Corrosion-resistant tungsten-based high-specific-gravity alloy material and preparation method thereof

Abstract

The invention provides a corrosion-resistant tungsten-based high-specific-gravity alloy material and a preparation method thereof, and relates to the technical field of rare refractory metals, and the corrosion-resistant tungsten-based high-specific-gravity alloy material comprises the following components in percentage by mass: 89% < = W < = 95%, 0 < Ni < = 8%, 0 < Cu < = 4% and 0 lt; co < = 4% and 0 lt; cr < = 0.5%; wherein the content ratio of Ni to Cu is 1.5 to 4; the Co content is less than the Ni content; and the content of Cr is less than or equal to 20% of the content of Co. The corrosion-resistant tungsten alloy material is obtained through optimization design of alloy components, the tungsten alloy material and a product thereof can be stored and used for a long time in a damp, hot and salt mist environment, further, by adding alloy elements and optimizing a heat treatment process, the mechanical property of the W-Ni-Cu high-specific-gravity alloy material is improved, and the use range of the material is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of rare refractory metals, and particularly to a corrosion-resistant tungsten-based high-density alloy material and a preparation method thereof. Background Art

[0002] Tungsten-based high-density alloys generally refer to two-phase alloys with tungsten as the matrix and Ni-Fe or Ni-Cu as the binder phase. High-density alloys have a series of excellent properties such as high density, high strength, high hardness, good plasticity and toughness, good machining performance, small thermal expansion coefficient, and large thermal conductivity. They are widely used in cutting-edge medical, military, and civilian industrial fields. Due to their good mechanical properties and high material density, they have received increasing attention and applications in the fields of weapons and aerospace. In recent years, with the development of social science and technology and the continuous upgrading of military engineering equipment, while the performance requirements for tungsten-based high-density alloy materials have been continuously improved, higher requirements have also been put forward for their corrosion resistance to meet the needs of long-term storage and use in special environments such as high temperature, high humidity, and high salt spray. However, the addition of Fe in W-Ni-Fe high-density alloys will cause the high-density alloys to have magnetism and a significant increase in magnetic permeability. While W-Ni-Cu alloys do not contain Fe elements and are widely used in application fields such as gyroscope rotors that require non-magnetism, the addition of Cu will significantly reduce the corrosion resistance of W-Ni-Cu alloys and cannot improve the corrosion resistance of Ni. When W-Ni-Cu high-density alloys are stored or used in a humid and hot environment or a salt spray environment for a long time, obvious corrosion products and corrosion pits will be generated on the material surface due to oxidation corrosion and salt spray corrosion, resulting in a decrease in assembly accuracy and seriously affecting the appearance state and service performance of tungsten-based high-density alloy products. Therefore, improving the humidity and salt spray resistance of tungsten-based high-density alloy materials has become a difficult problem that must be overcome for their application in cutting-edge fields.

[0003] In view of this, the present invention is specifically proposed. Summary of the Invention

[0004] The present invention aims at the phenomena of humidity and heat corrosion and salt spray corrosion during the storage and use of conventional W-Ni-Cu high-density materials, and provides a tungsten-based high-density alloy material and a preparation method thereof that are resistant to humidity and heat and salt spray environment corrosion. The present invention obtains a corrosion-resistant tungsten alloy material by optimizing the design of alloy components, enabling the tungsten alloy material and its products to be stored and used in a humid and hot environment and a salt spray environment for a long time. Further, by adding alloy elements and optimizing the heat treatment process, the mechanical properties of W-Ni-Cu high-density alloy materials are improved, and the material usage range is broadened.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A corrosion-resistant tungsten-based high specific gravity alloy material provided by the present invention comprises the following components by mass percentage: 89% ≤ W ≤ 95%, 0 < Ni ≤ 8%, 0 < Cu ≤ 4%, 0 < Co ≤ 4% and 0 < Cr ≤ 0.5%;

[0007] Among them, the content ratio of Ni / Cu is 1.5 - 4;

[0008] The Co content < the Ni content;

[0009] The content of Cr ≤ 20% of the Co content.

[0010] The present invention also provides a preparation method of the corrosion-resistant tungsten-based high specific gravity alloy material as described above, comprising the following steps:

[0011] S1. Tungsten alloy powder mixing: Mix tungsten powder, nickel powder, copper powder, cobalt powder and chromium powder, and then screen the mixed powder to obtain the undersize powder;

[0012] S2. Powder pretreatment: Subject the undersize powder obtained in step S1 to high-energy ball milling treatment to obtain pretreated powder;

[0013] S3. Compression molding: Load the pretreated powder obtained in step S2 into a designed mold for compression molding treatment to obtain a corrosion-resistant tungsten-based high specific gravity alloy green compact;

[0014] S4. Sintering treatment: Subject the corrosion-resistant tungsten-based high specific gravity alloy green compact obtained in step S3 to sintering treatment to obtain a sintered compact;

[0015] S5. Vacuum heat treatment: Subject the sintered compact obtained in step S4 to vacuum heat treatment to obtain a heat-treated sintered compact;

[0016] S6. Solution quenching treatment: Subject the heat-treated sintered compact obtained in step S5 to solution quenching treatment to obtain the corrosion-resistant tungsten-based high specific gravity alloy material.

