Powder metallurgical forming process based on cold isostatic pressing
By employing cold isostatic pressing and hot pressing processes, combined with nano-solid lubricants and metal-based fillers, the problem of density inhomogeneity after powder metallurgy aluminum alloy pressing was solved, achieving high density and uniformity, and improving the mechanical properties and service life of the material.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU HAORAN NEW MATERIAL CO LTD
- Filing Date
- 2026-03-31
- Publication Date
- 2026-06-02
AI Technical Summary
In existing powder metallurgy processes, the uneven density distribution of powder metallurgy aluminum alloys after pressing results in compromised material mechanical properties and service life. Furthermore, the incomplete elimination of internal porosity further affects the mechanical properties and service life of the resulting components.
The process employs a cold isostatic pressing (CIP) powder metallurgy forming technology. It involves a pre-treatment process using spray granulation, followed by powder loading and encapsulation. The process utilizes a cold isostatic pressing process, combined with spray granulation pre-treatment, to grind nano-solid lubricants and metal-based fillers using nano-grinding machinery. This is further enhanced by staged pressure and temperature variations to optimize pressure transmission efficiency and particle arrangement.
It improves the density and uniformity of the powder blank, enhances the mechanical properties and service life of the material, reduces frictional resistance, and minimizes pressing defects.
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Abstract
Description
Technical Field
[0001] This invention relates to a powder metallurgy forming process based on cold isostatic pressing, belonging to the field of powder metallurgy technology. Background Technology
[0002] Aluminum alloys, with their low density, high specific strength, and excellent thermal and electrical conductivity, corrosion resistance, and machinability, have become an important research subject in the field of powder metallurgy. Some high-strength aluminum alloys have mature applications in aerospace, automotive electronics, and new energy fields. In existing powder metallurgy processes, aluminum alloys are formed by pressing and sintering. However, conventional pressing leads to uneven density distribution in the pressed blank, and internal porosity is difficult to completely eliminate, resulting in insufficient material density, which in turn affects the mechanical properties and service life of the components. Summary of the Invention
[0003] In response to at least one problem in the prior art, the present invention provides a powder metallurgy forming process based on cold isostatic pressing, which can improve the density and uniformity of the microstructure of the powder blank.
[0004] To achieve the above objectives, the present invention adopts the following technical solution: a powder metallurgy forming process based on cold isostatic pressing, comprising the following steps: forming aluminum alloy powder by spray granulation, pre-treating and packaging the powder with nano solid lubricant and metal-based filler, and then forming the powder blank by cold isostatic pressing and hot pressing.
[0005] Preferably, the amount of the nano solid lubricant is 0.5 to 1.2% of the aluminum alloy powder.
[0006] Preferably, the particle size of the nano-solid lubricant is 10~100nm.
[0007] Preferably, the nano solid lubricant is one or both of nano graphite lubricant and nano molybdenum disulfide lubricant.
[0008] Preferably, the nano-solid lubricant is composed of nano-graphite lubricant and nano-molybdenum disulfide lubricant.
[0009] Preferably, the mass ratio of the nano-graphite lubricant to the nano-molybdenum disulfide lubricant is 1:3~4.
[0010] Preferably, the amount of the metal-based filler is 1.5 to 2.1% of the aluminum alloy powder.
[0011] Preferably, the metal-based filler includes a metal-based fine powder filler and nano-alumina particles.
[0012] Preferably, the mass ratio of the metal-based fine powder filler to the nano-alumina particles is 2~3:1.
[0013] Preferably, the particle size of the metal-based fine powder filler is 2~10μm.
[0014] Preferably, the alumina nanoparticles have a particle size of 10~100nm.
[0015] Preferably, the metal-based fine powder filler is a high-purity aluminum fine powder filler or an aluminum-based alloy fine powder filler.
[0016] Preferably, the specific process of pretreatment powder packaging is as follows: first, aluminum alloy powder and nano solid lubricant are mechanically ground and mixed evenly, then metal-based filler is added and ground and mixed evenly, then in a nitrogen environment, the powder is loaded into the mold cavity while vibrating to make it uniform and dense, and after the powder is loaded, it is vacuum sealed.
[0017] Preferably, the cold isostatic pressing process is a staged pressure transformation process performed at room temperature.
