertical side surface 102 of the lower transverse section of the blade body 1. This creates a continuous blade-shaped structure in the lateral region of the cutting edge 2, which helps to laterally constrain the material during cutting, preventing material slippage or escape along the blade's side during pelletizing. This results in particles with regular shape and consistent size. By connecting the lower extension side cutting edge 203 to the blade body 1, the cutting edge 2 smoothly transitions with the blade body 1 in the width direction section, avoiding abrupt contour changes at the lateral boundary of the cutting edge. This reduces wear concentration in a specific area of ​​the cutting edge, thus preventing chipping. It should be noted that... Figure 2 This application merely illustrates the structure of the blade portion 2 provided in this application, and the structure to be protected in this application is not necessarily limited to that described in the previous application. Figure 2 Exactly the same.

[0044] The blade portion 2 of a pelletizer cutting blade provided in this application embodiment is a gradient functional composite material, which includes, from the inner layer to the outer layer: a metal-ceramic interpenetrating network composite layer 21 bonded to the blade body, a transition gradient layer 22 with continuously changing composition and properties, and an ultra-high hardness wear-resistant layer 23 located on the outermost working surface.

[0045] In some embodiments, the raw materials for preparing the metal-ceramic interpenetrating network composite layer 21, by mass percentage, include: 70%-85% iron-based alloy powder, 5%-15% nano-titanium carbide (Nano-TiC), 5%-10% micron-sized chromium powder, 0.5%-2% nano-Y2O3, with the balance being unavoidable impurities; the iron-based alloy powder is Fe-Cr-Mo-V alloy powder.

[0046] The method for preparing the metal-ceramic interpenetrating network composite layer 21 according to the embodiments of this application includes the following steps:

[0047] S11: Weigh each raw material powder according to the types and corresponding proportions of the raw materials to be prepared, place them in a planetary ball mill, and mill them under argon protection. The ball-to-material ratio of the planetary ball mill is 5:1–15:1, the spindle speed is 200–400 rpm, and the milling time is 4–8 hours to obtain a uniformly mixed composite powder; S12: Load the composite powder into a graphite mold and place it in a vacuum hot pressing sintering furnace;

[0048] S13: When the vacuum degree is ≤10 -2 Under Pa conditions, the temperature is increased to 1000℃-1150℃ at a rate of 15℃ / min-20℃ / min, and a pressure of 25MPa-35MPa is applied. The temperature and pressure are maintained for 30 minutes-60 minutes, which allows the metal matrix to flow plastically and encapsulate ceramic particles. At the same time, chromium diffuses to the interface to form a strong metallurgical bond.

[0049] S14: Cool to room temperature in the furnace and demold to obtain the blank of the metal-ceramic interpenetrating network composite layer 21.

[0050] Furthermore, the raw material composition of the transition gradient layer 22 includes a first metal powder, a second metal powder, and a ceramic powder. From the innermost side of the metal-ceramic interpenetrating network composite layer 21 outwards, the mass fraction of the first metal powder decreases from a first gradient percentage to a second gradient percentage, while the sum of the mass fractions of the second metal powder and the ceramic powder increases from a third gradient percentage to a fourth gradient percentage. The first metal powder is an Fe-Cr-Mo-V alloy powder compatible with the metal-ceramic interpenetrating network composite layer 21, the second metal powder is a WC-Co alloy powder, and the ceramic powder is nano-TiB2 or nano-Cr3C2 powder.

[0051] In some embodiments, the first gradient percentage and the fourth gradient percentage are both in the range of 75%–80%, and the second gradient percentage and the third gradient percentage are both in the range of 20%–25%. However, it is not limited that the first gradient percentage must be equal to the fourth gradient percentage, or that the second gradient percentage must be equal to the third gradient percentage.

[0052] In the embodiments of this application, the Fe-Cr-Mo-V alloy powder is a commercially available iron-based pre-alloyed powder. Its composition system is consistent with the H13 type hot work die steel powder widely used in the industry. This type of alloy powder has been mass-produced in the existing powder metallurgy and additive manufacturing fields and can be obtained through conventional and compliant channels. It can meet the requirements of the matrix alloy composition and performance stability in the preparation process of the metal-ceramic interpenetrating network composite layer of this application.

[0053] Example 1

[0054] In this embodiment, the raw materials for the metal-ceramic interpenetrating network composite layer 21, calculated by mass percentage, consist of 78% Fe-Cr-Mo-V alloy powder, 12% nano-TiC, 8% micron-sized metallic Cr powder, 1% nano-Y2O3, with the balance being 1% impurities. In this embodiment, the Fe-Cr-Mo-V alloy powder is 180 mesh, the average particle size D50 of the nano-TiC is 90 nm, the micron-sized Cr powder is 300 mesh, and the average particle size D50 of the nano-Y2O3 is 80 nm.

[0055] In Example 1, the specific preparation of the synthetic metal-ceramic interpenetrating network composite layer 21 includes the following steps:

[0056] S11: Under the protection of an argon atmosphere, the above-mentioned raw materials are dry-mixed for 6 hours using a planetary ball mill. The ball-to-material ratio of the planetary ball mill is 8:1, and its spindle speed is set to 260 rpm. During the dry mixing process, idling and stopping constitute one mixing cycle. The dry mixing is carried out for a predetermined duration. The alternation of idling and stopping in each mixing cycle is to control the excessive collision heat generated during the raw material mixing process, which could lead to excessively high temperatures inside the planetary ball mill.

[0057] S12: Use a graphite mold to load the raw materials mixed in step S11 into the mold. Before loading the mold, lay a thin layer of graphite paper inside the graphite mold to prevent sticking during the subsequent demolding process.

