A high-temperature-bearing, erosion-resistant, and oxidation-resistant tungsten-based alloy and its preparation method

Abstract

The present invention discloses a high-temperature-bearing, erosion-resistant, and oxidation-resistant tungsten-based alloy and a preparation method thereof, relating to the field of high-temperature oxidation-resistant material preparation, specifically including the preparation of tungsten-based alloy, surface treatment, transition rhenium coating preparation, and oxidation-resistant iridium composite coating preparation. The tungsten-based alloy uses a metal raw material with a purity of >99.99%, adds oxide or carbide particles to strengthen the phase, and during surface treatment, first performs surface etching and then performs surface stabilization treatment. The transition rhenium coating is prepared by molten salt electrodeposition or chemical vapor deposition. The oxidation-resistant iridium composite coating uses an electrodeposition method to prepare an iridium-hafnium or iridium-thorium composite coating. The present invention can improve the high-temperature strength of the tungsten-based alloy and solve the limitation that it cannot be used in a high-temperature oxidizing atmosphere, expand its application temperature range, and the prepared coating has good bonding strength with the substrate. It can be applied to a variety of scenarios such as high temperature bearing, erosion resistance, and oxidation resistance, further expanding the application field of the tungsten-based alloy.

Description

Technical Field

[0001] The present invention relates to the field of high-temperature anti-oxidation material preparation, and in particular to a high-temperature-bearing, erosion-resistant, anti-oxidation tungsten-based alloy and a preparation method thereof. Background Art

[0002] Tungsten-based alloys have a melting point of up to 3000°C and have the advantages of good high-temperature performance, good plasticity after recrystallization, and good welding performance. They are widely used in non-ferrous metal metallurgy, aerospace, aviation, nuclear energy and other fields. However, during use, tungsten-based alloys do not have antioxidant properties and will undergo severe oxidation above 500°C, so they cannot serve in extreme environments. One of the available methods to improve the oxidation resistance of tungsten-based alloys above 2000°C is surface modification, that is, preparing an antioxidant surface coating with moderate thickness that meets the requirements of use on the surface of the tungsten-based alloy. Common ones include ceramic and metal antioxidant layers. Preparing a ceramic antioxidant coating on the surface of a tungsten-based alloy is currently a more common method. However, since the thermal expansion coefficient of ceramics is larger than that of tungsten-based alloys, the thermal shock resistance is poor, and the interface is easy to separate during use, which will lose its protective effect. Selecting a metal antioxidant layer with a matching thermal expansion coefficient can hopefully improve the performance of tungsten-based alloys in high-temperature oxidizing environments. At present, there are few reports on the preparation of metal anti-oxidation layers on the surface of tungsten-based alloys. CN201510925325.5 adds antioxidant elements to the prepared tungsten-based alloy to improve the antioxidant performance of the substrate, but it only reduces the oxidation rate and cannot solve the problem of substrate oxidation well; CN202111059137.0 prepares a high-temperature and erosion-resistant surface coating on the surface of tungsten or tungsten alloy. The coating system is relatively simple, but it does not synergistically improve the overall performance of tungsten alloy from the perspective of tungsten matrix optimization. In high-temperature environments, tungsten alloys are prone to failure due to grain boundary merging and growth, reduced strength, and other reasons. Summary of the Invention

[0003] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a high-temperature-bearing, erosion-resistant and oxidation-resistant tungsten-based alloy and a preparation method thereof.

[0004] The technical solutions of the present invention are as follows:

[0005] A method for preparing a high-temperature-resistant, erosion-resistant, and oxidation-resistant tungsten-based alloy comprises the following steps: mixing tungsten powder, rhenium powder, molybdenum powder, or tantalum powder, and a reinforcing phase to obtain tungsten-based alloy powder; subjecting the tungsten-based alloy powder to sequential molding, pressing, sintering, swaging, annealing, and surface treatment; and then depositing a transition coating and an anti-oxidation coating on the surface-treated tungsten-based alloy.

[0006] Preferably, the steps include:

[0007] S1: mixing tungsten powder, rhenium powder or molybdenum powder or tantalum powder and a reinforcing phase to obtain a mixed powder, wherein the reinforcing phase accounts for 1.0 to 4.0% by weight of the tungsten-based alloy powder after mixing;

[0008] S2: putting the mixed powder into a double cone mixer for mixing to obtain tungsten-based alloy powder;

[0009] S3: pressing the tungsten-based alloy powder into billets;

[0010] S4: performing medium frequency induction sintering on the billet in a hydrogen protective atmosphere at a sintering temperature of 2200-2400° C. to obtain a tungsten-based alloy billet;

[0011] S5: rotary forging the tungsten-based alloy blank at a heating temperature of 1400-1500° C. to obtain a tungsten-based alloy;

[0012] S6: After cleaning the tungsten-based alloy, perform stress relief annealing at a temperature of 900-1050°C. Argon or hydrogen is used as a protective atmosphere during the annealing process.

