Titanium alloy injection molding method and titanium alloy part

Abstract

The application discloses a titanium alloy injection molding method and a titanium alloy part and relates to the technical field of titanium alloy part production. The titanium alloy injection molding method comprises the following steps: preparing raw materials, preparing the raw materials according to mass fractions, titanium metal powder 50-68%, complex-phase additives 4-8%, organic binders 20-38% and sintering aids 3-5%; drying, drying the titanium metal powder; dense mixing and granulation, mixing the dried titanium metal powder and the complex-phase additives, then adding the organic binders for dense mixing, and then performing granulation to obtain a feed; injection molding and sintering, injection molding and forming the feed after heating to obtain a green body; and sintering the green body again to obtain the titanium alloy part. The titanium alloy injection molding method can guarantee the stability in the part production process, improve the efficiency, and guarantee that the part has excellent performances such as high strength and high-temperature resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of titanium alloy part production, in particular to a titanium alloy injection molding method and a titanium alloy part. BACKGROUND

[0002] Titanium and titanium alloy have been widely used as structural materials in aerospace, automobile, submarine and medical implant due to its high specific strength, low modulus and excellent biocompatibility. Porous titanium and titanium alloy have high surface area and low modulus by introducing pores, which extends the application of titanium and titanium alloy in orthopedic implant materials, battery electrode materials, sound absorption materials and filter materials. The pore structure of porous titanium can be divided into two types: closed pore structure and open pore structure. Closed pore structure porous titanium has high damping, sound absorption and heat insulation functions due to its closed pores, and is mainly used in sound absorption materials and thermal protection materials. Open pore structure porous titanium has the functional properties of closed pore structure porous titanium, and also has filtering properties due to the interpenetration of pores, and is mainly used in orthopedic implant materials, battery electrode materials and filter materials.

[0003] At present, the preparation method of porous titanium and titanium alloy related parts mainly uses traditional powder metallurgy technology, including powder loose sintering, adding pore-forming agent method, organic foam impregnation method, freeze casting and fiber sintering. In the powder loose sintering, titanium metal powder is loose, and the sintered parts have high porosity and high permeability, which cannot meet the requirements of high precision and density. Therefore, organic binder is often added to form a green body before sintering, which can meet the requirements of higher density, strength and precision.

[0004] However, the existing titanium metal powder injection molding green body is prone to problems such as bubbling, internal delamination and surface whitening. These defects will cause the final parts sintered by the green body after subsequent processes to have low strength, be prone to cracking and have uneven surface.

[0005] Therefore, for titanium alloy parts, a titanium alloy injection molding method is needed to prevent the green body from having problems such as bubbling, internal delamination and surface whitening during the preparation of the titanium alloy green body. At the same time, special process and process parameters are provided to prevent the final parts sintered from having problems such as cracking and uneven surface, ensure the stability of the part production process, improve the efficiency, and at the same time ensure that the parts have high strength, high temperature resistance and other excellent properties. SUMMARY

[0006] In view of the defects of the prior art, the present application provides a titanium alloy injection molding method, which can prevent the green body from having problems such as bubbling, internal layering and surface whitening when preparing a titanium alloy green body, and provides special process operations to prevent the final part sintered out from having problems such as cracking and uneven surface, guarantee the stability in the production process of the part, improve the efficiency, and guarantee the part to have excellent properties such as high strength and high temperature resistance.

[0007] Specifically, the present application discloses a titanium alloy injection molding method, comprising the following steps:

[0008] Preparing raw materials, preparing raw materials according to mass fraction, titanium metal powder 50-68%, complex additive 4-8%, organic binder 20-38%, sintering aid 3-5%;

[0009] Drying, drying the titanium metal powder;

[0010] Intensive mixing and granulation, mixing the dried titanium metal powder and the complex additive, then adding the organic binder for intensive mixing, and then granulating to obtain the feedstock;

[0011] Injection molding and sintering, heating the feedstock and injection molding to obtain a green body; and then sintering the green body to obtain a titanium alloy part;

[0012] The organic binder comprises paraffin, polyethylene, stearic acid, polyethylene glycol, low-density polyethylene and ethylene-vinyl acetate copolymer.

