Preparation method of medical high-strength zirconium-niobium alloy rod

Abstract

This invention belongs to the field of medical zirconium-niobium alloy processing, specifically a method for preparing high-strength zirconium-niobium alloy rods for medical use. The chemical composition and mass percentage of the zirconium-niobium alloy are: Nb 2.0%–3.0%, O ≤ 0.2%, Hf ≤ 0.01%, C ≤ 0.02%, Fe ≤ 0.15%, with the balance being Zr. First, nuclear-grade sponge zirconium is selected as the raw material, with the addition of a small amount of pure niobium or zirconium-niobium alloy and zirconium dioxide. The forging billet is obtained by melting in a vacuum arc furnace. Then, homogenization heat treatment is performed at a temperature of 900℃–1000℃ for 2–10 hours, followed by air cooling. Subsequently, multiple forging passes are performed at 800–950℃, with the deformation controlled at 20%–80% per pass, and the final forging temperature not lower than 600℃ per pass. Finally, straightening and polishing are performed. This invention can produce qualified zirconium-niobium alloy rods, providing qualified raw materials for the manufacture of orthopedic medical devices.

Description

Technical Field

[0001] This invention belongs to the field of medical zirconium-niobium alloy processing, specifically a method for preparing high-strength medical zirconium-niobium alloy rods. Background Technology

[0002] Artificial hip joint prostheses mainly consist of the femoral stem, femoral head, acetabular cup, and liner. Depending on the materials of the artificial femoral head and acetabular liner, their friction interfaces are primarily classified as metal-to-metal, metal-to-polyethylene, ceramic-to-polyethylene, and ceramic-to-ceramic. Currently, ceramic-to-ceramic interfaces have the lowest wear rate, and due to their bioinertness, the probability of wear particles causing inflammatory reactions in the surrounding tissues is minimized, effectively reducing osteolysis and postoperative aseptic loosening. However, ceramics are inherently brittle and have weak bending resistance; poor prosthesis positioning can easily lead to the prosthesis being subjected to stress exceeding its load-bearing capacity, resulting in fracture.

[0003] Zirconium-niobium alloy (Zr-2.5Nb) is one of the most biocompatible metallic materials and a new generation of artificial joint head material. After machining the joint prosthesis, the surface undergoes an oxidation treatment to form a ZrO2 ceramic layer, giving the prosthesis surface the smoothness and wear resistance of ceramic materials. Simultaneously, the matrix possesses high fatigue strength and high toughness, avoiding the risk of fragility associated with ceramic components. Furthermore, the price of this material's head is only half that of ceramic heads, offering a significant price advantage. However, the high melting point of niobium in zirconium-niobium alloys makes it prone to becoming high-density inclusions. Additionally, domestically produced rods exhibit low uniformity in microstructure and properties, significantly reduced dimensional accuracy after machining, and the surface zirconium oxide ceramic is prone to peeling off, severely limiting the development and innovation of artificial joint products in my country. Therefore, there is an urgent need to conduct research and development on high-performance zirconium-niobium alloy materials and joint products. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing high-strength zirconium-niobium alloy rods for medical use, which solves the problems of high melting point of niobium in existing zirconium-niobium alloys, which easily become high-density inclusions, low uniformity of microstructure and properties, significant reduction in dimensional accuracy after machining ball heads, and easy peeling off of surface zirconium oxide ceramic.

[0005] To solve the problem of Zr-Nb alloy bar processing, the technical solution adopted in this invention is as follows:

[0006] A method for preparing a high-strength zirconium-niobium alloy rod for medical use, wherein the chemical composition and mass percentage of the zirconium-niobium alloy are: Nb 2.0%–3.0%, O ≤ 0.2%, Hf ≤ 0.01%, C ≤ 0.02%, Fe ≤ 0.15%, and the balance is Zr;

[0007] The preparation method of the high-strength zirconium-niobium alloy rod for medical use includes the following steps:

[0008] Step 1: Zr-Nb alloy ingots were prepared by melting in a vacuum consumable arc furnace;

[0009] Step 2: Homogenize the zirconium-niobium alloy ingot at a temperature of 900–1000℃.

