Medical instrument titanium alloy powder metallurgy injection molding and production process thereof

Abstract

The invention provides a medical instrument titanium alloy powder metallurgy injection molding production process which comprises the steps that spherical titanium alloy powder is prepared in a gas atomization mode, and the titanium alloy powder is composed of, by mass, 6%-8% of Al, 4%-5% of Nb, 1%-2% of V, 0.4%-0.6% of Cu, 0.05%-0.07% of C, 0.1%-0.16% of O and the balance Ti and inevitable impurities; a binder and titanium alloy powder are mixed and subjected to banburying, and injection molding feed is obtained; placing the injection molding feed in a powder injection molding machine to obtain a primary blank; degreasing the initial blank with nitric acid to remove the binder; and after cooling, a titanium alloy metallurgy injection molding product is obtained. The hardness and corrosion resistance of the product manufactured by the method meet the requirements of clamping or retracting surgical instruments, and the method is suitable for automatic production.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, and in particular to medical device titanium alloy powder metallurgy injection molding and a production process thereof. Background Art

[0002] Titanium alloy powder metallurgy injection molding process injection molding, as a new type of titanium alloy near-net forming technology. Titanium alloy is widely used in the medical device industry. Titanium alloy plates have high material costs, long processing time, complex processing technology, slow mass production, large individuality, high labor costs, and high enterprise operation costs. Titanium alloy powder metallurgy injection molding process injection molding, through the precision mold injection titanium alloy powder feeding injection molding process has made a historic innovation in the processing technology.

[0003] According to the characteristics of titanium alloy medical devices, it is required to make titanium alloy medical devices and difficult to machine them, because the thermal conductivity of titanium alloy is small, about 1 / 3 of iron, and the heat generated during machining is difficult to release through the workpiece; at the same time, due to the small specific heat of titanium alloy, the local temperature rises quickly during machining, so it is easy to cause the tool temperature to be very high, causing the tip of the tool to wear sharply and reduce the service life. Experiments have shown that the front temperature of the tool for cutting titanium alloy is 2-3 times higher than that of cutting steel. The low elastic modulus of titanium alloy makes it easy for the machined surface to rebound, especially the machining rebound of thin-walled parts is more serious, which is easy to cause strong friction between the back tool face and the machined surface, thereby wearing the tool and breaking the edge. Titanium alloy is very chemically active and easily reacts with oxygen, hydrogen, and nitrogen at high temperatures, increasing its hardness and reducing its plasticity. The oxygen-rich layer formed during heating and forging is difficult to machine.

[0004] There are many traditional machining methods for titanium alloy medical devices, mainly including: turning, milling, boring, drilling, grinding, tapping, sawing, EDM, punching, wire cutting, etc. The traditional machining methods for titanium alloy medical devices have a large margin on the product cost, the size of the blank is larger than the finished product, and the geometric tolerance is relatively discrete, which cannot realize automated production, and the waste of raw materials is nearly half (50% of the raw materials are punched and cut off and cannot be used), repeated heating production (such as hot forging, rough pressing and annealing or rough pressing, rough cutting and annealing, etc.), repeated heating will lose the inherent properties of the material, the structure of clamping or retracting surgical instruments (such as teeth, spring grooves, etc. on surgical forceps, finger rings on surgical forceps, etc.) still need to be processed, forging production noise is large, and a large number of skilled workers are required, the operating cost of the enterprise is high, and the production cycle of the product is long, which increases the operating cost of the enterprise.

[0005] Based on this, the present invention provides a titanium alloy powder metallurgy injection molding production process for medical devices. Summary of the invention

[0006] The purpose of the present invention is to provide a titanium alloy powder metallurgy injection molding production process for medical devices, so that the hardness and corrosion resistance of the manufactured products meet the requirements of clamping or retraction surgical instruments, 100% of the raw materials are utilized, the geometric size tolerance is reduced, and it is suitable for automated production. It makes sufficient technical preparations for subsequent manual automated production, reduces the demand for labor, shortens the production cycle, and reduces the operating costs of the enterprise.