[0013] Preferably, the paraffin accounts for 7-13% of the total mass of the raw materials, the polyethylene accounts for 3-5% of the total mass of the raw materials, the stearic acid accounts for 2-5% of the total mass of the raw materials, the polyethylene glycol accounts for 2-5% of the total mass of the raw materials, the low-density polyethylene accounts for 3-5% of the total mass of the raw materials, and the ethylene-vinyl acetate copolymer accounts for 3-5% of the total mass of the raw materials.

[0014] Preferably, the titanium metal powder has a mesh number of 180-220.

[0015] Preferably, the polyethylene, low-density ethylene, ethylene-vinyl acetate copolymer and stearic acid in the organic binder need to be dried before use.

[0016] Preferably, the complex additive is a titanium additive.

[0017] Preferably, the intensive mixing is stirring for 4-6h at 90-110℃.

[0018] Preferably, the injection molding is forming by pressing, cooling and solidifying after being in a molten flow state at 80-110℃.

[0019] Preferably, the sintering comprises a baking debinding stage, a semi-sintering stage and a full sintering stage; the semi-sintering stage is to heat to 880-920℃ at a heating rate of 200-230℃ / h, and keep for 2-3h; the full sintering stage is to heat to 1300-1400℃ at a heating rate of 90-120℃ / h, and keep for 3-5h.

[0020] Preferably, the baking debinding stage is to heat to 140-160℃ at a heating rate of 15-25℃ / h, and keep for 2-3h, then heat to 280-320℃ at a heating rate of 25-35℃ / h, and keep for 2-4h, then heat to 480-520℃ at a heating rate of 35-55℃ / h, and keep for 4-6h.

[0021] The application further discloses a titanium alloy part prepared by the titanium alloy injection molding method.

[0022] Beneficial effects:

[0023] (1) The titanium alloy injection molding method has the advantages that the moisture content in the green body is strictly limited by fully drying the raw material and matching the injection molding feeding process, thereby preventing the green body from having problems such as bubbling, internal layering and surface whitening, and the specific sintering process can be matched to prepare the titanium alloy part with high quality, and the whole production process is stable and has a high yield.

[0024] (2) The titanium alloy part prepared by the titanium alloy injection molding method has low porosity, stable structure, high strength, and excellent properties such as high-temperature resistance and corrosion resistance, and the titanium alloy part has excellent performance and a wide application range, and can be used as a shell, a part and the like. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical scheme of the application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative effort.

[0026] Figure 1 Fig. 1 is a schematic diagram of the titanium alloy part of the embodiment 1 of the application;

[0027] Figure 2 Fig. 2 is a microstructure schematic diagram of the titanium alloy part of the embodiment 1 of the application;

[0028] Figure 3 Fig. 3 is a microstructure schematic diagram of the part of the comparative example 1. DETAILED DESCRIPTION

[0029] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0030] It should be understood that the terms "comprising" and "including" as used in the specification and the appended claims indicate the presence of the described features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0031] It should also be understood that the terms used in the present application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the present application specification and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0032] It should be further understood that the term "and / or" as used in the present application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0033] It should be further understood that the term "concentration" as used in the present application specification and the appended claims refers to mass concentration, and "%" refers to mass percentage; otherwise, it is explained.

[0034] A titanium alloy injection molding method,

[0035] First, titanium metal powder is thoroughly dried with an organic binder, then uniformly mixed and kneaded, and then the kneaded feed is granulated and injected into a mold cavity under a heated plasticized state (i.e. 80-110℃ molten flow state) to solidify and form, then the binder in the formed blank is removed by thermal decomposition, and finally high-temperature sintering densification is performed to obtain the final titanium alloy part.

[0036] Specifically, the method comprises the following steps:

[0037] Prepare raw materials, prepare raw materials according to mass fraction, titanium metal powder 50-68%, multiphase additive 4-8%, organic binder 20-38%, and sintering aid 3-5%;

[0038] Drying, drying the titanium metal powder;

[0039] Mixing granulation, mixing the dried titanium metal powder and the composite additive, then adding the organic binder to mix, and then granulating to obtain the feedstock;

[0040] Injection sintering, heating the feedstock and injection molding to obtain the green body, and then sintering the green body to obtain the titanium alloy part.

