Low friction coefficient interface screw and method of making same

Abstract

The application provides an interface screw with low friction coefficient and a preparation method thereof, relates to the field of medical metal materials and medical devices, and is prepared from a medical titanium alloy, and the chemical components are as follows in percentage by weight: Al: 5.2-6.7%, V: 3.4-4.3%, Cu: 4.3-6.2%, and Ti: the balance. The titanium alloy is processed into the interface screw through a special process, so that the friction coefficient of the interface screw is further reduced under the condition that the interface screw has excellent tissue compatibility and high plasticity, and the problem of fracture during use is prevented; meanwhile, the interface screw can inhibit the formation of bacterial biofilm of methicillin-resistant Staphylococcus aureus on the surface of the interface screw.

Description

Technical Field

[0001] This invention relates to the field of medical metal materials and medical devices, and in particular to an interface screw with a low coefficient of friction and its preparation method. Background Technology

[0002] Interface screws are implants primarily used in cruciate ligament reconstruction to fix tendon or ligament bone fragments to the femoral and tibial bone tunnels. Currently, interface screws are mostly made of titanium or titanium alloys. Titanium alloys are a biocompatible metal with high specific strength and are widely used in bone trauma repair, such as bone pins, intramedullary nails, bone plates, screws, and artificial joints. During fracture rehabilitation, the poor stability of the fracture ends can exert significant shear forces on the interface screws. In patients with high BMI or slow bone healing, interface screw breakage may occur. If a methicillin-resistant Staphylococcus aureus (MRSA) biofilm forms on the implant surface, persistent infection is highly likely. Due to the methicillin resistance of this bacteria, existing antibiotics and other drugs are difficult to intervene in or treat such infections, and the worsening of the infection ultimately leads to loosening or even detachment of the interface screw.

[0003] Therefore, there is an urgent need to develop a titanium alloy interface screw with a low coefficient of friction that can inhibit the formation of bacterial biofilms by methicillin-resistant Staphylococcus aureus. Summary of the Invention

[0004] The purpose of this invention is to provide an interface screw with a low coefficient of friction and a method for its preparation. While ensuring that the interface screw has excellent tissue compatibility and strong plasticity, it further inhibits the attachment and proliferation of methicillin-resistant Staphylococcus aureus on its surface, thereby inhibiting the formation of methicillin-resistant Staphylococcus aureus bacterial biofilm.

[0005] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0006] In a first aspect, the present invention provides an interface screw with a low coefficient of friction, prepared by a method comprising the following steps:

[0007] 1) Smelting: The raw materials sponge titanium, TiCu master alloy, AlV master alloy, aluminum briquettes and aluminum mesh are weighed and proportioned as follows: Al: 5.2-6.7%, V: 3.4-4.3%, Cu: 4.3-6.2%, Ti balance;

[0008] The aluminum mesh is made into a container, filled with sponge titanium, TiCu master alloy, AlV master alloy and aluminum granules, pressed into a melting electrode using an electrode mold, and then melted into an alloy ingot.

[0009] 2) Forging: Heat the alloy ingot to 950-1150℃, hold for 4-5 hours and then hot forge. The total forging ratio is 5-6. Forge the ingot into a slab along the axial direction. Cut the slab into square bars along the length direction. Reheat the square bars to 820-1030℃, hold for 0.5-1 hour and then water cool.

[0010] 3) Hot rolling: The alloy square bar is heated to 700-830℃, held for 1.2-2.2 hours and then hot rolled for a total of 9-10 passes to produce bars with a diameter of 10-13mm. The deformation amount of each pass in the first to fifth passes is 10-15%, and the interval between two adjacent passes in the first to fifth passes is 15-30s. The deformation amount of each pass in the sixth pass and subsequent passes is not higher than 23%, and the interval between two adjacent passes in the sixth pass and subsequent passes is 25-45s.

[0011] 4) Oxidation annealing treatment: The bar is subjected to oxidation annealing treatment at a temperature of 560~730℃, held at that temperature for 0.8~1.8 hours, and then air-cooled;

[0012] 5) Hot drawing: The bars after oxidation annealing are heated in a tube furnace for hot drawing and water cooling at the exit. The drawing temperature is 740-900℃, the drawing speed is 0.49-0.95m / min, the number of drawing passes is 13-33, and the diameter of the bars obtained after drawing is 0.8-5mm.