[0007] On the one hand, the present invention provides a production process for titanium alloy powder metallurgy injection molding of medical devices, comprising the following steps: (1) preparing spherical titanium alloy powder by atomization, wherein the titanium alloy powder is composed of the following elements by weight: 6-8% Al, 4-5% Nb, 1-2% V, 0.4-0.6% Cu, 0.05%-0.07% C, 0.1-0.16% O, and the remainder is Ti and inevitable impurities; (2) mixing a binder and the titanium alloy powder and performing internal refining to obtain an injection molding feed; (3) placing the injection molding feed in a powder injection molding machine to obtain a blank; (4) degreasing the blank with nitric acid to remove the binder; and (5) performing vacuum sintering to obtain a titanium alloy metallurgy injection molding product after cooling.

[0008] Furthermore, the powder particle size D50 of the titanium alloy powder is 8-10 um.

[0009] Furthermore, the binder comprises polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of (80-90):(7-9):(5-8):(2-4).

[0010] Furthermore, the preparation method of the adhesive comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio, and mixing them in a mixer at 120-130° C. for 3-4 hours to obtain the adhesive.

[0011] Furthermore, the volume ratio of the binder to the titanium alloy powder is (11-13): (87-89).

[0012] Furthermore, the banburying temperature is 155-165° C., the banburying time is 80-90 min, and the oxygen content during banburying is 2000-2500 ppm.

[0013] Furthermore, the injection molding step parameters include: mold temperature of 40-50°C, temperature of the first section of the injection molding screw of 165-175°C, temperature of the second section of 175-185°C, temperature of the third section of 195-205°C, nozzle temperature of 210-220°C, injection pressure of 100-120MPa, holding pressure of 85-95MPa, injection time of 3-5s, and cooling time of 6-8s.

[0014] Furthermore, the degreasing acid feeding amount is 2-4 g / min, the degreasing temperature is 115-125° C., and the degreasing time is 6-8 h.

[0015] Furthermore, during the sintering, the temperature is increased to 650-750°C at a heating rate of 5-7°C / min, kept at this temperature for 50-70min, and then increased to between 1340°C and 1380°C at a heating rate of 8-10°C / min, and kept at this temperature for 120-140min.

[0016] Furthermore, the vacuum degree during sintering is 1-3×10 -2 .

[0017] The beneficial effects of the present invention are:

[0018] (1) The present invention achieves good bonding between the binder and the titanium alloy powder by precisely controlling the elemental composition of the titanium alloy powder and the raw materials and proportion of the binder, while ensuring the smooth progress of the degreasing process; wherein polyoxymethylene has excellent mechanical properties and thermal stability, high-density polyethylene and ethylene-vinyl acetate copolymer provide good flexibility and processability, and stearic acid as a lubricant can reduce the friction between the powder and the mold; the reasonable combination of these components enables the binder to be tightly bonded to the titanium alloy powder and to be easily removed during the degreasing process;

[0019] (2) The elemental composition of the titanium alloy powder in the present invention is carefully designed to meet the requirements of clamping or retraction surgical instruments for hardness and corrosion resistance, wherein the addition of Al and Nb can improve the strength and hardness of the titanium alloy, while the addition of Cu helps to improve its corrosion resistance; further, when the titanium alloy powder contains 6-8% Al, 4-5% Nb, 1-2% V, and 0.4-0.6% Cu at the same time, the hardness and corrosion resistance of the prepared product meet the requirements of clamping or retraction surgical instruments;

[0020] (3) The parameters of the injection molding step in the present invention include: mold temperature of 40-50°C, temperature of the first section of the injection molding screw of 165-175°C, temperature of the second section of the injection molding screw of 175-185°C, temperature of the third section of the injection molding screw of 195-205°C, nozzle temperature of 210-220°C, injection pressure of 100-120MPa, holding pressure of 85-95MPa, injection time of 3-5s, and cooling time of 6-8s; wherein the control of parameters such as mold temperature and injection pressure is crucial to the precision and quality of the preform; appropriate mold temperature and injection pressure can ensure uniform filling and tight compaction of the powder in the mold, thereby obtaining a high-quality preform; reasonable injection pressure and holding pressure can ensure the compactness and dimensional accuracy of the preform; accurate injection time and cooling time can ensure sufficient solidification of the preform and stability before demolding;

