Method for improving corrosion resistance of titanium alloy and titanium-based composite material
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-14
- Publication Date
- 2026-03-10
AI Technical Summary
Titanium alloys and titanium-based composite materials suffer from localized corrosion failure when operating under extreme conditions such as high pressure and high salinity in the deep sea and corrosive media in oil extraction. Existing technologies are insufficient to meet the long-term corrosion resistance requirements of high-end equipment.
The hydrogen plasma vacuum consumable electrode arc furnace melting technology is used to melt titanium alloys and titanium-based composite materials in a hydrogen-argon mixed atmosphere. The hydrogen atoms are efficiently inserted into the melt under the action of the plasma arc, which optimizes the density of the oxide film on the material surface, removes harmful impurities in the melt, and improves the corrosion resistance of the material.
It significantly improves the corrosion resistance of titanium alloys and titanium-based composite materials, reduces the risk of corrosive media penetration, and is suitable for extreme environments such as deep sea and oil extraction. It is economical, safe and reliable to operate, and is suitable for high-end equipment manufacturing.
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Figure CN121629201A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of metal matrix composites and preparation, and in particular, relates to a method for improving the corrosion resistance of titanium alloy and titanium matrix composite. BACKGROUND
[0002] Titanium alloy and titanium matrix composite have irreplaceable application value in extreme service fields such as deep sea exploration and oil exploitation due to their excellent specific strength and inherent corrosion resistance. The service environment in these fields is harsh. In deep sea environment, there is long-term corrosion of high pressure and high salinity seawater. In the process of oil exploitation, strong acid and chlorine-containing medium corrosion is faced, which puts high requirements on the corrosion resistance and stability of the material. The characteristics of titanium alloy and titanium matrix composite make it the preferred material for such scenarios.
[0003] However, although titanium alloy and titanium matrix composite have certain corrosion resistance, under extreme conditions such as deep sea high pressure and high salinity, oil exploitation containing corrosive medium, long-term service may still cause local corrosion failure, which is difficult to fully meet the demand for long-term corrosion resistance of high-end equipment. The industry has tried surface coating, composition optimization and other solutions, but the coating is easy to fall off under extreme pressure, and composition optimization increases the cost and has limited effect. Liquid hydrogenation technology can refine the grain size and improve the density of the oxide film by controlling the dissolution and precipitation of hydrogen, providing a new path to solve the problem.
[0004] However, at present, there is no systematic solution focusing on titanium alloy and titanium matrix composite, with liquid hydrogenation technology as the core and emphasis on corrosion resistance strengthening, so it is urgent to develop a special method to fully utilize the advantages of liquid hydrogenation technology and meet the stringent requirements of materials corrosion resistance in extreme environments. SUMMARY
[0005] The present application solves the problem that the existing titanium alloy and titanium matrix composite may still have local corrosion failure under extreme conditions such as deep sea high pressure and high salinity, oil exploitation containing corrosive medium, and provides a method for improving the corrosion resistance of titanium alloy and titanium matrix composite.
[0006] In order to achieve the above technical problems, the present application adopts the following technical solutions: The method for improving the corrosion resistance of titanium alloy or titanium matrix composite by using hydrogen plasma vacuum consumable electrode arc furnace smelting is carried out according to the following steps: Step 1, pretreat the mixed titanium alloy raw materials or pretreat the titanium matrix composite raw materials respectively, then load them into the water-cooled copper crucible in the vacuum non-consumable electrode arc furnace, seal and vacuumize to remove the air in the furnace; Step 2, hydrogen and argon mixed gas is introduced, argon is supplemented after the arc is started, the melting is carried out at a preset current and voltage after complete melting for a certain time, the ingot is turned over after cooling for a certain time, and the above melting process is repeated, fresh mixed gas is filled before each melting, residual gas in the furnace is extracted after the melting is completed, and the ingot is taken out, The purpose of the present application is to provide a method for improving the corrosion resistance of titanium alloy by using hydrogen plasma vacuum consumable electrode arc furnace, which comprises the following steps: Step one, pretreat the titanium alloy raw material, clean the vacuum non-consumable arc melting system (grind the tungsten electrode, clean the water-cooled copper crucible), check the circulating water pump waterway pressure; put the pretreated raw material into the water-cooled copper crucible and seal the furnace door; Step two, start the mechanical pump and the pre-evacuation valve to pre-evacuate, then start the molecular pump, and continuously evacuate until the ionization unit of the digital vacuum gauge reads 5x10 -3 Pa, close the related valves and equipment; Step three, start the JF-2200 type gas control system, fill in the set proportion of hydrogen and argon mixed gas, supplement argon to stabilize the pressure in the furnace at 0.05MPa, and monitor the gas proportion in real time; Step four, start the rectifier power supply, adjust the tungsten electrode to about 0.5mm from the surface of the raw material to strike the arc; after the raw material is completely melted, melt at a preset current and voltage of 30V-40V for 1 minute; after the melting is completed, the tungsten electrode height is raised during cooling, the ingot is turned over after cooling, and the melting is repeated 1-8 times as needed, and fresh mixed gas is filled before each melting; Step five, after the melting is completed, the residual gas in the furnace is extracted, the furnace door is opened to take out the ingot, the equipment is cleaned, and the vacuum system, power supply and circulating water pump are closed.