[0017] Further, on the basis of the above technical solution, in step S1, the tungsten powder is industrial tungsten powder with a particle size of 2.0 - 4.0 μm; the nickel powder is electrolytic nickel powder or carbonyl nickel powder; the copper powder is electrolytic copper powder; both the cobalt powder and the chromium powder are industrial powders.

[0018] Further, on the basis of the above technical solution, in step S1, the mixing refers to mixing on a three-dimensional mixer;

[0019] The mixing time is 6 - 12 h, and the rotation speed is 20 - 80 r / min.

[0020] And / or, in step S1, the mesh number of the sieve through which the mixed powder passes is: 80 - 140 meshes. After sieving treatment, take the undersize powder for subsequent treatment.

[0021] Further, on the basis of the above technical solution, in step S2, in the high-energy ball milling treatment, the ball-to-material ratio of the grinding balls to the raw material powder during the high-energy ball milling process is 1:1 to 5:1, the rotational speed of the ball mill is 50 to 120 r / min, and the high-energy ball milling duration is 6 to 12 h.

[0022] Further, on the basis of the above technical solution, in step S3, loading the pretreated powder obtained in step S2 into the designed mold means loading the pretreated powder obtained in step S2 into a rubber sleeve, sealing it, immersing it in an oil cylinder, and performing cold isostatic pressing and forming in an isotropic pressure manner;

[0023] Preferably, in the cold isostatic pressing and forming treatment, the pressing pressure is 180 to 250 MPa, and the pressure holding time is 30 to 120 min.

[0024] Further, on the basis of the above technical solution, in step S4, the sintering treatment refers to liquid-phase sintering treatment;

[0025] Preferably, in the liquid-phase sintering treatment, the atmosphere in the sintering furnace is hydrogen, the sintering temperature is 1350 to 1420 °C, and the heat preservation time is 0.5 to 4 h.

[0026] Further, on the basis of the above technical solution, in step S5, in the vacuum heat treatment, the vacuum degree is less than 10 -1 Pa, the temperature of the vacuum heat treatment is 900 to 1250 °C, and the time of the vacuum heat treatment is 4 to 8 h.

[0027] Further, on the basis of the above technical solution, in step S6, in the solution quenching treatment, the solution quenching protective atmosphere is an inert gas or a vacuum state;

[0028] Preferably, the protective atmosphere includes nitrogen or argon;

[0029] Preferably, the solution quenching treatment temperature is 1000 to 1250 °C, and the solution quenching heat preservation time is 1 to 3 h;

[0030] Preferably, the quenching medium is quenching oil.

[0031] Further, on the basis of the above technical solution, the preparation method further includes machining treatment, namely shaping the blank after cold isostatic pressing and forming and performing finished product processing on the sintered blank after vacuum heat treatment.

[0032] A corrosion-resistant tungsten-based high-density alloy material and its preparation method provided by the present invention have the following beneficial effects:

[0033] 1. The present invention adds Co and Cr elements to the corrosion-resistant tungsten-based high-density alloy, which significantly improves the resistance of the blank to damp heat corrosion and salt spray corrosion.

[0034] 2. The present invention adds alloy elements such as Ni, Cu, Co, and Cr, and is supplemented with vacuum heat treatment and solution quenching treatment, which can effectively improve the plasticity and toughness of the blank, and significantly improve the mechanical properties and processing performance of the material.

[0035] 3. The present invention conducts research on the optimization of alloy composition and process. By adjusting parameters such as W content, Ni / Cu ratio, addition amounts of Co and Cr elements, and heat treatment after sintering, a corrosion-resistant tungsten-based high-density alloy is provided, which has the advantages of controllable density, good corrosion resistance, excellent mechanical properties, etc., and can meet the application requirements of non-magnetic and corrosion-resistant tungsten-based high-density materials in fields such as gyroscope rotors. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 It is a process flow chart of a preparation method of a corrosion-resistant tungsten-based high-density alloy material provided by the present invention;

[0038] Figure 2 It is a metallographic structure diagram of the corrosion-resistant tungsten-based high-density alloy material prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in combination with the embodiments of the present invention. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. The process parameters not specified in the following embodiments are usually in accordance with conventional conditions.