[0021] (4) In the degreasing process of the present invention, the selection of oxalic acid and the control of degreasing conditions are intended to ensure the complete removal of the binder while avoiding damage to the titanium alloy powder. During the sintering process, the temperature is raised to 650-750°C at a heating rate of 5-7°C / min, kept warm for 50-70 minutes, and then raised to between 1340°C and 1380°C at a heating rate of 8-10°C / min, and kept warm for 120-140 minutes. By precisely controlling the heating rate, sufficient diffusion and bonding between powder particles can be ensured, so that the titanium alloy powder is fully sintered and densified, and the control of the holding time and vacuum degree helps to eliminate pores and reduce impurity content, thereby improving the hardness and corrosion resistance of the product, and finally obtaining a titanium alloy metallurgical injection molding product with excellent performance. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that the weight average molecular weight of the raw material polyoxymethylene used in the present invention is 20,000 Daltons; the weight average molecular weight of the high-density polyethylene is 50,000 Daltons; and the weight average molecular weight of the ethylene-vinyl acetate copolymer is 2,000 Daltons.

[0024] Example 1

[0025] This embodiment provides a titanium alloy powder metallurgy injection molding production process for medical devices, the steps comprising:

[0026] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 7% Al, 4.5% Nb, 1.5% V, 0.5% Cu, 0.06% C, 0.13% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 9 um;

[0027] (2) mixing a binder and titanium alloy powder in a volume ratio of 12:88 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 160° C., the internal kneading time is 85 min, and the oxygen content during internal kneading is 2250 ppm;

[0028] The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of 85:8:7:3, mixing them in a mixer at 125° C. for 3.5 hours to prepare the binder;

[0029] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 45° C., injection molding screw first section temperature of 170° C., second section temperature of 180° C., third section temperature of 200° C., nozzle temperature of 215° C., injection pressure of 110 MPa, holding pressure of 90 MPa, injection time of 4 s, and cooling time of 7 s;

[0030] (4) Degreasing the blank with nitric acid to remove the binder; the degreasing acid feed rate is 3 g / min, the degreasing temperature is 120° C., and the degreasing time is 7 h;

[0031] (5) Vacuum sintering was performed. During sintering, the temperature was raised to 700°C at a heating rate of 6°C / min, kept at this temperature for 60 min, and then raised to 1360°C at a heating rate of 9°C / min, and kept at this temperature for 130 min. The vacuum degree during sintering was 2×10 -2 After cooling, the titanium alloy metallurgical injection molding product is obtained.

[0032] Example 2

[0033] This embodiment provides a titanium alloy powder metallurgy injection molding production process for medical devices, the steps comprising:

[0034] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 6% Al, 4% Nb, 1% V, 0.4% Cu, 0.05% C, 0.1% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 8 um;

[0035] (2) mixing a binder and titanium alloy powder in a volume ratio of 11:89 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 155° C., the internal kneading time is 80 min, and the oxygen content during internal kneading is 2000 ppm;

[0036] The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of 80:7:5:2, mixing them in a mixer at 120° C. for 3 hours to prepare the binder;

[0037] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 40° C., injection molding screw first section temperature of 165° C., second section temperature of 175° C., third section temperature of 195° C., nozzle temperature of 210° C., injection pressure of 100 MPa, holding pressure of 85 MPa, injection time of 3 s, and cooling time of 6 s;

[0038] (4) Degreasing the blank with nitric acid to remove the binder; the degreasing acid feed rate is 2 g / min, the degreasing temperature is 115° C., and the degreasing time is 6 h;

[0039] (5) Vacuum sintering was performed. During sintering, the temperature was raised to 650°C at a heating rate of 5°C / min, and kept at this temperature for 50 min. Then, the temperature was raised to 1340°C at a heating rate of 8°C / min, and kept at this temperature for 120 min. The vacuum degree during sintering was 1×10 -2 After cooling, the titanium alloy metallurgical injection molding product is obtained.

