Preparation method of powder metallurgy pressure-resistant composite metal material

Abstract

The invention discloses a preparation method of a powder metallurgy pressure-resistant composite metal material, and relates to the technical field of composite metal material preparation. Preparing a pressure-resistant reinforcing agent; mixing the metal matrix powder with the pressure-resistant reinforcing agent, adding a composite binder, and uniformly stirring to obtain a mixture; pressing the mixture into a green body; and the blank is subjected to segmented sintering, and the pressure-resistant composite metal material is obtained after cooling. By optimizing the composition proportion of metal matrix powder and a pressure-resistant reinforcing agent and combining a specific composite binder system and a segmented sintering process, good interface bonding of a metal matrix and a ceramic reinforced phase is achieved, and the surface strengthening treatment process achieves the surface strengthening effect through the synergistic effect of shot blasting treatment and chemical vapor deposition. The surface hardness and wear resistance of the material are remarkably improved, and the overall preparation process enables the obtained composite material to have excellent mechanical properties and pressure resistance by accurately controlling process parameters of all stages.

Description

Technical Field

[0001] The invention relates to the technical field of composite metal material preparation, in particular to a method for preparing a powder metallurgy pressure-resistant composite metal material. Background Art

[0002] Composite metal material preparation technology refers to the technology of combining two or more metal or non-metal materials with different physical and chemical properties to form a new material. The technology aims to utilize the advantages of each component and overcome the limitations of a single material to obtain a new material with special properties.

[0003] In the field of composite metal material preparation, traditional metal powder metallurgy products have a large number of pores inside the material due to the loose bonding between particles, which reduces the overall density and mechanical properties of the material. When different types of metal powders are used or reinforcing agents are added, the material is prone to stratification or peeling when subjected to stress. At the same time, some traditional composite metal materials perform poorly in high temperature or corrosive environments, limiting their application range. Summary of the Invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a method for preparing powder metallurgy pressure-resistant composite metal materials to solve the problem that traditional metal powder metallurgy products have loose bonding between particles, resulting in a large number of pores inside the material, which reduces the overall density and mechanical properties of the material. When different types of metal powders are used or reinforcing agents are added, the material is prone to stratification or peeling when subjected to stress. At the same time, some traditional composite metal materials perform poorly in high temperature or corrosive environments, limiting their application range.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: In a first aspect, the present invention provides a method for preparing a powder metallurgy pressure-resistant composite metal material, comprising: preparing metal matrix powder; Prepare pressure-resistant enhancer; Mixing the metal matrix powder with the pressure-resistant reinforcing agent, adding a composite binder, and stirring evenly to obtain a mixture; Pressing the mixed material into a green body; Sintering the green body in sections, and obtaining a pressure-resistant composite metal material after cooling; The pressure-resistant enhancer comprises tungsten carbide particles and silicon nitride particles in a mass ratio of (60-70): (30-40); The metal matrix powder includes iron powder, nickel powder, chromium powder and molybdenum powder, and the mass ratio thereof is (65-75): (15-25): (5-10): (3-8); The composite binder comprises polyvinyl alcohol and zinc stearate in a mass ratio of (40-50): (50-60).

[0007] As a preferred embodiment of the method for preparing the powder metallurgy pressure-resistant composite metal material according to the present invention, the preparation process of the metal matrix powder includes: mixing iron powder, nickel powder, chromium powder and molybdenum powder in proportion, and then performing high-energy ball milling treatment under argon protection, wherein the ball milling time is 4 to 6 hours, the ball-to-material ratio is 8:1, the rotation speed is 300-400 r / min, and a uniform mixed powder with a particle size of 10-50 μm is obtained.

[0008] As a preferred embodiment of the method for preparing the powder metallurgy pressure-resistant composite metal material according to the present invention, the preparation process of the pressure-resistant enhancer includes: mixing tungsten carbide particles and silicon nitride particles in proportion, adding a silane coupling agent with a mass fraction of 0.5% to 1%, ultrasonically dispersing the mixture in an ethanol solution for 30 to 60 minutes, and then drying the mixture at 80-100°C for 2 to 4 hours to obtain surface-modified enhancer particles.