[0040] The endpoints and any values within the ranges disclosed in the present invention are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0041] According to the first aspect of the present invention, a corrosion-resistant tungsten-based high-density alloy material is provided, which includes the following components by mass percentage: 89% ≤ W ≤ 95% (such as 90%, 91%, 92%, 93%, 94%, 94.5%, etc.), 0 < Ni ≤ 8% (such as 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 7.5%, 7.8%, etc.), 0 < Cu ≤ 4% (such as 0.5%, 1%, 2%, 3%, 3.5%, 3.7%, 3.9%, etc.), 0 < Co ≤ 4% (such as 0.5%, 1%, 2%, 3%, 3.5%, 3.7%, 3.9%, etc.) and 0 < Cr ≤ 0.5% (such as 0.1%, 0.2%, 0.3%, 0.4%, 0.45%, etc.); to ensure the density, relative density, mechanical properties and corrosion resistance of the material, each element is an essential addition element;

[0042] Among them, the content ratio of Ni / Cu is 1.5 - 4 (such as 2, 2.5, 3, 3.5, 3.6, 3.7, 3.8, 3.9, etc.);

[0043] The content of Co is less than the content of Ni;

[0044] The content of Cr is ≤ 20% of the content of Co.

[0045] Specifically, in the corrosion-resistant tungsten-based high-density alloy material of the present invention, tungsten is the alloy matrix phase, and its mass percentage in the tungsten alloy material is 89% - 95%, which ensures the most important performance parameters such as the density and strength of the material. In the present invention, if the mass percentage of tungsten is greater than 95%, the plastic mechanical properties of the prepared corrosion-resistant tungsten-based high-density alloy material will be significantly reduced, and it is not easy to achieve full liquid-phase sintering, resulting in poor relative density of the material; if the mass percentage of tungsten is lower than 89%, the density of the prepared corrosion-resistant tungsten-based high-density alloy material will be too low to meet the actual application requirements of high-density alloys.

[0046] Ni and Cu are the most common binder phase components in current tungsten-based high-density alloys. The addition of these two elements ensures the basic properties such as the strength, toughness and plasticity of the tungsten-based high-density alloy.

[0047] Furthermore, the purpose of limiting Ni / Cu to 1.5 - 4 in the present invention is to ensure that the material has the best mechanical properties. When the Ni / Cu ratio is greater than 4, hard and brittle secondary phases such as Ni4W are likely to appear in the material, resulting in a serious decline in mechanical properties; when the Ni / Cu ratio is less than 1.5, the liquid-phase sintering process is difficult during the material sintering process, and the dissolution and precipitation of W elements are blocked, resulting in problems such as low density and poor mechanical properties of the material.

[0048] W-Ni-Cu high specific gravity alloys are commonly used in fields such as gyroscope rotors and non-magnetic counterweights. By adding Co and Cr alloying elements to the W-Ni-Cu high specific gravity alloy material, the moisture and salt spray resistance of the tungsten-based high specific gravity alloy can be improved, and at the same time, the strength and plasticity of the tungsten-based high specific gravity alloy can be increased, enhancing the plastic mechanical properties of the high specific gravity alloy.

[0049] Furthermore, the present invention limits the Cr element within the range of 0 < Cr ≤ 0.5%. The purpose is to effectively improve the corrosion resistance of the alloy, and the density of the Cr element is relatively lower than that of other alloying elements. When the addition amount is within 0 < Cr ≤ 0.5%, the impact on the overall density of the alloy is small; if the Cr content is greater than 0.5%, on the one hand, it will cause the overall density of the alloy to decrease, and on the other hand, when the Cr content is relatively large, oxidation is likely to occur, resulting in sintering pores inside the material, further seriously reducing the alloy density and mechanical properties.

[0050] The present invention limits the Co element within the range of 0 < Co ≤ 4%. On the one hand, because the addition of the Co element will increase the wettability of the binder phase to the W grains and improve the interfacial bonding strength between the W grains and the binder phase. On the other hand, the addition of Co can increase the corrosion resistance of the W-Ni-Cu alloy and is non-magnetic, ensuring the non-magnetic characteristics of the alloy. If the addition amount of the Co element exceeds 4%, the liquid-phase sintering temperature will increase, resulting in an increase in preparation cost. At the same time, it is not easy to reach the liquid-phase sintering state during the sintering process, and the preparation difficulty increases. When the Co content exceeds 4%, the enhancement effect of its mechanical properties and corrosion resistance is not obvious.