[0013] 6) The drawn bars are subjected to vacuum hot straightening at a temperature of 640-790℃, and the resulting bars are longitudinally cut into interface screws.

[0014] The following is a detailed explanation of each step:

[0015] Step 1)

[0016] The chemical composition of the alloy ingot, by weight percentage, is as follows: Al: 5.2–6.7% (e.g., 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6.0%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%); V: 3.4–4.3% (e.g., 3.4%, 3.5%, 3.6%, 3.7%). 3.9% to 4.3% (e.g., 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%), preferably 3.9% to 4.3%; Cu: 4.3% to 6.2% (e.g., 4.3%, 4.5%, 4.6%, 4.8%, 5.0%, 5.2%, 5.4%, 5.5%, 5.6%, 5.8%, 5.9%), preferably 4.8% to 5.8%, more preferably 5.2% to 5.6%; Ti balance;

[0017] The alloy ingot is made by pressing raw materials such as sponge titanium, TiCu master alloy, AlV master alloy, aluminum briquettes, and high-purity aluminum mesh as a container into electrodes and then melting them.

[0018] Preferably, the sponge titanium is grade 0 sponge titanium; the aluminum briquettes are high-purity aluminum briquettes with a purity of 99.99%.

[0019] Preferably, the aluminum mesh is rolled into two cylindrical aluminum mesh barrels with different bottom diameters, the two aluminum mesh barrels are nested together, the space between the two aluminum mesh barrels is filled with TiCu master alloy, and the interior of the aluminum mesh barrels is filled with a mixture of aluminum granules, sponge titanium and AlV master alloy.

[0020] Then, an aluminum mesh barrel is embedded in an electrode mold using a mixture of aluminum briquettes, sponge titanium, and AlV master alloy, and pressed into a smelting electrode, which is then smelted into an alloy ingot with the above composition.

[0021] Preferably, the smelting is carried out in a vacuum arc furnace.

[0022] Step 2)

[0023] The alloy ingot is heated to 950–1150℃ (e.g., 950, 1000, 1050, 1100, 1150℃), held at that temperature for 4–5 hours, and then hot-forged. The total forging ratio is 5–7. The ingot is forged along its axial direction into a slab 50–60 mm thick and 500–550 mm wide. The slab is cut into square bars along its length, and then heated again to 820–1030℃ (e.g., 820, 850, 900, 950, 1000, 1030℃), held at that temperature for 0.5–1 hour, and then water-cooled.

[0024] Step 3)

[0025] The alloy square bar is heated to 700–830℃ (e.g., 700, 720, 750, 800, 830℃), held at that temperature for 1.2–2.2 hours (e.g., 1.2, 1.5, 1.8, 2, 2.2 hours), and then hot-rolled in 9–10 passes to produce bars with a diameter of 10–13 mm. The deformation in each of the first to fifth passes is 10–15% (e.g., 10%, 11%, 12%, 13%, 14%, 15%). The interval between two adjacent rolling passes in the first five passes is 15-30 s (e.g., 15 s, 17 s, 22 s, 25 s, 28 s, 30 s). The deformation of each pass in the sixth pass and subsequent passes is no more than 23% (e.g., 10%, 12%, 14%, 15%, 16%, 18%, 20%). The interval between two adjacent rolling passes in the sixth pass and subsequent passes is 25-45 s (e.g., 28 s, 32 s, 36 s, 38 s, 40 s).

[0026] Step 4)

[0027] The oxidation annealing temperature is, for example, 570, 620, 650, 660, 680, 700, 720℃, and the holding time is, for example, 0.9, 1.2, 1.4, 1.6 hours.

[0028] Preferably, a centerless lathe is used to remove surface defects of the bar before oxidation annealing.

[0029] Step 5)

[0030] The drawing temperature is, for example, 740, 780, 820, 860, 900℃, the drawing speed is, for example, 0.5, 0.6, 0.7, 0.8, 0.9 m / min, and the number of drawing passes is, for example, 14, 16, 19, 22, 25, 29, 30.

[0031] Preferably, the cooling water temperature is 10-20℃ (e.g., 10, 12, 14, 15, 16, 18, 20℃), the number of cooling water nozzles is 2-4, and the water flow rate is 1.2-1.9m / s (e.g., 1.4, 1.5, 1.6, 1.8m / s), preferably 1.6-1.8m / s.