[0013] S7: performing surface etching and surface stabilization treatment on the annealed tungsten-based alloy;

[0014] S8: preparing a metal transition coating on the surface of the surface-treated tungsten-based alloy by molten salt electrodeposition or chemical vapor deposition, wherein the transition coating is a rhenium coating;

[0015] S9: preparing an anti-oxidation composite coating on the surface of the tungsten-based alloy for preparing the metal transition coating by electrodeposition, wherein the anti-oxidation coating is an iridium composite coating, including an iridium-hafnium coating and an iridium-thorium coating.

[0016] Preferably, in step S1, the purity of the tungsten powder, rhenium powder, molybdenum powder or tantalum powder is not less than 99.99%;

[0017] The reinforcing phase is at least one of thorium oxide, lanthanum oxide, hafnium oxide, titanium carbide, hafnium carbide, zirconium carbide and niobium carbide.

[0018] Preferably, in step S2, the variable speed of the double-cone mixer is 10 to 50 r / min, and the mixing time is 60 to 180 min.

[0019] Preferably, in step S3, cold isostatic pressing is used for pressing, specifically: the mixed tungsten-based alloy powder is placed in a polyurethane sheath and cold isostatically pressed at a pressing pressure of 120 to 180 MPa, a holding time of 15 to 120 seconds, and a density of the formed billet greater than 60%;

[0020] And / or, in step S4, sintering is performed in a reducing atmosphere.

[0021] Preferably, in step S5, the heat preservation time during rotary forging is 8 to 12 minutes, and the deformation amount per pass is 8 to 15%.

[0022] Preferably, in step S7, during the surface treatment, the surface is first etched with an etching solution, and then the surface is stabilized with a treatment solution;

[0023] The etching solution includes sodium hydroxide, potassium ferrocyanide, potassium dichromate, sodium tungstate and water. The etching process is carried out in an ultrasonic environment for 20 to 100 seconds.

[0024] The surface stabilization treatment solution includes sodium hydroxide, anhydrous ethanol, 2-methyl-1-hexane, sodium sulfate and water. The current density of the DC regulated power supply ranges from 1.0 to 4.0 A / cm 2 , the stabilization treatment time is not less than 30s.

[0025] Preferably, in step S8, the molten salt used for molten salt electrodeposition includes sodium chloride, potassium chloride, cesium chloride and potassium hexachlororhenate. The electrodeposition process is carried out in a salt bath electrolytic furnace, argon gas is introduced for protection, rhenium wire is used as anode, and electrolytically polished tungsten-based alloy is used as cathode. The current density range is 3 to 300 mA / cm 2 , electrodeposition temperature 750~950℃, electrodeposition time 5~200min;

[0026] Alternatively, a rhenium transition layer is prepared by chemical vapor deposition, wherein the evaporation source of the chemical vapor deposition is rhenium pentachloride, the evaporation temperature range is 350-450° C., the loading amount is 0.5-20 g, the transport gas is an argon-hydrogen mixed gas, the deposition temperature range is 1000-1250° C., and the deposition time is 30-300 min. After the rhenium transition coating is prepared, the sample is placed in anhydrous ethanol, isopropanol, and deionized water for ultrasonic cleaning in sequence, and then dried for use.

[0027] Preferably, in step S8, the molten salt for electrodeposition includes one or more main salts selected from iridium salt, hafnium salt, and thorium salt, and a conductive salt;

[0028] The iridium salt includes one or more of iridium fluoride, iridium chloride, iridium bromide and iridium iodide.

[0029] The hafnium salt includes one or more of hafnium fluoride, hafnium chloride, and hafnium bromide.

[0030] The thorium salt comprises one or more of thorium chloride and thorium chloride, wherein the mass fraction of iridium is 5-10wt.%, the mass fraction of hafnium is 0.05-0.2wt.%, and the mass fraction of thorium is 0.05-0.2wt.%. The conductive salt comprises two or more of sodium chloride, potassium chloride, lithium chloride, sodium fluoride, potassium fluoride, sodium cyanide, potassium cyanide, and cesium chloride, and the mass fraction of the conductive salt is 15-60wt.%. A tungsten-based alloy containing a rhenium transition layer is used as a cathode, and an iridium wire, hafnium wire, or thorium wire is used as an anode. During electrodeposition, the molten salt temperature is raised to 550-650°C and kept warm. The current density is 1.0-5.0A / dm 2 ; Electrodeposition time 0.1 ~ 10h; After preparation, place the sample in boiling water to clean the residual salt on the surface, ultrasonically clean it with anhydrous ethanol, and dry it for later use.