[0051] Furthermore, when designing the composition of high specific gravity alloys with different W contents, while ensuring that the Ni / Cu ratio is within the range of 1.5 - 4, it is also necessary to ensure that the addition amount of the Co element is less than the Ni element content to ensure sufficient liquid-phase sintering at a relatively low sintering temperature; Cr is added as a trace element, and generally the addition amount is set to be less than 20% of the Co element content to ensure that the Cr element is completely dissolved in the binder phase at the sintering temperature, ensuring the mechanical properties and corrosion resistance of the material.

[0052] According to the second aspect of the present invention, as Figure 1 shown, a preparation method of the corrosion-resistant tungsten-based high specific gravity alloy material as described above is provided, including the following steps:

[0053] S1. Tungsten alloy powder mixing: Mix tungsten powder, nickel powder, copper powder, cobalt powder and chromium powder, and then screen the mixed powder to obtain the undersize powder.

[0054] S2. Powder pretreatment: Perform high-energy ball milling on the undersize powder obtained in step S1 to obtain pretreated powder.

[0055] S3. Compression molding: Load the pretreated powder obtained in step S2 into a designed mold for compression molding to obtain a corrosion-resistant tungsten-based high-density alloy green compact.

[0056] S4. Sintering treatment: Sinter the corrosion-resistant tungsten-based high-density alloy green compact obtained in step S3 to obtain a sintered compact.

[0057] S5. Vacuum heat treatment: Perform vacuum heat treatment on the sintered compact obtained in step S4 to obtain a heat-treated sintered compact.

[0058] S6. Solution quenching treatment: Perform solution quenching treatment on the heat-treated sintered compact obtained in step S5 to obtain a corrosion-resistant tungsten-based high-density alloy material.

[0059] As an optional embodiment of the present invention, in step S1, the tungsten powder is conventional industrial tungsten powder with a particle size (such as Fisher particle size) of 2.0 - 4.0 μm (such as 2.2 μm, 2.5 μm, 3 μm, 3.5 μm, 3.8 μm), the nickel powder is electrolytic nickel powder or carbonyl nickel powder, the copper powder is electrolytic copper powder, and the cobalt powder and chromium powder are conventional industrial powders.

[0060] As an optional embodiment of the present invention, in step S1, the mixing refers to mixing on a three-dimensional mixer.

[0061] The mixing time is 6 - 12 h (such as 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h), and the rotation speed is 20 - 80 r / min (such as 20 r / min, 30 r / min, 40 r / min, 50 r / min, 60 r / min, 70 r / min, 80 r / min).

[0062] As an optional embodiment of the present invention, in step S1, the mesh number of the screen through which the mixed powder passes is 80 - 140 meshes (such as 80 meshes, 90 meshes, 100 meshes, 110 meshes, 120 meshes, 130 meshes, 140 meshes). After screening, take the undersize powder for subsequent treatment.

[0063] Specifically, the purpose of screening here is to disperse the mixed powder, prevent the mixing of other impurities and the agglomeration of large-particle powder. After mixing, the powder is basically evenly mixed, and screening will not cause changes in the elemental ratio relationship of the powder, and basically all raw material powders enter the undersize.

[0064] As an alternative embodiment of the present invention, in step S2, during the high-energy ball milling treatment, the ball-to-material ratio of the grinding balls and the raw material powder during the high-energy ball milling process is 1:1 to 5:1 (such as 1:1, 2:1, 3:1, 4:1, 5:1), the rotational speed of the ball mill is 50 to 120 r / min (such as 60 r / min, 70 r / min, 80 r / min, 90 r / min, 100 r / min, 110 r / min, 120 r / min, etc.), and the high-energy ball milling duration is 6 to 12 h (such as 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h).

[0065] As an alternative embodiment of the present invention, in step S3, loading the pre-treated powder obtained in step S2 into the designed mold means loading the pre-treated powder obtained in step S2 into a rubber sleeve, sealing it, immersing it in an oil cylinder, and performing cold isostatic pressing and forming in an isotropic pressure manner;

[0066] During the cold isostatic pressing and forming treatment, the pressing pressure is 180 to 250 MPa (such as 185 MPa, 200 MPa, 220 MPa, 235 MPa, 245 MPa), and the pressure holding time is 30 to 120 min (such as 30 min, 40 min, 45 min, 50 min, 60 min, 80 min, 90 min, 105 min, 110 min, 115 min, 120 min).

[0067] As an alternative embodiment of the present invention, in step S4, the sintering treatment refers to liquid-phase sintering treatment; during the liquid-phase sintering treatment, the atmosphere in the sintering furnace is hydrogen, and the normal sintering temperature is 1350 to 1420 °C (such as 1350 °C, 1370 °C, 1390 °C, 1400 °C, 1410 °C, 1420 °C), and the heat preservation time is 0.5 to 4 h (such as 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h).