[0032] Step 6)

[0033] Hot straightening temperatures are, for example, 650, 660, 680, 700, 720, 740, and 750°C;

[0034] Preferably, after hot straightening, the bar is ground and polished by centerless grinding, then cleaned, and the resulting bar is longitudinally cut into interface screws.

[0035] The interface screw has dimensions of Φ3~4mm × 5~15mm, a coefficient of friction of 0.44~0.45, an elongation of ≥13%, a cytotoxicity rating of ≤1, and a pitting potential of ≥2321mV. Using the co-culture results of TC4 titanium alloy contaminated with methicillin-resistant Staphylococcus aureus (MRSA) bacteria as a benchmark, the interface screw can provide a relative antibacterial rate of over 99% in a co-culture model of implants contaminated with MRSA bacteria.

[0036] According to a second aspect of the present invention, a method for preparing an interface screw with a low coefficient of friction is provided, comprising the following steps:

[0037] 1) Smelting: The raw materials sponge titanium, TiCu master alloy, AlV master alloy, aluminum briquettes and aluminum mesh are weighed and proportioned as follows: Al: 5.2-6.7%, V: 3.4-4.3%, Cu: 4.3-6.2%, Ti balance;

[0038] The aluminum mesh is made into a container, filled with sponge titanium, TiCu master alloy, AlV master alloy and aluminum granules, pressed into a melting electrode using an electrode mold, and then melted into an alloy ingot.

[0039] 2) Forging: Heat the alloy ingot to 950-1150℃ and hold for 4-5 hours for hot forging. The total forging ratio is 5-6. Forge the ingot into a slab along the axial direction. Cut the slab into square bars along the length direction. Reheat the square bars to 820-1030℃ and hold for 0.5-1 hour. Water cool.

[0040] 3) Hot rolling: The alloy square bar is heated to 700-830℃, held for 1.2-2.2 hours and then hot rolled for a total of 9-10 passes to produce bars with a diameter of 10-13mm. The deformation amount of each pass in the first to fifth passes is 10-15%, and the interval between two adjacent passes in the first to fifth passes is 15-30s. The deformation amount of each pass in the sixth pass and subsequent passes is not higher than 23%, and the interval between two adjacent passes in the sixth pass and subsequent passes is 25-45s.

[0041] 4) Oxidation annealing treatment: The bar is subjected to oxidation annealing treatment at a temperature of 560~730℃, held at that temperature for 0.8~1.8 hours, and then air-cooled;

[0042] 5) Hot drawing: The bars after oxidation annealing are heated in a tube furnace for hot drawing and water cooling at the exit. The drawing temperature is 740-900℃, the drawing speed is 0.49-0.95m / min, the number of drawing passes is 13-33, and the diameter of the bars obtained after drawing is 0.8-5mm.

[0043] 6) The drawn bars are subjected to vacuum hot straightening at a temperature of 640-790℃, and the resulting bars are longitudinally cut into interface screws.

[0044] The content of the second aspect is the same as the corresponding content in the first aspect, and will not be repeated here.

[0045] Beneficial effects:

[0046] (1) This invention addresses the application requirements of interface screws and the design of alloy composition. It uses a special processing technology to obtain interface screws with low friction coefficient. The required equipment and processing technology are simple and can meet the needs of mass production.

[0047] (2) The interface screw rod produced by the present invention can achieve a low coefficient of friction (0.44 to 0.45) and ensure excellent strength and plasticity. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the cross-section of the pressed double-layer high-purity aluminum mesh electrode.

[0049] Figure 2 This is a schematic diagram of the hot drawing water cooling device.

[0050] Attached reference numerals: 1-High-purity aluminum mesh drum, 2-Tube furnace, 3-Cooling water nozzle, 4-Drawing die. Detailed Implementation

[0051] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0053] raw material:

[0054] Grade 0 sponge titanium (99.8%), purchased from Jinda Titanium Industry Co., Ltd.

[0055] TiCu master alloy (wt% composition: 50% Ti, 50% Cu) and AlV master alloy (wt% composition: 40% Al, 60% V) were purchased from Beijing Xingrongyuan Metal Materials Co., Ltd.

[0056] High-purity aluminum briquettes (99.9%) were purchased from Dongfang High-Tech Metal Materials Co., Ltd.

