Injection molding preparation method of powder metallurgy amorphous composite material

Abstract

The invention discloses a powder metallurgy injection molding preparation method capable of preparing an amorphous composite product with a complex shape. The basic preparation process comprises the steps of powder treatment, feed preparation, injection molding, degreasing and pre-sintering, hot isostatic pressing sintering and heat treatment.

Description

Technical Field

[0001] The invention relates to a method for preparing a composite material, in particular to an injection molding method for preparing an amorphous composite material. Background Art

[0002] Amorphous alloys have a unique atomic arrangement, that is, short-range order and long-range disorder. This structure makes them immune to defects such as grain boundaries and dislocations, thus exhibiting better mechanical properties than traditional crystalline alloys, such as high strength, high hardness and large elastic limit. However, the brittleness of amorphous alloys at room temperature limits their wider application. In order to overcome this problem, researchers have found that adding reinforcing phases to amorphous alloys can effectively improve their room temperature plasticity. In addition, the preparation of large-sized amorphous has always been very difficult due to the formation ability of amorphous. Therefore, it is also very difficult to prepare products with complex shapes and structures by casting and rapid cooling.

[0003] Metal Injection Molding (MIM) is a molding technology that mixes metal powder with a binder to make a feed material, then uses a special injection molding equipment to heat the feed material and inject it into a mold with a designed shape cavity, and obtains a green body after cooling. The green body becomes a dense product after subsequent degreasing and sintering. The advantages of MIM technology are that it can form parts with complex shapes and structures at one time, with high raw material utilization, high mass production efficiency and low cost.

[0004] Hot isostatic pressing applies a large and uniform pressure to the product during the sintering process, so that the powder can be densified at a relatively low temperature. At the same time, it can sinter parts with complex shapes and large sizes. It is a sintering method for the preparation of excellent powder metallurgical products.

[0005] In the prior art, the patent "2022106563175 Groove Needles for Warp Knitting Machines and Method for Making Groove Needles by Injection Molding Process of Amorphous Alloys" involves the injection molding process, but the injection molding method used is not the traditional injection molding technology. It uses block raw materials, no adhesives, and the injection temperature is high, which places extremely high requirements on the equipment. At present, there are few reports on the preparation of amorphous materials using metal injection molding methods. The combination of amorphous materials and injection molding technology provides technical support for the preparation of complex parts of amorphous materials, and also provides a guarantee for the widespread application of amorphous materials. Summary of the invention

[0006] In order to solve the problems of the prior art, the present invention provides a method for preparing amorphous composite materials by injection molding of powder metallurgy, which combines the characteristics of amorphous materials with the advantages of injection molding and hot isostatic pressing sintering technology to provide a method for preparing amorphous composite parts with complex shapes.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A preferred solution is a method for preparing a powder metallurgy amorphous composite material by injection molding, wherein the preparation process comprises:

[0009] A. Powder treatment: soak the reinforcing phase powder in 30-40% HF for 10-15h, then wash it with water and alcohol ultrasonic immersion, and finally dry it at 80-100℃. Mix the amorphous powder and the treated reinforcing phase powder with a ball mill according to the designed ratio. Fill it with high-purity Ar2 after vacuuming before ball milling, with a ball-to-material mass ratio of 5:1, a rotation speed of 200-350rpm, and a time of 15-20h.

[0010] B. Preparation of feed: wax-based feed, with specific mass ratio of components: 50-55% paraffin PA, 30-35% polypropylene PP, 10-15% polyethylene PE, 2-3% polyvinyl butyral PVB, 1-2% dioctyl phthalate DOP, 1-2% oleic acid OA;

[0011] C. Injection molding: feed the material into the injection molding machine and inject it to obtain the green body, the injection temperature is 165-175℃;

[0012] D. Degreasing and pre-sintering: first, the green body is placed in an organic solvent at 30-45°C for 8-15 hours for solvent degreasing. After solvent degreasing, hot degreasing and pre-sintering are performed to remove the binder and give the green body a certain strength, with a relative density of 90-93%;

[0013] E. Hot isostatic pressing sintering: placing the pre-sintered blank in a hot isostatic pressing furnace for sintering;

[0014] F. Heat treatment: After sintering, keep the temperature at 750-800℃ for 5-10 minutes for quenching. After quenching, keep the temperature at 250-300℃ for 30-60 minutes for annealing.