[0058] S13: In 1×10 -2 Under vacuum of 18 MPa, the temperature is increased to 1100 °C at a heating rate of 18 °C / min; and hot pressing of 30 MPa is applied, and the temperature and pressure are maintained at this state for 45 min. In this step, the metal matrix undergoes plastic flow, and Cr diffuses to the metal / ceramic interface to form metallurgical bonds, promoting the formation of an interpenetrating network (IPN) continuous phase.

[0059] S14: After cooling to room temperature in the furnace, the blank of metal-ceramic interpenetrating network composite layer 21 is obtained by demolding.

[0060] Example 2

[0061] In this embodiment, the raw materials for the metal-ceramic interpenetrating network composite layer 21, calculated by mass percentage, include 72% Fe-Cr-Mo-V alloy powder, 15% nano-TiC, 10% micron-sized Cr powder, 1.5% nano-Y2O3 as a rare earth oxide powder additive, and the balance being 1.5% impurities. In this embodiment, the Fe-Cr-Mo-V alloy powder is 300 mesh, the average particle size D50 of the nano-TiC is 70 nm, the particle size of the micron-sized Cr powder is 150 mesh, and the average particle size D50 of the nano-Y2O3 is 50 nm.

[0062] In Example 2, the specific preparation of the synthetic metal-ceramic interpenetrating network composite layer 21 includes the following steps:

[0063] S11: Also under argon atmosphere protection, dry mixing was carried out in a planetary ball mill for 8 hours (low-speed section + short-time high-speed section to improve dispersion), with a ball-to-powder ratio of 10:1 and a rotation speed of 300 rpm. This process aims to achieve uniform mixing, which is beneficial to the dispersion of nano-TiC on the surface of the Fe-Cr-Mo-V alloy powder, which is an iron-based material. At the same time, the interface between the micron-sized Cr powder and the matrix powder can be pre-contacted, creating conditions for Cr diffusion and metallurgical bonding in the subsequent hot pressing sintering stage, and allowing the nanoparticles to be appropriately dispersed and attached to the surface of larger metal particles.

[0064] S12: The raw material powder mixture ball-milled in step S11 is filled with a graphite mold, and light vibration is performed during the filling process to eliminate large pores.

[0065] S13: In the range of less than or equal to 8 × 10 -3 Under a vacuum of Pa, the temperature is increased to 1150℃ at a rate of 20℃ / min, maintained at 1150℃, and hot pressure of 35MPa is applied. The temperature and hot pressure are then maintained for 60 min.

[0066] S14: Demold after the furnace has cooled to room temperature.

[0067] Comparative Example 1

[0068] In Comparative Example 1, the raw materials for the metal-ceramic interpenetrating network composite layer 21, calculated by mass percentage, include 85% Fe-Cr-Mo-V alloy powder, 12.8% nano-boron (Nano-BN), 1% nano-Y2O3, and the balance being 1.2% impurities. Compared with Examples 1 and 2, Comparative Example 1 does not include micron-sized Cr powder and uses nano-boron (Nano-BN) to replace nano-TiC as the ceramic phase.

[0069] S11: Also under argon atmosphere protection, dry mix for 4 hours in a planetary ball mill.

[0070] S12: In 5×10 -2 Under a vacuum of Pa, the temperature is increased to 1000℃ at a rate of 15℃ / min, maintained at 1000℃, and hot pressure of 25MPa is applied. The temperature and hot pressure are then maintained for 30min.

[0071] The difference between the preparation method of Comparative Example 1 and Examples 1 and 2 is that after grinding the raw material in the planetary ball mill, the graphite abrasive is not loaded and the heating and high-temperature and high-pressure sintering steps under vacuum conditions are carried out directly.

[0072] Table 1 Comparison of Mechanical Properties and Microstructure Parameters of Metal-Ceramic Interpenetrating Network Composite Layers

[0073]

[0074] The detection methods for the various indicators obtained from Examples 1-2 and Comparative Example 1 are as follows:

[0075] 1) Vickers hardness (HV0.5) test

[0076] The micro Vickers hardness test was conducted with a test force of 0.5 kgf (4.903 N) and a holding time of 10–15 s. The average value was taken from at least five points on the polished section. The test was performed according to the requirements of national standard GB / T 4340.1-2024.

[0077] 2) Testing of fracture toughness

[0078] The three-point bending method using a single-edged V-notch beam was employed, tested at room temperature. Commonly used specimen dimensions were 3 x 4 x 45 mm, with a span of approximately 40 mm and a notch root radius of less than 15 micrometers. The method was performed in accordance with the provisions of GB / T 23806-2009.

[0079] 3) Bending strength

[0080] The three-point bending method was used for testing, with a span-to-sample thickness ratio of approximately 20:1, and the loading rate controlled within the range of 0.5 to 1 millimeter per minute. The test was conducted in accordance with the provisions of GB / T 6569-2006.

[0081] 4) Wear rate

[0082] A pin-disc dry friction and wear test was adopted. The mass loss of each sample was recorded and converted into volume loss according to the material density. The volume loss was then divided by the normal load and sliding distance to obtain the wear rate. The test procedure and parameters were in accordance with the method of GB / T 12444-2006.

[0083] 5) Porosity

[0084] The pore area fraction was obtained through metallographic image analysis of the polished cross-section. It was then calculated using thresholding and binarization, and this was used to approximate the volume fraction. The helium gravity method was used for verification when necessary.

[0085] 6) Interfacial shear strength

[0086] This parameter represents the load-bearing capacity of the interface between the metal matrix and the ceramic reinforcing phase under shear load. The test for this property uses a single-lap shear method to prepare the interface specimen. The maximum load is obtained by stretching to failure, and the strength is calculated based on the shear area, referring to the test principles of GB / T 7124-2008.