[0031] The present invention also discloses a high temperature bearing, erosion resistant and oxidation resistant tungsten based alloy, which is prepared by any of the above preparation methods.

[0032] The present invention has the following beneficial effects: By selecting impurity elements and adding reinforcing phases to tungsten-based alloys, the present invention can effectively improve the high-temperature strength and other properties of the alloy itself. To address the limitation of tungsten-based alloys that cannot be used in oxidizing atmospheres, the present invention adopts surface modification and antioxidant composite coating preparation technology. Through this method, the prepared coating has good adhesion to the substrate and can be used in various scenarios such as high temperature bearing, erosion resistance and oxidation resistance. For example, tungsten-rhenium alloys are used in the field of temperature measurement, and tungsten-thorium alloys are used in the field of high-temperature erosion structural parts, further expanding the application field of tungsten-based alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the composite coating structure of the present invention, in which: 1-tungsten-based alloy substrate, 2-rhenium transition layer, 3-oxidation-resistant iridium composite layer.

[0034] Figure 2 This is the microscopic morphology of the high-temperature-bearing, erosion-resistant, and oxidation-resistant tungsten-based alloy and oxidation-resistant iridium composite coating of Example 1 of the present invention.

[0035] Figure 3 This is the microscopic morphology of the high-temperature-bearing, erosion-resistant, and oxidation-resistant tungsten-based alloy anti-oxidation iridium composite coating of Example 2 of the present invention after oxyacetylene flame testing.

[0036] Figure 4 This is the microscopic morphology of the high-temperature-bearing, erosion-resistant, and oxidation-resistant tungsten-based alloy anti-oxidation iridium composite coating of Example 3 of the present invention after oxyacetylene flame testing. DETAILED DESCRIPTION

[0037] A method for preparing a high-temperature-resistant, erosion-resistant, and anti-oxidation tungsten-based alloy comprises mixing tungsten powder, rhenium powder, molybdenum powder, or tantalum powder with a reinforcing phase, and uniformly mixing to obtain a tungsten-based alloy powder. The tungsten-based alloy powder is then subjected to molding, pressing, sintering, swaging, annealing, and surface treatment in sequence, and then the surface-treated tungsten-based alloy is subjected to deposition of a transition coating and an anti-oxidation coating in sequence. Specifically, a high-temperature-resistant, erosion-resistant, and anti-oxidation tungsten-based alloy is described. Figure 1 , from bottom to top, it includes a tungsten-based alloy substrate 1, a rhenium transition layer 2, and an oxidation-resistant iridium composite layer 3.

[0038] Specifically, the method includes the following steps:

[0039] S1: mixing tungsten powder, rhenium powder or molybdenum powder or tantalum powder and a reinforcing phase to obtain a mixed powder, wherein the reinforcing phase accounts for 1.0 to 4.0% by weight of the tungsten-based alloy powder after mixing;

[0040] S2: putting the mixed powder into a double cone mixer for mixing to obtain tungsten-based alloy powder;

[0041] S3: pressing the tungsten-based alloy powder into billets;

[0042] S4: performing medium frequency induction sintering on the billet in a hydrogen protective atmosphere at a sintering temperature of 2200-2400° C., preferably 2300° C., to obtain a tungsten-based alloy billet;

[0043] S5: rotary forging the tungsten-based alloy blank at a rotary forging heating temperature of 1400-1500° C., preferably 1450° C., to obtain a tungsten-based alloy;

[0044] S6: After cleaning the tungsten-based alloy, perform stress relief annealing at a temperature of 900-1050° C., preferably 1000° C., using argon or hydrogen as a protective atmosphere during the annealing process;

[0045] S7: performing surface etching and surface stabilization treatment on the annealed tungsten-based alloy;

[0046] S8: preparing a metal transition coating on the surface of the surface-treated tungsten-based alloy by molten salt electrodeposition or chemical vapor deposition, wherein the transition coating is a rhenium coating;

[0047] S9: preparing an anti-oxidation composite coating on the surface of the tungsten-based alloy for preparing the metal transition coating by electrodeposition, wherein the anti-oxidation coating is an iridium composite coating, including an iridium-hafnium coating and an iridium-thorium coating.

[0048] Preferably, in step S1, the purity of the tungsten powder, rhenium powder, molybdenum powder or tantalum powder is not less than 99.99%;

[0049] The reinforcing phase is at least one of thorium oxide, lanthanum oxide, hafnium oxide, titanium carbide, hafnium carbide, zirconium carbide and niobium carbide.