[0015] In a preferred embodiment, the amorphous powder has an atomic molar ratio of (Zr 35 Ti 15 Cu 15 Ni 12 Be 24 )100- x Y x , x=2~3, the powder is spherical or nearly spherical, and the particle size is not greater than 80μm.

[0016] In a preferred embodiment, the reinforcing phase powder is crystalline tungsten powder with a particle size of 50 to 200 μm.

[0017] In a preferred solution, the mass percentage of the amorphous powder and the reinforcing phase powder raw materials is 12-15%:85-88%.

[0018] The preferred scheme, the thermal debinding and pre-sintering process is: heating to 220-250°C at 1-3°C / min, keeping warm for 30-60min, then heating to 300-320°C at 1-3°C / min, keeping warm for 60-90min, heating to 380-400°C at 1-3°C / min, heating to 420-450°C at 5-10°C, keeping warm for 10-20min, with Ar2 or N2 protection throughout the process.

[0019] In a preferred embodiment, the hot isostatic pressing sintering adopts staged sintering, firstly heating to 560-600°C and keeping warm for 20 minutes, with a pressure of 100-150 MPa, then reducing the pressure to 30-50 MPa after the keeping warm, heating to 670-720°C and keeping warm for 10 minutes.

[0020] Principles and advantages:

[0021] The present invention uses the advantages of injection molding technology and hot isostatic pressing technology, combined with the principle of optimizing the performance of amorphous materials, to develop a preparation method that can produce amorphous composite parts with both excellent room temperature performance and complex shape structures.

[0022] In the design of the amorphous raw material components, the present invention adds a certain amount of rare metal element Y. The characteristic of Y is that it can combine with oxygen to form Y2O3. In addition, among the selected amorphous components, compared with Zr, Cu, Ti, Ni and Be, Y has a stronger ability to form O. When the amorphous is in liquid state, O tends to combine with Y to form Y2O3. Y2O3 is different from the oxides of other constituent elements and will not form a crystalline phase as a heterogeneous nucleation point in the amorphous. Therefore, the addition of Y purifies the melt, prevents the formation of other metal oxides, and is conducive to high amorphization.

[0023] The present invention uses crystalline tungsten as the strengthening phase. On the one hand, tungsten powder and zirconium-based amorphous have good wettability. During the sintering process, zirconium-based amorphous can fill pores well. Moreover, at the temperature when the amorphous melts, the tungsten powder does not change in properties and is still evenly distributed in powder form, which will not affect the strengthening effect. On the other hand, for conventional tungsten alloy sintering, because the powder needs to have high activity, the tungsten powder needs to be very fine, such as 1μm. However, because the conventional W powder particles are fine and the fluidity itself is poor, when mixed with the adhesive, the shear force is large, the powder micro-region heats up seriously, resulting in the volatilization of the adhesive, and the powder and the adhesive are difficult to mix evenly. The powder and the adhesive are easily separated during the injection process. Therefore, the obtained feed has poor fluidity, high brittleness, and is prone to injection defects, such as obvious flow lines, pores, and incomplete injection. However, the present invention does not require the tungsten powder to have high sintering activity. On the contrary, it is hoped that the tungsten powder will not change in properties during the sintering process and will not react with the amorphous. Therefore, a coarse-grained crystalline tungsten powder with good fluidity, particle size uniformity, high bulk density and tap density powder characteristics is selected, which is suitable for injection molding.