[0057] High-purity aluminum mesh (99.9%), purchased from Dongfang High-Tech Metal Materials Co., Ltd.

[0058] Examples 1-8, Comparative Examples 1-8

[0059] A low-friction interface screw is prepared by a method comprising the following steps:

[0060] 1) Melting: Melting is carried out using a vacuum arc remelting furnace. The raw materials are grade 0 sponge titanium, TiCu master alloy, AlV master alloy, high-purity aluminum briquettes, and high-purity aluminum mesh. A mixer is used to mechanically mix the aluminum briquettes, sponge titanium, and AlV master alloy. The aluminum mesh is rolled into a cylindrical shape, with two mesh cylinders nested together. The space between the mesh cylinders is filled with TiCu master alloy, and the interior of the mesh cylinders is filled with a mixture of aluminum briquettes, sponge titanium, and AlV master alloy. Finally, the aluminum mesh cylinders are embedded into an electrode mold using the mixture of aluminum briquettes, sponge titanium, and AlV master alloy, and pressed to form a molten electrode, such as... Figure 1 As shown, the pressed electrodes are melted into alloy ingots.

[0061] 2) Forging: The alloy ingot is heated to 1000℃ and held for 4 hours for hot forging. The total forging ratio is 5-6. The ingot is forged into a slab along the axial direction, and the slab is cut into square bars along its length. The square bars are then heated to 900℃, held for 1 hour, and water-cooled.

[0062] 3) Hot rolling: The alloy square bar is heated to 800℃ and held at that temperature for 2 hours for hot rolling. The rolling parameters are shown in Table 2. Finally, it is rolled into bars with a diameter of 10-13mm.

[0063] 4) Oxidation annealing treatment: The rolled bars are subjected to surface defects by a centerless lathe. The oxidation annealing temperature of the bars is 700℃, held for 1.5 hours, and then air-cooled.

[0064] 5) Hot drawing: The oxidized bars are hot drawn using a device equipped with a water cooling system, the structure of which is as follows: Figure 2 As shown, the system includes a tube furnace 2, cooling water nozzles 3, and drawing dies 4. The bar stock enters the heating chamber through one end of the tube furnace, and after heating, it exits through the other end and is water-cooled at the cooling water nozzles at the outlet. The drawing parameters are shown in Table 3.

[0065] 6) The drawn bar is vacuum hot straightened at a temperature of 700℃, then ground and polished by a centerless grinder and cleaned. The resulting bar is then longitudinally cut into interface screws.

[0066] The alloy composition and preparation process of each embodiment and comparative example are shown in Table 1.

[0067] Table 1. Titanium alloy composition (wt.%) and preparation process used in the examples and comparative examples.

[0068]

[0069]

[0070] Table 2 Rolling process parameters

[0071]

[0072] Table 3 Hot drawing process parameters

[0073]

[0074]

[0075] Test Example 1 Performance Test

[0076] The friction coefficients of the materials in the examples and comparative examples were tested using a ball-on-disk tribometer (MS-T300, China). The experimental mode was reciprocating linear sliding friction, with a sliding speed of 0.06 m / s, a load of 5 N, and 300 reciprocations. The grinding pair consisted of Si3N4 balls with a diameter of 4 mm.

[0077] The room temperature tensile mechanical properties of the materials in the examples and comparative examples were tested using an Instron 8872 tensile testing machine at a tensile rate of 0.5 mm / min. Before testing, the materials were machined into standard tensile specimens with a thread diameter of 10 mm, a gauge length of 5 mm, and a gauge length of 30 mm using a lathe. Three parallel specimens were taken from each group of heat-treated specimens. The mechanical properties obtained from the experiment included tensile strength and elongation. The specific results are shown in Table 4.

[0078] According to the national standard GB / T16886.5-2017 Biological Evaluation of Medical Devices, cell viability was determined using the MTT assay to evaluate the biosafety of the titanium alloys in the examples and comparative examples. Then, the results of each group were evaluated according to the five-level toxicity evaluation standard (levels 0 and 1 meet the requirements for biomedical materials). The results are shown in Table 4.

[0079] The change in pitting potential during electrochemical corrosion performance testing reflects the material's resistance to microbial corrosion. The corrosion resistance of the titanium alloys in the examples and comparative examples was tested using the stainless steel pitting potential measurement method (National Standard: GB / T 17899-1999) to obtain anodic polarization curves and determine their corrosion resistance. The test results are shown in Table 4.

