Titanium alloy powder metallurgy injection molding process for metal orthodontic bracket of oral cavity

Abstract

The invention provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket. The process comprises the following steps: mixing titanium alloy powder and a binder in a volume ratio of (90-92): (8-10), and banburying; performing injection molding after internal mixing to obtain a primary blank; then the primary blank is degreased; and finally, high-vacuum sintering is conducted, and the titanium alloy part is obtained after cooling. The titanium alloy powder is composed of the following elements of, by mass, 2%-6% of Mn, 4%-6% of Mo, 8%-10% of Nb, 1%-2% of V, 0.8%-1.2% of Ta, 0.4%-0.6% of Pd and the balance Ti and inevitable impurities. The product manufactured by the titanium alloy powder metallurgy injection molding process for the oral metal orthodontic bracket has high hardness and wear resistance, and also has good corrosion resistance and toughness, and the problem that nickel irritates people can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, and in particular to a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket. Background Art

[0002] With the rapid development of stomatology, metal orthodontic brackets are important orthodontic devices, and their quality and performance have a vital impact on the effect of orthodontic treatment. The traditional metal orthodontic bracket manufacturing process has problems such as low material utilization, low processing accuracy, and high cost, which makes it difficult to meet the needs of modern orthodontic treatment for high-precision and high-quality orthodontic brackets. Therefore, titanium alloy powder metallurgy injection molding technology came into being, providing a new solution for the manufacture of oral metal orthodontic brackets.

[0003] Titanium alloy material is an important structural metal. Titanium alloy has high strength, good corrosion resistance, high heat resistance, plasticity, toughness, weldability, good biocompatibility and other properties. Titanium alloy human implants are special materials closely related to human health and are widely used in the medical device industry. Usually, stainless steel wire cutting and stainless steel machined wire cutting 304 / 17-4, and stainless steel MIM stainless steel (17-4) injection molding are used in the medical oral device metal orthodontic bracket industry. Moreover, the corrosion resistance and wear resistance of stainless steel implanted in the human body will destroy the release of metal ions, leading to toxic side effects. Moreover, 304 / 17-4 stainless steel belongs to martensitic stainless steel with a nickel content of 3.5 to 4.5. These two materials belong to martensitic stainless steel and need to be passivated or electroplated on the surface before they can be used normally to achieve the corrosion resistance of medical equipment materials.

[0004] Titanium alloy powder metallurgy injection molding is an advanced manufacturing technology, which mixes titanium alloy powder with a binder, injects the mixture into a mold through an injection molding machine, and then undergoes processes such as degreasing and sintering to finally obtain a titanium alloy product of the desired shape. This technology has the advantages of high molding accuracy, high production efficiency, and high material utilization, and is particularly suitable for manufacturing medical implants with complex shapes and high precision requirements, such as oral metal orthodontic brackets.

[0005] In the traditional manufacturing process of metal orthodontic brackets, the material utilization rate is low, the processing cost is high, and the processing and process are complex. It is difficult to achieve, and the material has high limitations on tool equipment, which greatly increases the investment cost and accessory cost, resulting in a high price for orthodontic brackets. The titanium alloy powder metallurgy injection molding process uses powder metallurgy technology to maximize the utilization rate of materials, reduce material waste, and thus reduce manufacturing costs. At the same time, since the process can achieve mass production, the cost of a single orthodontic bracket is further reduced, providing patients with more high-quality and low-cost medical products. Based on this, the present invention provides a titanium alloy powder metallurgy injection molding process for oral metal orthodontic brackets. Summary of the invention

[0006] The purpose of the present invention is to provide an oral metal orthodontic bracket titanium alloy powder metallurgy injection molding process, so that the manufactured product has both high hardness and wear resistance, and good corrosion resistance and toughness.

[0007] On the one hand, the present invention provides an oral metal orthodontic bracket titanium alloy powder metallurgy injection molding process, the steps comprising: mixing titanium alloy powder and a binder in a volume ratio of (90-92): (8-10) and kneading them; injection molding after kneading to obtain a blank; then degreasing the blank; and finally high vacuum sintering to obtain a titanium alloy part after cooling.