[0007] Further limitation, in step one, the tungsten electrode is high-purity tungsten material, the tip is polished at an angle of 30°~45° to ensure stable arc striking.
[0008] Further limitation, in step one, the raw material is titanium sponge, and the corresponding elemental substance or intermediate alloy of the type of alloying element to be added. The raw material is sequentially ultrasonically cleaned with acetone and anhydrous ethanol and dried at 100℃ for 2h.
[0009] Further limitation, in step two, the mechanical pump and the pre-evacuation valve are started to evacuate the furnace, the molecular pump is started after the resistance unit of the digital vacuum gauge reads 5Pa, the main evacuation valve is opened after the molecular pump speed exceeds 3000rpm, and the vacuum is continuously evacuated until the ionization unit of the digital vacuum gauge reads 5x10 -3 Pa. The mechanical pump pre-evacuation time is greater than or equal to 30 minutes to ensure that there is no residual air in the furnace.
[0010] Further limited, in step three, the purity of hydrogen-argon mixed gas is ≥ 99.999%, the hydrogen partial pressure is 20%, and the furnace pressure fluctuation is ≤ ± 0.002 MPa.
[0011] Further limited, in step four, the smelting current is controlled at 200A-400A, the single smelting time deviation is ≤ ± 5 seconds, and the cooling time is ≥ 5 minutes during repeated smelting of ingot turning.
[0012] Further limited, in step five, the ingot needs to be detected by ultrasonic flaw detection after being taken out, and the internal defect size is ≤ 0.1mm to be judged as qualified.
[0013] In addition, a method for smelting titanium-based composite material with improved corrosion resistance by hydrogen plasma vacuum consumable electrode arc furnace is also provided, which comprises the following steps: Step one, pretreat the base material and reinforcing body reactants, clean the hydrogen plasma vacuum consumable electrode arc furnace (grind the electrode and clean the water-cooled copper crucible), check the water pressure; arrange the raw materials according to the preset ratio and put them into the crucible, and seal the furnace door; Step two, start the mechanical pump and pre-evacuation valve to pre-evacuate, then start the molecular pump, and continue to evacuate until the ionization unit reading reaches 5×10 -3 Pa, close the related valves and equipment; Step three, start the gas control system, charge the set proportion of hydrogen-argon mixed gas, supplement argon to stabilize the furnace pressure at 0.05 MPa, and monitor the gas composition in real time; Step four, start the power to strike an arc, after the raw materials are completely melted, smelt for 1 minute at a preset current and voltage of 30V-40V to promote in-situ generation of reinforcing bodies; after smelting, raise the tungsten electrode height during cooling, turn over the ingot after cooling, repeat smelting 2-8 times as needed, and charge fresh mixed gas before each smelting; Step five, after smelting, evacuate the residual gas, open the furnace door to take out the ingot, clean the equipment, and close the vacuum system, power supply and circulating water pump.
[0014] Further limited, in step one, the electrode material is high-purity tungsten, and the tip grinding angle is 30°-45° to ensure stable arc striking and uniform melt.