[0080] Table 4. Performance of the materials in the examples and comparative examples.

[0081]

[0082]

[0083] Test Example 2: In Vitro Co-culture Experiment

[0084] Methicillin-resistant Staphylococcus aureus (MRSA) strains were inoculated onto nutrient agar (NA) slant culture medium, cultured at (37±1)℃ for 24 h, and then stored at 0℃~5℃ (not exceeding 1 month) as slant culture culture.

[0085] Transfer the slant culture to nutrient agar plates and incubate at (37±1)℃ for 24 hours. Substitute once a day for no more than 2 weeks. Fresh bacterial cultures (substituted within 24 hours) after two consecutive subcultures should be used in the experiment.

[0086] Take a small amount (1-2 loops) of fresh bacteria from the culture medium using an inoculation loop, add it to the culture medium, and perform 10-fold serial dilutions. Count the bacteria using a cell counting chamber, and select a bacterial concentration of 5.0 × 10⁻⁶. 5 cfu / m1~10.0×10 5 A CFU / ml dilution was used as the bacterial culture for the test.

[0087] Prepare 15 For sterilized petri dishes, place 5-6 sheets of [unspecified material] on the bottom of the petri dish. Use sterile filter paper and pour in an appropriate amount of sterile purified water to fully absorb the water. The filter paper should be able to absorb the water when pressed with sterile tweezers without releasing a large amount of water.

[0088] Take 15 sheets A sterile filter membrane is placed over the sterile filter paper on each petri dish, spreading it out evenly. 0.2 ml of the test bacterial suspension is then dropped onto... On the sterile filter membrane.

[0089] Using sterile forceps, pick up the negative control TC4 alloy sample (A), the blank control medical high-density polyethylene sample (B), and the test sample (C). Perform five replicates for each sample, covering them with sterile forceps. Place the bacterial solution onto a sterile filter membrane to ensure uniform contact with the sample, and incubate at (37±1)℃ for 24h.

[0090] Take the samples cultured for 24 hours, add 20 ml of elution buffer to each sample, and repeatedly wash samples A, B, and C, as well as the covering film (preferably using tweezers to pick up the film and rinse), shaking thoroughly. Using a sterile pipette tip, transfer 1 ml of the stock eluent to a sterile petri dish. Immediately add approximately 15 ml of nutrient agar medium cooled to 46°C to the dish and rotate to mix thoroughly. Repeat the plating process twice to obtain two petri dishes containing the stock eluent. Take another 1 ml of the stock eluent and slowly pour it along the wall of a test tube containing 9 ml of sterile physiological saline (be careful not to let the pipette tip touch the diluent in the tube). Shake the test tube to mix thoroughly, preparing a 1:10 eluent dilution. Transfer 1 ml of the 1:10 eluent dilution to a sterile petri dish, immediately add approximately 15 ml of nutrient agar medium cooled to 46°C to the dish, and rotate to mix thoroughly. Repeat the plating process twice to obtain two petri dishes containing the 1:10 eluent dilution. Take 1 ml of 1:10 elution buffer and slowly pour it along the wall of a test tube containing 9 ml of sterile physiological saline (be careful not to let the tip of the pipette touch the diluent in the tube). Shake the test tube to mix thoroughly, making a 1:100 elution buffer. Transfer 1 ml of the 1:100 elution buffer to a sterile petri dish, and immediately pour about 15 ml of nutrient agar medium cooled to 46°C into the petri dish, rotating the petri dish to mix thoroughly. Repeat the plating process twice to obtain two petri dishes with the 1:100 elution buffer. Take 1 ml of the 1:100 elution buffer and slowly pour it along the wall of a test tube containing 9 ml of sterile physiological saline (be careful not to let the tip of the pipette touch the diluent in the tube). Shake the test tube to mix thoroughly, making a 1:1000 elution buffer. Transfer 1 ml of the 1:1000 elution dilution to a sterile petri dish. Immediately pour approximately 15 ml of nutrient agar medium, cooled to 46°C, into the dish and rotate to mix thoroughly. Repeat the plating process twice to obtain two petri dishes containing the 1:1000 elution dilution.