[0041] Preferably, the organic binder includes paraffin, polyethylene, stearic acid, polyethylene glycol, low-density polyethylene, and ethylene-vinyl acetate copolymer; the polyethylene, low-density polyethylene, and ethylene-vinyl acetate copolymer in the organic binder need to be dried before use, and the stearic acid also needs to be dried before use.

[0042] Preferably, the mixing is stirring for 4-6 h at 90-110℃.

[0043] Preferably, the injection molding is pressing and cooling after being in a molten flow state at 80-110℃, and then solidifying and shaping.

[0044] Preferably, the sintering includes a baking and debinding stage, a semi-sintering stage, and a complete sintering stage; the semi-sintering stage is heating to 880-920℃ at a heating rate of 200-230℃ / h and holding for 2-3 h; the complete sintering stage is heating to 1300-1400℃ at a heating rate of 90-120℃ / h and holding for 3-5 h; the baking and debinding stage is preferably heating to 140-160℃ at a heating rate of 15-25℃ / h and holding for 2-3 h, then heating to 280-320℃ at a heating rate of 25-35℃ / h and holding for 2-4 h, and then heating to 480-520℃ at a heating rate of 35-55℃ / h and holding for 4-6 h.

[0045] More specifically,

[0046] Preparing raw materials: preparing raw materials according to mass fraction, titanium metal powder 50-68%, composite additive 4-8%, organic binder 20-38%, and sintering aid 3-5%;

[0047] The titanium metal powder has a mesh size of 180-220 mesh;

[0048] The organic binder includes paraffin, polyethylene, stearic acid, polyethylene glycol, low-density polyethylene, and ethylene-vinyl acetate copolymer; according to mass fraction, the paraffin accounts for 7-13% of the total mass of the raw materials, the polyethylene accounts for 3-5% of the total mass of the raw materials, the stearic acid accounts for 2-5% of the total mass of the raw materials, the polyethylene glycol accounts for 2-5% of the total mass of the raw materials, the low-density polyethylene accounts for 3-5% of the total mass of the raw materials, and the ethylene-vinyl acetate copolymer accounts for 3-5% of the total mass of the raw materials;

[0049] The complex phase additive is preferably a titanium additive, specifically, one or a mixture of more of Ti40B4, Ti30B4, Ti30B3, and Ti60B, and similar component structure titanium additives; Ti40B4 is a titanium additive containing boron, wherein the mass fraction of titanium is 40%, and the mass fraction of boron is 4%; Ti30B4, Ti30B3, and Ti60B (i.e., Ti60B1) are the same.

[0050] The sintering aid lowers the interface melting point between titanium alloy material particles, facilitates and promotes the sintering of titanium alloy material particles, thereby forming a sintering network, greatly improving the sintering strength of the manufactured parts; the sintering aid can be preferably one or a mixture of more of boron oxide (B2O3), corundum (Al2O3), magnesia, bauxite.

[0051] Then, the titanium metal powder and part of the organic binder (the organic binder needs to be dried before use, including polyethylene, stearic acid, polyethylene glycol, low-density polyethylene, and ethylene-vinyl acetate copolymer) are dried; preferably, the drying conditions of the titanium metal powder are 100-120°C for 2-4h; the drying conditions of polyethylene (PE) are 50-75°C for 2-4h; the drying conditions of low-density polyethylene (LDPE) are 50-75°C for 2-4h; the drying conditions of ethylene-vinyl acetate copolymer (EVA) are 40-50°C for 2-4h; the drying conditions of stearic acid (SA) are 60-80°C for 2-3h; in the above drying conditions, the temperature and time can be appropriately increased or extended according to the environmental humidity to ensure that the water content in the raw materials is low; the water content of other raw materials is negligible, so they can be dried.

[0052] Next, the dried titanium metal powder and the complex phase additive are added to a three-dimensional mixer, mixed at a speed of 100-120r / min for 4-6 hours, and collected after mixing is completed.