[0087] 7) Density

[0088] The Archimedes method was used to determine the sample in deionized water at 25 degrees Celsius. If necessary, the sample with open pores was immersed before testing. The method is in accordance with GB / T 5163-2006 or GB / T 20123-2006.

[0089] 8) Average grain size

[0090] In Table 1, "nm, ceramic" in parentheses indicates that this index only counts the particle size of the ceramic reinforcing phase, and the unit of measurement is nanometers, excluding the grains of the metal matrix. Statistics were performed using high-resolution scanning electron microscopy images, and the average value was calculated and the standard deviation given for at least three hundred particles using the line intercept method or the equivalent circle method.

[0091] Based on the mechanical and wear resistance test results shown in Table 1, Example 2 is superior to the blank of Example 1 in terms of hardness and bearing capacity, while still maintaining high fracture toughness; the comparative example shows a significant decrease in hardness and strength and an increase in wear rate.

[0092] Based on the mechanical and wear resistance test results shown in Table 1, Example 2 is superior to the blank of Example 1 in terms of hardness and bearing capacity, while still maintaining high fracture toughness; the comparative example shows a significant decrease in hardness and strength and an increase in wear rate.

[0093] Both Examples 1 and 2 of this disclosure use Fe-Cr-Mo-V alloy powder as a substrate, reinforced with nano-TiC ceramics, and introduce micron-sized Cr powder as an interface agent, with a content of less than or equal to 10 -2 Up to 8 × 10 -3Under vacuum conditions of Pa, the temperature is gradually increased to 1100℃–1150℃, and a hot pressing of 30MPa–35MPa is applied while maintaining the temperature for a corresponding holding time to obtain a dense interpenetrating network (IPN) structure. In Example 2, the processing in step S13 allows the final metal-ceramic interpenetrating network composite layer 21 to have a higher nano-TiC content, thus enabling it to withstand greater loading pressure at all times. At the same time, the porosity of the blank is further reduced to 0.40%, the average microparticles are finer, the interfacial shear strength reaches 150MPa, exhibiting higher microhardness and flexural strength, and the lowest wear rate. The comparative example eliminated the use of Cr powder as an interface agent and reduced the densification process parameters during preparation. This resulted in insufficient interfacial bonding, leading to interconnected pores. Consequently, the Vickers hardness, flexural strength, and fracture toughness of the metal-ceramic interpenetrating network composite layer 21 blank obtained in the comparative example were significantly deteriorated, and the wear rate increased. The above examples verify that using Cr powder as an interface agent can effectively diffuse the metallurgical bonding of the raw materials used in the preparation of the metal-ceramic interpenetrating network composite layer 21 and achieve sufficient densification during the preparation process, thus playing a key role in the wear resistance of the blade.

[0094] Figure 4 The images show scanning electron microscope (SEM) images of the interface regions of the metal-ceramic interpenetrating network (MCB) composite layers synthesized in Examples 1, 2, and Comparative Example 1 of this application, along with corresponding EDS elemental surface distribution and line scan results. Figure 4 As shown, the first column contains scanning electron microscope (SEM) images of the interface regions in Examples 1, 2, and Comparative Example 1 (containing nano-TiC and a substitute (nano-BN)), illustrating the contact boundary between the metal matrix and the ceramic reinforcing phase, as well as the sampling path location of the line scan. The first row corresponds to the interface between the nano-TiC particles and the metal matrix in Example 1, the second row to the interface between the nano-TiC particles and the metal matrix in Example 2, and the third row to the interface between the nano-BN particles and the metal matrix in Comparative Example C. The second column contains EDS elemental distribution maps of the corresponding regions in the interface regions shown in the SEM images of the same examples. This visually characterizes the spatial enrichment relationship of elements such as Cr and Ti in the transition region between the Fe matrix and the interface, and compares the interface continuity and element diffusion effects under different formulations and processes. The third column shows the EDS line scan curves obtained along the scanning path shown in the first column. The horizontal axis represents distance, and the vertical axis represents the content of each element (compared after normalization). This is used to quantitatively reflect the variation of element concentration with position when passing through the interface transition zone from the metal matrix region to the ceramic phase region. The curve colors and element correspondences are consistent in the three sub-graphs: blue corresponds to Fe, red to Cr, yellow to Ti, cyan to O, and green to V. In addition, BN-related elements appear in the comparative examples to characterize their ceramic phase features.

[0095] As can be seen from the sub-figures in the first and second columns of Examples 1, 2, and Comparative Example 1, both Examples 1 and 2 formed an interpenetrating network structure in which the continuous metallic phase and the ceramic reinforcing phase were interconnected. The transition zone at the interface was continuous and uniform, and no obvious interface fracture zone or large-scale pore interconnection region was observed. Consistent with this, the EDS linear scan curves of the element concentrations corresponding to the third column are shown in Examples 1 and 2. The dark red area indicates that the Cr element signal reaches its peak and forms a relatively concentrated segment on the scan path. When the scan path enters the TiC enrichment region from the Fe element matrix, the Ti element content shows a stable increase from low to high, while the Fe element content gradually decreases from high to low, indicating that there is a clear but continuous phase boundary between the metallic phase and the ceramic phase. More importantly, Cr exhibits a significant peak near the interface, forming a relatively concentrated enrichment region. This Cr-rich region coincides spatially with the transition zone from the matrix to the ceramic phase in the Ti region, indicating that Cr effectively diffuses during hot-pressing sintering and forms a Cr-rich layer at the TiC-metal matrix interface, thus promoting interfacial metallurgical bonding and load transfer. The light red area in the third column subfigure represents the transition zone extending to both sides of the Cr-rich peak region around the interface. While the Cr concentration in this zone is relatively lower, it remains significantly higher than the background level in the matrix far from the interface. This region corresponds to the compositional gradient region formed during the diffusion of Cr from the metal matrix to the ceramic phase. The existence of this gradient region suggests that the interface is not an abrupt contact, but rather a continuous transition layer of a certain width. This helps alleviate the mismatch in elastic modulus and thermal expansion coefficient between the metal and ceramic phases, thereby reducing the risk of interfacial stress concentration and microcrack initiation. Further comparison of Examples 1 and 2 reveals that the Cr-rich region at the interface in Example 2 is more concentrated and continuous, and the elemental gradient transition at the interface is smoother. Combined with the results in Table 1 showing that Example 2 has lower porosity and higher interfacial shear strength, it can be concluded that Example 2 achieves a more complete interfacial diffusion reaction and more stable interpenetrating network connectivity at a higher degree of densification. This is consistent with its higher hardness and superior flexural strength. On the other hand, the V element in Examples 1 and 2 exhibits relatively discernible distribution changes at the interface and matrix sides, reflecting that the alloying elements of the Fe-Cr-Mo-V alloy powder participate in matrix strengthening and interfacial transition zone stabilization. This helps improve the matrix's ability to encapsulate the ceramic phase and reduces the risk of microcrack initiation caused by interfacial mismatch, supporting the simultaneous improvement of wear resistance and load-bearing performance at the microscopic level.