[0091] When performing plate colony counting, visual inspection can be used, and a magnifying glass can be used if necessary to prevent omissions. After recording the colony count on each plate, calculate the average total colony count for each plate at the same dilution. Select plates with colony counts between 30 and 300 as the standard for total colony count determination. If two plates are used for one dilution, the average of the two plates should be used. If one plate has large, sheet-like colonies, it should not be used; instead, the plate without sheet-like colonies should be used as the colony count for that dilution. If sheet-like colonies cover less than half of the plate, but the colonies in the remaining half are evenly distributed, the count for half the plate can be multiplied by 2 to represent the total colony count. If chain-like colonies grow on the plate (with no clear boundaries between colonies), if there is only one chain, it can be considered as one colony; if there are several chains from different sources, each chain should be counted as one colony. A dilution with an average colony count between 30 and 300 should be selected and multiplied by the dilution factor when filling out the report. If two dilutions both produce colony counts between 30 and 300, the decision depends on their ratio. If the ratio is less than or equal to 2, report the average; if greater than 2, report the smaller number. If the average colony count for all dilutions is greater than 300, report the highest average colony count multiplied by the dilution factor. If the average colony count for all dilutions is less than 30, report the lowest average colony count multiplied by the dilution factor. If no colonies grow at any dilution, report a value less than 1 multiplied by the lowest dilution factor (see Example 6 in Table 5). If the average colony count for all dilutions is not between 30 and 300, but some are greater than 300 or less than 30, report the average colony count closest to 30 or 300 multiplied by the dilution factor (see Example 7 in Table 5).

[0092] When the colony count is less than 100, report the actual number. When it is greater than 100, use two significant figures. The value after the two significant figures is rounded. To shorten the number of zeros, it can also be expressed as a power of 10 (see Table 5).

[0093] Table 5. Dilution Selection and Colony Count Reporting Method

[0094]

[0095]

[0096] Multiply the measured viable count by 100 to obtain the actual recovered viable counts of samples A, B, and C after 24 hours of incubation. The values ​​are A, B, and C, respectively. Ensure the test results meet the following requirements; otherwise, the test is invalid:

[0097] For the same blank control sample B, the five parallel viable cell counts should meet the requirement that the logarithm of (highest logarithm - lowest logarithm) / average viable cell count is no greater than 0.3;

[0098] The actual recovered viable bacteria count (A) of sample A should not be less than 1.0 × 10⁻⁶. 5 CFU / tablet, and the actual recovered viable bacteria count of sample B should not be less than 1.0 × 10⁻⁶. 4 cfu / film.

[0099] The antibacterial rate is calculated according to formula (A.1).

[0100] R(%)=(BC) / B×100 (A.1)

[0101] In the formula:

[0102] R – Antibacterial rate, %;

[0103] B—Average recovered bacterial count in blank control sample, CFU / tablet;

[0104] C – Average number of recovered bacteria in antibacterial samples, CFU / tablet.

[0105] The results are shown in Table 6.

[0106] Table 6 Antibacterial rate data for examples and comparative examples

[0107]

[0108]

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-friction coefficient interface screw, characterized in that, Prepared by a method including the following steps: 1) Smelting: The raw materials sponge titanium, TiCu master alloy, AlV master alloy, aluminum briquettes and aluminum mesh are weighed and proportioned as follows: Al: 5.2~6.7%, V: 3.4~4.3%, Cu: 4.3~6.2%, Ti balance; The aluminum mesh is made into a container, filled with sponge titanium, TiCu master alloy, AlV master alloy and aluminum granules, pressed into a melting electrode using an electrode mold, and then melted into an alloy ingot. 2) Forging: Heat the alloy ingot to 950~1150℃, hold for 4~5 hours and then hot forge. The total forging ratio is 5~7. Forge the ingot into a slab along the axial direction. Cut the slab into square bars along the length direction. Reheat the square bars to 820~1030℃, hold for 0.5~1 hours and then water cool. 3) Hot rolling: The alloy square bar is heated to 700~830℃, held for 1.2~2.2 hours and then hot rolled. A total of 9~10 passes are rolled to produce bars with a diameter of 10~13mm. The deformation amount of each pass in the first to fifth passes is 10~15%, and the interval between two adjacent passes in the first to fifth passes is 15~30s. The deformation amount of each pass in the sixth pass and subsequent passes is not higher than 23%, and the interval between two adjacent passes in the sixth pass and subsequent passes is 25~45s. 4) Oxidation annealing treatment: The bar is subjected to oxidation annealing treatment at a temperature of 560~730℃, held at that temperature for 0.8~1.8 hours, and then air-cooled; 5) Hot drawing: The bars after oxidation annealing are heated in a tube furnace for hot drawing and water cooling at the exit. The drawing temperature is 740~900℃, the drawing speed is 0.49~0.95m / min, the number of drawing passes is 13~33, and the diameter of the bars after drawing is 0.8~5mm. The cooling water temperature is 10~20℃, the number of cooling water nozzles is 2~4, and the water flow rate is 1.2~1.9m / s. 6) The drawn bar is vacuum hot straightened at a temperature of 640~790℃. The resulting bar is then longitudinally cut into interface screws. The resulting interface screws have a friction coefficient of 0.44~0.45, an elongation of ≥13%, a cytotoxicity rating of ≤1, and a pitting potential of ≥2321mV.