[0053] The paraffin, polyethylene (PE), stearic acid (SA), polyethylene glycol (PEG), low-density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), and sintering aid are put into an internal mixer together and mechanically stirred at a temperature of 90-110°C for 4-6 hours, then taken out and cooled. During the cooling process, the mixed feed is divided into 10cm square blocks for standby use.

[0054] The 10cm square feed is put into a crusher and crushed into 2cm irregular particles.

[0055] The broken feed particles are put into a granulator to be granulated into regular particles similar to rice grains, and the granulated feed particles are obtained.

[0056] The granulated feed particles are added into the barrel of an injection molding machine and heated to 80-110℃ to become a molten flow state, and then pushed into a closed mold by the screw of the barrel of the injection molding machine at a speed of 10-30mm / s (mold temperature 35-45℃), and then kept at a pressure of 20-50bar for 2-4s, and then cooled for 10-15s to solidify and shape, and then the mold is opened to take out the required green body.

[0057] The metal green body is put into a sintering furnace to be sintered to obtain the final product (titanium alloy part). The sintering includes a baking and debinding stage, a semi-sintering stage and a full sintering stage; in the semi-sintering stage, the temperature is raised to 880-920℃ at a rate of 200-230℃ / h, and kept for 2-3h; in the full sintering stage, the temperature is raised to 1300-1400℃ at a rate of 90-120℃ / h, and kept for 3-5h.

[0058] Specifically, in the baking and debinding stage, the temperature is first slowly raised to completely remove the water in the furnace, and then the water in the green body is evaporated and the binder is removed; to avoid the water vapor rapidly escaping from the green body and causing cracks and bubbles, the rate of temperature rise and the holding time are also limited; preferably, in the baking and debinding stage, the temperature is raised to 140-160℃ at a rate of 15-25℃ / h, and kept for 2-3h, then raised to 280-320℃ at a rate of 25-35℃ / h, and kept for 2-4h, and then raised to 480-520℃ at a rate of 35-55℃ / h, and kept for 4-6h.

[0059] A titanium alloy part,

[0060] Prepared by the above titanium alloy injection molding method; the shape of the titanium alloy part can be determined by the mold shape in the feed process, and can be used as a shell, a part, etc., with a wide range of applications.

[0061] Example 1,

[0062] A method for injection molding of a titanium alloy shell part of an electronic cigarette is as follows:

[0063] (1) Put the raw materials into a drying machine for drying treatment according to a certain process:

[0064] Put the titanium metal powder into a drying oven at 100℃ for 2 hours to reduce the water content;

[0065] Polyethylene (PE) dried at 75°C for 2 hours;

[0066] Low density polyethylene (LDPE) dried at 75°C for 2 hours;

[0067] Ethylene-vinyl acetate copolymer (EVA) dried at 50°C for 2 hours;

[0068] Stearic acid (SA) dried at 80°C for 2 hours.

[0069] (2) The dried raw materials are prepared by injection molding feed preparation;

[0070] Titanium metal powder of 200 mesh is weighed at 68%, and composite additive is weighed at 8%, and is added to a three-dimensional mixer, and is mixed for 4 hours under the condition that the rotating speed is 120 r / min, and is collected after mixing is completed. The composite additive is a titanium additive, and is preferably Ti 60B.

[0071] Then: paraffin 7%; polyethylene (PE) 3%; stearic acid (SA) 2%; polyethylene glycol (PEG) 2%; low density polyethylene (LDPE) 3%; ethylene-vinyl acetate copolymer (EVA) 3%; and sintering aid 4% are put into an internal mixer, and are mechanically stirred for 4 hours at a temperature of 100°C, and are taken out and cooled, and in the cooling process, the mixed feed is divided into 10 cm blocks for standby. The sintering aid is preferably boron oxide.

[0072] The 10 cm block feed is put into a crusher to be crushed into irregular particles of about 2 cm.