[0050] Preferably, in step S2, the variable speed of the double-cone mixer is 10 to 50 r / min, and the mixing time is 60 to 180 min.

[0051] Preferably, in step S3, cold isostatic pressing is used for pressing, specifically: the mixed tungsten-based alloy powder is placed in a polyurethane sheath and cold isostatically pressed at a pressing pressure of 120 to 180 MPa, a holding time of 15 to 120 seconds, and a density of the formed billet greater than 60%;

[0052] And / or, in step S4, sintering is performed in a reducing atmosphere.

[0053] Preferably, it is characterized in that, in step S5, the heat preservation time during rotary forging is 8 to 12 minutes, preferably 10 minutes, and the deformation amount per pass is 8 to 15%.

[0054] Preferably, in step S7, during the surface treatment, the surface is first etched with an etching solution, and then the surface is stabilized with a treatment solution;

[0055] The etching solution includes sodium hydroxide, potassium ferrocyanide, potassium dichromate, sodium tungstate and water. The concentration of sodium hydroxide is in the range of 20 to 60 g / L, the concentration of potassium ferrocyanide is in the range of 10 to 30 g / L, the concentration of potassium dichromate is in the range of 20 to 60 g / L, and the concentration of sodium tungstate is in the range of 1 to 10 g / L. The etching process is carried out in an ultrasonic environment with a frequency of 2840 KHz and the etching time is 20 to 100 seconds.

[0056] The surface stabilization treatment liquid includes sodium hydroxide, anhydrous ethanol, 2-methyl-1-hexene, sodium sulfate and water, wherein the concentration of sodium hydroxide is 20-40 g / L, the concentration of anhydrous ethanol is 10-50 g / L, the concentration of 2-methyl-1-hexene is 1-5 g / L, the concentration of sodium sulfate is 50-100 g / L, and the current density range of the DC regulated power supply is 1.0-4.0 A / cm 2 , the stabilization treatment time is not less than 30s.

[0057] Preferably, in step S8, the molten salt used for molten salt electrodeposition includes sodium chloride, potassium chloride, cesium chloride and potassium hexachlororhenate, the mass fraction of sodium chloride is 10-20wt.%, the mass fraction of potassium chloride is 10-20wt.%, the mass fraction of cesium chloride is 40-80wt.%, and the mass fraction of potassium hexachlororhenate is 2-15wt.%. The electrodeposition process is carried out in a salt bath electrolytic furnace, argon gas is introduced for protection, rhenium wire is used as anode, and the tungsten-based alloy after electrolytic polishing is used as cathode. The current density range is 3-300 mA / cm 2 , electrodeposition temperature 750~950℃, electrodeposition time 5~200min;

[0058] Alternatively, a rhenium transition layer is prepared by chemical vapor deposition, wherein the evaporation source of the chemical vapor deposition is rhenium pentachloride, the evaporation temperature range is 350-450°C, the loading amount is 0.5-20g, the transport gas is an argon-hydrogen mixed gas, the deposition temperature range is 1000-1250°C, and the deposition time is 30-300min; after preparation of the rhenium transition coating, the sample is placed in anhydrous ethanol, isopropanol, and deionized water in turn for ultrasonic cleaning for 10-30min, and then dried at 50-80°C for 24h for use.

[0059] Preferably, in step S8, the molten salt for electrodeposition includes one or more main salts selected from iridium salt, hafnium salt, and thorium salt, and a conductive salt;

[0060] The iridium salt includes one or more of iridium fluoride, iridium chloride, iridium bromide and iridium iodide.

[0061] The hafnium salt includes one or more of hafnium fluoride, hafnium chloride, and hafnium bromide.

[0062] The thorium salt comprises one or more of thorium chloride and thorium chloride, wherein the mass fraction of iridium is 5-10wt.%, the mass fraction of hafnium is 0.05-0.2wt.%, and the mass fraction of thorium is 0.05-0.2wt.%. The conductive salt comprises two or more of sodium chloride, potassium chloride, lithium chloride, sodium fluoride, potassium fluoride, sodium cyanide, potassium cyanide, and cesium chloride, and the mass fraction of the conductive salt is 15-60wt.%. A tungsten-based alloy containing a rhenium transition layer is used as a cathode, and an iridium wire, hafnium wire, or thorium wire is used as an anode. During electrodeposition, the molten salt temperature is raised to 550-650°C and kept warm. The current density is 1.0-5.0A / dm 2 ; Electrodeposition time 0.1 ~ 10h; After preparation, place the sample in boiling water to clean the residual salt on the surface, and use anhydrous ethanol ultrasonic cleaning for later use.