[0068] As an alternative embodiment of the present invention, in step S5, during the vacuum heat treatment, the vacuum degree is less than 10 -1 Pa (such as 10 -1 Pa, 5×10 -2 Pa, 1×10 -2 Pa, 8×10 -3 Pa, 5×10 -3 Pa), the temperature of the vacuum heat treatment is 900 to 1250 °C (such as 950 °C, 1000 °C, 1050 °C, 1100 °C, 1150 °C, 1200 °C, 1250 °C), and the time of the vacuum heat treatment is 4 to 8 h (such as 4 h, 4.5 h, 5 h, 6 h, 7 h, 7.5 h, 8 h).

[0069] Specifically, in the present invention, the purpose of vacuum heat treatment is, on the one hand, to remove hydrogen, removing the residual hydrogen elements during the hydrogen sintering process to prevent the material from having a tendency of hydrogen embrittlement; on the other hand, it is to adjust the solid solubility of each element of the material in the binder phase and homogenize the material structure.

[0070] As an alternative embodiment of the present invention, in step S6, in the solution quenching treatment, the protective atmosphere for solution quenching is an inert gas or a vacuum state. Preferably, the protective atmosphere includes nitrogen or argon; the solution quenching treatment temperature is 1000 - 1250 °C (such as 1000 °C, 1050 °C, 1100 °C, 1150 °C, 1200 °C, 1250 °C), the solution quenching holding time is 1 - 3 h (such as 1 h, 1.5 h, 2 h, 2.5 h, 3 h), and the quenching medium is quenching oil.

[0071] Specifically, the purpose of solution quenching in the present invention is to dissolve the hard and brittle second phase generated during the sintering and cooling process of the material and the impurity segregation at the grain boundaries into the binder phase through quenching, thereby improving the mechanical properties of the material.

[0072] As an alternative embodiment of the present invention, in the preparation method of the corrosion-resistant tungsten-based high-density alloy material, it further includes machining treatment, which can be realized through conventional operations, including shaping the blank after cold isostatic pressing and finishing the sintered blank after vacuum heat treatment.

[0073] The present invention will be further described in detail below with specific examples and comparative examples.

[0074] Example 1

[0075] (1) Powder mixing: The designed composition of the material is 93W3Ni2Cu1.9Co0.1Cr (the numbers in front of the elements are the mass percentages of the elements following them). Weigh 18.6 kg of tungsten powder with a Fisher particle size of 3.5 μm, 0.6 kg of nickel carbonyl powder, 0.4 kg of electrolytic copper powder, 0.38 kg of cobalt powder, and 0.02 kg of chromium powder respectively, and mix them with a three-dimensional mixer at a rotation speed of 50 r / min for 6 h to obtain 20 kg of tungsten alloy powder mixed with cobalt and trace chromium elements. Then, it is sieved through an 80-mesh sieve, and the undersize powder is used.

[0076] (2) Powder pretreatment: Place the undersize powder from the above step (1) into a tilting ball mill, put 100 kg of cemented carbide grinding balls according to a ball-to-material ratio of 5:1, and perform high-energy ball milling pretreatment for 6 h at a ball mill rotation speed of 60 r / min. After the pretreatment is completed, use a discharge hopper to pour the pretreated powder into a clean stainless steel bucket.

[0077] (3) Compaction: The pre-treated powder in step (2) above is filled into a mold and vibrated to compact it. Then, the mold filled with raw materials is placed into an oil cylinder and kept under pressure at 220 MPa for 30 min to obtain a corrosion-resistant tungsten-based heavy alloy green compact with a relative density of 65%. After machining, the size of the green compact is Φ118×165 mm.

[0078] (4) Sintering treatment: The green compact in step (3) is placed in an intermittent sintering furnace for sintering treatment. The sintering atmosphere is hydrogen, the maximum sintering temperature is 1385 °C, and it is kept warm for 2 hours. After machining, the size of the sintered blank is Φ100×140 mm.

[0079] (5) Vacuum heat treatment: The blank sintered in step (4) is subjected to vacuum heat treatment. The heat treatment temperature is 1150 °C, the vacuum degree is 5×10 -2 Pa, and the heat preservation time is 5 hours.

[0080] (6) Solution quenching treatment: The blank after vacuum heat treatment in step (5) is placed in a nitrogen environment, heated to 1050 °C, kept warm for 2 hours, and then the heavy alloy blank after heat preservation is quenched in oil.