[0008] Furthermore, the titanium alloy powder is composed of the following elements in 100% by mass: 2-6% of Mn, 4-6% of Mo, 8-10% of Nb, 1-2% of V, 0.8-1.2% of Ta, 0.4-0.6% of Pd, and the remainder is Ti and inevitable impurities.

[0009] Furthermore, the titanium alloy powder is a gas atomized powder, the titanium alloy powder has a D10 particle size of 8-10 microns, a D50 particle size of 16-20 microns, and an oxygen content of 1600-2000 ppm.

[0010] Furthermore, the binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin with a number average molecular weight of 30,000 to 40,000 in a weight ratio of (16-20): (10-14): (2-6): (22-24): (4-8): (30-34).

[0011] Furthermore, the banburying step includes: mixing the titanium alloy powder with polyoxymethylene, polyethylene glycol, polymethyl methacrylate, and polypropylene with a number average molecular weight of 30,000-40,000, and then performing the first banburying for 20-30 minutes, and then adding stearic acid and paraffin for the second banburying for 50-70 minutes.

[0012] Furthermore, during the banburying, the oxygen content is 1000-1500 ppm and the banburying temperature is 170-180°C.

[0013] Furthermore, during the injection molding, the screw barrel temperature is 165-220° C., the mold temperature is 60-70° C., the injection pressure is 100-120 MPa, and the holding pressure is 85-95 MPa.

[0014] Furthermore, the degreasing step is to degrease the preform obtained by injection molding in an oxalic acid atmosphere.

[0015] Furthermore, the degreasing temperature is 70-130° C., the acid feeding amount is 0.8-1.8 g / min, and the degreasing time is 6-10 h.

[0016] Furthermore, the vacuum degree during sintering is greater than 10 -2 Pa, sintering temperature is 1150-1400℃, and sintering time is 30-300min.

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

[0018] (1) The content of each element in the titanium alloy powder of the present invention is regulated to ensure that the hardness and wear resistance are improved without sacrificing toughness and corrosion resistance; Mo is a hard metal element that can significantly improve the hardness and wear resistance of titanium alloys; the addition of Nb also helps to improve the hardness and strength of titanium alloys while maintaining good toughness; the Mn element can form a stable oxide layer in the titanium alloy, improving the corrosion resistance and toughness of the titanium alloy; V and Ta can refine the grains of the titanium alloy, reduce the generation of cracks, and thus improve toughness; and the addition of Pd can increase the corrosion resistance of titanium in acidic fluorine-containing media, which makes the titanium alloy product of the present invention have further advantages in oral metal orthodontic brackets; on this basis, the addition of Ta can promote the corrosion resistance when the Pd content is only 0.4-0.6%, thereby reducing the overall production cost of the product;

[0019] (2) Titanium alloy powder is prepared by gas atomization method, which has the advantages of high sphericity and uniform particle size distribution. This powder can fill the mold more easily during the injection molding process, reduce the generation of pores and defects, and thus improve the mechanical properties of the product. In addition, the D10 and D50 particle sizes of the powder are strictly controlled to ensure the uniformity of the powder during mixing and injection molding;

[0020] (3) In the present invention, the high molecular polymer is selected as the binder, which can form a uniform mixture with the titanium alloy powder during the banburying process, ensuring close contact and uniform distribution between the powder particles; the addition of stearic acid and paraffin further improves the fluidity and plasticity of the mixture, providing good conditions for subsequent injection molding; further, through two banburying processes, the titanium alloy powder is first mixed with the high molecular polymer, and then stearic acid and paraffin are added for further banburying, ensuring uniform mixing of the powder and the binder;

[0021] (4) In the present invention, polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin with a weight ratio of (16-20): (10-14): (2-6): (22-24): (4-8): (30-34) and a number average molecular weight of 30,000-40,000 are selected as binders, which have good fluidity and plasticity, so that they can be fully mixed with titanium alloy powder during the mixing process to form a uniform mixture. This uniformity is crucial for the subsequent injection molding process because it ensures the uniform distribution and tight filling of the powder in the mold; in addition, although there are many types of binders, in the process provided by the present invention, the binder can be effectively removed without leaving any residue that is harmful to the performance of the titanium alloy, which also ensures the purity and performance of the final product;

[0022] (5) In the process of internal mixing of the present invention, parameters such as internal mixing time, temperature and oxygen content are strictly controlled to ensure the uniform mixing and stability of the titanium alloy powder and the binder; parameters such as the screw barrel temperature, mold temperature, injection pressure and holding pressure are accurately controlled during the injection molding process to ensure the accuracy and strength of the preform; parameters such as the degreasing temperature, acid addition amount, degreasing time, sintering temperature and sintering time are strictly controlled during the degreasing and sintering process to ensure that the final product has both high hardness and wear resistance and good corrosion resistance and toughness. DETAILED DESCRIPTION

[0023] 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.