[0040] Example 3

[0041] This embodiment provides a titanium alloy powder metallurgy injection molding production process for medical devices, the steps comprising:

[0042] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 8% Al, 5% Nb, 2% V, 0.6% Cu, 0.07% C, 0.16% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 10 um;

[0043] (2) mixing a binder and titanium alloy powder in a volume ratio of 13:87 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 165° C., the internal kneading time is 90 min, and the oxygen content during the internal kneading is 2500 ppm;

[0044] The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of 90:9:8:4, mixing them in a mixer at 130° C. for 4 hours to prepare the binder;

[0045] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 50° C., injection molding screw first section temperature of 175° C., second section temperature of 185° C., third section temperature of 205° C., nozzle temperature of 220° C., injection pressure of 120 MPa, holding pressure of 95 MPa, injection time of 5 s, and cooling time of 8 s;

[0046] (4) Degreasing the preform with nitric acid to remove the binder; the degreasing acid feed rate is 4 g / min, the degreasing temperature is 125° C., and the degreasing time is 8 h;

[0047] (5) Vacuum sintering was performed. During sintering, the temperature was raised to 750°C at a heating rate of 7°C / min, kept at this temperature for 70 min, and then raised to 1380°C at a heating rate of 10°C / min, kept at this temperature for 140 min. The vacuum degree during sintering was 3×10 -2After cooling, the titanium alloy metallurgical injection molding product is obtained.

[0048] Example 4

[0049] This embodiment provides a titanium alloy powder metallurgy injection molding production process for medical devices, the steps comprising:

[0050] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 6% Al, 5% Nb, 1% V, 0.6% Cu, 0.05% C, 0.16% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 9 um;

[0051] (2) mixing a binder and titanium alloy powder in a volume ratio of 13:87 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 165° C., the internal kneading time is 80 min, and the oxygen content during internal kneading is 2500 ppm;

[0052] The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of 80:9:5:4, mixing them in a mixer at 120° C. for 4 hours to prepare the binder;

[0053] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 40° C., injection molding screw first section temperature of 170° C., second section temperature of 180° C., third section temperature of 195° C., nozzle temperature of 220° C., injection pressure of 100 MPa, holding pressure of 95 MPa, injection time of 3 s, and cooling time of 8 s;

[0054] (4) Degreasing the blank with nitric acid to remove the binder; the degreasing acid feed rate is 2 g / min, the degreasing temperature is 125° C., and the degreasing time is 6 h;

[0055] (5) Vacuum sintering was performed. During sintering, the temperature was raised to 650°C at a heating rate of 7°C / min, and kept at this temperature for 70 min. Then, the temperature was raised to 1380°C at a heating rate of 8°C / min, and kept at this temperature for 120 min. The vacuum degree during sintering was 3×10 -2 After cooling, the titanium alloy metallurgical injection molding product is obtained.

[0056] Comparative Example 1

[0057] This comparative example provides a medical device titanium alloy powder metallurgy injection molding production process, the steps comprising:

[0058] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 7% Al, 2% Nb, 1.5% V, 0.5% Cu, 0.06% C, 0.13% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 9 um;

[0059] (2) mixing a binder and titanium alloy powder in a volume ratio of 12:88 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 160° C., the internal kneading time is 85 min, and the oxygen content during internal kneading is 2250 ppm;

[0060] The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of 85:8:7:3, mixing them in a mixer at 125° C. for 3.5 hours to prepare the binder;

[0061] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 45° C., injection molding screw first section temperature of 170° C., second section temperature of 180° C., third section temperature of 200° C., nozzle temperature of 215° C., injection pressure of 110 MPa, holding pressure of 90 MPa, injection time of 4 s, and cooling time of 7 s;

[0062] (4) Degreasing the blank with nitric acid to remove the binder; the degreasing acid feed rate is 3 g / min, the degreasing temperature is 120° C., and the degreasing time is 7 h;

[0063] (5) Vacuum sintering was performed. During sintering, the temperature was raised to 700°C at a heating rate of 6°C / min, kept at this temperature for 60 min, and then raised to 1360°C at a heating rate of 9°C / min, and kept at this temperature for 130 min. The vacuum degree during sintering was 2×10 -2 After cooling, the titanium alloy metallurgical injection molding product is obtained.