[0024] The present invention adopts segmented hot isostatic pressing sintering and then heat treatment to obtain an amorphous composite material. In order to obtain a higher amorphous content, conventional sintering methods often perform sintering in the supercooled liquid phase region between the glass transition point and the first crystallization temperature, but it is difficult to sinter densely at a lower temperature, and special methods such as SPS cannot sinter complex structure products, which are easy to crystallize at high temperatures. The present invention combines segmented hot isostatic pressing sintering with subsequent heat treatment to prepare an amorphous composite material. The first stage is sintered at low temperature and high pressure (below the liquidus line) to increase the overall density of the material and reduce the porosity, preparing for the second stage of sintering. The second stage is sintered at high temperature and low pressure (above the liquidus line) to convert the amorphous powder into a liquid phase to fill the pores, while reducing the pressure to prevent the liquid phase from seeping out. After sintering and densification, quenching + tempering treatment is performed to obtain a highly amorphous amorphous composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 For amorphous (Zr 35 Ti 15 Cu 15 Ni 12 Be 24 ) 98 XRD picture of Y2

[0026] Figure 2 XRD picture of the composite material in Example 3 DETAILED DESCRIPTION

[0027] The method of the present invention is further described below in conjunction with three embodiments.

[0028] Example 1

[0029] A method for preparing a powder metallurgy amorphous composite material by injection molding, the preparation process of which comprises:

[0030] A. Powder treatment: 100-200 μm spherical crystalline tungsten powder is placed in 30% HF for 15 hours, then cleaned by water and alcohol ultrasonic immersion, and finally dried at 80 ° C. 35 Ti 15 Cu 15 Ni 12 Be 24 ) 98 Y2 amorphous powder and treated crystalline tungsten powder were mixed in a ball mill at a designed ratio of 12%:88%. High-purity Ar2 was filled in after vacuuming before ball milling. The ball-to-material mass ratio was 5:1, the speed was 200rpm, and the time was 20h. After ball milling, the amorphous powder adhered to the reinforcing phase powder.

[0031] B. Preparation of feed: wax-based feed, with specific mass ratio of components: 50% paraffin PA, 35% polypropylene PP, 10% polyethylene PE, 2% polyvinyl butyral PVB, 1% dioctyl phthalate DOP, 2% oleic acid OA;

[0032] C. Injection molding: feed the material into the injection molding machine and inject it to obtain the green body, the injection temperature is 175℃;

[0033] D. Debinding and pre-sintering: first, the green body is placed in an organic solvent at 30°C and soaked for 15 hours for solvent debinding. After solvent debinding, hot debinding and pre-sintering are performed. The hot debinding and pre-sintering process is: heating to 220°C at 1°C / min, keeping warm for 60 minutes, then heating to 320°C at 1°C / min, keeping warm for 60 minutes, heating to 400°C at 1°C / min, heating to 420°C at 5°C, keeping warm for 20 minutes, and N2 protection is passed throughout the process to remove the binder and make the green body have a certain strength, and the relative density reaches 90%;

[0034] E. Hot isostatic pressing sintering: Place the pre-sintered blank in a hot isostatic pressing furnace for sintering. Use segmented sintering. First, heat to 560°C and keep warm for 20 minutes. Pressure is 150MPa. After the heat preservation, reduce the pressure to 50MPa, heat to 670°C, and keep warm for 10 minutes.

[0035] F. Heat treatment: After sintering, quench at 750℃ for 10 minutes. After quenching, anneal at 250℃ for 60 minutes.

[0036] Example 2

[0037] A method for preparing a powder metallurgy amorphous composite material by injection molding, the preparation process of which comprises:

[0038] A. Powder treatment: 50-100 μm spherical crystalline tungsten powder is immersed in 35% HF for 13 hours, then washed with water and alcohol ultrasonic immersion, and finally dried at 100 ° C. 35 Ti 15 Cu 15 Ni 12 Be 24 ) 97 Y3 amorphous powder and treated crystalline tungsten powder were mixed in a ball mill at a designed ratio of 15%:85%. High-purity Ar2 was filled in after vacuuming before ball milling. The ball-to-material mass ratio was 5:1, the speed was 300rpm, and the time was 18h. After ball milling, the amorphous powder adhered to the reinforcing phase powder.