[0073] The crushed feed particles are put into a granulator for granulation, and regular particles similar to rice size are obtained, and at this time, the feed required for injection molding is obtained. (Granulator process parameters: temperature of rear section of material pipe 60°C, temperature of middle section of material pipe 75°C, temperature of front section of material pipe 80°C, temperature of discharge port 85°C, rotating speed of screw 45 mpr, rotating speed of cutter 60 mpr)

[0074] (3) The prepared feed is injection molded

[0075] The granulated feed is added to the barrel of an injection molding machine, and is heated to 100°C to become a molten flow state, and then is pushed into a closed mold (mold temperature 40°C) by the screw of the injection molding machine at a speed of 30 mm / s, and then is kept at a pressure of 30 bar for 2 s, and then is cooled for 10 s for solidification and setting, and then the mold is opened to take out the required green body.

[0076] (4) The green body is debound and sintered to obtain the final product

[0077] Put the metal green body into the sintering furnace, heat up to 150℃ at 15℃ / h, keep for 2h, heat up to 300℃ at 25℃ / h, keep for 2h, heat up to 500℃ at 35℃ / h, keep for 4h, heat up to 900℃ at 200℃ / h, keep for 2h, heat up to 1350℃ at 90℃ / h, keep for 3h, cool to room temperature. The final electronic cigarette shell part is obtained.

[0078] Example 2,

[0079] A method for injection molding of an electronic cigarette titanium alloy shell part is as follows:

[0080] (1) Put the raw materials into the dryer for drying treatment according to a certain process:

[0081] Put the titanium metal powder into the drying oven at 120℃ for 2 hours to reduce the water content;

[0082] Polyethylene (PE) is dried at 50℃ for 4 hours;

[0083] Low-density polyethylene (LDPE) is dried at 50℃ for 4 hours;

[0084] Ethylene-vinyl acetate copolymer (EVA) is dried at 40℃ for 4 hours;

[0085] Stearic acid (SA) is dried at 60℃ for 3 hours.

[0086] (2) Prepare the injection feed material by drying the raw materials;

[0087] Weigh 50% of 180 mesh titanium metal powder, weigh 7% of composite additive, add to the three-dimensional mixer, mix at a speed of 100r / min for 6 hours, and collect after mixing is completed. The composite additive is preferably a mixture of Ti40B4, Ti30B4 and Ti30B3, and the mass ratio of the three is 3:3:1.

[0088] Then put: paraffin wax 13%; polyethylene (PE) 5%; stearic acid (SA) 5%; polyethylene glycol (PEG) 5%; low-density polyethylene (LDPE) 5%; ethylene-vinyl acetate copolymer (EVA) 5%; and sintering aid 5% into the internal mixer and mechanically stir at a temperature of 90℃ for 6 hours, then take out and cool. During the cooling process, the mixed feed material is divided into 10cm squares for standby use. The sintering aid is a mixture of boron oxide, magnesia and alumina, and the mass ratio of the three is 3:1:1.

[0089] Put the 10cm square feed material into the crusher to crush into irregular particles of about 2cm.

[0090] The broken feed particles are put into a granulator for granulation to form regular particles similar to rice grains, and the granulated feed particles are obtained.

[0091] (3) The prepared feed particles are subjected to injection molding

[0092] The granulated feed particles are added into the barrel of an injection molding machine and heated to 80°C to become a molten flow state, and then pushed into a closed mold at a speed of 10 mm / s by the screw of the barrel of the injection molding machine (mold temperature 45°C), and then kept at a pressure of 20 bar for 4 s, and then cooled for 15 s for solidification and setting, and then the mold is opened to take out the required green body.

[0093] (4) The green body is subjected to debinding and sintering to obtain the final product

[0094] The metal green body is placed in a sintering furnace, heated to 160°C at a rate of 25°C / h, kept for 3 h, heated to 320°C at a rate of 35°C / h, kept for 4 h, heated to 520°C at a rate of 55°C / h, kept for 6 h, heated to 920°C at a rate of 230°C / h, kept for 3 h, heated to 1400°C at a rate of 120°C / h, kept for 5 h, and cooled to room temperature. The final electronic cigarette shell part is obtained.