[0064] Comparative Example 2

[0065] This comparative example provides a medical device titanium alloy powder metallurgy injection molding production process, the steps comprising:

[0066] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 7% Al, 6% Nb, 1.5% V, 0.5% Cu, 0.06% C, 0.13% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 9 um;

[0067] (2) mixing a binder and titanium alloy powder in a volume ratio of 12:88 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 160° C., the internal kneading time is 85 min, and the oxygen content during internal kneading is 2250 ppm;

[0068] The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of 85:8:7:3, mixing them in a mixer at 125° C. for 3.5 hours to prepare the binder;

[0069] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 45° C., injection molding screw first section temperature of 170° C., second section temperature of 180° C., third section temperature of 200° C., nozzle temperature of 215° C., injection pressure of 110 MPa, holding pressure of 90 MPa, injection time of 4 s, and cooling time of 7 s;

[0070] (4) Degreasing the blank with nitric acid to remove the binder; the degreasing acid feed rate is 3 g / min, the degreasing temperature is 120° C., and the degreasing time is 7 h;

[0071] (5) Vacuum sintering was performed. During sintering, the temperature was raised to 700°C at a heating rate of 6°C / min, kept at this temperature for 60 min, and then raised to 1360°C at a heating rate of 9°C / min, and kept at this temperature for 130 min. The vacuum degree during sintering was 2×10 -2 After cooling, the titanium alloy metallurgical injection molding product is obtained.

[0072] Comparative Example 3

[0073] This comparative example provides a medical device titanium alloy powder metallurgy injection molding production process, the steps comprising:

[0074] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 7% Al, 4.5% Nb, 0.5% V, 0.5% Cu, 0.06% C, 0.13% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 9 um;

[0075] (2) mixing a binder and titanium alloy powder in a volume ratio of 12:88 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 160° C., the internal kneading time is 85 min, and the oxygen content during internal kneading is 2250 ppm;

[0076] The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of 85:8:7:3, mixing them in a mixer at 125° C. for 3.5 hours to prepare the binder;

[0077] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 45° C., injection molding screw first section temperature of 170° C., second section temperature of 180° C., third section temperature of 200° C., nozzle temperature of 215° C., injection pressure of 110 MPa, holding pressure of 90 MPa, injection time of 4 s, and cooling time of 7 s;

[0078] (4) Degreasing the blank with nitric acid to remove the binder; the degreasing acid feed rate is 3 g / min, the degreasing temperature is 120° C., and the degreasing time is 7 h;

[0079] (5) Vacuum sintering was performed. During sintering, the temperature was raised to 700°C at a heating rate of 6°C / min, kept at this temperature for 60 min, and then raised to 1360°C at a heating rate of 9°C / min, and kept at this temperature for 130 min. The vacuum degree during sintering was 2×10 -2 After cooling, the titanium alloy metallurgical injection molding product is obtained.

[0080] Comparative Example 4

[0081] This comparative example provides a medical device titanium alloy powder metallurgy injection molding production process, the steps comprising:

[0082] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 7% Al, 4.5% Nb, 2.5% V, 0.5% Cu, 0.06% C, 0.13% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 9 um;

[0083] (2) mixing a binder and titanium alloy powder in a volume ratio of 12:88 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 160° C., the internal kneading time is 85 min, and the oxygen content during internal kneading is 2250 ppm;

[0084] The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of 85:8:7:3, mixing them in a mixer at 125° C. for 3.5 hours to prepare the binder;