[0039] B. Preparation of feed: wax-based feed, with specific mass ratio of components: 50% paraffin PA, 30% polypropylene PP, 15% polyethylene PE, 3% polyvinyl butyral PVB, 1% dioctyl phthalate DOP, 1% oleic acid OA;

[0040] C. Injection molding: feed the material into the injection molding machine and inject it to obtain the green body, the injection temperature is 170℃;

[0041] D. Debinding and pre-sintering: first, the green body is placed in an organic solvent at 40°C for 12 hours for solvent debinding, and then hot debinding and pre-sintering are performed. The hot debinding and pre-sintering process is to heat up to 250°C at 3°C / min, keep warm for 30 minutes, then heat up to 320°C at 3°C / min, keep warm for 60 minutes, heat up to 400°C at 3°C / min, heat up to 430°C at 10°C, keep warm for 20 minutes, and pass Ar2 protection throughout the process to remove the binder and make the green body have a certain strength, and the relative density reaches 91%;

[0042] E. Hot isostatic pressing sintering: Place the pre-sintered blank in a hot isostatic pressing furnace for sintering. Use segmented sintering. First, heat to 580℃ and keep warm for 20min. Pressure is 125MPa. After the heat preservation, reduce the pressure to 40MPa, heat to 700℃ and keep warm for 10min.

[0043] F. Heat treatment: After sintering, quench at 780℃ for 8 minutes. After quenching, anneal at 300℃ for 60 minutes.

[0044] Example 3

[0045] A method for preparing a powder metallurgy amorphous composite material by injection molding, the preparation process of which comprises:

[0046] A. Powder treatment: 50-100 μm spherical crystalline tungsten powder is soaked in 40% HF for 10-15 hours, then washed with water and alcohol ultrasonic immersion, and finally dried at 100 ° C. 35 Ti 15 Cu 15 Ni 12 Be 24 ) 97 Y3 amorphous powder and treated crystalline tungsten powder were mixed in a ball mill at a designed ratio of 15%:85%. High-purity Ar2 was filled in after vacuuming before ball milling. The ball-to-material mass ratio was 5:1, the speed was 350rpm, and the time was 15h. After ball milling, the amorphous powder adhered to the reinforcing phase powder.

[0047] B. Preparation of feed: wax-based feed, with specific mass ratio of components: 55% paraffin PA, 30% polypropylene PP, 10% polyethylene PE, 2% polyvinyl butyral PVB, 2% dioctyl phthalate DOP, 1% oleic acid OA;

[0048] C. Injection molding: feed the material into the injection molding machine and inject it to obtain the green body, the injection temperature is 165℃;

[0049] D. Debinding and pre-sintering: first, the green body is immersed in an organic solvent at 45°C for 8h for solvent debinding, and then hot debinding and pre-sintering are performed. The hot debinding and pre-sintering process is: heating to 250°C at 3°C / min, keeping warm for 30min, then heating to 300°C at 3°C / min, keeping warm for 90min, heating to 400°C at 3°C / min, heating to 450°C at 10°C, keeping warm for 10min, and Ar2 protection is used throughout the process to remove the binder and make the green body have a certain strength, and the relative density reaches 93%;

[0050] E. Hot isostatic pressing sintering: Place the pre-sintered blank in a hot isostatic pressing furnace for sintering. Use segmented sintering. First, heat to 600℃ and keep warm for 20min. Pressure is 100MPa. After the heat preservation, reduce the pressure to 30MPa, heat to 720℃ and keep warm for 10min.

[0051] F. Heat treatment: After sintering, quench at 800℃ for 5 minutes. After quenching, anneal at 300℃ for 60 minutes.

[0052] Comparative Example 1

[0053] This comparative example adopts the same process steps as Example 3, except that fine tungsten powder with a particle size of 1 to 10 μm is used. As a result, the powder volatilizes greatly during the mixing process, the mixing is uneven, and injection defects occur.