[0063] The following is a further description of the technical solution of the present invention for specific implementation.

[0064] Example 1

[0065] (1) Ingredients: Tungsten powder with a purity of 99.99% and rhenium powder with a purity of 99.99% are used for the ingredients, and the weight percentage of the added reinforcing phase thorium oxide is 2.2%;

[0066] (2) Batch mixing: The weighed tungsten powder, rhenium powder and thorium oxide are placed in a double cone mixer for mixing at a variable frequency speed of 45 r / min and a mixing time of 120 min to obtain a uniform tungsten-based mixed powder;

[0067] (3) Molding and sintering: The mixed tungsten-based alloy powder was placed in a polyurethane bag and cold isostatically pressed at a pressing pressure of 140 MPa and a holding time of 60 s to obtain a formed billet with a relative density of 61.72%. The formed billet was sintered in a medium-frequency induction furnace under a hydrogen protective atmosphere at a sintering temperature of 2300°C and a holding time of 180 min.

[0068] (4) Rotary forging: The sintered tungsten-based alloy rod is subjected to multiple rotary forgings. The rotary forging heating is carried out in a hydrogen protective atmosphere furnace at a rotary forging heating temperature of 1450°C to obtain a tungsten-based alloy substrate; the tungsten-based alloy is cleaned and subjected to stress relief annealing at a temperature of 1000°C. Argon or hydrogen is used as a protective atmosphere during the annealing process;

[0069] (5) The tungsten-based alloy after annealing was subjected to surface etching and surface stabilization treatment: the surface etching solution had a sodium hydroxide concentration of 40 g / L, a potassium ferrocyanide concentration of 20 g / L, a potassium dichromate concentration of 40 g / L, and a sodium tungstate concentration of 5 g / L, and the etching treatment time was 60 s; the surface stabilization treatment solution had a sodium hydroxide concentration of 30 g / L, an anhydrous ethanol concentration of 30 g / L, a 2-methyl-1-hexene concentration of 4 g / L, and a sodium sulfate concentration of 70 g / L, and the current density range of the DC regulated power supply was 3.0 A / cm 2 , polishing time 120s;

[0070] (6) Preparation of transition rhenium coating: The mass fraction of sodium chloride in the molten salt electrodeposition salt is 15 wt.%, the mass fraction of potassium chloride is 15 wt.%, the mass fraction of cesium chloride is 60 wt.%, and the mass fraction of potassium hexachlororhenate is 8 wt.%. The electrodeposition process is carried out in a salt bath electrolytic furnace, and argon gas is introduced for protection. The rhenium wire is used as the anode and the electrolytically polished tungsten-based alloy is used as the cathode. The current density range is 120 mA / cm 2 , electrodeposition temperature 800℃, electrodeposition time 60min;

[0071] (7) Preparation of anti-oxidation iridium composite coating: Weigh 5 wt.% of iridium trichloride (in terms of iridium), weigh 95 wt.% of sodium chloride, potassium chloride, and cesium chloride to prepare a mixed salt, heat it to 150°C and vacuum dry it for 24 hours, use a tungsten-based alloy containing a rhenium transition layer as the cathode, and an iridium wire as the anode. Heat the molten salt to 580°C and keep it warm for 0.5 hours. The current density is 2.0 A / dm 2 , the electrodeposition time is 1h. After the preparation is completed, the sample is placed in boiling water to clean the residual salt on the surface, and then ultrasonically cleaned with anhydrous ethanol for later use;

[0072] (8) Strength test: The high temperature tensile strength test was carried out in accordance with GB / T 228.2-2015. The prepared tungsten-based alloy was subjected to a temperature of 1600°C and a strain rate of 0.06 min -1Tested under the conditions, the high temperature tensile strength was measured to be 190MPa;

[0073] (9) Assessment: The tungsten-based alloy with the anti-oxidation coating was placed in an oxyacetylene flame for thermal ablation at 3000K for 10 seconds. After the assessment, the surface morphology of the sample was not damaged. Figure 2 .

[0074] Example 2

[0075] (1) Ingredients: Tungsten powder with a purity of 99.99% and tantalum powder with a purity of 99.99% are used for the ingredients, and the weight percentage of titanium carbide added is 1.6%;

[0076] (2) Batch mixing: The weighed tungsten powder, tantalum powder and titanium carbide are placed in a double cone mixer for mixing at a variable frequency speed of 50 r / min and a mixing time of 160 min to obtain a uniform tungsten-based mixed powder;

[0077] (3) Molding and sintering: The mixed tungsten-based alloy powder was placed in a polyurethane bag and cold isostatically pressed at a pressing pressure of 140 MPa and a holding time of 100 s to obtain a formed billet with a relative density of 62.16%. The formed billet was sintered in a medium-frequency induction furnace under a hydrogen protective atmosphere at a sintering temperature of 2300°C and a holding time of 180 min.