[0015] Further limited, in step one, the base material is sponge titanium and corresponding alloy element single / middle alloy, and the reinforcing body reactant is graphite powder (for in-situ generation of TiC) or boron source powder (for in-situ generation of TiB).
[0016] Further limited, in step one, the reinforcing body reactant is wrapped with high-purity aluminum foil with a thickness of 0.1-0.2mm, and the raw materials are arranged according to the melting point gradient to avoid being blown away by the arc during smelting.
[0017] To further specify, in step one, all raw materials are sequentially ultrasonically cleaned with acetone and anhydrous ethanol, and dried at 100°C for 2 hours to remove surface impurities.
[0018] Further specifying step two, the mechanical pump and pre-evacuation valve are started to evacuate the furnace. Once the digital vacuum gauge resistance unit reading drops to 5 Pa, the molecular pump is started. After the molecular pump speed exceeds 3000 rpm, the main evacuation valve is opened, and evacuation continues until the digital vacuum gauge ionization unit reading reaches 5 × 10⁻⁶ Pa. -3 Pa. During the vacuuming process, the mechanical pump should be pre-evacuated for at least 30 minutes to ensure that there is no residual air inside the furnace.
[0019] Further specifying, in step three, the purity of the hydrogen-argon mixture is ≥99.999%, and the hydrogen partial pressure is 20%, to meet the requirements of in-situ reaction and deoxygenation.
[0020] Further, in step four, the melting current is 250A~450A, the single melting time deviation is ≤±5 seconds, and the cooling time is ≥8 minutes when melting is repeated.
[0021] Further specifying that in step five, the ingot must undergo ultrasonic testing (internal defects ≤0.1mm), and the uniformity of reinforcement distribution ≥90% is considered qualified.
[0022] Compared with the prior art, the present invention has the following beneficial effects: This invention innovatively employs a core technology of hydrogen atom addition, melting titanium alloys and titanium-based composite materials in a mixed atmosphere of hydrogen and argon. During the melting process, elements are efficiently incorporated into the melt in the form of hydrogen atoms under the action of a plasma arc, remaining in the ingot during solidification. This technology breaks through the limitations of traditional melting processes, possessing both novelty and advancement, providing crucial support for a leap in material performance. Regarding corrosion resistance, the strong reducing properties of hydrogen atoms can efficiently remove harmful impurities such as oxygen from the melt, while simultaneously optimizing the density and stability of the oxide film on the material surface, significantly reducing the risk of corrosive media penetration. This results in a qualitative improvement in the corrosion resistance of titanium alloys and titanium-based composite materials, effectively solving the problem of corrosion failure in extreme environments such as deep sea and oil extraction, and significantly improving corrosion resistance compared to traditional processes. Furthermore, this invention is technically economical, safe, reliable, and highly controllable, ensuring both the stability of performance improvement and the feasibility of large-scale application, showing excellent application prospects in the field of high-end equipment manufacturing.
[0023] For a deeper understanding of the features and technical content of this invention, please refer to the accompanying detailed description and drawings. It should be noted that the drawings are provided for illustrative purposes only and are not intended to limit the scope of the invention. Attached Figure Description
[0024] Figure 1The curves show the evolution of OCP over time for Ti6Al4V alloys with different hydrogen contents: (a) 3.5 wt.% NaCl solution; (b) 5 M HCl solution. Figure 2(a) shows the potentiodynamic polarization curves of Ti6Al4V alloys with different hydrogen contents in 3.5 wt.% NaCl solution; Figure 2(b) shows the potentiodynamic polarization curves of Ti6Al4V alloys with different hydrogen contents in 5 M HCl solution; Figure 3 The images show the EIS spectra of Ti6Al4V alloys with different hydrogen contents in 3.5 wt.% NaCl solution and 5 M HCl solution. (a) Nyquist plot of 3.5 wt.% NaCl solution, (b) Bode plot of 3.5 wt.% NaCl solution, (c) Nyquist plot of 5 M HCl solution, and (d) Bode plot of 5 M HCl solution. Figure 4 The bar graphs show the changes in polarization resistance Rp of Ti6Al4V alloys with different hydrogen contents as a function of hydrogen content: (a) 3.5 wt.% NaCl solution; (b) 5 M HCl solution. Figure 5 The curves show the evolution of OCP over time for TiC / Ti6Al4V composites with different hydrogen contents: (a) 3.5 wt.% NaCl solution; (b) 5 M HCl solution. Figure 6 The following are the potentiodynamic polarization curves of TiC / Ti6Al4V with different hydrogen contents: (a) 3.5 wt.% NaCl solution; (b) 5 M HCl solution; Figure 7 The images show the EIS spectra of TiC / Ti6Al4V composite materials with different hydrogen contents in 3.5 wt.% NaCl solution and 5 M HCl: (a) Nyquist plot of 3.5 wt.% NaCl solution, (b) Bode plot of 3.5 wt.% NaCl solution, (c) Nyquist plot of 5 M HCl solution, and (d) Bode plot of 5 M HCl solution. Figure 8 The polarization resistance Rp of TiC / Ti6Al4V composite materials with different hydrogen contents varies with hydrogen content, (a) 3.5 wt.% NaCl solution, (b) 5 M HCl solution. Detailed Implementation
[0025] The present invention will be described in detail below with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but should not be considered as limiting the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.