[0054] Comparative Example 2

[0055] This comparative example adopts the same process steps as Example 3, except that the crystalline tungsten powder is not immersed in the HF solution. As a result, the product density is relatively low, with a relative density of 94%.

[0056] Comparative Example 3

[0057] This comparative example adopts the same process steps as Example 3, except that the crystalline tungsten powder and the amorphous powder are not ball-milled, resulting in uneven sintering structure and agglomeration of the tungsten powder.

[0058] Comparative Example 4

[0059] This comparative example adopts the same process steps as Example 3, except that the sintering process is different. The results are shown in the following table.

[0060]

[0061] The above-described examples are only preferred implementation methods of the present invention, and therefore cannot be used to limit the scope of implementation of the present invention. Other equivalent changes, modifications, substitutions and combinations made in accordance with the principles and contents of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for preparing a powder metallurgy amorphous composite material by injection molding, the preparation process comprising: A. Powder treatment: soak the reinforcing phase powder in 30~40% HF for 10~15h, then wash it with water and alcohol ultrasonic immersion, and finally dry it at 80~100℃. Mix the amorphous powder and the treated reinforcing phase powder in a ball mill according to the designed ratio. Fill it with high-purity Ar2 after vacuuming before ball milling, with a ball-to-material mass ratio of 5:1, a rotation speed of 200~350rpm, and a time of 15~20h. B. Preparation of feed: wax-based feed, with specific mass ratio of components: 50-55% paraffin PA, 30-35% polypropylene PP, 10-15% polyethylene PE, 2-3% polyvinyl butyral PVB, 1-2% dioctyl phthalate DOP, 1-2% oleic acid OA; C. Injection molding: feed the material into the injection molding machine and inject it to obtain the green body. The injection temperature is 165~175℃; D. Degreasing and pre-sintering: first, the green body is placed in an organic solvent at 30-45℃ for 8-15 hours for solvent degreasing. After solvent degreasing, hot degreasing and pre-sintering are performed to remove the binder and give the green body a certain strength, with a relative density of 90-93%; E. Hot isostatic pressing sintering: placing the pre-sintered blank in a hot isostatic pressing furnace for sintering; F. Heat treatment: After sintering, keep it at 750~800℃ for 5~10min for quenching. After quenching, keep it at 250~300℃ for 30~60min for annealing.

2. The method for preparing a powder metallurgy amorphous composite material by injection molding according to claim 1, characterized in that: The atomic molar ratio of the amorphous powder is (Zr 35 Ti 15 Cu 15 Ni 12 Be 24 ) 100-x Y x , x=2~3, the powder is spherical or nearly spherical, and the particle size is not more than 80μm.

3. The method for preparing a powder metallurgy amorphous composite material by injection molding according to claim 1, characterized in that: The reinforcing phase powder is crystalline tungsten powder with a particle size of 50~200μm.

4. The method for preparing a powder metallurgy amorphous composite material by injection molding according to claim 1, characterized in that: The mass percentage of the amorphous powder and the reinforcing phase powder raw materials is 12-15%:85-88%.

5. The method for preparing a powder metallurgy amorphous composite material by injection molding according to claim 1, characterized in that: The thermal debinding and pre-sintering process is: heat up to 220~250℃ at 1~3℃ / min, keep warm for 30~60min, then heat up to 300~320℃ at 1~3℃ / min, keep warm for 60~90min, heat up to 380~400℃ at 1~3℃ / min, heat up to 420~450℃ at 5~10℃, keep warm for 10~20min, with Ar2 or N2 protection throughout the process.

6. The method for preparing a powder metallurgy amorphous composite material by injection molding according to claim 1, characterized in that: Hot isostatic pressing sintering adopts staged sintering, first heating to 560~600℃ and keeping warm for 20min, with pressure of 100~150MPa, then reducing pressure to 30~50MPa after keeping warm, heating to 670~720℃ and keeping warm for 10min.

Images