[0078] (4) Rotary forging: The sintered tungsten-based alloy rod is subjected to multiple rotary forgings. The rotary forging heating is carried out in a hydrogen protective atmosphere furnace at a rotary forging heating temperature of 1450°C to obtain a tungsten-based alloy substrate; the tungsten-based alloy is cleaned and subjected to stress relief annealing at a temperature of 1000°C. Argon or hydrogen is used as a protective atmosphere during the annealing process;

[0079] (5) The tungsten-based alloy after annealing was subjected to surface etching and surface stabilization treatment: the surface etching solution had a sodium hydroxide concentration of 35 g / L, a potassium ferrocyanide concentration of 25 g / L, a potassium dichromate concentration of 35 g / L, and a sodium tungstate concentration of 8 g / L, and the texturing treatment time was 80 s; the surface stabilization solution had a sodium hydroxide concentration of 35 g / L, an anhydrous ethanol concentration of 35 g / L, a 2-methyl-1-hexene concentration of 3 g / L, and a sodium sulfate concentration of 80 g / L, and the current density range of the DC regulated power supply was 2.0 A / cm 2 , polishing time 180s;

[0080] (6) Preparation of transition rhenium coating: The rhenium transition layer was prepared by chemical vapor deposition technology. The evaporation source was rhenium pentachloride, the evaporation temperature range was 400°C, the loading amount was 2g, the transport gas was argon-hydrogen mixed gas, the deposition temperature range was 1200°C, and the deposition time was 60min.

[0081] (7) Preparation of anti-oxidation iridium composite coating: Weigh 5 wt.% of iridium trichloride (calculated as iridium), 0.05 wt.% of hafnium tetrachloride (calculated as hafnium), and weigh 94.95 wt.% of sodium chloride, potassium chloride, and cesium chloride to prepare a mixed salt. Heat to 150°C and dry in vacuum for 24 hours. A tungsten-based alloy containing a rhenium transition layer is used as the cathode and an iridium wire is used as the anode. The molten salt is heated to 600°C and kept warm for 0.5 hours. The current density is 2.5 A / dm 2 , the electrodeposition time is 1h. After the preparation is completed, the sample is placed in boiling water to clean the residual salt on the surface, and then ultrasonically cleaned with anhydrous ethanol for later use;

[0082] (8) Strength test: The high temperature tensile strength test was carried out in accordance with GB / T 228.2-2015. The prepared tungsten-based alloy was subjected to a temperature of 1600°C and a strain rate of 0.06 min -1 Tested under the conditions, the high temperature tensile strength was measured to be 255MPa;

[0083] (9) Assessment: The tungsten-based alloy with the anti-oxidation coating was placed in an oxyacetylene flame for thermal ablation at 3000K for 10 seconds. After the assessment, the surface morphology of the sample was not damaged. Figure 3 .

[0084] Example 3

[0085] (1) Ingredients: Tungsten powder with a purity of 99.99% and rhenium powder with a purity of 99.99% are used for the ingredients, and the weight percentage of lanthanum oxide added is 1.2%;

[0086] (2) Batch mixing: The weighed tungsten powder and rhenium powder-based lanthanum oxide were placed in a double cone mixer for mixing at a variable frequency speed of 50 r / min and a mixing time of 160 min to obtain a uniform tungsten-based mixed powder;

[0087] (3) Molding and sintering: The mixed tungsten-based alloy powder was placed in a polyurethane bag and cold isostatically pressed at a pressing pressure of 140 MPa and a holding time of 100 s to obtain a formed billet with a relative density of 62.16%. The formed billet was sintered in a medium-frequency induction furnace under a hydrogen protective atmosphere at a sintering temperature of 2300°C and a holding time of 180 min.

[0088] (4) Rotary forging: The sintered tungsten-based alloy rod is subjected to multiple rotary forgings, and the rotary forging heating is carried out in a hydrogen protective atmosphere furnace to obtain a tungsten-based alloy substrate; the tungsten-based alloy is cleaned and subjected to stress relief annealing at an annealing temperature of 1000°C, using argon or hydrogen as a protective atmosphere during the annealing process;