[0096] In contrast, Comparative Example 1 exhibits more pronounced pore connectivity (leading to relatively lower porosity) and interface discontinuities in the scanning electron microscope (SEM) morphology image shown in the first column and the EDS elemental distribution map shown in the second column. The interface region displays a coarser structural scale and a non-uniform elemental distribution. Comparison with the corresponding data from Examples 1 and 2 using the normalized comparison curves of elemental content shown in the third column further indicates that Comparative Example 1 struggles to form the same Cr enrichment peak at the interface as the examples. Cr is generally weak and lacks a clear interface enrichment region. Meanwhile, BN-related elements dominate the ceramic phase region and exhibit a wider distribution band near the interface, indicating a more diffuse interface transition zone and a lack of effective metallurgical bonding layer support. This difference suggests that Comparative Example 1 relies more on mechanical interlocking or weak interface bonding, limiting interface load transfer efficiency and anti-stripping ability. It is prone to forming wear initiation points and crack propagation channels at pore connectivity and interface discontinuities, resulting in a higher wear rate and lower hardness and strength. Combining the images in the first two columns and the line scan curve in the third column, it can be seen that this application, by introducing nano-TiC into the matrix formed by Fe-Cr-Mo-V alloy powder and using micron-sized Cr powder as an interface agent, and coordinating with the temperature and pressure window of high vacuum hot pressing sintering, has achieved a stable Cr-rich metallurgical bonding layer and a dense and continuous interpenetrating network structure at the interface, which significantly reduces porosity and improves the interfacial shear bearing capacity. Ultimately, in terms of hardness, flexural strength and wear resistance, it exhibits superior properties compared to the metal-ceramic interpenetrating mesh composite layer synthesized in Comparative Example 1.

[0097] The technical solution of this application will be further illustrated below based on the raw materials and preparation method for the transition metal layer 22 as described in the claims, through Examples 3-5 and Comparative Example 2.

[0098] Example 3: Preparation of transition metal layer 22

[0099] In this embodiment, the raw material composition of the transition gradient layer 22 is Fe-Cr-Mo-V alloy powder, WC-10Co alloy powder, and TiB2 ceramic powder. In step S21 of the preparation process, Fe-Cr-Mo-V alloy powder is loaded into the first powder feeder, and WC-10Co alloy powder and ceramic powder in a mass ratio of 3:1 are loaded into the second powder feeder. In step S22, a laser cladding process with linearly increasing or decreasing powder feeding rates from multiple feeders is used. In this embodiment, the laser power for laser cladding is 1200W, the laser scanning speed is 10mm / s, the laser spot diameter is controlled to be 2.0mm, the single-pass thickness of the cladding layer is controlled to be 0.6mm, and the protective gas is argon. During the laser cladding process, the initial powder feeding rate of the Fe-Cr-Mo-V alloy powder, i.e., the first initial value V, is simultaneously controlled. A1 The feed rate is 18 g / min, and the final feed rate is: first final value V A2The feed rate is 5 g / min; the feed rate of the second feeder is: the second initial value V. D1 The rate was 5 g / min, and the second final value V D2 The rate is 18 g / min; during laser cladding, the sum of the real-time powder feeding rates of the first and second powder feeders is the total real-time powder feeding rate, which remains constant. The total real-time powder feeding rate is maintained at a constant 23 g / min.

[0100] X-ray diffraction analysis revealed that, from the innermost side of the metal-ceramic interpenetrating network composite layer 21, the mass fraction of Fe-Cr-Mo-V alloy powder in the transition gradient layer 22 prepared in this embodiment linearly decreased from 79.2% to 20.5%, while the sum of the mass fractions of WC-10Co alloy powder and TiB2 ceramic powder linearly increased from 20.8% to 79.5%.

[0101] Example 4: Another embodiment for the preparation of transition metal layer 22

[0102] In this embodiment, the ceramic powder used to prepare the transition gradient layer 22 is Cr3C2, the second metal powder raw material is WC-12Co alloy powder, and the first metal powder raw material is still Fe-Cr-Mo-V alloy powder. In this embodiment, during the laser cladding process of linearly increasing or decreasing the powder feeding rate of the first metal powder, the second metal powder, and the ceramic powder, the mass ratio of WC-12Co alloy powder to Cr3C2 ceramic powder loaded in the second powder feeder is 4:1. In this embodiment, the laser power for laser cladding is 1400W, the laser scanning speed is 8mm / s, the laser spot diameter is controlled at 2.2mm, the single-pass thickness of the cladding layer is controlled at 0.8mm, and the protective gas is argon. Furthermore, the powder feeding rate of the Fe-Cr-Mo-V alloy powder starts from a first initial value V of 16.3g / min. A1 The mixing feed rate of WC-12Co alloy powder and Cr3C2 ceramic powder decreased linearly to a first final value VA2 of 6.15 g / min, and the second initial value V was 5.7 g / min. D1 The second final value V was increased to 15.85 g / min. D2 The total powder delivery rate remained constant at 22 g / min.