[0009] As a preferred embodiment of the method for preparing the powder metallurgy pressure-resistant composite metal material according to the present invention, during the preparation of the mixture, the amount of the composite binder added is 3% to 5% of the total mass of the metal matrix powder and the pressure-resistant enhancer, wherein the mixing process is carried out in a vacuum mixer with a stirring speed of 50-80 r / min, a stirring time of 30 to 60 min, and a mixing uniformity of ≥98%.

[0010] As a preferred solution of the method for preparing the powder metallurgy pressure-resistant composite metal material of the present invention, the pressing process adopts isostatic pressing, and the pressing pressure is 600-700 MPa, and the holding time is 2 to 5 minutes.

[0011] As a preferred embodiment of the method for preparing the powder metallurgy pressure-resistant composite metal material of the present invention, the segmented sintering process includes: In the first stage, the temperature is raised from room temperature to 600°C at a rate of 5-8°C / min and kept at this temperature for 1-2 hours for degreasing; In the second stage, the temperature is raised to 900°C at a rate of 3-5°C / min and kept at this temperature for 2-3 hours for pre-sintering. The third stage is to heat up to 1200-1250℃ at a rate of 1-2℃ / min and keep it at that temperature for 1-1.5h for final sintering; The sintering process is carried out under argon protection, wherein the argon flow rate is 8-10 L / min.

[0012] As a preferred solution of the method for preparing the powder metallurgy pressure-resistant composite metal material of the present invention, during the third stage sintering process, an axial pressure of 20-30 MPa is applied to promote material densification and obtain a sintered body with a relative density ≥98%.

[0013] As a preferred solution of the method for preparing the powder metallurgy pressure-resistant composite metal material of the present invention, the cooling process adopts a gradient cooling method, specifically: First, furnace cool to 600℃ at a rate of 5-10℃ / min; Then air-cool to room temperature and perform cryogenic treatment, keeping it in liquid nitrogen for 1 to 2 hours.

[0014] As a preferred embodiment of the method for preparing the powder metallurgy pressure-resistant composite metal material of the present invention, after the pressure-resistant composite metal material is prepared, a surface strengthening treatment is performed, and the surface strengthening treatment includes shot peening and chemical vapor deposition titanium carbide coating, and the coating thickness is 5-10 μm.

[0015] As a preferred embodiment of the method for preparing the powder metallurgy pressure-resistant composite metal material of the present invention, the shot peening treatment uses ceramic shots with a particle size of 0.1 to 0.3 mm, and sets the spray pressure to 0.4 to 0.6 MPa, the spray angle to 75 to 90 degrees, and the treatment time to 10 to 15 minutes, so that a compressive residual stress layer of 0.05 to 0.1 mm is generated on the surface of the material; The chemical vapor deposition titanium carbide coating is formed by introducing a mixed gas of TiCl4, CH4 and H2 under vacuum conditions of 1 to 5 Pa and a temperature of 850-950°C, wherein the volume ratio of TiCl4:CH4:H2 is 1:(1.2-1.5):(8-10), and the deposition time is set to 2 to 4 hours, thereby forming a dense TiC coating with a thickness of 5 to 10 μm.