[0018] Preferably, the cold isostatic pressing conditions are as follows: pressurize to 100-120 MPa at a rate of 0.1-0.25 MPa / s, hold for 3-6 minutes, then pressurize to 250-310 MPa at a rate of 0.5-0.75 MPa / s, hold for 10-15 minutes, and then unload to atmospheric pressure at a rate of 0.5-0.65 MPa / s to obtain the initial billet.
[0019] Preferably, the hot pressing treatment is a staged pressure and temperature variable treatment under an argon atmosphere.
[0020] Preferably, the hot pressing conditions are as follows: under an argon atmosphere, the temperature is increased to 520-570℃ at a rate of 5-10℃ / min, held at that temperature, and then pressurized to 150-180MPa at a rate of 10-15MPa / min, held at that temperature and pressure for 45-60min, then cooled to 120-150℃ at a rate of 5-10℃ / min, and then unloaded to atmospheric pressure at a rate of 0.75-0.85MPa / s, and then cooled with the furnace to obtain the powder blank.
[0021] Preferably, the particle size (D90) of the aluminum alloy powder is between 80 and 150 μm.
[0022] The beneficial effects of this invention are as follows: Based on cold isostatic pressing powder metallurgy forming process, this invention enables powder blanks to have high density and high microstructure uniformity. In addition, it also enables the finished powder blanks to have excellent mechanical properties and good service life. The process of this invention adopts a staged variable pressure cold isostatic pressing treatment, which optimizes pressure transmission efficiency and promotes the rearrangement and plastic deformation of powder particles, thereby improving the overall density of the pressed blank. Combined with staged variable pressure and temperature hot pressing treatment, it promotes diffusion and bonding between particles, optimizes the microstructure, and makes the grains finer and the microstructure more uniform. The process of this invention also effectively reduces frictional resistance by using nano solid lubricants and metal-based fillers, further optimizing particle filling rearrangement and plastic deformation, significantly and effectively improving density and uniformity, while reducing pressing defects and avoiding surface scratches or cracks in the powder blank. Detailed Implementation
[0023] The following is a clear and complete description of the technical solutions in the implementation of this invention. The described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents, instruments, and components used that do not specify the manufacturer are all conventional products that can be purchased commercially.
[0024] In this invention, 7055 aluminum alloy powder is used. The aluminum alloy powder is made into granules by spray granulation equipment. The spray gas pressure is set at 0.5~1.5MPa, the granulation inlet temperature is 180~270℃, and the outlet temperature is 80~150℃, so that the particle size D90 of the aluminum alloy powder is 80~150μm, and the particle shape is good and uniform.
[0025] This invention uses high-purity aluminum fine powder filler, with the purity of the high-purity aluminum being greater than 99.8%.
[0026] Example 1 A powder metallurgical forming process based on cold isostatic pressing includes the following steps: 7055 aluminum alloy powder is formed by spray granulation, with the particle size (D90) of the 7055 aluminum alloy powder being 80~150μm. Pre-treatment and powder packaging are then performed: the aluminum alloy powder is mechanically ground and mixed uniformly with nano-molybdenum disulfide lubricant with a particle size of 10~100nm. The amount of nano-solid lubricant used is 0.8% of the aluminum alloy powder. Then, high-purity aluminum fine powder filler with a particle size of 2~10μm and nano-alumina particles with a particle size of 10~100nm are added and ground and mixed uniformly. The amount of high-purity aluminum fine powder filler is 1% of the aluminum alloy powder, and the amount of nano-alumina particles is 0.5% of the aluminum alloy powder. Finally, under a nitrogen atmosphere, the mixture is filled into a mold cavity. The powder was loaded while vibrating to ensure uniformity and density, and then vacuum-sealed after loading. Cold isostatic pressing was then performed: the pressure was increased to 100 MPa at a rate of 0.1 MPa / s, held for 6 minutes, then increased to 300 MPa at a rate of 0.75 MPa / s, held for 10 minutes, and then unloaded to atmospheric pressure at a rate of 0.5 MPa / s to obtain the initial blank. Hot pressing was then performed: under an argon atmosphere, the temperature was increased to 520℃ at a rate of 5℃ / min, held, and then increased to 150 MPa at a rate of 15 MPa / min, held for 50 minutes, then decreased to 120℃ at a rate of 10℃ / min, and then unloaded to atmospheric pressure at a rate of 0.75 MPa / s, and then cooled in the furnace to obtain the powder blank. The density and uniformity index were tested and are shown in the table.