[0103] X-ray diffraction analysis revealed that, from the innermost side of the metal-ceramic interpenetrating network composite layer 21, the mass fraction of Fe-Cr-Mo-V alloy powder in the transition gradient layer 22 prepared in this embodiment linearly decreased from 75.23% to 25.05%, while the sum of the mass fractions of WC-12Co alloy powder and Cr3C2 ceramic powder linearly increased from approximately 24.77% to 74.95%.

[0104] Example 5: Another example of the preparation of the transition metal layer 22

[0105] In this embodiment, the ceramic powder of the transition gradient layer 22 is composed of a composite of TiB2 ceramic powder and Cr3C2 ceramic powder, and the second metal powder is WC-8Co alloy powder. The first metal powder used is still Fe-Cr-Mo-V alloy powder, which is loaded into the first powder feeder. The mass ratio of WC-8Co alloy powder, TiB2 ceramic powder and Cr3C2 ceramic powder loaded into the second powder feeder is 6:2:2. In this embodiment, the laser power of laser cladding is 2000W, the laser scanning speed is 20mm / s, the laser spot diameter is controlled at 3.0mm, the single-pass thickness of the cladding layer is controlled at 1.15mm, and the protective gas is argon. In this embodiment, during the laser cladding preparation of the transition gradient layer 22 with a constant total real-time powder feeding rate, the powder feeding rate of Fe-Cr-Mo-V alloy powder starts from a first initial value V of 19.87g / min. A1 The mixing and feeding rate of WC-8Co alloy powder, TiB2 ceramic powder, and Cr3C2 ceramic powder decreased linearly to a first final value VA2 of 4.55 g / min, and the second initial value V was 4.13 g / min. D1 The second final value V was increased to 19.45 g / min. D2 The total powder delivery rate was kept constant at 24 g / min.

[0106] X-ray diffraction analysis revealed that, from the innermost side of the metal-ceramic interpenetrating network composite layer 21 to the outermost side of the transition gradient layer 22 prepared in this embodiment, the mass fraction of Fe-Cr-Mo-V alloy powder linearly decreased from 77.68% to 21.89%, while the sum of the mass fractions of WC-8Co alloy powder and Cr3C2 ceramic powder linearly increased from approximately 22.32% to 78.11%.

[0107] Comparative Example 2

[0108] Instead of gradient powder feeding control, the transition layer directly used a fixed mass percentage mixture of 50% Fe-Cr-Mo-V alloy powder, 35% WC-10Co alloy powder, and 15% TiB2 ceramic powder for single-component cladding, with a constant powder feeding rate. In Comparative Example 2, the powder feeding rate remained constant throughout the cladding process. Fe-Cr-Mo-V alloy powder was still loaded into the first powder feeder, and the corresponding weighed WC-10Co alloy powder and TiB2 ceramic powder were mixed and loaded into the second powder feeder. The powder feeding rates of both the first and second powder feeders were consistently 10 g / min, with a total powder feeding rate of 20 g / min. In this comparative example, the laser power for laser cladding was 1200 W, the laser scanning speed was 10 mm / s, the laser spot diameter was controlled at 2.0 mm, the single-pass thickness of the cladding layer was controlled at 0.6 mm, and the protective gas was argon.

[0109] It should be noted that the laser cladding equipment used in the laser cladding method of this application is a conventional powder feeding laser cladding system. This laser cladding system is a common powder feeding laser cladding equipment both domestically and internationally. It is equipped with an adjustable fiber laser output power (800 to 2000 watts), and the scanning control system supports real-time synchronous control of the powder feeder rate. The laser cladding system was obtained by those skilled in the art through compliant means, such as equipment with publication numbers CN110184599A and CN105331974B, which includes conventional components such as an adjustable power laser, a multi-powder feeding control system, and a three-axis or five-axis worktable.

[0110] The X-ray diffraction analysis method of this application involves sampling the cross-section or surface of the transition gradient layer 22 synthesized in Examples 3-5 and Comparative Example 2, and lightly polishing the surface to remove the oxide film. Then, conventional θ-to-2θ scanning tests are performed using an X-ray diffractometer. Cu target Kα radiation is selected as the X-ray source. The tube voltage and tube current are set to normal operating conditions, and the scanning is performed in steps within the 2θ range of 30 to 90 degrees. The diffraction intensity curve as a function of 2θ is recorded. Then, peak matching and phase identification are performed on the Fe matrix phase, the WC-related phase, and the TiB2 and Cr3C2 phases using a standard diffraction database. A commercially available floor-standing X-ray diffractometer is used for the tests. When performing θ-2θ scanning tests, the X-ray source is Cu target Kα radiation, the operating tube voltage is 40 kV, and the tube current is 40 mA. The scanning angle range is set to 2θ equal to 30 to 90 degrees, the step angle is 0.02 degrees, and the scanning speed is 2 degrees per minute. The above detection parameters are maintained consistently in all embodiments and comparative examples to compare and analyze the phase composition of the transition gradient layer samples, thereby ensuring the comparability and repeatability of the test results. Figure 5 The peak values ​​shown in the XRD diffraction analysis are as follows: Figure 5For the peak positions of the synthesized raw materials in Examples 3-5 and Comparative Example 2, the horizontal axis 2θ represents twice the diffraction angle, in degrees. It is determined by the Bragg diffraction conditions of X-rays on the crystal plane. Different phases have different lattice parameters and interplanar spacings, thus characteristic peaks appear at specific 2θ positions. The vertical axis represents diffraction intensity, usually expressed as the normalized diffraction intensity of the synthesized raw material, reflecting the relative intensity of the diffraction count detected at that angle. Peak height is related to content, crystallographic orientation, grain size, and instrument conditions, and is mainly used for phase identification and relative comparison rather than being directly equivalent to absolute content. The different heights of the four curves relative to the lowest position on the vertical axis do not represent different minimum values, but rather are arranged from top to bottom to clearly indicate the appearance of characteristic peaks at different 2θ positions.