[0016] The beneficial effects of the present invention are as follows: by optimizing the composition ratio of metal matrix powder and pressure-resistant reinforcing agent, combined with a specific composite binder system and a staged sintering process, a good interface bonding between the metal matrix and the ceramic reinforcement phase is achieved; the surface strengthening treatment process significantly improves the surface hardness and wear resistance of the material through the synergistic effect of shot peening and chemical vapor deposition; the overall preparation process precisely controls the process parameters of each stage, so that the resulting composite material has both excellent mechanical properties and pressure-resistant characteristics, improves the toughness and high-temperature stability of the material while maintaining high strength, and provides a new technical solution for the preparation of high-performance pressure-resistant components. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a flow chart of the method for preparing the powder metallurgy pressure-resistant composite metal material in Example 1. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0020] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0022] Example 1, with reference to Figure 1 , which is the first embodiment of the present invention, provides a method for preparing a pressure-resistant composite metal material using powder metallurgy, comprising the following steps: S1. preparing metal matrix powder; Furthermore, the metal matrix powder includes iron powder, nickel powder, chromium powder and molybdenum powder in a mass ratio of (65-75): (15-25): (5-10): (3-8); After mixing iron powder, nickel powder, chromium powder and molybdenum powder in proportion, high-energy ball milling is performed under argon protection, wherein the ball milling time is 4 to 6 hours, the ball-to-material ratio is 8:1, and the rotation speed is 300-400 r / min to obtain a uniform mixed powder with a particle size of 10-50 μm; In this step, iron powder serves as the primary matrix component, providing excellent strength and machinability. The addition of nickel powder improves the alloy's corrosion resistance and high-temperature stability. Chromium powder enhances oxidation resistance and hardness. Molybdenum powder significantly improves the material's high-temperature strength and wear resistance. The ratio of these four elements has been optimized through extensive experimentation to achieve an optimal balance between cost, performance, and process adaptability. During high-energy ball milling, the mechanical energy generated by high-speed rotation induces cold welding, fracture, and redispersion of the particles, ultimately achieving homogenized mixing at the nanometer or submicron scale, which is beneficial for improving subsequent sintering density and mechanical properties. It should be noted that iron powder, nickel powder, chromium powder and molybdenum powder are all high-purity metal powders with a purity of not less than 99.5%; by controlling the ball milling parameters (time, rotation speed and ball-to-material ratio), metal oxidation can be effectively avoided under an argon protective atmosphere, and different metal powders can be fully mixed to form a composite metal matrix powder with excellent physical properties; the obtained powder particle size distribution is controllable and suitable for subsequent molding and sintering processes.

[0023] The selection of the above-mentioned metal powder system is not a conventional combination, but is based on the research results of the synergistic effect of multiple metal elements under high temperature and high pressure environments. In particular, the introduction of molybdenum powder, although more expensive, its dispersion strengthening effect at high temperature is significantly better than that of traditional alloy additives, and it is one of the keys to achieving high strength and high wear resistance of the material.

[0024] S2. Prepare pressure-resistant enhancer; Furthermore, the pressure-resistant enhancer includes tungsten carbide particles and silicon nitride particles in a mass ratio of (60-70): (30-40) After mixing tungsten carbide particles and silicon nitride particles in proportion, adding 0.5% to 1% by mass of a silane coupling agent, ultrasonically dispersing the mixture in an ethanol solution for 30 to 60 minutes, and then drying the mixture at 80-100°C for 2 to 4 hours to obtain surface-modified reinforcing agent particles; It should be noted that tungsten carbide particles have extremely high hardness and wear resistance, while silicon nitride particles have good high-temperature strength and chemical stability. The combination of the two as a reinforcing phase can significantly improve the mechanical properties and pressure resistance of the material; adding a silane coupling agent and performing ultrasonic dispersion and drying treatments can help improve the interface bonding performance between the reinforcing agent particles and the metal matrix, preventing agglomeration or interface separation during subsequent processing; Tungsten carbide (WC) is one of the hardest known engineering materials, with excellent compressive and wear resistance, and is widely used in high-strength composite materials; silicon nitride (Si3N4) is selected as a high-temperature structural material due to its outstanding thermal shock stability and corrosion resistance; the synergistic effect of the two enables the composite reinforcement system to maintain good performance under high temperature and high pressure environments; the introduction of a silane coupling agent (KH550) can form chemical bonds with inorganic particles (WC / Si3N4) and organic / metal matrices at both ends of its molecule, thereby significantly enhancing the interfacial bonding strength; ultrasonic-assisted dispersion can break the van der Waals forces between particles, avoid agglomeration, and ensure the uniform distribution of the reinforcement in the matrix.

[0025] The specific ratio of tungsten carbide to silicon nitride (60-70):30-40) is the optimal ratio determined based on systematic experiments. Exceeding this range can lead to decreased reinforcement efficiency or interfacial stress concentration. Furthermore, optimizing the type and amount of coupling agent is also a key factor in achieving strong interfacial bonding.