[0085] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 45° C., injection molding screw first section temperature of 170° C., second section temperature of 180° C., third section temperature of 200° C., nozzle temperature of 215° C., injection pressure of 110 MPa, holding pressure of 90 MPa, injection time of 4 s, and cooling time of 7 s;

[0086] (4) Degreasing the blank with nitric acid to remove the binder; the degreasing acid feed rate is 3 g / min, the degreasing temperature is 120° C., and the degreasing time is 7 h;

[0087] (5) Vacuum sintering was performed. During sintering, the temperature was raised to 700°C at a heating rate of 6°C / min, kept at this temperature for 60 min, and then raised to 1360°C at a heating rate of 9°C / min, and kept at this temperature for 130 min. The vacuum degree during sintering was 2×10 -2 After cooling, the titanium alloy metallurgical injection molding product is obtained.

[0088] Comparative Example 5

[0089] This comparative example provides a medical device titanium alloy powder metallurgy injection molding production process, the steps comprising:

[0090] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 7% Al, 4.5% Nb, 1.5% V, 0.5% Cu, 0.06% C, 0.13% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 9 um;

[0091] (2) mixing a binder and titanium alloy powder in a volume ratio of 12:88 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 160° C., the internal kneading time is 85 min, and the oxygen content during internal kneading is 2250 ppm;

[0092] The preparation method of the binder comprises: taking polyoxymethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of 85:7:3, mixing them in a mixer at 125° C. for 3.5 hours to prepare the binder;

[0093] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 45° C., injection molding screw first section temperature of 170° C., second section temperature of 180° C., third section temperature of 200° C., nozzle temperature of 215° C., injection pressure of 110 MPa, holding pressure of 90 MPa, injection time of 4 s, and cooling time of 7 s;

[0094] The preform prepared by the above method is softened and cannot maintain its shape.

[0095] Comparative Example 6

[0096] This comparative example provides a medical device titanium alloy powder metallurgy injection molding production process, the steps comprising:

[0097] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 7% Al, 4.5% Nb, 1.5% V, 0.5% Cu, 0.06% C, 0.13% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 9 um;

[0098] (2) mixing a binder and titanium alloy powder in a volume ratio of 12:88 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 160° C., the internal kneading time is 85 min, and the oxygen content during internal kneading is 2250 ppm;

[0099] The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene and stearic acid in a weight ratio of 85:8:3, mixing them in a mixer at 125° C. for 3.5 hours to prepare the binder;

[0100] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 45° C., injection molding screw first section temperature of 170° C., second section temperature of 180° C., third section temperature of 200° C., nozzle temperature of 215° C., injection pressure of 110 MPa, holding pressure of 90 MPa, injection time of 4 s, and cooling time of 7 s;

[0101] The preform prepared by the above method is softened and cannot maintain its shape.

[0102] Comparative Example 7

[0103] This comparative example provides a medical device titanium alloy powder metallurgy injection molding production process, the steps comprising:

[0104] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 7% Al, 4.5% Nb, 1.5% V, 0.5% Cu, 0.06% C, 0.13% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 9 um;

[0105] (2) mixing a binder and titanium alloy powder in a volume ratio of 12:88 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 160° C., the internal kneading time is 85 min, and the oxygen content during internal kneading is 2250 ppm;

[0106] The preparation method of the adhesive comprises: taking polyoxymethylene, high-density polyethylene and ethylene-vinyl acetate copolymer in a weight ratio of 85:8:7, mixing them in a mixer at 125° C. for 3.5 hours to prepare the adhesive;

[0107] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 45° C., injection molding screw first section temperature of 170° C., second section temperature of 180° C., third section temperature of 200° C., nozzle temperature of 215° C., injection pressure of 110 MPa, holding pressure of 90 MPa, injection time of 4 s, and cooling time of 7 s;

[0108] The preform prepared by the above method is softened and cannot maintain its shape.