[0010] Step 3: Perform billet forging on the homogenized zirconium-niobium alloy ingot;

[0011] Step 4: Perform continuous high-temperature forging to produce bars of various specifications;

[0012] Step 5: Straighten and anneal the forged bar stock;

[0013] Step 6: Continue to perform centerless surface polishing on the straightened and annealed bars to prepare qualified bars.

[0014] The preparation method of the high-strength zirconium-niobium alloy rod for medical use, in step one, uses small-particle nuclear-grade sponge zirconium with a particle size of 3-12.7 mm, pure niobium or zirconium-niobium alloy, and zirconium dioxide compound, and is fed according to the alloy composition, and is melted in a vacuum consumable electric arc furnace to obtain an ingot.

[0015] The preparation method of the high-strength zirconium-niobium alloy rod for medical use, in step one, firstly, a vacuum consumable arc furnace is used with high-power deep-pool melting technology, with a power range of 500-1500 kW·h / t, a pool depth of 500-800 mm, and a time of 1-4 hours; then, a vacuum consumable arc furnace is used with low-power shallow-pool refining technology and arc-stabilizing stirring technology, with a power range of 300-800 kW·h / t, a pool depth of 300-600 mm, and a time of 2-8 hours.

[0016] In the preparation method of the high-strength zirconium-niobium alloy rod for medical use, step two involves homogenization treatment, in which the ingot is heated to 900-1000℃ in the furnace, held for 2-10 hours, and then air-cooled after being taken out of the furnace.

[0017] In the preparation method of the high-strength zirconium-niobium alloy rod for medical use, step three involves a forging process in which the temperature is raised to 900–1050°C, held for 3–8 hours, and the deformation is 20–80%.

[0018] In the preparation method of the high-strength zirconium-niobium alloy rod for medical use, step four involves a continuous high-temperature forging process in which the temperature is raised to 800-950°C and held for 1-5 hours for forging. The final forging temperature for each forging is above 600°C, and the rod is forged in 1-10 forging cycles with a deformation of 20-80% per cycle.

[0019] In the preparation method of the high-strength zirconium-niobium alloy rod for medical use, step five involves using a two-roller or multi-roller straightener to straighten the rod, ensuring that the curvature is less than 0.03 mm.

[0020] In the preparation method of the high-strength zirconium-niobium alloy rod for medical use, in step five, the annealing temperature is 500-750℃, the holding time is 1-4 hours, and the rod is cooled to room temperature in the furnace.

[0021] In the preparation method of the high-strength zirconium-niobium alloy rod for medical use, step six, centerless polishing is to polish or machine the rod to meet the dimensional tolerance requirements.

[0022] The design concept of this invention is:

[0023] This invention eliminates high-melting-point niobium inclusions through high-power deep-pool smelting technology; improves the compositional uniformity of zirconium-niobium alloy ingots through low-power shallow-pool refining technology and stable arc stirring technology; and refines the grain size, texture distribution, and residual stress of zirconium-niobium alloys by combining multi-pass high-temperature forging and heat treatment processes, thereby significantly improving their mechanical properties and ball-end machining accuracy.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] 1. This invention provides a method for preparing high-strength zirconium-niobium alloy rods for medical use. This method can produce qualified rod products, providing qualified raw materials for orthopedic medical devices.

[0026] 2. The raw materials of this invention have high purity, and the alloy composition uniformity can be effectively controlled by melting in a vacuum consumable arc furnace.

[0027] 3. The preparation method provided by this invention is easy to operate, requires simple equipment, and can achieve mass production of qualified zirconium-niobium alloy rods and wires with specifications of Φ3~Φ80mm. Detailed Implementation

[0028] In the specific implementation process, the present invention first selects nuclear-grade sponge zirconium as raw material, adds a small amount of pure niobium or zirconium-niobium alloy and zirconium dioxide, and obtains forging billets by vacuum arc furnace melting; then it performs homogenization heat treatment, with a heat treatment temperature of 900℃~1000℃, holding for 2 hours to 10 hours, and air cooling; then it performs multi-fire forging at 800~950℃, with the deformation amount of each forging controlled at 20%~80%, and the final forging temperature of each forging not lower than 600℃; finally, it performs straightening and polishing.

[0029] The present invention will now be further described with reference to the embodiments.