[0026] S3, mixing the metal matrix powder and the pressure-resistant reinforcing agent, adding a composite binder, and stirring evenly to obtain a mixture; Furthermore, the composite binder includes polyvinyl alcohol and zinc stearate in a mass ratio of (40-50):(50-60); The amount of the composite binder added is 3% to 5% of the total mass of the metal matrix powder and the pressure-resistant reinforcing agent. The mixing process is carried out in a vacuum mixer at a stirring speed of 50-80 r / min, a stirring time of 30 to 60 min, and a mixing uniformity of ≥98%; It should be noted that polyvinyl alcohol has good adhesion and water solubility, while zinc stearate has both lubrication and demoulding functions. The combined use of the two can effectively improve the fluidity and pressing performance of the mixture. Under vacuum stirring conditions, the materials are not easily oxidized and the mixing is more uniform, ensuring that the final product has a dense structure and stable performance. A mixing uniformity of ≥98% is one of the prerequisites for achieving high-quality sintering. Polyvinyl alcohol (PVA), a polymer binder, not only enhances inter-powder adhesion but also gradually decomposes and volatilizes during the heating and degreasing stage, reducing residual contamination of the sintered body. Zinc stearate, a lubricant, reduces the friction coefficient between powder particles, improving filling efficiency and demolding performance during pressing. Combining these two in a specific ratio ensures effective bonding while balancing formability and subsequent degreasing efficiency. Vacuum mixing not only prevents oxidative deterioration caused by oxygen in the reaction but also removes air trapped between the powders, improving mixing accuracy and subsequent molding consistency.

[0027] This composite binder system is specially designed to solve the problem of high-content ceramic particles being difficult to form in the present invention. The selection of its proportion cannot be covered by conventional experience, and its compatibility with ceramic particles needs to be verified through a large number of experiments.

[0028] S4, pressing the mixed material into a green body; Furthermore, the pressing process adopts isostatic pressing, and the pressing pressure is 600-700 MPa and the holding time is 2-5 minutes; It should be noted that the use of isostatic pressing technology enables the pressure to be evenly applied to the entire surface of the green body, thereby obtaining a green body with high density and uniform structure. The high pressure of 600-700 MPa combined with a holding time of 2-5 minutes is conducive to reducing internal defects, improving the green body strength, and providing a good foundation for densification in the subsequent sintering process. Isostatic Pressing is divided into cold isostatic pressing (CIP) and hot isostatic pressing (HIP). Cold isostatic pressing is preferred in this process and is suitable for the preparation of compacts with complex shapes and high density requirements. 600-700MPa is in the ultra-high pressing pressure range, which is much higher than conventional compacting pressure (≤300MPa), and can significantly increase the density of the compact, reduce porosity, and enhance sintering activity. A holding time of 2-5 minutes allows the pressure to be fully transmitted to all parts of the powder, promoting particle rearrangement and plastic deformation, thereby obtaining a dense, dimensionally stable green compact, providing an excellent prerequisite for subsequent sintering.

[0029] This combination of high-pressure pressing parameters is extremely rare in similar powder metallurgy processes, especially in the case of a high proportion of ceramic particles, it can still achieve high-density molding, indicating its breakthrough in molding technology.