[0109] Comparative Example 8

[0110] This comparative example provides a medical device titanium alloy powder metallurgy injection molding production process, the steps comprising:

[0111] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 7% Al, 4.5% Nb, 1.5% V, 0.5% Cu, 0.06% C, 0.13% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 9 um;

[0112] (2) mixing a binder and titanium alloy powder in a volume ratio of 12:88 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 160° C., the internal kneading time is 85 min, and the oxygen content during internal kneading is 2250 ppm;

[0113] The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of 85:8:7:3, mixing them in a mixer at 125° C. for 3.5 hours to prepare the binder;

[0114] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 45° C., injection molding screw first section temperature of 160° C., second section temperature of 170° C., third section temperature of 190° C., nozzle temperature of 205° C., injection pressure of 100 MPa, holding pressure of 80 MPa, injection time of 4 s, and cooling time of 7 s;

[0115] (4) Degreasing the blank with nitric acid to remove the binder; the degreasing acid feed rate is 3 g / min, the degreasing temperature is 120° C., and the degreasing time is 7 h;

[0116] (5) Vacuum sintering was performed. During sintering, the temperature was raised to 700°C at a heating rate of 6°C / min, kept at this temperature for 60 min, and then raised to 1360°C at a heating rate of 9°C / min, and kept at this temperature for 130 min. The vacuum degree during sintering was 2×10 -2 After cooling, the titanium alloy metallurgical injection molding product is obtained.

[0117] Comparative Example 9

[0118] This comparative example provides a medical device titanium alloy powder metallurgy injection molding production process, the steps comprising:

[0119] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 7% Al, 4.5% Nb, 1.5% V, 0.5% Cu, 0.06% C, 0.13% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 9 um;

[0120] (2) mixing a binder and titanium alloy powder in a volume ratio of 12:88 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 160° C., the internal kneading time is 85 min, and the oxygen content during internal kneading is 2250 ppm;

[0121] The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of 85:8:7:3, mixing them in a mixer at 125° C. for 3.5 hours to prepare the binder;

[0122] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 45° C., injection molding screw first section temperature of 180° C., second section temperature of 190° C., third section temperature of 210° C., nozzle temperature of 225° C., injection pressure of 120 MPa, holding pressure of 100 MPa, injection time of 4 s, and cooling time of 7 s;

[0123] (4) Degreasing the blank with nitric acid to remove the binder; the degreasing acid feed rate is 3 g / min, the degreasing temperature is 120° C., and the degreasing time is 7 h;

[0124] (5) Vacuum sintering was performed. During sintering, the temperature was raised to 700°C at a heating rate of 6°C / min, kept at this temperature for 60 min, and then raised to 1360°C at a heating rate of 9°C / min, and kept at this temperature for 130 min. The vacuum degree during sintering was 2×10 -2 After cooling, the titanium alloy metallurgical injection molding product is obtained.

[0125] Comparative Example 10

[0126] This comparative example provides a medical device titanium alloy powder metallurgy injection molding production process, the steps comprising:

[0127] (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements by weight: 7% Al, 4.5% Nb, 1.5% V, 0.5% Cu, 0.06% C, 0.13% O, and the remainder is Ti and unavoidable impurities; the powder particle size D50 of the titanium alloy powder is 9 um;

[0128] (2) mixing a binder and titanium alloy powder in a volume ratio of 12:88 and performing internal kneading to obtain an injection molding feedstock; the internal kneading temperature is 160° C., the internal kneading time is 85 min, and the oxygen content during internal kneading is 2250 ppm;

[0129] The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of 85:8:7:3, mixing them in a mixer at 125° C. for 3.5 hours to prepare the binder;

[0130] (3) placing the injection molding feed in a powder injection molding machine to obtain a preform; the injection molding step parameters include: mold temperature of 45° C., injection molding screw first section temperature of 170° C., second section temperature of 180° C., third section temperature of 200° C., nozzle temperature of 215° C., injection pressure of 110 MPa, holding pressure of 90 MPa, injection time of 4 s, and cooling time of 7 s;

[0131] (4) Degreasing the blank with nitric acid to remove the binder; the degreasing acid feed rate is 3 g / min, the degreasing temperature is 120° C., and the degreasing time is 7 h;

[0132] (5) Vacuum sintering was performed, and the temperature was raised to 1360°C at a heating rate of 8°C / min and kept at this temperature for 190 min. The vacuum degree during sintering was 2×10 -2 After cooling, the titanium alloy metallurgical injection molding product is obtained.