[0030] Example 1

[0031] In this embodiment, the preparation method of Zr-Nb alloy rods is as follows:

[0032] Step 1: Using small-particle nuclear-grade sponge zirconium with a particle size of 3-12.7 mm, pure Nb shavings, and zirconium dioxide compounds, the materials are prepared according to requirements, the electrodes are pressed, and the Zr-Nb alloy ingot is obtained by melting in a vacuum consumable arc furnace.

[0033] First, the vacuum self-consuming electric arc furnace adopts high-power deep molten pool smelting technology with a power of 1200 kW·h / t, a molten pool depth of 600 mm, and a time of 3 hours; then, the vacuum self-consuming electric arc furnace adopts low-power shallow molten pool refining technology and arc stabilization stirring technology with a power of 350 kW·h / t, a molten pool depth of 350 mm, and a time of 5 hours.

[0034] The chemical composition and mass percentage of the Zr-Nb alloy ingot are as follows: Nb 2.2%, O 0.15%, Hf 0.004%, C 0.013%, Fe 0.09%, with the balance being Zr.

[0035] Step 2: Homogenize the zirconium-niobium alloy ingot. Heat the ingot to 980℃ in the furnace, hold for 8 hours, and then air cool to room temperature after removing it from the furnace.

[0036] Step 3: Forging the homogenized zirconium-niobium alloy ingot into a billet, heating it to 1000℃, holding it for 5 hours, and forging it into a square billet with a cross-sectional size of 300×300mm, with a deformation of 60%.

[0037] Step 4: Continuous high-temperature forging is carried out. The temperature is raised to 900℃ and held for 3 hours before forging begins. The square billet after the initial forging is forged in 5 passes. The forging size is Φ65mm. The deformation amount in each pass is controlled at 40-50%, and the final forging temperature in each pass is 650℃.

[0038] Step 5: Straighten and anneal the forged bar using a two-roll straightener to ensure that the curvature is less than 0.03 mm. The annealing temperature is 630℃, the holding time is 2 hours, and the bar is cooled to room temperature in the furnace.

[0039] Step 6: Continue to perform centerless grinding on the surface of the straightened and annealed bar to prepare a qualified bar with a finished size of Φ61.0mm.

[0040] Table 1 shows the mechanical properties of the Φ61mm Zr-Nb alloy rods prepared in Example 1.

[0041] Sample 1 570 385 24.0 Sample 2 576 386 27.0

[0042] Example 2

[0043] In this embodiment, the preparation method of Zr-Nb alloy rods is as follows:

[0044] Step 1: Using small-particle nuclear-grade sponge zirconium with a particle size of 3-12.7 mm, pure Nb shavings, and zirconium dioxide compounds, the materials are prepared according to requirements, the electrodes are pressed, and the Zr-Nb alloy ingot is obtained by melting in a vacuum consumable arc furnace.

[0045] First, the vacuum arc remelting furnace adopts high-power deep-pool smelting technology with a power of 1300 kW·h / t, a pool depth of 720 mm, and a time of 3.5 hours. Then, the vacuum arc remelting furnace adopts low-power shallow-pool refining technology and arc-stabilizing stirring technology with a power of 480 kW·h / t, a pool depth of 410 mm, and a time of 5.5 hours.

[0046] The chemical composition and mass percentage of the Zr-Nb alloy are as follows: Nb 2.4%, O 0.10%, Hf 0.07%, C 0.016%, Fe 0.14%, and the balance is Zr.

[0047] Step 2: Homogenize the zirconium-niobium alloy ingot. Heat the ingot to 1000℃ in the furnace and hold for 6 hours. After removing it from the furnace, air cool it to room temperature.

[0048] Step 3: The homogenized zirconium-niobium alloy ingot is forged into a billet by heating to 980℃ and holding for 6 hours. The billet is forged into a square billet with a cross-sectional size of 280×280mm and a deformation of 50%.

[0049] Step 4: Continuous high-temperature forging is carried out. The temperature is raised to 820℃ and held for 5 hours to start forging. The square billet after the initial forging is forged 5 times. The forging size is Φ60mm. The deformation of each forging is controlled at 45-55%. The final forging temperature of each forging is 600℃.