[0024] Example 1

[0025] This embodiment provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0026] Titanium alloy powder and binder with a volume ratio of 91:9 were mixed and kneaded; first, titanium alloy powder was mixed with polyoxymethylene, polyethylene glycol, polymethyl methacrylate and polypropylene with a number average molecular weight of 35,000 and then kneaded for the first time for 25 minutes, then stearic acid and paraffin were added for the second time for 60 minutes; during kneading, the oxygen content was 1250ppm and the kneading temperature was 175°C;

[0027] The titanium alloy powder is composed of the following elements by mass: 4% Mn, 5% Mo, 9% Nb, 1.5% V, 1% Ta, 0.5% Pd, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 9 microns, the D50 particle size is 18 microns, and the oxygen content is 1800ppm;

[0028] The binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin in a weight ratio of 18:12:4:23:6:32 and a number average molecular weight of 35,000;

[0029] After mixing, the blank is obtained by injection molding; during injection molding, the temperature of the screw barrel is 200°C, the mold temperature is 65°C, the injection pressure is 110MPa, and the holding pressure is 90MPa;

[0030] Then, the preform obtained by injection molding was degreased in an oxalic acid atmosphere; the degreasing temperature was 100°C, the acid feeding amount was 1.3 g / min, and the degreasing time was 8 h;

[0031] Finally, high vacuum sintering is carried out, and the vacuum degree during sintering is greater than 10 -2 Pa, the sintering temperature is 1300℃, and the sintering time is 150min; after cooling, the titanium alloy parts are obtained.

[0032] Example 2

[0033] This embodiment provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0034] Titanium alloy powder and binder with a volume ratio of 90:10 were mixed and kneaded; first, titanium alloy powder was mixed with polyoxymethylene, polyethylene glycol, polymethyl methacrylate and polypropylene with a number average molecular weight of 30,000 and then kneaded for the first time for 20 minutes, then stearic acid and paraffin were added for the second time for 50 minutes; during kneading, the oxygen content was 1000ppm and the kneading temperature was 170°C;

[0035] The titanium alloy powder is composed of the following elements by mass: 2% Mn, 4% Mo, 8% Nb, 1% V, 0.8% Ta, 0.4% Pd, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 8 microns, the D50 particle size is 16 microns, and the oxygen content is 1600ppm;

[0036] The binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin in a weight ratio of 16:10:2:22:4:30 with a number average molecular weight of 30,000;

[0037] After mixing, the blank is obtained by injection molding; during injection molding, the temperature of the screw barrel is 165°C, the mold temperature is 60°C, the injection pressure is 100MPa, and the holding pressure is 85MPa;

[0038] Then, the preform obtained by injection molding was degreased in an oxalic acid atmosphere; the degreasing temperature was 70°C, the acid feeding amount was 0.8g / min, and the degreasing time was 6h;

[0039] Finally, high vacuum sintering is carried out, and the vacuum degree during sintering is greater than 10 -2 Pa, the sintering temperature is 1150℃, and the sintering time is 100min; after cooling, the titanium alloy parts are obtained.

[0040] Example 3

[0041] This embodiment provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0042] Titanium alloy powder and binder with a volume ratio of 92:8 were mixed and kneaded; first, titanium alloy powder was mixed with polyoxymethylene, polyethylene glycol, polymethyl methacrylate and polypropylene with a number average molecular weight of 40,000 and then kneaded for the first time for 30 minutes, then stearic acid and paraffin were added for the second time for 70 minutes; during kneading, the oxygen content was 1500ppm and the kneading temperature was 180°C;

[0043] The titanium alloy powder is composed of the following elements in 100% by mass: 6% Mn, 6% Mo, 10% Nb, 2% V, 1.2% Ta, 0.6% Pd, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 10 microns, the D50 particle size is 20 microns, and the oxygen content is 2000ppm;