[0111] Combination Figure 5 As indicated by the peak positions, all four diffraction analysis peak curves show characteristic Fe-related peaks around approximately 44.7°, 65.0°, and 82.3°. This aligns with the fact that the transition gradient layer 22 uses Fe-Cr-Mo-V alloy powder as a compatible substrate, indicating that during the laser cladding process with multiple powder feeders, powders from different sources can achieve stable eutectic melting and synergistic solidification within the same molten pool, forming a composite structure with controllable phase composition under rapid solidification conditions. In Examples 3, 4, and 5, and Comparative Example 2, characteristic peak positions corresponding to the WC-Co system also appear together. For example, peaks around approximately 31.6°, 35.6°, 48.4°, 64.0°, and 73.3° are all marked as WC-Co alloy powder-related peaks within the second powder feeder. This suggests that the WC-type hard phase is retained or formed within the transition layer in each sample. Both Example 3 and Comparative Example 2 contained TiB2 ceramic powder in their raw materials. The characteristic peaks of the TiB2 powder in Example 3 appeared around 34.5 degrees and 60.6 degrees, respectively (as did Comparative Example 2). This indicates that during the continuous transition from Fe-Cr-Mo-V alloy powder to the second metal powder (WC-Co alloy powder) and ceramic powder at the powder feeding rate, the hard phase (i.e., the gradient phase formed by the WC-Co alloy powder) can be effectively retained and uniformly introduced into the transition layer (i.e., the substrate gradient phase formed by the first metal powder), providing a progressively reinforcing phase basis for the subsequent wear-resistant layer. However, the correlation peaks of the WC-Co alloy powder and ceramic powder in Examples 3 to 5 showed more stable peak shapes and more prominent relative peak heights in the figures, while the corresponding peaks in Comparative Example 2 were weaker. Examples 3 to 5, through the powder feeding rate transitioning from Fe-Cr-Mo-V alloy powder to the second metal powder (WC-Co alloy powder) and then to ceramic powder, showed a more stable peak shape and more prominent relative peak heights. A1 To V A2 And from V D1 To V D2The synchronous adjustment allows the hard phase to be introduced in stages during the formation of the transition layer, achieving more sufficient metallurgical embedding and stabilizing the crystal structure of the final transition metal layer. In contrast, Comparative Example 2, which uses a fixed mass ratio and a fixed powder feeding rate to feed the three powders during laser cladding, is more likely to cause local enrichment and dilution of raw materials. Ultimately, this results in insufficient volume fraction of the hard phase effectively participating in diffraction and insufficient crystal integrity, thus making the diffraction intensity less prominent than that of Examples 3-5.

[0112] Furthermore, examples 3 to 5 and Comparative Example 2 all exhibit superposition of multiphase peaks. The most significant difference between Examples 4 and 5 and Examples 3 and Comparative Example 2 is the appearance of characteristic peaks corresponding to Cr3C2 around approximately 37.2 degrees, 39.6 degrees, 42.5 degrees, and approximately 75.0 degrees. These peaks are clearly present in Examples 4 and 5, but not in Examples 3 and Comparative Example 2. This is entirely consistent with whether or not Cr3C2 ceramic powder is introduced into the material system.

[0113] That is, by Figure 5 It can be seen that the peak intensity of the hard phase in Comparative Example 2 is relatively weak and lacks hierarchical variation, reflecting that the transition layer formed under the fixed powder feeding condition is closer to a uniform mixed structure, making it difficult to reflect the phase composition characteristics of a gradual transition from the matrix to the wear-resistant phase. This difference indicates that the method provided in this application, which uses multiple powder feeders to feed different raw materials of the substrate material in the first powder feeding box and the hard gradient phase in the second powder feeding box at linearly increasing or decreasing powder feeding rates during laser cladding, can effectively regulate the generation and distribution state of each phase in the transition metal layer 22, enabling the hard phase to be gradually introduced while maintaining phase stability, thereby significantly improving the structural continuity and service reliability of the transition layer. The comparison of XRD diffraction peak results shows that Examples 3 to 5 are superior to Comparative Example 2 in terms of phase composition integrity and phase synergistic stability, which provides the transition metal layer 22 with stronger load-bearing capacity, wear resistance, and thermal shock resistance during the granulation and pelletizing process.

[0114] In some specific embodiments, the manufacturing process of the pelletizing blade for the pelletizer in this disclosure includes the following steps: First, the cutting edge area of ​​the blade blank is pretreated by removing surface oil and oxide layers through mechanical grinding, sandblasting, or chemical cleaning, and the cutting edge is moderately roughened. Simultaneously, the blade is preheated to reduce thermal stress generated during subsequent high-temperature processes. Then, according to different embodiments, a metal-ceramic interpenetrating network composite layer is prepared in the cutting edge area of ​​the blade. This composite layer can be pre-formed using a vacuum hot-pressing sintering process and metallurgically connected to the blade using vacuum brazing. The vacuum brazing is completed in a vacuum brazing furnace, with the brazing temperature set to 850°C to 1050°C, the holding time to 10 to 30 minutes, and the vacuum degree not exceeding 10. -3 Pa, the equipment used is a conventional industrial vacuum brazing furnace, which can be obtained and implemented by those skilled in the art through compliant channels. Alternatively, in another embodiment, the metal-ceramic interpenetrating network composite layer can be prepared in situ in the cutting edge area of ​​the blade using a laser cladding and simultaneous powder feeding method.