[0026] Example 1 Step 1: Take 26.46g of 99.9wt.% pure sponge titanium, 2.04g of 99.99wt.% pure high-purity aluminum particles, and 1.5g of 99.9wt.% pure aluminum-vanadium master alloy (V=58.15wt.%) according to the Ti6Al4V composition ratio and mix them together; then clean them sequentially with acetone and anhydrous ethanol using ultrasonic cleaning for 15min each time, and dry them in a vacuum drying oven at 100℃ for 2h; at the same time, polish the high-purity tungsten electrode with a tip angle of 35°, clean the oxide on the inner wall of the water-cooled copper crucible, and check that the water pressure of the circulating water pump is 0.3MPa.
[0027] Step 2: Place the pretreated raw material into the crucible and seal the furnace door. Use a hydrogen plasma vacuum consumable electrode arc melting system. First, pre-evacuate the furnace for 35 minutes using a mechanical pump, then start the molecular pump to evacuate until the ionization unit reading reaches 5 × 10⁻³ Pa. Subsequently, start the JF-2200 gas control system, introduce a hydrogen-argon mixture, and replenish argon until the furnace pressure stabilizes at 0.05 MPa. Adjust the tungsten electrode to 0.5 mm from the raw material surface to ignite the arc. Set the current to 300 A and the voltage to 40 V, and melt for 1 minute. After the ingot cools for 5 minutes, flip it using a robotic arm. Repeat the melting process 5 times, introducing fresh hydrogen-argon mixture before each melting. After melting, extract the residual gas from the furnace, remove the ingot, and confirm that the internal defects are ≤0.08 mm by ultrasonic testing.
[0028] In step 2, the hydrogen-argon mixture is a mixture of hydrogen with a purity of 99.999% and argon with a purity of 99.999% (by mass or volume), with hydrogen accounting for 20% of the volume of the mixture.
[0029] The resulting ingot, after testing, showed a hydrogen mass fraction of 6.23 × 10⁻⁶. -2 The sample was processed by wire cutting into a size of 10 mm × 10 mm × 5 mm and electrochemically tested on a CHI660 electrochemical workstation using a standard three-electrode system: a saturated calomel electrode (SCE) as the reference electrode, a platinum sheet electrode as the auxiliary electrode, and the sample to be tested as the working electrode.
[0030] Comparative Example 1 The difference between this comparative example and Example 1 is that the raw materials were placed in a vacuum non-consumable arc furnace, and a vacuum degree of 5 × 10⁻⁶ was achieved. -3 After Pa, a mixture of 10% hydrogen and 90% argon with a purity of 99.999% is introduced. The remaining operating steps are exactly the same as in Example 1, and the target ingot is obtained.
[0031] The resulting ingot, after testing, showed a hydrogen mass fraction of 3.12 × 10⁻⁶. -2wt.%, and electrochemical tests were also performed.