[0030] S5, sintering the green body in sections, and obtaining a pressure-resistant composite metal material after cooling; Furthermore, the staged sintering process includes: In the first stage, the temperature is raised from room temperature to 600°C at a rate of 5-8°C / min and kept at this temperature for 1-2 hours for degreasing; In the second stage, the temperature is raised to 900°C at a rate of 3-5°C / min and kept at this temperature for 2-3 hours for pre-sintering. The third stage is to heat up to 1200-1250℃ at a rate of 1-2℃ / min and keep it at that temperature for 1-1.5h for final sintering; The sintering process is carried out under argon protection, wherein the argon flow rate is 8-10 L / min; During the third stage of sintering, an axial pressure of 20-30 MPa is applied to promote material densification and obtain a sintered body with a relative density of ≥98%; The cooling process adopts a gradient cooling method, specifically: First, furnace cool to 600℃ at a rate of 5-10℃ / min; Then air-cool to room temperature and perform cryogenic treatment, keeping it in liquid nitrogen for 1 to 2 hours; After the pressure-resistant composite metal material is prepared, it is subjected to surface strengthening treatment, which includes shot peening and chemical vapor deposition of titanium carbide coating with a coating thickness of 5-10μm; Shot peening uses ceramic shots with a particle size of 0.1-0.3 mm, and sets the spray pressure to 0.4-0.6 MPa, the spray angle to 75-90°, and the treatment time to 10-15 min, so that a compressive residual stress layer of 0.05-0.1 mm is generated on the material surface; The chemical vapor deposition titanium carbide coating is formed by introducing a mixed gas of TiCl4, CH4 and H2 under the conditions of vacuum degree 1-5 Pa and temperature 850-950°C, wherein the volume ratio of TiCl4:CH4:H2 is 1:(1.2-1.5):(8-10), setting the deposition time to 2-4 hours, and forming a dense TiC coating with a thickness of 5-10 μm; The pressure sintering process combined with gradient cooling and cryogenic treatment not only achieves high densification but also effectively suppresses grain coarsening and internal stress accumulation, which is a key technical means to improve material fatigue life and dimensional stability. In addition, the dual surface strengthening process of shot peening + TiC coating not only improves the surface hardness and wear resistance, but also significantly improves the crack initiation resistance through the residual stress layer, reflecting the synergistic enhancement effect of surface engineering and material properties. It should be noted that the staged temperature-controlled sintering method can effectively control the release of internal stress in the material, avoiding cracking or deformation caused by sudden temperature changes. The degreasing, pre-sintering and final sintering stages correspond to different reaction mechanisms. Applying axial pressure in the final sintering stage helps promote material densification and obtain a sintered body close to the theoretical density. Gradient cooling and cryogenic treatment can further optimize the material microstructure and improve its comprehensive mechanical properties. Surface strengthening treatment (shot peening + TiC coating) not only improves the surface hardness and wear resistance of the material, but also enhances its fatigue resistance and corrosion resistance, making it more suitable for high-intensity working environments. Segmented sintering is a precisely controlled heat treatment process, especially suitable for composite materials containing binders. In the first stage, the temperature is quickly raised to 600°C mainly to remove residual organic binder (PVA). This process is called the degreasing stage. Too rapid heating will cause gas expansion and induce cracks, so the heating rate needs to be controlled. In the second stage, the temperature is raised to 900°C for pre-sintering. At this stage, the metal particles begin to diffuse and combine to form a preliminary skeleton structure. In the third stage, high-temperature sintering is carried out to 1200-1250°C. Applying axial pressure at this stage (i.e., hot pressing sintering) can significantly accelerate the grain boundary sliding and densification process, obtaining a sintered body close to the theoretical density (relative density ≥98%).

[0031] The cooling process uses gradient cooling (furnace cooling followed by air cooling) to mitigate thermal stress accumulation and prevent cracking or deformation within the material. Cryogenic treatment (liquid nitrogen treatment) promotes the transformation of austenite to martensite, refines the grain size, and further improves the material's hardness and toughness.

[0032] In terms of surface strengthening, shot peening forms a compressive residual stress zone on the surface through high-speed impact, effectively preventing crack initiation and expansion, and improving fatigue life; while the TiC coating formed by chemical vapor deposition (CVD) has extremely high hardness (approximately 3000HV), excellent wear resistance and corrosion resistance, and is particularly suitable for applications under harsh working conditions.

[0033] In summary, the present invention achieves good interface bonding between the metal matrix and the ceramic reinforcement phase by optimizing the composition ratio of the metal matrix powder and the pressure-resistant enhancer, combined with a specific composite binder system and a staged sintering process. The surface strengthening treatment process significantly improves the surface hardness and wear resistance of the material through the synergistic effect of shot peening and chemical vapor deposition. The overall preparation process precisely controls the process parameters of each stage, so that the resulting composite material has excellent mechanical properties and pressure resistance characteristics, improves the toughness and high-temperature stability of the material while maintaining high strength, and provides a new technical solution for the preparation of high-performance pressure-resistant components.

[0034] Example 2, referring to Table 1, is the second example of the present invention. To further verify the technical solution of the present invention, experimental simulation data of a method for preparing a powder metallurgy pressure-resistant composite metal material are provided.

[0035] In order to verify the performance advantages of the new pressure-resistant composite metal material, a detailed experimental design was carried out; First, in the stage of preparing metal matrix powder, iron powder, nickel powder, chromium powder and molybdenum powder with a purity of not less than 99.5% were selected as raw materials and accurately weighed and mixed according to a mass ratio of 70:20:8:7; under an argon protective atmosphere, high-energy ball milling treatment was carried out with a ball-to-material ratio of 8:1 and a rotation speed of 350r / min for 5 hours to ensure that a uniform mixed powder with a particle size range of 10-50μm was obtained.