[0044] The binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin in a weight ratio of 20:14:6:24:8:34 with a number average molecular weight of 40,000;

[0045] After mixing, the blank is obtained by injection molding; during injection molding, the temperature of the screw barrel is 220°C, the mold temperature is 70°C, the injection pressure is 120MPa, and the holding pressure is 95MPa;

[0046] Then, the preform obtained by injection molding was degreased in an oxalic acid atmosphere; the degreasing temperature was 130°C, the acid feeding amount was 1.8 g / min, and the degreasing time was 10 h;

[0047] Finally, high vacuum sintering is carried out, and the vacuum degree during sintering is greater than 10 -2 Pa, the sintering temperature is 1400℃, and the sintering time is 300min; after cooling, the titanium alloy parts are obtained.

[0048] Example 4

[0049] This embodiment provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0050] Titanium alloy powder and binder with a volume ratio of 91:9 were mixed and kneaded; first, titanium alloy powder was mixed with polyoxymethylene, polyethylene glycol, polymethyl methacrylate and polypropylene with a number average molecular weight of 35,000 and then kneaded for the first time for 20 minutes, then stearic acid and paraffin were added for the second time for 70 minutes; during kneading, the oxygen content was 1000ppm and the kneading temperature was 180°C;

[0051] The titanium alloy powder is composed of the following elements by mass: 2% Mn, 6% Mo, 8% Nb, 2% V, 0.8% Ta, 0.6% Pd, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 8 microns, the D50 particle size is 20 microns, and the oxygen content is 1600ppm;

[0052] The binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin in a weight ratio of 16:14:2:24:4:34 with a number average molecular weight of 35,000;

[0053] After mixing, the blank is obtained by injection molding; during injection molding, the temperature of the screw barrel is 165°C, the mold temperature is 70°C, the injection pressure is 100MPa, and the holding pressure is 95MPa;

[0054] Then, the preform obtained by injection molding was degreased in an oxalic acid atmosphere; the degreasing temperature was 70°C, the acid feeding amount was 1.8 g / min, and the degreasing time was 6 h;

[0055] Finally, high vacuum sintering is carried out, and the vacuum degree during sintering is greater than 10 -2 Pa, the sintering temperature is 1400℃, and the sintering time is 100min; after cooling, the titanium alloy parts are obtained.

[0056] Comparative Example 1

[0057] This comparative example provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0058] Titanium alloy powder and binder with a volume ratio of 91:9 were mixed and kneaded; first, titanium alloy powder was mixed with polyoxymethylene, polyethylene glycol, polymethyl methacrylate and polypropylene with a number average molecular weight of 35,000 and then kneaded for the first time for 25 minutes, then stearic acid and paraffin were added for the second time for 60 minutes; during kneading, the oxygen content was 1250ppm and the kneading temperature was 175°C;

[0059] The titanium alloy powder is composed of the following elements by mass: 4% Mn, 5% Mo, 9% Nb, 1.5% V, 0.5% Pd, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 9 microns, the D50 particle size is 18 microns, and the oxygen content is 1800ppm;

[0060] The binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin in a weight ratio of 18:12:4:23:6:32 and a number average molecular weight of 35,000;

[0061] After mixing, the blank is obtained by injection molding; during injection molding, the temperature of the screw barrel is 200°C, the mold temperature is 65°C, the injection pressure is 110MPa, and the holding pressure is 90MPa;

[0062] Then, the preform obtained by injection molding was degreased in an oxalic acid atmosphere; the degreasing temperature was 100°C, the acid feeding amount was 1.3 g / min, and the degreasing time was 8 h;

[0063] Finally, high vacuum sintering is carried out, and the vacuum degree during sintering is greater than 10 -2 Pa, the sintering temperature is 1300℃, and the sintering time is 150min; after cooling, the titanium alloy parts are obtained.