[0032] Comparative Example 2 The difference between this comparative example and Example 1 is that the raw materials were placed in a vacuum non-consumable arc furnace, and a vacuum degree of 5 × 10⁻⁶ was achieved. -3 After Pa, a mixture of pure argon gas with a purity of 99.999% is introduced, and the remaining operation steps are exactly the same as in Example 1, to obtain the target unhydrogenated ingot, which is then subjected to electrochemical testing.
[0033] Example 2 Based on the target composition of 5 vol.% TiC / Ti6Al4V composite material, 25.14 g of 99.9 wt.% pure sponge titanium, 1.94 g of 99.99 wt.% high-purity aluminum particles, and 1.42 g of 99.9 wt.% aluminum-vanadium master alloy were taken according to the Ti6Al4V composition ratio. Additionally, 1.5 g of 99.9 wt.% pure graphite powder (3 μm particle size) was taken (as a carbon source for the in-situ self-generated reaction of TiC). The materials were ultrasonically cleaned with acetone and anhydrous ethanol for 15 min each, and then dried in a vacuum oven at 100℃ for 2 h. After drying, the graphite powder was wrapped with 0.15 mm thick 99.99 wt.% high-purity aluminum foil (to prevent it from being blown away by the electric arc during melting). Simultaneously, a high-purity tungsten electrode with a 35° tip angle was polished, oxides on the inner wall of the water-cooled copper crucible were cleaned, and the circulating water pump pressure was checked to be 0.3 MPa. The raw materials were arranged in the crucible according to the melting point gradient principle: 2 g of raw materials were placed at the bottom. High-purity aluminum particles, with aluminum-vanadium intermediate alloy and graphite powder wrapped in aluminum foil stacked in the middle layer, and sponge titanium placed on the top layer.
[0034] The prepared raw materials were placed into the crucible and the furnace door was sealed. A hydrogen plasma vacuum consumable electrode arc melting system was used. First, a mechanical pump was used to pre-evacuate the furnace for 35 minutes, then a molecular pump was started to evacuate until the ionization unit reading reached 5 × 10⁻⁶. -3 Pa; then the JF-2200 gas control system was activated, a hydrogen-argon mixture was introduced, and argon was added until the furnace pressure stabilized at 0.05 MPa. The tungsten electrode was adjusted to 0.5 mm from the surface of the top layer of sponge titanium to ignite the arc. The first melting was set with a current of 350 A (to ensure full melting of the bottom raw materials and the in-situ reaction of TiC) and a voltage of 40 V for 1 min. After the ingot cooled for 8 min, it was flipped by a robotic arm. The subsequent four meltings were repeated with a current of 300 A and a voltage of 40 V, each melting for 1 min. Fresh mixed gas was introduced before each melting. After melting, the residual gas in the furnace was extracted, and the ingot was taken out and ultrasonically tested to confirm that the internal defects were ≤0.08 mm.
[0035] The resulting ingot, after testing, showed a hydrogen mass fraction of 5.97 × 10⁻⁶. -2The sample was processed by wire cutting into a size of 10 mm × 10 mm × 5 mm and electrochemically tested on a CHI660 electrochemical workstation using a standard three-electrode system: a saturated calomel electrode (SCE) as the reference electrode, a platinum sheet electrode as the auxiliary electrode, and the sample to be tested as the working electrode.
[0036] Comparative Example 3 The difference between this comparative example and Example 2 is that the raw materials were placed in a vacuum non-consumable arc furnace, and a vacuum degree of 5 × 10⁻⁶ was achieved. -3 After Pa, a mixture of 10% (by volume) hydrogen and 90% (by volume) argon gas with a purity of 99.999% is introduced. The remaining operating steps are exactly the same as in Example 2, and the target ingot is obtained.
[0037] The resulting ingot, after testing, showed a hydrogen mass fraction of 3.23 × 10⁻⁶. -2 wt.%, and electrochemical tests were also performed.
[0038] Comparative Example 4 The difference between this comparative example and Example 2 is that the raw materials were placed in a vacuum non-consumable arc furnace, and a vacuum degree of 5 × 10⁻⁶ was achieved. -3 After Pa, a mixture of pure argon gas with a purity of 99.999% is introduced, and the remaining operation steps are exactly the same as in Example 1, to obtain the target unhydrogenated ingot, which is then subjected to electrochemical testing.