2. The interface screw according to claim 1, characterized in that, In step 1), the aluminum mesh is rolled into two cylindrical aluminum mesh barrels with different bottom diameters. The two aluminum mesh barrels are nested together, and the space between the two aluminum mesh barrels is filled with TiCu master alloy. The inside of the aluminum mesh barrels is filled with a mixture of aluminum granules, sponge titanium and AlV master alloy.

3. The interface screw according to claim 1, characterized in that, In step 4), a centerless lathe is used to remove surface defects of the bar before oxidation annealing.

4. A method for preparing an interface screw with a low coefficient of friction, characterized in that, Includes the following steps: 1) Smelting: The raw materials sponge titanium, TiCu master alloy, AlV master alloy, aluminum briquettes and aluminum mesh are weighed and proportioned as follows: Al: 5.2~6.7%, V: 3.4~4.3%, Cu: 4.3~6.2%, Ti balance; The aluminum mesh is made into a container, filled with sponge titanium, TiCu master alloy, AlV master alloy and aluminum granules, pressed into a melting electrode using an electrode mold, and then melted into an alloy ingot. 2) Forging: Heat the alloy ingot to 950~1150℃, hold for 4~5 hours and then hot forge. The total forging ratio is 5~7. Forge the ingot into a slab along the axial direction. Cut the slab into square bars along the length direction. Reheat the square bars to 820~1030℃, hold for 0.5~1 hours and then water cool. 3) Hot rolling: The alloy square bar is heated to 700~830℃, held for 1.2~2.2 hours and then hot rolled. A total of 9~10 passes are rolled to produce bars with a diameter of 10~13mm. The deformation amount of each pass in the first to fifth passes is 10~15%, and the interval between two adjacent passes in the first to fifth passes is 15~30s. The deformation amount of each pass in the sixth pass and subsequent passes is not higher than 23%, and the interval between two adjacent passes in the sixth pass and subsequent passes is 25~45s. 4) Oxidation annealing treatment: The bar is subjected to oxidation annealing treatment at a temperature of 560~730℃, held at that temperature for 0.8~1.8 hours, and then air-cooled; 5) Hot drawing: The bars after oxidation annealing are heated in a tube furnace for hot drawing and water cooling at the exit. The drawing temperature is 740~900℃, the drawing speed is 0.49~0.95m / min, the number of drawing passes is 13~33, and the diameter of the bars after drawing is 0.8~5mm. The cooling water temperature is 10~20℃, the number of cooling water nozzles is 2~4, and the water flow rate is 1.2~1.9m / s. 6) The drawn bar is vacuum hot straightened at a temperature of 640~790℃. The resulting bar is then longitudinally cut into interface screws. The resulting interface screws have a friction coefficient of 0.44~0.45, an elongation of ≥13%, a cytotoxicity rating of ≤1, and a pitting potential of ≥2321mV.

5. The preparation method according to claim 4, characterized in that, In step 1), the aluminum mesh is rolled into two cylindrical aluminum mesh barrels with different bottom diameters. The two aluminum mesh barrels are nested together, and the space between the two aluminum mesh barrels is filled with TiCu master alloy. The inside of the aluminum mesh barrels is filled with a mixture of aluminum granules, sponge titanium and AlV master alloy.

6. The preparation method according to claim 4, characterized in that, In step 4), a centerless lathe is used to remove surface defects of the bar before oxidation annealing.

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