[0064] Comparative Example 2

[0065] This comparative example provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0066] Titanium alloy powder and binder with a volume ratio of 91:9 were mixed and kneaded; first, titanium alloy powder was mixed with polyoxymethylene, polyethylene glycol, polymethyl methacrylate and polypropylene with a number average molecular weight of 35,000 and then kneaded for the first time for 25 minutes, then stearic acid and paraffin were added for the second time for 60 minutes; during kneading, the oxygen content was 1250ppm and the kneading temperature was 175°C;

[0067] The titanium alloy powder is composed of the following elements by mass: 4% Mn, 5% Mo, 9% Nb, 1.5% V, 1% Ta, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 9 microns, the D50 particle size is 18 microns, and the oxygen content is 1800ppm;

[0068] The binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin in a weight ratio of 18:12:4:23:6:32 and a number average molecular weight of 35,000;

[0069] After mixing, the blank is obtained by injection molding; during injection molding, the temperature of the screw barrel is 200°C, the mold temperature is 65°C, the injection pressure is 110MPa, and the holding pressure is 90MPa;

[0070] Then, the preform obtained by injection molding was degreased in an oxalic acid atmosphere; the degreasing temperature was 100°C, the acid feeding amount was 1.3 g / min, and the degreasing time was 8 h;

[0071] Finally, high vacuum sintering is carried out, and the vacuum degree during sintering is greater than 10 -2 Pa, the sintering temperature is 1300℃, and the sintering time is 150min; after cooling, the titanium alloy parts are obtained.

[0072] Comparative Example 3

[0073] This comparative example provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0074] Titanium alloy powder and binder with a volume ratio of 91:9 were mixed and kneaded; first, titanium alloy powder was mixed with polyoxymethylene, polyethylene glycol, polymethyl methacrylate and polypropylene with a number average molecular weight of 35,000 and then kneaded for the first time for 25 minutes, then stearic acid and paraffin were added for the second time for 60 minutes; during kneading, the oxygen content was 1250ppm and the kneading temperature was 175°C;

[0075] The titanium alloy powder is composed of the following elements by mass: 4% Mn, 5% Mo, 9% Nb, 1% Ta, 0.5% Pd, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 9 microns, the D50 particle size is 18 microns, and the oxygen content is 1800ppm;

[0076] The binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin in a weight ratio of 18:12:4:23:6:32 and a number average molecular weight of 35,000;

[0077] After mixing, the blank is obtained by injection molding; during injection molding, the temperature of the screw barrel is 200°C, the mold temperature is 65°C, the injection pressure is 110MPa, and the holding pressure is 90MPa;

[0078] Then, the preform obtained by injection molding was degreased in an oxalic acid atmosphere; the degreasing temperature was 100°C, the acid feeding amount was 1.3 g / min, and the degreasing time was 8 h;

[0079] Finally, high vacuum sintering is carried out, and the vacuum degree during sintering is greater than 10 -2 Pa, the sintering temperature is 1300℃, and the sintering time is 150min; after cooling, the titanium alloy parts are obtained.

[0080] Comparative Example 4

[0081] This comparative example provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0082] Titanium alloy powder and binder with a volume ratio of 91:9 were mixed and kneaded; first, titanium alloy powder was mixed with polyoxymethylene, polyethylene glycol, polymethyl methacrylate and polypropylene with a number average molecular weight of 35,000 and then kneaded for the first time for 25 minutes, then stearic acid and paraffin were added for the second time for 60 minutes; during kneading, the oxygen content was 1250ppm and the kneading temperature was 175°C;

[0083] The titanium alloy powder is composed of the following elements by mass: 4% Mn, 5% Mo, 9% Nb, 1.5% V, 1% Ta, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 9 microns, the D50 particle size is 18 microns, and the oxygen content is 1800ppm;

[0084] The binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin in a weight ratio of 18:12:4:23:6:32 and a number average molecular weight of 35,000;

[0085] After mixing, the blank is obtained by injection molding; during injection molding, the temperature of the screw barrel is 200°C, the mold temperature is 65°C, the injection pressure is 110MPa, and the holding pressure is 90MPa;

[0086] Then, the preform obtained by injection molding was degreased in an oxalic acid atmosphere; the degreasing temperature was 100°C, the acid feeding amount was 1.3 g / min, and the degreasing time was 8 h;

[0087] Finally, high vacuum sintering is carried out, and the vacuum degree during sintering is greater than 10 -2 Pa, the sintering temperature is 1300℃, and the sintering time is 150min; after cooling, the titanium alloy parts are obtained.