[0095] Example 3,

[0096] An injection molding method for an electronic cigarette titanium alloy shell part is as follows:

[0097] (1) The raw materials are placed in a drying machine for drying treatment according to a certain process:

[0098] Titanium metal powder is placed in a drying oven at 100°C for 4 hours to reduce the water content;

[0099] Polyethylene (PE) is dried at 65°C for 2 hours;

[0100] Low-density polyethylene (LDPE) is dried at 65°C for 3 hours;

[0101] Ethylene-vinyl acetate copolymer (EVA) is dried at 45°C for 3 hours;

[0102] Stearic acid (SA) is dried at 70°C for 5 hours.

[0103] (2) The dried raw materials are subjected to injection molding feed preparation;

[0104] The 58% of 220 mesh titanium metal powder is weighed, 6.5% of the composite additive is weighed, and is added to a three-dimensional mixer. The speed is 120 r / min. The mixing is carried out for 4 hours. After the mixing is completed, the mixture is collected. The composite additive is preferably a mixture of Ti30B4, Ti30B3 and Ti60B, and the mass ratio of the three is 2:2:2:5.

[0105] The paraffin 11%, polyethylene (PE) 4%, stearic acid (SA) 4.5%, polyethylene glycol (PEG) 4.5%, low-density polyethylene (LDPE) 4.5%, ethylene-vinyl acetate copolymer (EVA) 4%, and sintering aid 3% are put into a banbury mixer and mechanically stirred at 110°C for 4 hours, and then taken out and cooled. During the cooling process, the mixed feedstock is divided into 10 cm cubes for standby use. The sintering aid is a mixture of boron oxide, corundum and bauxite, and the mass ratio of the three is 1:1:1.

[0106] The 10 cm cube feedstock is put into a crusher and crushed into irregular particles of about 2 cm.

[0107] The crushed feedstock particles are put into a granulator for granulation, and regular particles similar to rice grains are obtained, which are the feedstock required for injection molding.

[0108] (3) The prepared feedstock is injection molded

[0109] The granulated feedstock is added to the barrel of an injection molding machine and heated to 110°C to become a molten flow state. Then the screw of the injection molding machine is pushed into a closed mold at a speed of 30 mm / s (mold temperature 35°C), and then the pressure is kept at 50 bar for 2 s, and then cooled for 12 s for solidification and setting. After that, the mold is opened and the required green body is taken out.

[0110] (4) The green body is debound and sintered to obtain the final product

[0111] The metal green body is put into a sintering furnace, and the temperature is raised to 140°C at a rate of 20°C / h, kept for 2 h, raised to 280°C at a rate of 30°C / h, kept for 2 h, raised to 480°C at a rate of 45°C / h, kept for 4 h, raised to 880°C at a rate of 210°C / h, kept for 2 h, raised to 1300°C at a rate of 90°C / h, kept for 3 h, and then cooled to room temperature. The final electronic cigarette shell part is obtained.

[0112] According to Example 1, a comparative example is set up. The difference between the comparative example and Example 1 is shown in Table 1.

[0113] Table 1 Difference between the comparative example and Example 1

[0114]

[0115]

[0116] The part not up to 100% in the above comparative example is made up to 100% by the sintering aid.

[0117] The green body and titanium alloy parts prepared by the examples and comparative examples are detected, and the results are shown in Tables 2-3.

[0118] Ultimate tensile strength test: the sample bar is 4mm*3mm in cross section and 10mm in gauge length, and is measured by an instron screw machine (5054, USA) at a speed of 1mm / min.

[0119] wherein, Figure 1 Fig. 1 is a schematic diagram of the titanium alloy part prepared in Example 1. The parts prepared in Example 1 and Comparative Example 1 are observed at the same magnification, and it is found that Figures 2-3 ; Figure 2 Fig. 1 is a schematic diagram of the titanium alloy part prepared in Example 1. The parts prepared in Example 1 and Comparative Example 1 are observed at the same magnification, and it is found that Figure 3 Fig. 1 is a schematic diagram of the titanium alloy part prepared in Example 1. The parts prepared in Example 1 and Comparative Example 1 are observed at the same magnification, and it is found that Figures 2-3 It can be seen that the titanium alloy part prepared in Example 1 has high density, while the part prepared in Comparative Example 1 is prone to have holes, resulting in reduced strength or other defects.