[0081] As Figure 2 shown, the W grains in the metallographic structure of the heat-treated heavy alloy after sintering are evenly distributed in the Ni-Fe-W-Co-Cr binder phase in an approximately spherical shape. The average grain size of the W grains is 30 - 50 μm, meeting the distribution state of the metallographic structure of the heavy alloy with better mechanical properties.

[0082] Example 2

[0083] (1) Powder mixing: The designed component of the material is 95W2Ni1Cu1.7Co0.3Cr. Weigh 47.5 kg of tungsten powder with a Fisher particle size of 3.2 μm, 1 kg of nickel carbonyl powder, 0.5 kg of electrolytic copper powder, 0.85 kg of cobalt powder, and 0.15 kg of chromium powder respectively. Use a three-dimensional mixer for mixing, with a rotation speed of 40 r / min and a mixing time of 8 h to obtain 50 kg of tungsten alloy powder mixed with cobalt element. Then, it is sieved through a 100-mesh sieve and the powder passing through the sieve is used.

[0084] (2) Powder pre-treatment: The powder in step (1) above is placed in a tilting ball mill. 100 kg of cemented carbide grinding balls are put in according to a ball-to-material ratio of 2:1 for high-energy ball milling pre-treatment. The treatment duration is 10 h, the rotation speed of the ball mill is 90 r / min. After the pre-treatment is completed, use a discharge hopper to pour the pre-treated powder into a clean stainless steel bucket.

[0085] (3) Compaction: The pre-treated powder in step (2) above is filled into a mold and tamped. Then, the mold filled with raw materials is placed into an oil cylinder and kept under pressure at 200 MPa for 60 minutes to obtain a corrosion-resistant tungsten-based heavy alloy green compact with a relative density of 60%. After machining, the size of the green compact is Φ221×117.5 mm.

[0086] (4) Sintering treatment: The green compact in step (3) is placed in an intermittent sintering furnace for sintering treatment. The sintering atmosphere is hydrogen, the highest sintering temperature is 1405 °C, and the holding time is 2.5 hours. After machining, the size of the sintered blank is Φ188×100 mm.

[0087] (5) Vacuum heat treatment: The blank after sintering in step (4) is subjected to vacuum heat treatment. The heat treatment temperature is 1200 °C, the vacuum degree is 1×10 -2 Pa, and the holding time is 6 hours.

[0088] (6) Solution quenching treatment: The blank after vacuum heat treatment in step (5) is placed in an argon environment, heated to 1100 °C, held for 3 hours, and then the heavy alloy blank after holding is quenched in oil.

[0089] Example 3

[0090] (1) Powder mixing: The material design component is 90W6Ni2Cu1.8Co0.2Cr. Weigh 4.5 kg of tungsten powder with a Fisher particle size of 2.5 μm, 0.3 kg of nickel carbonyl powder, 0.1 kg of electrolytic copper powder, 0.09 kg of cobalt powder, and 0.01 kg of chromium powder respectively. Use a three-dimensional mixer for mixing, with a rotation speed of 80 r / min and a mixing time of 12 h to obtain 5 kg of tungsten alloy powder mixed with cobalt and chromium elements. Then, it is sieved through a 120-mesh sieve, and the undersize powder is used.

[0091] (2) Powder pretreatment: The powder in step (1) above is placed in a tilting ball mill, and 5 kg of cemented carbide grinding balls are put in according to a ball-to-material ratio of 1:1 for high-energy ball milling pretreatment. The treatment duration is 12 h, the rotation speed of the ball mill is 60 r / min. After pretreatment, use a discharge hopper to pour the pretreated powder into a clean stainless steel bucket.

[0092] (3) Compaction: The pre-treated powder in step (2) above is filled into a mold and tamped. Then, the mold filled with raw materials is placed into an oil cylinder and kept under pressure at 245 MPa for 120 minutes to obtain a corrosion-resistant tungsten-based heavy alloy green compact with a relative density of 70%. After machining, the size of the green compact is D118 / d60×60 mm.

[0093] (4) Sintering treatment: Place the green compact from step (3) in an intermittent sintering furnace for sintering treatment. The sintering atmosphere is hydrogen, the maximum sintering temperature is 1370 °C, and keep the temperature for 1 hour. After machining, the size of the sintered blank is D100 / d50×50 mm.

[0094] (5) Vacuum heat treatment: Conduct vacuum heat treatment on the blank sintered in step (4). The heat treatment temperature is 1100 °C, the vacuum degree is 8×10 -3 Pa, and the holding time is 5 hours.

[0095] (6) Solution quenching treatment: Place the blank after vacuum heat treatment in step (5) in a nitrogen environment, heat it to 1050 °C, keep the temperature for 1.5 hours, and then quench the high specific gravity alloy blank after holding in oil.