[0027] Example 2 A powder metallurgical forming process based on cold isostatic pressing includes the following steps: 7055 aluminum alloy powder is formed by spray granulation, with the particle size (D90) of the 7055 aluminum alloy powder being 80-150 μm. Pre-treatment and powder packaging are then performed: the aluminum alloy powder is mechanically ground and mixed uniformly with nano-graphite lubricant with a particle size of 10-100 nm, the amount of nano-solid lubricant being 1.2% of the aluminum alloy powder. Then, high-purity aluminum fine powder filler with a particle size of 2-10 μm and nano-alumina particles with a particle size of 10-100 nm are added and ground and mixed uniformly, the amount of high-purity aluminum fine powder filler being 1.5% of the aluminum alloy powder and the amount of nano-alumina particles being 0.5% of the aluminum alloy powder. Finally, under a nitrogen atmosphere, the mixture is loaded into a mold. The powder was loaded into the cavity while vibrating to ensure uniformity and density. After loading, the cavity was vacuum sealed. Then, cold isostatic pressing was performed: the pressure was increased to 120 MPa at a rate of 0.2 MPa / s and held for 3 minutes, then increased to 280 MPa at a rate of 0.6 MPa / s and held for 12 minutes, and finally unloaded to atmospheric pressure at a rate of 0.65 MPa / s to obtain the initial blank. Next, hot pressing was performed: under an argon atmosphere, the temperature was increased to 530℃ at a rate of 8℃ / min, held, and then increased to 180 MPa at a rate of 12 MPa / min, held for 55 minutes, then decreased to 150℃ at a rate of 5℃ / min, and finally unloaded to atmospheric pressure at a rate of 0.8 MPa / s, and then cooled in the furnace to obtain the powder blank. The density and uniformity index were tested and are shown in the table.
[0028] Example 3 A powder metallurgical forming process based on cold isostatic pressing includes the following steps: 7055 aluminum alloy powder is formed by spray granulation, with the particle size (D90) of the 7055 aluminum alloy powder being 80-150 μm. Pre-treatment and powder packaging are performed first: the aluminum alloy powder is mechanically ground and mixed uniformly with nano-graphite lubricant (10-100 nm particle size) and nano-molybdenum disulfide lubricant (10-100 nm particle size). The amount of nano-graphite lubricant is 0.2% of the aluminum alloy powder, and the amount of nano-molybdenum disulfide lubricant is 0.8% of the aluminum alloy powder. Then, high-purity aluminum fine powder filler (2-10 μm particle size) and nano-alumina particles (10-100 nm particle size) are added and ground and mixed uniformly. The amount of high-purity aluminum fine powder filler is 1.5% of the aluminum alloy powder, and the amount of nano-alumina particles is 1.5% of the aluminum alloy powder. 0.6% of the powder was added to the mold cavity under nitrogen atmosphere while vibrating to ensure uniformity and density. After filling, the mold was vacuum sealed. Then, cold isostatic pressing was performed: the pressure was increased to 110 MPa at a rate of 0.25 MPa / s and held for 4 min, then increased to 250 MPa at a rate of 0.5 MPa / s and held for 15 min, and finally unloaded to atmospheric pressure at a rate of 0.6 MPa / s to obtain the initial blank. Next, hot pressing was performed: under argon atmosphere, the temperature was increased to 550℃ at a rate of 10℃ / min and held, then increased to 165 MPa at a rate of 10 MPa / min and held for 60 min, then decreased to 135℃ at a rate of 8℃ / min, and finally unloaded to atmospheric pressure at a rate of 0.85 MPa / s, and then cooled in the furnace to obtain the powder blank. The density and uniformity index were tested and are shown in the table.
[0029] Example 4 A powder metallurgical forming process based on cold isostatic pressing differs from Example 1 in that: pretreatment and powder loading are performed first: aluminum alloy powder and nano-molybdenum disulfide lubricant with a particle size of 10~100nm are mechanically ground and mixed evenly, with the amount of nano-solid lubricant being 0.8% of the aluminum alloy powder. Then, high-purity aluminum fine powder filler with a particle size of 2~10μm is added and ground and mixed evenly, with the amount of high-purity aluminum fine powder filler being 1.5% of the aluminum alloy powder. Then, under nitrogen atmosphere, the powder is loaded into the mold cavity while vibrating to make it uniform and dense. After the powder is loaded, it is vacuum sealed. The density and uniformity index are shown in the table after testing.