[0133] Test Example: The products prepared by the titanium alloy powder metallurgy injection molding production process for medical devices provided in the above-mentioned Examples 1-4 and Comparative Examples 1-10 were subjected to mechanical property tests and corrosion resistance tests (tested in an artificial simulated salt spray environment test in accordance with GB5938-86 "Corrosion Resistance Test Method for Metal Coatings and Chemical Treatment Layers of Light Industrial Products"). The test results are shown in Table 1 below:

[0134] Table 1

[0135]

[0136]

[0137] Among the 100 samples prepared by the method in Comparative Examples 8-10, there is a defective rate of 4-6%. The above comparative examples show that the binder formula, injection molding conditions and sintering conditions used will affect product performance and further affect the product qualification rate.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A titanium alloy powder metallurgy injection molding production process for medical devices. It is characterized in that The steps include: (1) Spherical titanium alloy powder is prepared by gas atomization, wherein the titanium alloy powder is composed of the following elements in % by weight: 6-8% Al, 4-5% Nb, 1-2% V, 0.4-0.6% Cu, 0.05%-0.07% C, 0.1-0.16% O, and the remainder is Ti and inevitable impurities; (2) A binder and the titanium alloy powder are mixed and kneaded to obtain an injection molding feed; (3) The injection molding feed is placed in a powder injection molding machine to obtain a blank; (4) The blank is degreased using nitric acid to remove the binder; (5) Vacuum sintering is performed, and after cooling, a titanium alloy metallurgical injection molding product is obtained.

2. A medical device titanium alloy powder metallurgy injection molding production process according to claim 1, It is characterized in that The titanium alloy powder has a particle size D50 of 8-10 um.

3. A medical device titanium alloy powder metallurgy injection molding production process according to claim 1, It is characterized in that The binder comprises polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio of (80-90): (7-9): (5-8): (2-4).

4. A medical device titanium alloy powder metallurgy injection molding production process according to claim 3, It is characterized in that The preparation method of the binder comprises: taking polyoxymethylene, high-density polyethylene, ethylene-vinyl acetate copolymer and stearic acid in a weight ratio, and mixing them in a mixer at 120-130° C. for 3-4 hours to prepare the binder.

5. A medical device titanium alloy powder metallurgy injection molding production process according to claim 1, It is characterized in that The volume ratio of the binder to the titanium alloy powder is (11-13):(87-89).

6. A medical device titanium alloy powder metallurgy injection molding production process according to claim 1, It is characterized in that The banburying temperature is 155-165° C., the banburying time is 80-90 min, and the oxygen content during banburying is 2000-2500 ppm.

7. A medical device titanium alloy powder metallurgy injection molding production process according to claim 1, It is characterized in that The injection molding step parameters include: mold temperature of 40-50°C, first section temperature of injection molding screw of 165-175°C, second section temperature of 175-185°C, third section temperature of 195-205°C, nozzle temperature of 210-220°C, injection pressure of 100-120MPa, holding pressure of 85-95MPa, injection time of 3-5s, and cooling time of 6-8s.

8. The titanium alloy powder metallurgy injection molding production process for medical devices according to claim 1, It is characterized in that The degreasing acid feeding amount is 2-4 g / min, the degreasing temperature is 115-125° C., and the degreasing time is 6-8 h.

9. A medical device titanium alloy powder metallurgy injection molding production process according to claim 1, It is characterized in that During the sintering, the temperature is raised to 650-750°C at a heating rate of 5-7°C / min, kept at this temperature for 50-70min, and then raised to between 1340°C and 1380°C at a heating rate of 8-10°C / min, and kept at this temperature for 120-140min.

10. A medical device titanium alloy powder metallurgy injection molding production process according to claim 9, It is characterized in that The vacuum degree during sintering is 1-3×10 -2 .

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