[0096] Example 4

[0097] (1) Powder mixing: The designed composition of the material is 92.5W4Ni1Cu2.1Co0.4Cr. Weigh 43.105 kg of tungsten powder with a Fisher particle size of 3.5 μm, 1.864 kg of nickel carbonyl powder, 0.466 kg of electrolytic copper powder, 0.979 kg of cobalt powder, and 0.186 kg of chromium powder respectively. Use a three-dimensional mixer for mixing, the rotation speed is 60 r / min, and the mixing time is 12 h to obtain 46.6 kg of tungsten alloy powder mixed with cobalt and chromium elements. Then, pass it through a 140-mesh sieve and use the powder passing through the sieve.

[0098] (2) Powder pretreatment: Place the sieved powder from the above step (1) in a tilting ball mill, put 140 kg of cemented carbide grinding balls according to a ball-to-material ratio of 3:1, conduct high-energy ball milling pretreatment, the treatment duration is 10 h, the rotation speed of the ball mill is 80 r / min. After pretreatment, use a discharge hopper to pour the pretreated powder into a clean stainless steel bucket.

[0099] (3) Cold isostatic pressing and forming: Vibrate and compact the pretreated powder from the above step (2) into a mold, then place the mold filled with raw materials into an oil cylinder, and keep the pressure at 200 MPa for 60 min to obtain a corrosion-resistant tungsten-based high specific gravity alloy green compact with a relative density of 65%. After machining, the size of the formed blank is 112×160×242 mm.

[0100] (4) Sintering treatment: Place the green compact from step (3) in an intermittent sintering furnace for sintering treatment. The sintering atmosphere is hydrogen, the maximum sintering temperature is 1410 °C, and keep the temperature for 2.5 hours. After machining, the size of the sintered blank is 95×135×205 mm.

[0101] (5) Vacuum heat treatment: Conduct vacuum heat treatment on the sintered blank. The heat treatment temperature is 1150 °C, the vacuum degree is 8×10 -3Pa, and the holding time is 8 hours.

[0102] (6) Solution quenching treatment: Place the blank in a nitrogen environment, heat it to 1250 °C, hold for 3 hours, and then quench the high specific gravity alloy blank after holding in oil.

[0103] Example 5

[0104] (1) Powder mixing: The designed composition of the material is 89W5Ni1.5Cu4Co0.5Cr. Weigh 2.729 kg of tungsten powder with a Fisher particle size of 3.0 μm, 0.153 kg of nickel carbonyl powder, 0.046 kg of electrolytic copper powder, 0.123 kg of cobalt powder, and 0.015 kg of chromium powder respectively. Use a three-dimensional mixer for mixing, with a rotation speed of 50 r / min and a mixing time of 10 h to obtain 3.066 kg of tungsten alloy powder mixed with cobalt and chromium elements. Then, pass it through a 120-mesh sieve and use the powder passing through the sieve.

[0105] (2) Powder pretreatment: Place the sieved powder from step (1) in a tilting ball mill, put 15 kg of cemented carbide grinding balls according to a ball-to-material ratio of 5:1, and carry out high-energy ball milling pretreatment for 12 h with a ball mill rotation speed of 70 r / min. After the pretreatment is completed, use a discharge hopper to pour the pretreated powder into a clean stainless steel bucket.

[0106] (3) Cold isostatic pressing and forming: Vigorously compact the pretreated powder from step (2) into a mold, and then place the mold filled with raw materials into an oil cylinder. Keep the pressure at 200 MPa for 60 min to obtain a corrosion-resistant tungsten-based high specific gravity alloy green compact with a relative density of 65%. After machining, the size of the formed blank is Φ60×100 mm.

[0107] (4) Sintering treatment: Place the green compact from step (3) in an intermittent sintering furnace for sintering treatment. The sintering atmosphere is hydrogen, the highest sintering temperature is 1365 °C, and the holding time is 1.5 hours. After machining, the size of the sintered blank is Φ52×85 mm.

[0108] (5) Vacuum heat treatment: Carry out vacuum heat treatment on the sintered blank. The heat treatment temperature is 1200 °C, the vacuum degree is 5×10 -2 Pa, and the holding time is 8 hours.

[0109] (6) Solution quenching treatment: Place the blank in a nitrogen environment, heat it to 1200 °C, hold for 2 hours, and then quench the high specific gravity alloy blank after holding in oil.

[0110] Comparative Example 1

[0111] (1) Powder mixing: The designed material components are 97W2Ni1Cu. Weigh 4.85 kg of tungsten powder with a Fisher particle size of 3.2 μm, 0.1 kg of nickel carbonyl powder, and 0.05 kg of electrolytic copper powder respectively. Use a three-dimensional mixer for mixing, with a rotation speed of 40 r / min and a mixing time of 8 h to obtain 5 kg of tungsten-based high-density alloy powder. Then, pass it through a 100-mesh sieve and use the powder passing through the sieve.