[0089] (5) The tungsten-based alloy after annealing was subjected to surface etching and surface stabilization treatment: the surface etching solution had a sodium hydroxide concentration of 30 g / L, a potassium ferrocyanide concentration of 25 g / L, a potassium dichromate concentration of 30 g / L, a sodium tungstate concentration of 5 g / L, and a texturing treatment time of 80 s; the surface stabilization solution had a sodium hydroxide concentration of 30 g / L, an anhydrous ethanol concentration of 40 g / L, a 2-methyl-1-hexene concentration of 5 g / L, a sodium sulfate concentration of 85 g / L, and a DC regulated power supply current density range of 2.0 A / cm 2 , polishing time 150s;

[0090] (6) Preparation of transition rhenium coating: The rhenium transition layer was prepared by chemical vapor deposition technology. The evaporation source was rhenium pentachloride, the evaporation temperature range was 400°C, the loading amount was 2g, the transport gas was argon-hydrogen mixed gas, the deposition temperature range was 1150°C, and the deposition time was 60min.

[0091] (7) Preparation of anti-oxidation iridium composite coating: Weigh 5 wt.% of iridium trichloride (calculated as iridium), 0.25 wt.% of hafnium tetrachloride (calculated as hafnium), and weigh 94.75 wt.% of sodium chloride, potassium chloride, and cesium chloride to prepare a mixed salt. Heat to 150 ° C and vacuum dry for 24 h. A tungsten-based alloy containing a rhenium transition layer is used as the cathode and an iridium wire is used as the anode. The molten salt is heated to 600 ° C and kept warm for 0.5 h. The current density is 2.5 A / dm 2 , the electrodeposition time is 1h. After the preparation is completed, the sample is placed in boiling water to clean the residual salt on the surface, and then ultrasonically cleaned with anhydrous ethanol for later use;

[0092] (8) Strength test: The high temperature tensile strength test was carried out in accordance with GB / T 228.2-2015. The prepared tungsten-based alloy was subjected to a temperature of 1600°C and a strain rate of 0.06 min -1 Tested under the conditions, the high temperature tensile strength was measured to be 230MPa;

[0093] (9) Assessment: The tungsten-based alloy with the anti-oxidation coating was placed in an oxyacetylene flame for thermal ablation at 3000K for 10 seconds. After the assessment, the surface morphology of the sample was not damaged. Figure 4 .

[0094] In summary, in an oxidizing atmosphere at a high temperature of 3000K, the coatings and substrates prepared in Examples 1-3 of the present invention were not damaged, indicating that the bonding between the coatings and the substrate was good, which can effectively improve the high-temperature strength performance of the alloy itself, overcome the limitation that tungsten-based alloys cannot be used in oxidizing atmospheres, and can be well applied to various scenarios such as high temperature bearing, erosion resistance and oxidation resistance, such as tungsten-rhenium alloys used in the field of temperature measurement, and tungsten-thorium alloys used in the field of high-temperature erosion structural parts, further expanding the application field of tungsten-based alloys.

[0095] The above-described embodiments merely represent preferred implementations of the present invention. While the descriptions thereof are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a high-temperature-bearing, erosion-resistant, and oxidation-resistant tungsten-based alloy, characterized in that: Tungsten powder, rhenium powder or molybdenum powder or tantalum powder and a reinforcing phase are mixed and uniformly mixed to obtain a tungsten-based alloy powder, the tungsten-based alloy powder is sequentially subjected to forming and pressing, sintering, swaging, annealing and surface treatment, and then the surface-treated tungsten-based alloy is sequentially subjected to deposition of a transition coating and an anti-oxidation coating; The specific steps include: S1: mixing tungsten powder, rhenium powder or molybdenum powder or tantalum powder and a reinforcing phase to obtain a mixed powder, wherein the reinforcing phase accounts for 1.0-4.0% by weight of the tungsten-based alloy powder after mixing; S2: putting the mixed powder into a double cone mixer for mixing to obtain tungsten-based alloy powder; S3: pressing the tungsten-based alloy powder into billets; S4: performing medium frequency induction sintering on the billet in a hydrogen protective atmosphere at a sintering temperature of 2200-2400°C to obtain a tungsten-based alloy billet; S5: rotary forging the tungsten-based alloy blank at a rotary forging heating temperature of 1400-1500° C. to obtain a tungsten-based alloy; S6: After cleaning the tungsten-based alloy, perform stress relief annealing at a temperature of 900-1050°C. Argon or hydrogen is used as a protective atmosphere during the annealing process. S7: performing surface etching and surface stabilization treatment on the annealed tungsten-based alloy; In step S7, during the surface treatment, the surface is first etched with an etching solution, and then the surface is stabilized with a treatment solution; The etching solution includes sodium hydroxide, potassium ferrocyanide, potassium dichromate, sodium tungstate and water. The etching process is carried out in an ultrasonic environment and the etching time is 20 to 100 seconds. The surface stabilization treatment solution includes sodium hydroxide, anhydrous ethanol, 2-methyl-1-hexane, sodium sulfate and water. The current density of the DC regulated power supply ranges from 1.0 to 4.0 A / cm 2 , stabilization treatment time is not less than 30s; S8: preparing a metal transition coating on the surface of the surface-treated tungsten-based alloy by molten salt electrodeposition or chemical vapor deposition, wherein the transition coating is a rhenium coating; S9: preparing an anti-oxidation composite coating by electrodeposition on the surface of the tungsten-based alloy on which the metal transition coating is prepared, wherein the anti-oxidation coating is an iridium composite coating, including an iridium-hafnium coating and an iridium-thorium coating; In step S1, the purity of the tungsten powder, rhenium powder, molybdenum powder or tantalum powder is not less than 99.99%; The reinforcing phase is at least one of thorium oxide, lanthanum oxide, hafnium oxide, titanium carbide, hafnium carbide, zirconium carbide and niobium carbide.