[0120] Table 2: detection results of Examples 1-3

[0121]

[0122] Table 3: detection results of Comparative Examples 1-13

[0123]

[0124]

[0125] As can be seen from Tables 2-3, the titanium alloy injection molding method of Examples 1-3 can prepare green bodies and parts with complete appearance and no defects, and the titanium alloy parts prepared have high yield, high strength and excellent performance. That is, the titanium alloy injection molding method has high efficiency, and can stably prepare titanium alloy parts with high strength and other excellent properties, and has high yield.

[0126] In the comparative examples, the defatting and sintering process parameters of Comparative Examples 10-13 are different from the parameter ranges of the present application. Although the effects on the appearance of the green body and the appearance of the sintered part are relatively small, the production efficiency will be low. In Comparative Example 8, the addition of stearic acid (SA) will affect the product demolding, resulting in the occurrence of the phenomenon of sticking to the mold. The role of stearic acid is to increase lubricity, so that the green body can be easily taken out of the mold. The remaining comparative examples will more or less have some problems. The items crossed out by " / " are unusable parts and are not counted.

[0127] In the above examples, the description of each example has its own emphasis, and the parts not described in detail in a certain example can be referred to the relevant description of other examples.

[0128] The above only describes the embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation, or direct or indirect application in other related technical fields, which is made by using the content of the present application specification and drawings, is also included in the patent protection scope of the present application.

Claims

1. A method for injection molding titanium alloys, characterized in that, Includes the following steps: Prepare raw materials according to the following mass fractions: titanium metal powder 50-68%, multiphase additives 4-8%, organic binders 20-38%, and sintering aids 3-5%. Drying: Drying the titanium metal powder; The process involves mixing dried titanium metal powder with multiphase additives, adding an organic binder, mixing the mixture, and then granulating it to obtain the feed. Injection molding and sintering involves heating the feed material and then injection molding it to obtain a green blank; the green blank is then sintered to obtain a titanium alloy part. The organic binder includes paraffin wax, polyethylene, stearic acid, polyethylene glycol, low-density polyethylene, and ethylene-vinyl acetate copolymer. The titanium metal powder has a mesh size of 180-220. The sintering process includes a baking and degreasing stage, a semi-sintering stage, and a complete sintering stage. The semi-sintering stage involves heating the temperature to 880-920℃ at a heating rate of 200-230℃ / h and holding it at that temperature for 2-3 hours. The complete sintering stage involves heating the temperature to 1300-1400℃ at a heating rate of 90-120℃ / h and holding it at that temperature for 3-5 hours.

2. The titanium alloy injection molding method as described in claim 1, characterized in that, By mass fraction, the paraffin wax accounts for 7-13% of the total mass of the raw materials, the polyethylene accounts for 3-5% of the total mass of the raw materials, the stearic acid accounts for 2-5% of the total mass of the raw materials, the polyethylene glycol accounts for 2-5% of the total mass of the raw materials, the low-density polyethylene accounts for 3-5% of the total mass of the raw materials, and the ethylene-vinyl acetate copolymer accounts for 3-5% of the total mass of the raw materials.

3. The titanium alloy injection molding method as described in claim 2, characterized in that, In the organic binder, polyethylene, low-density ethylene, ethylene-vinyl acetate copolymer, and stearic acid need to be dried before use.

4. The titanium alloy injection molding method as described in claim 1, characterized in that, The multiphase additive is a titanium additive.

5. The titanium alloy injection molding method as described in claim 1, characterized in that, The mixing process involves stirring at 90-110℃ for 4-6 hours.

6. The titanium alloy injection molding method as described in claim 1, characterized in that, The injection molding process involves melting and flowing the material at 80-110°C, followed by pressing, cooling, and solidification.

7. The titanium alloy injection molding method as described in claim 1, characterized in that, The baking and degreasing stage consists of heating to 140-160℃ at a rate of 15-25℃ / h, holding for 2-3 hours, then heating to 280-320℃ at a rate of 25-35℃ / h, holding for 2-4 hours, and then heating to 480-520℃ at a rate of 35-55℃ / h, holding for 4-6 hours.

8. A titanium alloy part, prepared by the titanium alloy injection molding method as described in any one of claims 1-7.

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