[0088] Comparative Example 5

[0089] This comparative example provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0090] Titanium alloy powder and binder with a volume ratio of 91:9 were mixed and kneaded; first, titanium alloy powder was mixed with polyoxymethylene, polymethyl methacrylate and polypropylene with a number average molecular weight of 35,000 and then kneaded for the first time for 25 minutes, then stearic acid and paraffin were added for the second time for 60 minutes; during kneading, the oxygen content was 1250ppm and the kneading temperature was 175°C;

[0091] The titanium alloy powder is composed of the following elements by mass: 4% Mn, 5% Mo, 9% Nb, 1.5% V, 1% Ta, 0.5% Pd, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 9 microns, the D50 particle size is 18 microns, and the oxygen content is 1800ppm;

[0092] The binder includes polyoxymethylene, polymethyl methacrylate, polypropylene, stearic acid and paraffin in a weight ratio of 18:4:23:6:32 and a number average molecular weight of 35,000;

[0093] After mixing, the blank is obtained by injection molding; during injection molding, the temperature of the screw barrel is 200°C, the mold temperature is 65°C, the injection pressure is 110MPa, and the holding pressure is 90MPa;

[0094] Then, the preform obtained by injection molding was degreased in an oxalic acid atmosphere; the degreasing temperature was 100°C, the acid feeding amount was 1.3 g / min, and the degreasing time was 8 h;

[0095] Finally, high vacuum sintering is carried out, and the vacuum degree during sintering is greater than 10 -2 Pa, the sintering temperature is 1300℃, and the sintering time is 150min; after cooling, the titanium alloy parts are obtained.

[0096] Comparative Example 6

[0097] This comparative example provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0098] Titanium alloy powder and binder with a volume ratio of 91:9 were mixed and kneaded; first, titanium alloy powder was mixed with polyoxymethylene, polyethylene glycol, polymethyl methacrylate and polypropylene with a number average molecular weight of 35,000 and then kneaded for the first time for 25 minutes, then stearic acid and paraffin were added for the second time for 60 minutes; during kneading, the oxygen content was 1250ppm and the kneading temperature was 175°C;

[0099] The titanium alloy powder is composed of the following elements by mass: 4% Mn, 5% Mo, 9% Nb, 1.5% V, 1% Ta, 0.5% Pd, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 9 microns, the D50 particle size is 18 microns, and the oxygen content is 1800ppm;

[0100] The binder includes polyoxymethylene, polyethylene glycol, polypropylene, stearic acid and paraffin in a weight ratio of 18:12:23:6:32 with a number average molecular weight of 35,000;

[0101] After mixing, the blank is obtained by injection molding; during injection molding, the temperature of the screw barrel is 200°C, the mold temperature is 65°C, the injection pressure is 110MPa, and the holding pressure is 90MPa;

[0102] Then, the preform obtained by injection molding was degreased in an oxalic acid atmosphere; the degreasing temperature was 100°C, the acid feeding amount was 1.3 g / min, and the degreasing time was 8 h;

[0103] Finally, high vacuum sintering is carried out, and the vacuum degree during sintering is greater than 10 -2 Pa, the sintering temperature is 1300℃, and the sintering time is 150min; after cooling, the titanium alloy parts are obtained.

[0104] Comparative Example 7

[0105] This comparative example provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0106] Titanium alloy powder and binder with a volume ratio of 91:9 were mixed and kneaded; first, titanium alloy powder was mixed with polyoxymethylene, polyethylene glycol, polymethyl methacrylate and polypropylene with a number average molecular weight of 35,000 and then kneaded for the first time for 25 minutes, then stearic acid was added for the second time for 60 minutes; during kneading, the oxygen content was 1250ppm and the kneading temperature was 175°C;

[0107] The titanium alloy powder is composed of the following elements by mass: 4% Mn, 5% Mo, 9% Nb, 1.5% V, 1% Ta, 0.5% Pd, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 9 microns, the D50 particle size is 18 microns, and the oxygen content is 1800ppm;

[0108] The binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene and stearic acid in a weight ratio of 18:12:4:23:6 with a number average molecular weight of 35,000;

[0109] After mixing, the blank is obtained by injection molding; during injection molding, the temperature of the screw barrel is 200°C, the mold temperature is 65°C, the injection pressure is 110MPa, and the holding pressure is 90MPa;

[0110] Then, the preform obtained by injection molding was degreased in an oxalic acid atmosphere; the degreasing temperature was 100°C, the acid feeding amount was 1.3 g / min, and the degreasing time was 8 h;

[0111] Finally, high vacuum sintering is carried out, and the vacuum degree during sintering is greater than 10 -2 Pa, the sintering temperature is 1300℃, and the sintering time is 150min; after cooling, the titanium alloy parts are obtained.