2. The method for preparing a high temperature bearing, erosion resistant and oxidation resistant tungsten-based alloy according to claim 1, characterized in that: In step S2, the variable speed of the double-cone mixer is 10-50 r / min, and the mixing time is 60-180 min.

3. The method for preparing a high temperature bearing, erosion resistant and oxidation resistant tungsten-based alloy according to claim 1, characterized in that: In step S3, cold isostatic pressing is used for pressing, specifically: the mixed tungsten-based alloy powder is placed in a polyurethane sleeve for cold isostatic pressing, the pressing pressure is 120-180 MPa, the pressure holding time is 15-120 seconds, and the density of the formed billet is greater than 60%; And / or, in step S4, sintering is performed in a reducing atmosphere.

4. The method for preparing a high temperature bearing, erosion resistant and oxidation resistant tungsten-based alloy according to claim 1, characterized in that: In step S5, the heat preservation time during rotary forging is 8 to 12 minutes, and the deformation amount per pass is 8 to 15%.

5. The method for preparing a high temperature bearing, erosion resistant and oxidation resistant tungsten-based alloy according to claim 1, characterized in that: In step S8, the molten salt used for molten salt electrodeposition includes sodium chloride, potassium chloride, cesium chloride and potassium hexachlororhenate. The electrodeposition process is carried out in a salt bath electrolytic furnace, argon gas is introduced for protection, rhenium wire is used as anode, and electrolytically polished tungsten-based alloy is used as cathode. The current density range is 3~300mA / cm 2 , electrodeposition temperature 750~950℃, electrodeposition time 5~200min; Alternatively, a rhenium transition layer is prepared by chemical vapor deposition. The evaporation source of the chemical vapor deposition is rhenium pentachloride, the evaporation temperature range is 350~450℃, the loading amount is 0.5~20g, the transport gas is an argon-hydrogen mixed gas, the deposition temperature range is 1000~1250℃, and the deposition time is 30~300min. After the rhenium transition coating is prepared, the sample is placed in anhydrous ethanol, isopropanol, and deionized water for ultrasonic cleaning in sequence, and then dried for use.

6. The method for preparing a high temperature bearing, erosion resistant and oxidation resistant tungsten-based alloy according to claim 1, characterized in that: In step S8, the molten salt for electrodeposition includes one or more main salts selected from iridium salt, hafnium salt, and thorium salt, and a conductive salt; The iridium salt includes one or more of iridium fluoride, iridium chloride, iridium bromide, and iridium iodide; the hafnium salt includes one or more of hafnium fluoride, hafnium chloride, and hafnium bromide. The thorium salt includes one or more of thorium chloride and thorium chloride, wherein the mass fraction of iridium is 5-10 wt.%, the mass fraction of hafnium is 0.05-0.2 wt.%, and the mass fraction of thorium is 0.05-0.2 wt.%. The conductive salt includes two or more of sodium chloride, potassium chloride, lithium chloride, sodium fluoride, potassium fluoride, sodium cyanide, potassium cyanide, and cesium chloride, and the mass fraction of the conductive salt is 15-60 wt.%. A tungsten-based alloy containing a rhenium transition layer is used as the cathode, and an iridium wire, hafnium wire, or thorium wire is used as the anode. During electrodeposition, the molten salt temperature is raised to 550-650°C and kept warm; the current density is 1.0-5.0 A / dm 2 ; Electrodeposition time 0.1~10h; After preparation, place the sample in boiling water to clean the residual salt on the surface, ultrasonically clean it with anhydrous ethanol, and dry it for later use.

7. A high temperature bearing, erosion resistant and oxidation resistant tungsten-based alloy, characterized in that: The method is as described in any one of claims 1 to 6.

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