[0030] Example 5 A powder metallurgical forming process based on cold isostatic pressing differs from Example 1 in that: pretreatment and powder packaging are performed first: aluminum alloy powder and nano-molybdenum disulfide lubricant with a particle size of 10~100nm are mechanically ground and mixed evenly, with the amount of nano-solid lubricant being 0.8% of the aluminum alloy powder. Then, nano-alumina particles with a particle size of 10~100nm are added and ground and mixed evenly, with the amount of nano-alumina particles being 1.5% of the aluminum alloy powder. Then, under a nitrogen atmosphere, the powder is loaded into the mold cavity while vibrating to make it uniform and dense. After the powder is loaded, it is vacuum sealed. The density and uniformity index are shown in the table after testing.
[0031] Comparative Example 1 A powder metallurgical forming process based on cold isostatic pressing differs from Example 2 in that: pretreatment and powder loading are performed first: aluminum alloy powder is ground and mixed evenly with high-purity aluminum fine powder filler with a particle size of 2~10μm and nano-alumina particles with a particle size of 10~100nm. The amount of high-purity aluminum fine powder filler is 1.5% of the aluminum alloy powder and the amount of nano-alumina particles is 0.5% of the aluminum alloy powder. Then, under nitrogen atmosphere, the powder is loaded into the mold cavity while vibrating to make it uniform and dense. After loading, it is vacuum sealed. The density and uniformity index are shown in the table.
[0032] Comparative Example 2 A powder metallurgical forming process based on cold isostatic pressing differs from Example 1 in that: pretreatment and powder loading are performed first: aluminum alloy powder and nano-molybdenum disulfide lubricant with a particle size of 10~100nm are mechanically ground and mixed evenly, and the amount of nano-solid lubricant is 0.8% of the aluminum alloy powder. Then, under nitrogen atmosphere, the powder is loaded into the mold cavity while vibrating to make it uniform and dense. After loading, it is vacuum sealed. The density and uniformity index are shown in the table after testing.
[0033] Comparative Example 3 A powder metallurgical forming process based on cold isostatic pressing differs from Example 1 in that no hot pressing is performed after the cold isostatic pressing process; the density and uniformity index are shown in the table after testing.
[0034] Comparative Example 4 A powder metallurgical forming process based on cold isostatic pressing differs from Example 3 in that: cold isostatic pressing is then performed: the pressure is increased to 250 MPa within 10 min, then held for 15 min, and then unloaded to atmospheric pressure at a rate of 0.6 MPa / s; the density and uniformity index are shown in the table after testing.
[0035] Comparative Example 5 A powder metallurgical forming process based on cold isostatic pressing differs from Example 3 in that it undergoes a hot pressing treatment: under an argon atmosphere, the powder is held at a constant temperature of 550℃ and a constant pressure of 165MPa for 60 minutes, then unloaded to atmospheric pressure at a rate of 0.85MPa / s and cooled with the furnace; the density and uniformity index are shown in the table after testing.
[0036] Comparative Example 6 A powder metallurgical forming process based on cold isostatic pressing differs from Example 3 in that: 7055 aluminum alloy powder is formed by spray granulation, with a particle size (D90) of 80~150μm. Pre-treatment and powder packaging are performed: the aluminum alloy powder is loaded into the mold cavity under nitrogen atmosphere while vibrating to ensure uniformity and density. After loading, the mold is vacuum-sealed. Then, cold isostatic pressing is performed: the pressure is increased to 220MPa in 15 minutes and held for 15 minutes. The density and uniformity index are shown in the table.
[0037] Table 1 Density and homogeneity index
[0038] Note: The closer the uniformity index in the table is to 1, the better the uniformity of the powder body.
[0039] As can be seen from the table above, the present invention is based on cold isostatic pressing powder metallurgy forming process, the density of the powder blank is 93.6%~96.2% and the uniformity index is 0.961~0.973, which has high density and high structure uniformity, thus which is conducive to the preparation of the finished product with excellent mechanical properties and good service life.