[0112] Comparative Example 8

[0113] This comparative example provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0114] The titanium alloy powder and the binder with a volume ratio of 91:9 were mixed and kneaded; first, the titanium alloy powder was mixed with polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin with a number average molecular weight of 35,000 and then kneaded for 85 minutes; the oxygen content during kneading was 1250ppm and the kneading temperature was 175°C;

[0115] The titanium alloy powder is composed of the following elements by mass: 4% Mn, 5% Mo, 9% Nb, 1.5% V, 1% Ta, 0.5% Pd, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 9 microns, the D50 particle size is 18 microns, and the oxygen content is 1800ppm;

[0116] The binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin in a weight ratio of 18:12:4:23:6:32 and a number average molecular weight of 35,000;

[0117] After mixing, the blank is obtained by injection molding; during injection molding, the temperature of the screw barrel is 200°C, the mold temperature is 65°C, the injection pressure is 110MPa, and the holding pressure is 90MPa;

[0118] Then, the preform obtained by injection molding was degreased in an oxalic acid atmosphere; the degreasing temperature was 100°C, the acid feeding amount was 1.3 g / min, and the degreasing time was 8 h;

[0119] Finally, high vacuum sintering is carried out, and the vacuum degree during sintering is greater than 10 -2 Pa, the sintering temperature is 1300℃, and the sintering time is 150min; after cooling, the titanium alloy parts are obtained.

[0120] Comparative Example 9

[0121] This comparative example provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0122] The titanium alloy powder and the binder are mixed in a volume ratio of 91:9 and then subjected to banburying. First, the titanium alloy powder and the binder are mixed and then subjected to banburying for 85 minutes. During banburying, the oxygen content is 1250 ppm and the banburying temperature is 175°C.

[0123] The titanium alloy powder is composed of the following elements by mass: 4% Mn, 5% Mo, 9% Nb, 1.5% V, 1% Ta, 0.5% Pd, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 9 microns, the D50 particle size is 18 microns, and the oxygen content is 1800ppm;

[0124] The binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, and polypropylene in a weight ratio of 18:12:4:23 and a number average molecular weight of 35,000;

[0125] After mixing, injection molding is performed to obtain a blank; the blank softens, has shape defects, and cannot maintain its shape.

[0126] Comparative Example 10

[0127] This comparative example provides a titanium alloy powder metallurgy injection molding process for an oral metal orthodontic bracket, the steps comprising:

[0128] The titanium alloy powder and the binder are mixed in a volume ratio of 91:9 and then subjected to banburying. First, the titanium alloy powder and the binder are mixed and then subjected to banburying for 85 minutes. During banburying, the oxygen content is 1250 ppm and the banburying temperature is 175°C.

[0129] The titanium alloy powder is composed of the following elements by mass: 4% Mn, 5% Mo, 9% Nb, 1.5% V, 1% Ta, 0.5% Pd, and the balance is Ti and unavoidable impurities; the titanium alloy powder is a gas atomized powder, the titanium alloy powder D10 particle size is 9 microns, the D50 particle size is 18 microns, and the oxygen content is 1800ppm;

[0130] The binder includes polyethylene glycol, polyethylene wax and stearic acid in a weight ratio of 75:24:1;

[0131] After mixing, injection molding is performed to obtain a blank; the blank softens, has shape defects, and cannot maintain its shape.