[0050] Step 5: Straighten and anneal the forged bar using a two-roll straightener to ensure that the curvature is less than 0.03 mm. The annealing temperature is 720℃, the holding time is 2.5 hours, and the bar is cooled to room temperature in the furnace.

[0051] Step 6: Continue to perform centerless grinding on the surface of the straightened and annealed bar to prepare a qualified bar with a finished size of Φ55.0mm.

[0052] Table 2 shows the mechanical properties of the Φ55mm Zr-Nb alloy rods prepared in Example 2.

[0053]

[0054]

[0055] Example 3

[0056] In this embodiment, the preparation method of Zr-Nb alloy rods is as follows:

[0057] Step 1: Using small-particle nuclear-grade sponge zirconium with a particle size of 3-12.7 mm, pure Nb shavings, and zirconium dioxide compounds, the materials are prepared according to requirements, the electrodes are pressed, and the Zr-Nb alloy ingot is obtained by melting in a vacuum consumable arc furnace.

[0058] First, the vacuum arc remelting furnace adopts high-power deep-pool smelting technology with a power of 1380 kW·h / t, a pool depth of 760 mm, and a time of 2 hours; then, the vacuum arc remelting furnace adopts low-power shallow-pool refining technology and arc-stabilizing stirring technology with a power of 620 kW·h / t, a pool depth of 510 mm, and a time of 4 hours.

[0059] The chemical composition and mass percentage of the Zr-Nb alloy are as follows: Nb 2.6%, O 0.12%, Hf 0.003%, C 0.010%, Fe 0.12%, and the balance is Zr.

[0060] Step 2: Homogenize the zirconium-niobium alloy ingot. Heat the ingot in the furnace to 940℃, hold for 10 hours, and air cool to room temperature after removing it from the furnace.

[0061] Step 3: The homogenized zirconium-niobium alloy ingot is forged into a billet by heating to 1020℃ and holding for 5 hours. The billet is forged into a square billet with a cross-sectional size of 220×220mm and a deformation of 40%.

[0062] Step 4: Continuous high-temperature forging is carried out. The temperature is raised to 870℃ and held for 4 hours before forging begins. The square billet after the initial forging is forged in 6 passes. The forging size is Φ42mm. The deformation amount in each pass is controlled at 40-50%, and the final forging temperature in each pass is 630℃.

[0063] Step 5: Straighten and anneal the forged bar using a multi-roll straightener to ensure that the curvature is less than 0.03 mm. The annealing temperature is 580℃, the holding time is 1.5 hours, and the bar is cooled to room temperature in the furnace.

[0064] Step 6: Continue to perform centerless grinding on the surface of the straightened and annealed bar to prepare a qualified bar with a finished size of Φ37.0mm.

[0065] Table 3 shows the mechanical properties of the Φ37mm Zr-Nb alloy rods prepared in Example 3.

[0066] Sample 1 637 423 21.0 Sample 2 638 427 20.5

[0067] Example 4

[0068] In this embodiment, the preparation method of Zr-Nb alloy rods is as follows:

[0069] Step 1: Using small-particle nuclear-grade sponge zirconium with a particle size of 3-12.7 mm, pure Nb shavings, and zirconium dioxide compounds, the materials are prepared according to requirements, the electrodes are pressed, and the Zr-Nb alloy ingot is obtained by melting in a vacuum consumable arc furnace.

[0070] First, the vacuum arc remelting furnace adopts high-power deep-pool smelting technology with a power of 900 kW·h / t, a pool depth of 540 mm, and a time of 3.5 hours. Then, the vacuum arc remelting furnace adopts low-power shallow-pool refining technology and arc-stabilizing stirring technology with a power of 700 kW·h / t, a pool depth of 560 mm, and a time of 6.5 hours.

[0071] The chemical composition and mass percentage of the Zr-Nb alloy are as follows: Nb 2.8%, O 0.08%, Hf 0.006%, C 0.014%, Fe 0.07%, and the balance is Zr.

[0072] Step 2: Homogenize the zirconium-niobium alloy ingot. Heat the ingot to 960℃ in the furnace, hold for 8 hours, and then air cool to room temperature after removing it from the furnace.