[0039] Corrosion performance of Example 1 and Comparative Examples 1 and 2 Depend on Figures 1-4 It can be known that the partial pressure of hydrogen at 20% (the mass fraction of hydrogen is 6.23 × 10⁻⁶) -2 The ingot with a hydrogen partial pressure of 20% (wt.%) compared to one with a hydrogen mass fraction of 3.12 × 10⁻⁶ (wt.%) -2 Ingots melted with pure argon (wt.%) and unhydrogenated exhibit higher open-circuit potential, lower corrosion current density, positively shifted corrosion potential, and higher polarization resistance in both 3.5wt.% NaCl and 5M HCl solutions, demonstrating that the present invention can improve the corrosion resistance of titanium alloys under simulated and strong acid conditions.
[0040] Corrosion performance of Examples 2 and 3 and 4 Depend on Figures 5-8 It can be known that the partial pressure of hydrogen at 20% (the mass fraction of hydrogen is 5.97 × 10⁻⁶) -2 The ingot with a hydrogen partial pressure of 20% (wt.%) compared to the ingot with a hydrogen mass fraction of 3.23 × 10⁻⁶ wt.% was 3.23 × 10⁻⁶ wt.%. -2Ingots melted with pure argon (wt.%) and unhydrogenated exhibit higher open-circuit potential, lower corrosion current density, positively shifted corrosion potential, and higher polarization resistance in both 3.5wt.% NaCl and 5M HCl solutions, demonstrating that the present invention can improve the corrosion resistance of titanium alloys under simulated and strong acid conditions.
[0041] The specific embodiments of the present invention have been described in detail above. It should be noted that the present invention is not limited to the specific embodiments described above. Various modifications or alterations can be made by those skilled in the art without departing from the scope of protection defined by the claims, and all such modifications or alterations fall within the scope of the present invention.
Claims
1. A method for improving corrosion resistance of titanium alloys and titanium matrix composites, characterized by, The method comprises the following steps: Step 1, pretreat the titanium alloy raw materials after mixing or the titanium matrix composite raw materials respectively, then load into a water-cooled copper crucible in a vacuum non-consumable electrode arc furnace, seal and vacuumize to remove air in the furnace; Step 2, introduce hydrogen and argon mixed gas, supplement argon, arc, completely melt, smelt for a certain time under preset current and voltage, cool for a certain time, turn over the ingot, repeat the above smelting process, fill fresh mixed gas before each smelting, extract residual gas in the furnace after smelting, and take out the ingot, The titanium matrix composite raw materials are sequentially loaded into the crucible.
2. The method of claim 1, wherein, The titanium alloy is Ti6Al4V alloy, and the raw materials are titanium sponge, high-purity aluminum particles and aluminum-vanadium intermediate alloy.
3. The method of claim 2, wherein, The raw materials of the Ti6Al4V alloy are titanium sponge, high-purity aluminum particles and aluminum-vanadium intermediate alloy.
4. The method of claim 1, wherein, The titanium matrix composite is TiC / Ti6Al4V.
5. The method of claim 4, wherein, The raw materials of the TiC / Ti6Al4V are titanium sponge, high-purity aluminum particles, aluminum-vanadium intermediate alloy and aluminum foil wrapped graphite powder, the high-purity aluminum particles are placed at the bottom layer, the aluminum-vanadium intermediate alloy and the aluminum foil wrapped graphite powder are stacked at the middle layer, and the titanium sponge is placed at the top layer.
6. The method of claim 1, wherein, Pretreatment: sequentially cleaned by ultrasonic cleaning with acetone and anhydrous ethanol, and dried.
7. The method of claim 1, wherein, evacuated to 5 x 10 -3 Pa.
8. The method of claim 1, wherein, The purity of hydrogen is 99.999%, 80% argon, and the volume of hydrogen accounts for 20% of the mixed gas.
9. The method of claim 1 wherein, Supplement argon to stabilize the pressure in the furnace at 0.05 MPa.
10. The method of claim 1, wherein, Smelting current is 250A-450A, voltage is 30V-40V, single smelting time deviation is ≤±5 seconds, and cooling time is ≥8 minutes when repeating smelting.