[0132] Test Example: The following tests were performed on the products prepared by the titanium alloy powder metallurgy injection molding process for the oral metal orthodontic brackets provided in the aforementioned Examples 1-4 and Comparative Examples 1-8:

[0133] 1. Mechanical properties test;

[0134] 2. Corrosion resistance test: According to the stainless steel pitting potential measurement method GB / T17899-1999, the anodic polarization curve is obtained to determine its corrosion resistance;

[0135] 3. Biocompatibility test: Tested in accordance with IS010993 biocompatibility test (biological evaluation of medical devices); the test includes IS010993 biocompatibility test Part 5: ISO10993-5 in vitro cytotoxicity test and Part 10: ISO10993-10 irritation and skin sensitization test;

[0136] 4. Alloy chemical composition analysis: Test according to GB / T 223.10-1991 Steel and Alloy Chemical Analysis Method;

[0137] The test results are shown in the following table:

[0138] Table 1

[0139]

[0140] Table 2

[0141] In vitro cytotoxicity assay Irritation and skin sensitization test Example 1 76 None Example 2 75 None Example 3 76 None Example 4 75 None Comparative Example 1 77 None Comparative Example 2 76 None Comparative Example 3 78 None Comparative Example 4 75 None Comparative Example 5 76 None Comparative Example 6 78 None Comparative Example 7 75 None Comparative Example 8 76 None

[0142] Table 3

[0143]

[0144]

[0145] 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. Oral metal orthodontic bracket titanium alloy powder metallurgy injection molding process, characterized in that the steps include: The titanium alloy powder and the binder are mixed in a volume ratio of (90-92): (8-10) and kneaded; after kneading, injection molding is performed to obtain a blank; The blank is then degreased and finally sintered in a high vacuum, and after cooling, a titanium alloy part is obtained.

2. The process for orthodontic bracket titanium alloy powder metallurgy injection molding according to claim 1, characterized in that: The titanium alloy powder is composed of the following elements in 100% by mass: 2-6% of Mn, 4-6% of Mo, 8-10% of Nb, 1-2% of V, 0.8-1.2% of Ta, 0.4-0.6% of Pd, and the remainder is Ti and inevitable impurities.

3. The process for orthodontic bracket titanium alloy powder metallurgy injection molding according to claim 1, characterized in that: The titanium alloy powder is a gas atomized powder, the titanium alloy powder has a D10 particle size of 8-10 microns, a D50 particle size of 16-20 microns, and an oxygen content of 1600-2000 ppm.

4. The titanium alloy powder metallurgy injection molding process for oral metal orthodontic brackets according to claim 1, characterized in that: The binder includes polyoxymethylene, polyethylene glycol, polymethyl methacrylate, polypropylene, stearic acid and paraffin with a number average molecular weight of 30,000 to 40,000 in a weight ratio of (16-20): (10-14): (2-6): (22-24): (4-8): (30-34).

5. The process for orthodontic bracket titanium alloy powder metallurgy injection molding according to claim 1, characterized in that: The banburying step includes: mixing titanium alloy powder with polyoxymethylene, polyethylene glycol, polymethyl methacrylate and polypropylene with a number average molecular weight of 30,000-40,000, and then performing the first banburying for 20-30 minutes, and then adding stearic acid and paraffin for the second banburying for 50-70 minutes.

6. The process for titanium alloy powder metallurgy injection molding of oral metal orthodontic brackets according to claim 5, characterized in that: The oxygen content during the banburying is 1000-1500 ppm, and the banburying temperature is 170-180°C.

7. The process for orthodontic bracket titanium alloy powder metallurgy injection molding according to claim 1, characterized in that: During the injection molding, the temperature of the screw barrel is 165-220° C., the mold temperature is 60-70° C., the injection pressure is 100-120 MPa, and the holding pressure is 85-95 MPa.

8. The titanium alloy powder metallurgy injection molding process for oral metal orthodontic brackets according to claim 1, characterized in that: The degreasing step is to degrease the preform obtained by injection molding in an oxalic acid atmosphere.

9. The titanium alloy powder metallurgy injection molding process for oral metal orthodontic brackets according to claim 8, characterized in that: The degreasing temperature is 70-130° C., the acid feeding amount is 0.8-1.8 g / min, and the degreasing time is 6-10 h.

10. The titanium alloy powder metallurgy injection molding process for oral metal orthodontic brackets according to claim 1, characterized in that: The vacuum degree during sintering is greater than 10 -2 Pa, sintering temperature is 1150-1400℃, and sintering time is 30-300min.

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