[0115] After the metal-ceramic interpenetrating network composite layer 21 is prepared, a transition gradient layer with continuously varying composition and properties is further prepared on its surface using multi-feeder laser cladding technology. By synchronously and linearly adjusting the powder feeding rate of different feeders, the metallic phase and hard phase of the transition gradient layer gradually transition along the thickness direction, thereby achieving stress relief and performance matching between the high-toughness layer and the wear-resistant layer. Finally, the blade area after cladding or brazing is precision ground to meet the design size and shape requirements. The pelletizing blade is then subjected to stress-relief annealing and deep cryogenic treatment, either entirely or partially, to further stabilize the microstructure, release residual stress, and improve the crystal structure stability of the blade during pelletizing in the pelletizer, thereby improving its wear resistance and flexural strength.

[0116] In one specific embodiment, the mounting part 3 is formed by machining during the forming stage of the blade body 1 or after heat treatment. Specifically, mounting holes are machined at predetermined positions on the blade body using CNC drilling, milling, or a combination of machining processes. The hole diameter, hole spacing, and positional accuracy are controlled according to the assembly requirements of the pelletizer's rotating shaft or cutter head. After machining, the mounting holes can be chamfered or deburred to improve assembly reliability and avoid stress concentration. The mounting part 3 formed in this way is an integral structure with the blade body 1, which helps to ensure the assembly stability and overall structural strength of the pelletizer under high-speed rotation conditions.

[0117] In another specific embodiment, the manufacturing and testing method for pelletizing blades for pelletizers provided in this disclosure can be integrated with the pelletizing blade preparation process. That is, the testing method is applied during and after the manufacturing of the pelletizing blade, and includes the following steps:

[0118] D1: After the metal-ceramic interpenetrating network composite layer 21 is prepared, its cross-section is examined by microstructure detection. The metal continuous phase and the ceramic reinforcing phase are observed by scanning electron microscopy to see whether an interpenetrating network structure is formed and whether there are obvious pores or unbonded areas at the interface.

[0119] D2: During or after the laser cladding of the transition gradient layer 22, the composition distribution at different thickness locations is detected, and the continuous variation characteristics of the corresponding elements of the first metal powder, the second metal powder, and the ceramic powder along the thickness direction are verified by energy spectrum analysis and line scanning.

[0120] D3: The phase analysis of the transition gradient layer 22 of the blade part 2 after the pelletizer is prepared is carried out. The presence of iron matrix phase, hard phase and ceramic phase is confirmed by X-ray diffraction method, and the correspondence between the hard phase types in the transition gradient layer in different embodiments is verified.

[0121] D4: Based on the results of microhardness testing or wear performance testing, comprehensively determine the structural integrity and gradient effectiveness of the metal-ceramic interpenetrating network composite layer 21 and the transition gradient layer 22 to confirm whether the pelletizer meets the performance requirements during use.

[0122] The sampling, observation, and judgment in steps D1 to D4 can be completed by operators in stages according to process specifications, or automated control and data recording can be achieved by computer programs and detection devices linked to the laser cladding equipment. For example, during the transition gradient layer cladding stage, the control program synchronously adjusts the powder feeding rate of the powder feeder and synchronously records the linear real-time changes in the powder feeding rates of the first and second powder feeders. After cladding is completed, microstructure, composition distribution, and phase detection are triggered at preset sampling positions, and corresponding detection results are generated to confirm the consistency of the interpenetrating network structure integrity, gradient continuity, and phase composition matching. The specific operation procedures, detection position selection, and result comparison methods for steps D1 to D4 have been given in the descriptions of the foregoing embodiments and comparative examples. Those skilled in the art can use this information to perform in-process and post-process quality verification of the prepared pelletizer.

[0123] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A pelletizing blade for a pelletizer, characterized in that, include: The blade body (1) is a long strip-shaped base; the blade edge (2) is fixedly connected to the cutting edge of the blade body (1); The mounting part (3) is located on the blade body (1) and is used to fix the pelletizing blade to the rotating shaft of the pelletizer; The blade portion (2) forms a wrap-around blade profile in the cross section of the width direction of the pelletizer; the blade portion (2) includes: a wrap-around blade base portion (201), which connects downward from the upper surface of the blade body (1) and surrounds the first corner of the blade body (1); an outwardly protruding blade edge portion (202) located outside the wrap-around blade base portion (201) and connected to it, which protrudes obliquely upward; and a lower extension side blade portion (203) connected downward from the outwardly protruding blade edge portion (202), which extends downward and smoothly connects to the lower part of the blade body (1); The material of the blade part (2) is a gradient functional composite material, which includes, from the inner layer to the outer layer, a metal-ceramic interpenetrating network composite layer (21) combined with the blade body (1) and a transition gradient layer (22) with continuously changing composition and properties.

2. The pelletizing blade for a pelletizer according to claim 1, characterized in that, The raw materials for preparing the metal-ceramic interpenetrating network composite layer (21) include, by mass percentage, 70%-85% iron-based alloy powder, 5%-15% nano titanium carbide, 5%-10% micron-sized chromium powder, 0.5%-2% nano Y2O3, with the balance being unavoidable impurities; the iron-based alloy powder is Fe-Cr-Mo-V alloy powder.