[0073] Step 3: The homogenized zirconium-niobium alloy ingot is forged into a billet by heating to 1040℃ and holding for 5 hours. The billet is forged into a square billet with a cross-sectional size of 220×220mm and a deformation of 40%.

[0074] Step 4: Continuous high-temperature forging is carried out. The temperature is raised to 910℃ and held for 2 hours before forging begins. The square billet after the initial forging is forged in 6 passes. The forging size is Φ29mm. The deformation amount per pass is controlled at 35-45%, and the final forging temperature per pass is 700℃.

[0075] Step 5: Straighten and anneal the forged bar using a multi-roll straightener to ensure that the curvature is less than 0.03 mm. The annealing temperature is 520℃, the holding time is 4 hours, and the bar is cooled to room temperature in the furnace.

[0076] Step 6: Continue to perform centerless grinding on the surface of the straightened and annealed bar to prepare a qualified bar with a finished size of Φ25.0mm.

[0077] Table 4 shows the mechanical properties of the Φ25mm Zr-Nb alloy rods prepared in Example 4.

[0078] Sample 1 660 462 23.0 Sample 2 658 459 23.5

[0079] The mechanical property test results of the embodiment show that, due to the use of matching homogenization treatment (temperature 940℃~1000℃, holding time 6~10h), billet forging (temperature 980℃~1040℃, holding time 5~6h), continuous high-temperature forging (temperature 820℃~910℃, holding time 2~5h), and annealing (annealing temperature 520~720℃, holding time 1.5~4h), the optimized process scheme of the embodiment can achieve Rm 547~660MPa and Rp 0.2 The rods have a strength of 379–462 MPa and an alumina content of 20.5–27.0%. Therefore, this invention enables the production of qualified zirconium-niobium alloy rods, providing suitable raw materials for the manufacture of orthopedic medical devices.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength zirconium-niobium alloy rod for medical use, characterized in that, The chemical composition and mass percentage of the zirconium-niobium alloy are as follows: Nb 2.0%~3.0%, O≤0.2%, Hf≤0.01%, C≤0.02%, Fe≤0.15%, with the balance being Zr; The preparation method of the high-strength zirconium-niobium alloy rod for medical use is as follows: Step 1: Zr-Nb alloy ingots were prepared by melting in a vacuum consumable arc furnace; Step 2: Homogenize the zirconium-niobium alloy ingot at a temperature of 900~1000℃. Step 3: Perform billet forging on the homogenized zirconium-niobium alloy ingot; Step 4: Perform continuous high-temperature forging to produce bars of various specifications; Step 5: Straighten and anneal the forged bar stock; Step 6: Continue to perform centerless surface polishing on the straightened and annealed bars to prepare qualified bars; In step one, firstly, the vacuum consumable arc furnace adopts high-power deep-pool smelting technology with a power range of 500~1500kW·h / t, a molten pool depth of 500~800mm, and a time of 1~4 hours; then, the vacuum consumable arc furnace adopts low-power shallow-pool refining technology and arc-stabilizing stirring technology with a power range of 300~800kW·h / t, a molten pool depth of 300~600mm, and a time of 2~8 hours. In step two, the homogenization process involves heating the ingot to 900-1000℃ in the furnace, holding it at that temperature for 2-10 hours, and then air-cooling it after it is removed from the furnace. In step three, the selected forging process involves heating to 900~1050℃, holding at that temperature for 3~8 hours, and achieving a deformation rate of 20~80%. In step four, the selected continuous high-temperature forging process involves heating to 800~950℃ and holding at that temperature for 1~5 hours for forging. The final forging temperature for each pass is above 600℃, and the bar stock is formed after 1~10 passes, with a deformation of 20~80% per pass. In step five, the annealing temperature is 500~750℃, the holding time is 1~4 hours, and the furnace is cooled to room temperature. In step six, centerless polishing involves polishing or machining the bar stock to meet dimensional tolerance requirements.

2. The method for preparing the high-strength zirconium-niobium alloy rod for medical use according to claim 1, characterized in that, In step one, small-particle nuclear-grade sponge zirconium with a particle size of 3~12.7mm, pure niobium or zirconium-niobium alloy, and zirconium dioxide compound are used. The alloy is prepared according to the alloy composition and melted in a vacuum consumable electric arc furnace to obtain an ingot.

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