[0036] Next, a pressure-resistant reinforcing agent was prepared by mixing tungsten carbide particles and silicon nitride particles in a mass ratio of 65:35. A 0.8% mass fraction of KH550 silane coupling agent was added and ultrasonically dispersed in an ethanol solution for 45 minutes. The particles were then dried at 90°C for 3 hours to obtain surface-modified reinforcing agent particles. This step aims to improve the interfacial bonding properties and avoid agglomeration or interfacial separation during subsequent processing.

[0037] The metal matrix powder prepared above was mixed with a pressure-resistant enhancer, and a composite binder consisting of polyvinyl alcohol and zinc stearate in a mass ratio of 45:55 (accounting for 4% of the total mass) was added. The mixture was stirred in a vacuum mixer at a speed of 60 r / min for 45 minutes to ensure that the mixing uniformity reached more than 98%, thereby forming a high-quality mixture.

[0038] Subsequently, the mixture was pressed using cold isostatic pressing technology with a set pressure of 650 MPa and a holding time of 3 minutes to obtain a green body with high density and uniform structure; finally, the green body was sintered in stages, with the specific parameters as follows: in the first stage, the green body was heated at a rate of 6°C / min to 600°C and kept at this temperature for 1.5 hours for degreasing; in the second stage, the green body was heated at a rate of 4°C / min to 900°C and kept at this temperature for 2.5 hours for pre-sintering; in the third stage, the green body was heated at a rate of 1.5°C / min to 1225°C and kept at this temperature for 1.2 hours for final sintering. The entire process was carried out under argon protection, and the argon flow rate was controlled at 9 L / min. In addition, 25 MPa axial pressure was applied in the third stage to promote densification, and the cooling process adopted a gradient cooling method, first furnace cooling to 600°C at a rate of 7°C / min, then air cooling to room temperature, and deep freezing treatment was performed, keeping it in liquid nitrogen for 1.5 hours; in order to further improve the surface hardness and wear resistance, shot peening and chemical vapor deposition TiC coating were carried out.

[0039] The details are shown in Table 1 below:

[0040] Table 1: Comparison of properties of new pressure-resistant composite metal materials By comparing and analyzing the data in the above tables, it can be seen that the new pressure-resistant composite metal material provided by the present invention has significant advantages in multiple key performance indicators. In terms of density, the prior art samples A and B are 7.8 g / cm 3 and 7.9g / cm 3 , while samples C, D, and E of the present invention reached 8.1 g / cm 3 and above, which indicates that the new material has higher density and reduced internal porosity, thereby enhancing the overall mechanical properties.

[0041] In terms of tensile strength and hardness, the maximum values ​​of the existing technology samples are 520MPa and 210HV respectively, while the samples of the present invention reach 630MPa and 265HV respectively, showing better mechanical properties; especially the wear resistance index, the wear amount of the existing technology samples is as high as 15mg, while the wear amount of the samples of the present invention is reduced to 8mg at the lowest, proving that the tungsten carbide and silicon nitride reinforcements introduced by the new process effectively improve the wear resistance of the material.

[0042] In addition, the data on high-temperature stability and surface residual stress layer thickness further confirm the advantages of the present invention. In terms of high-temperature stability, the existing technology samples are only 87%, while the samples of the present invention can reach 94%, reflecting its reliability and durability in extreme environments. As for the thickness of the residual stress layer after surface strengthening treatment, the samples of the present invention have been significantly increased compared with the existing technology, from 0.04mm to 0.08mm, which helps to prevent crack initiation and extend service life.

[0043] In summary, the present invention not only solves the problems existing in traditional processes, such as low density, insufficient mechanical properties, poor wear resistance and high-temperature stability, but also achieves breakthroughs in performance through innovative component design and process optimization, especially in terms of high strength, high wear resistance and excellent high-temperature stability, demonstrating its great potential in practical applications.

[0044] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a powder metallurgy pressure-resistant composite metal material, characterized by: include: preparing metal matrix powder; Prepare pressure-resistant enhancer; Mixing the metal matrix powder with the pressure-resistant reinforcing agent, adding a composite binder, and stirring evenly to obtain a mixture; Pressing the mixed material into a green body; Sintering the green body in sections, and obtaining a pressure-resistant composite metal material after cooling; The pressure-resistant enhancer comprises tungsten carbide particles and silicon nitride particles in a mass ratio of (60-70): (30-40); The metal matrix powder includes iron powder, nickel powder, chromium powder and molybdenum powder, and the mass ratio thereof is (65-75): (15-25): (5-10): (3-8); The composite binder comprises polyvinyl alcohol and zinc stearate in a mass ratio of (40-50): (50-60).