3. The pelletizing blade for a pelletizer according to claim 2, characterized in that, The Fe-Cr-Mo-V alloy powder is a micron-sized pre-alloyed atomized powder or a micron-sized gas atomized powder with a particle size of 150-300 mesh; the average particle size D50 of the nano-titanium carbide is 70nm-90nm; the particle size of the micron-sized metallic chromium powder is 300-500 mesh; and the average particle size D50 of the nano-Y2O3 is 50nm-80nm.

4. The pelletizing blade for a pelletizer according to claim 3, characterized in that, The preparation method of the metal-ceramic interpenetrating network composite layer (21) includes the following steps: S11: Weigh each raw material powder according to the types and corresponding proportions of the raw materials to be prepared, place them in a planetary ball mill, and mill them under argon protection. The ball-to-material ratio of the planetary ball mill is 5:1–15:1, the spindle speed is 200–400 rpm, and the milling time is 4–8 hours to obtain a uniformly mixed composite powder; S12: Load the composite powder into a graphite mold and place it in a vacuum hot pressing sintering furnace; S13: under the vacuum degree ≤ 10 -2 Pa, at the rate of 15 ℃ / min-20 ℃ / min, to 1000 ℃-1150 ℃, and apply a pressure of 25 MPa-35 MPa, holding for 30 minutes-60 minutes, so that the metal matrix flows plastically and wraps the ceramic particles, while the chromium element diffuses to the interface to form strong metallurgical bonding; S14: Cool to room temperature in the furnace and demold to obtain the blank of the metal-ceramic interpenetrating network composite layer (21).

5. The pelletizing blade for a pelletizer according to claim 1, characterized in that, The raw material composition of the transition gradient layer (22) includes a first metal powder, a second metal powder, and a ceramic powder. From the innermost side of the metal-ceramic interpenetrating network composite layer (21) to the outer side, the mass fraction of the first metal powder decreases from a first gradient percentage to a second gradient percentage, and the sum of the mass fractions of the second metal powder and the ceramic powder increases from a third gradient percentage to a fourth gradient percentage. The first metal powder is Fe-Cr-Mo-V alloy powder that is compatible with the metal-ceramic interpenetrating network composite layer (21), the second metal powder is WC-Co alloy powder, and the ceramic powder is nano TiB2 or nano Cr3C2 powder.

6. The pelletizing blade for a pelletizer according to claim 5, wherein the first gradient percentage and the fourth gradient percentage are both in the range of 75%–80%, and the second gradient percentage and the third gradient percentage are both in the range of 20%–25%.

7. The pelletizing blade for a pelletizer according to claim 5, characterized in that, The method for preparing the transition gradient layer (22) includes the following steps: S21: Set the raw materials required for the transition gradient layer to be loaded into at least two powder feeders respectively. The first powder feeder is filled with Fe-Cr-Mo-V alloy powder, and the second powder feeder is filled with WC-Co alloy powder and ceramic powder. S22: Synchronously control the powder feeding rate of each powder feeder, and further prepare a transition gradient layer (22) using laser cladding method, controlling the powder feeding rate of the first powder feeder from the first initial value V. A1 Linearly decreasing to the final value, first final value V A2 Simultaneously, control the powder feeding rate of the second powder feeder from the second initial value V. D1 Linearly increasing to the second final value V D2 And the linear increase rate or linear decrease rate of the powder feeding rate is constant; S23: Under the irradiation of the laser beam during the laser cladding process, an alloy melt with continuously changing composition is formed in the molten pool. After the laser beam is removed, the molten pool solidifies, thus obtaining a transition gradient layer with continuously changing composition and properties (22).

8. The pelletizing blade for a pelletizer according to claim 7, characterized in that, In step S23, the laser power used for laser cladding is 800W-2000W, the laser scanning speed is 5mm / s-20mm / s, the laser spot diameter is controlled to be 1.0mm-3.0mm, and the cladding layer thickness is 0.3mm-1.2mm.

9. The pelletizing blade for a pelletizer according to claim 7, characterized in that, The first starting value V A1 The first final value V is 15 g / min–21 g / min. A2 The flow rate is 3g / min–8g / min, and the second initial value V D1 The second final value V is 3g / min–8g / min. D2 The total powder feeding rate is 15 g / min–21 g / min, and the total real-time powder feeding rate is kept constant during the laser cladding process; the total real-time powder feeding rate is maintained at 22 g / min–24 g / min.

10. A manufacturing and testing method for detecting the pelletizing blade for a pelletizer as described in any one of claims 1-7, characterized in that, The detection method is applied during and after the manufacturing process of the pelletizing blade, and includes the following steps: D1: After the metal-ceramic interpenetrating network composite layer (21) is prepared, its cross-section is subjected to microstructure detection. The metal continuous phase and the ceramic reinforcing phase are observed by scanning electron microscopy to see whether they form an interpenetrating network structure, and whether there are obvious pores or unbonded areas at the interface. D2: During or after the laser cladding of the transition gradient layer (22), the composition distribution at different thickness positions is detected, and the continuous variation characteristics of the corresponding elements of the first metal powder, the second metal powder and the ceramic powder along the thickness direction are verified by energy spectrum analysis and line scanning. D3: The phase detection of the transition gradient layer (22) of the blade part (2) after the pelletizer is prepared is carried out. The presence of iron matrix phase, hard phase and ceramic phase is confirmed by X-ray diffraction method, and the correspondence of hard phase type in the transition gradient layer in different embodiments is verified. D4: Based on the results of microhardness test or wear performance test, the structural integrity and gradient effectiveness of the metal-ceramic interpenetrating network composite layer (21) and the transition gradient layer (22) are comprehensively judged to confirm whether the pelletizer meets the performance requirements when in use.

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