[0040] Compared with Comparative Examples 1, 2 and 6, Examples 1 to 5 effectively reduced frictional resistance by using the synergistic effect of nano-solid lubricants and metal-based fillers, further optimized particle filling rearrangement and plastic deformation, significantly and effectively improved density and uniformity, and also reduced pressing defects, avoiding surface scratches or cracks in the powder blank.
[0041] Compared with Comparative Examples 3-6, Examples 1-5 adopted a staged variable pressure cold isostatic pressing treatment method, which optimized the pressure transmission efficiency, promoted the rearrangement and plastic deformation of powder particles, improved the overall density of the compact, and combined with staged variable pressure and temperature hot pressing treatment, promoted the diffusion and bonding between particles, optimized the microstructure, and made the grains finer and the structure more uniform.
[0042] In summary, the powder metallurgy forming process based on cold isostatic pressing of the present invention effectively improves the density and uniformity of the microstructure of the powder blank.
[0043] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit and essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
[0044] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A powder metallurgy forming process based on cold isostatic pressing, characterized in that, Includes the following steps: Aluminum alloy powder is formed by spray granulation, pretreated with nano solid lubricant and metal-based filler, packaged, and then formed by cold isostatic pressing and hot pressing to obtain powder blank; The particle size (D90) of the aluminum alloy powder is 80~150μm.
2. The powder metallurgy forming process based on cold isostatic pressing according to claim 1, characterized in that, The nano solid lubricant is one or both of nano graphite lubricant and nano molybdenum disulfide lubricant; The particle size of the nano-solid lubricant is 10~100nm.
3. The powder metallurgy forming process based on cold isostatic pressing according to claim 1, characterized in that, The metal-based filler includes a metal-based fine powder filler and nano-alumina particles; The particle size of the metal-based fine powder filler is 2~10μm; the particle size of the nano-alumina particles is 10~100nm.
4. The powder metallurgy forming process based on cold isostatic pressing according to claim 1, characterized in that, The mass ratio of the metal-based fine powder filler to the nano-alumina particles is 2~3:
1.
5. A powder metallurgy forming process based on cold isostatic pressing according to claim 3 or 4, characterized in that, The metal-based fine powder filler is either an aluminum fine powder filler or an aluminum-based alloy fine powder filler.
6. The powder metallurgy forming process based on cold isostatic pressing according to claim 1, characterized in that, The specific process of pretreatment powder filling and packaging is as follows: First, aluminum alloy powder and nano solid lubricant are mechanically ground and mixed evenly. Then, metal-based filler is added and ground and mixed evenly. Then, under nitrogen atmosphere, the powder is loaded into the mold cavity while vibrating to make it uniform and dense. After the powder is loaded, it is vacuum sealed.
7. The powder metallurgy forming process based on cold isostatic pressing according to claim 1, characterized in that, The cold isostatic pressing process is a staged pressure variation process at room temperature; the hot pressing process is a staged pressure variation and temperature variation process under an argon atmosphere.
8. A powder metallurgy forming process based on cold isostatic pressing according to claim 1 or 7, characterized in that, The cold isostatic pressing conditions are as follows: pressurize to 100-120 MPa at a rate of 0.1-0.25 MPa / s, hold for 3-6 minutes, then pressurize to 250-310 MPa at a rate of 0.5-0.75 MPa / s, hold for 10-15 minutes, and then unload to atmospheric pressure at a rate of 0.5-0.65 MPa / s to obtain the initial billet.
9. A powder metallurgy forming process based on cold isostatic pressing according to claim 1 or 7, characterized in that, Hot pressing conditions: Under an argon atmosphere, the temperature is increased to 520-570℃ at a rate of 5-10℃ / min, held at that temperature, and then pressurized to 150-180MPa at a rate of 10-15MPa / min. The pressure and temperature are held for 45-60min, then the temperature is decreased to 120-150℃ at a rate of 5-10℃ / min. The temperature is then unloaded to atmospheric pressure at a rate of 0.75-0.85MPa / s, and then cooled with the furnace to obtain the powder blank.
10. The powder metallurgy forming process based on cold isostatic pressing according to claim 1, characterized in that, The amount of the nano solid lubricant is 0.5-1.2% of the aluminum alloy powder; the amount of the metal-based filler is 1.5-2.1% of the aluminum alloy powder.