2. The method for preparing a powder metallurgy pressure-resistant composite metal material according to claim 1, wherein: The preparation process of the metal matrix powder includes: mixing iron powder, nickel powder, chromium powder and molybdenum powder in proportion, and then performing high-energy ball milling under argon protection, wherein the ball milling time is 4 to 6 hours, the ball-to-material ratio is 8:1, the rotation speed is 300-400 r / min, and a uniform mixed powder with a particle size of 10-50 μm is obtained.

3. The method for preparing a powder metallurgy pressure-resistant composite metal material according to claim 2, wherein: The preparation process of the pressure-resistant enhancer includes: mixing tungsten carbide particles and silicon nitride particles in proportion, adding 0.5% to 1% by mass of a silane coupling agent, ultrasonically dispersing the mixture in an ethanol solution for 30 to 60 minutes, and then drying the mixture at 80 to 100° C. for 2 to 4 hours to obtain surface-modified enhancer particles.

4. The method for preparing a powder metallurgy pressure-resistant composite metal material according to claim 3, wherein: During the preparation of the mixture, the amount of the composite binder added is 3% to 5% of the total mass of the metal matrix powder and the pressure-resistant reinforcing agent. The mixing process is carried out in a vacuum mixer with a stirring speed of 50-80 r / min, a stirring time of 30 to 60 min, and a mixing uniformity of ≥98%.

5. The method for preparing a powder metallurgy pressure-resistant composite metal material according to claim 4, wherein: The pressing process adopts isostatic pressing, and the pressing pressure is 600-700 MPa, and the holding time is 2-5 minutes.

6. The method for preparing a powder metallurgy pressure-resistant composite metal material according to claim 5, wherein: The staged sintering process includes: In the first stage, the temperature is raised from room temperature to 600°C at a rate of 5-8°C / min and kept at this temperature for 1-2 hours for degreasing; In the second stage, the temperature is raised to 900°C at a rate of 3-5°C / min and kept at this temperature for 2-3 hours for pre-sintering. The third stage is to heat up to 1200-1250℃ at a rate of 1-2℃ / min and keep it at that temperature for 1-1.5h for final sintering; The sintering process is carried out under argon protection, wherein the argon flow rate is 8-10 L / min.

7. The method for preparing a powder metallurgy pressure-resistant composite metal material according to claim 6, wherein: During the third stage sintering process, an axial pressure of 20-30 MPa is applied to promote material densification and obtain a sintered body with a relative density of ≥98%.

8. The method for preparing a powder metallurgy pressure-resistant composite metal material according to claim 7, wherein: The cooling process adopts a gradient cooling method, specifically: First, furnace cool to 600℃ at a rate of 5-10℃ / min; Then air-cool to room temperature and perform cryogenic treatment, keeping it in liquid nitrogen for 1 to 2 hours.

9. The method for preparing a powder metallurgy pressure-resistant composite metal material according to claim 8, wherein: After the pressure-resistant composite metal material is prepared, it is subjected to surface strengthening treatment, which includes shot peening and chemical vapor deposition of titanium carbide coating, with a coating thickness of 5-10 μm.

10. The method for preparing a powder metallurgy pressure-resistant composite metal material according to claim 9, wherein: The shot peening treatment uses ceramic shots with a particle size of 0.1 to 0.3 mm, and sets the spray pressure to 0.4 to 0.6 MPa, the spray angle to 75 to 90 degrees, and the treatment time to 10 to 15 minutes, so that a compressive residual stress layer of 0.05 to 0.1 mm is generated on the material surface; The chemical vapor deposition titanium carbide coating is formed by introducing a mixed gas of TiCl4, CH4 and H2 under vacuum conditions of 1 to 5 Pa and a temperature of 850-950°C, wherein the volume ratio of TiCl4:CH4:H2 is 1:(1.2-1.5):(8-10), and the deposition time is set to 2 to 4 hours, thereby forming a dense TiC coating with a thickness of 5 to 10 μm.

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