[0112] (2) Powder pretreatment: Place the powder passing through the sieve in step (1) into an inclinable ball mill. Put 10 kg of cemented carbide grinding balls according to a ball-to-material ratio of 2:1 and carry out high-energy ball milling pretreatment for 10 h with a ball mill rotation speed of 90 r / min. After the pretreatment is completed, use a discharge hopper to pour the pretreated powder into a clean stainless steel bucket.

[0113] (3) Compression molding: Compact the pretreated powder in step (2) into a mold, and then place the mold filled with raw materials into an oil cylinder. Keep the pressure at 200 MPa for 60 min to obtain a corrosion-resistant tungsten-based high-density alloy green compact with a relative density of 60%. After machining, the size of the green compact is Φ35×450 mm.

[0114] (4) Sintering treatment: Place the green compact in step (3) into an intermittent sintering furnace for sintering treatment. The sintering atmosphere is hydrogen, the highest sintering temperature is 1405 °C, and keep the temperature for 2 h. After machining, the size of the sintered blank is Φ31×385 mm.

[0115] (5) Vacuum heat treatment: Carry out vacuum heat treatment on the blank sintered in step (4). The heat treatment temperature is 1200 °C, the vacuum degree is 1×10 -2 Pa, and the holding time is 6 h.

[0116] (6) Solution quenching treatment: Place the blank after vacuum heat treatment in step (5) in a nitrogen environment, heat it to 1100 °C, keep the temperature for 3 h, and then quench the high-density alloy blank after holding in oil.

[0117] Comparative Example 2

[0118] (1) Powder mixing: The designed material components are 93W5Ni2Cu. Weigh 9.3 kg of tungsten powder with a Fisher particle size of 3.5 μm, 0.5 kg of nickel carbonyl powder, and 0.2 kg of electrolytic copper powder respectively. Use a three-dimensional mixer for mixing, with a rotation speed of 50 r / min and a mixing time of 6 h to obtain 10 kg of tungsten alloy powder mixed with cobalt and trace chromium elements. Then, pass it through an 80-mesh sieve and use the powder passing through the sieve.

[0119] (2) Powder pretreatment: Place the undersize powder from step (1) above in a tilting ball mill. Put 50 kg of cemented carbide grinding balls into the mill according to a ball-to-material ratio of 5:1, and conduct high-energy ball milling pretreatment for 6 hours at a ball mill rotation speed of 60 r / min. After the pretreatment is completed, use a discharge hopper to pour the pretreated powder into a clean stainless steel bucket.

[0120] (3) Compression molding: Vibrate and compact the pretreated powder from step (2) above into a mold, and then place the mold filled with raw materials into an oil cylinder. Keep the pressure at 220 MPa for 30 minutes to obtain a corrosion-resistant tungsten-based high specific gravity alloy green compact with a relative density of 65%. After machining, the size of the green compact is Φ70×235 mm.

[0121] (4) Sintering treatment: Place the green compact from step (3) in an intermittent sintering furnace for sintering treatment. The sintering atmosphere is hydrogen, the highest sintering temperature is 1385 °C, and keep the temperature for 2 hours. After machining, the size of the sintered blank is Φ60×200 mm.

[0122] (5) Vacuum heat treatment: Conduct vacuum heat treatment on the blank sintered in step (4). The heat treatment temperature is 1150 °C, the vacuum degree is 5×10 -2 Pa, and the holding time is 5 hours.

[0123] (6) Solution quenching treatment: Place the blank after vacuum heat treatment in step (5) in a nitrogen environment, heat it to 1050 °C, keep the temperature for 2 hours, and then quench the high specific gravity alloy blank after holding in oil.

[0124] Comparative Example 3

[0125] The difference between this comparative example and Example 1 is that the last step of solution quenching treatment is omitted, and the alloy composition ratio and other operation steps are the same as those in Example 1.

[0126] Comparative Example 4

[0127] The difference between this comparative example and Example 1 is that the designed alloy composition (wt%) is 93W2.5Ni2.5Cu1.9Co0.1Cr, and the remaining operation steps and technical parameters are the same as those in Example 1.

[0128] Comparative Example 5

[0129] The difference between this comparative example and Example 3 is that the designed alloy composition (wt%) is 90W6.8Ni1.2Cu1.8Co0.2Cr, and the remaining operation steps and technical parameters are the same as those in Example 3.

[0130] Comparative Example 6

[0131] The difference between this comparative example and Example 1 lies in that the alloy design components (wt%) are 93W3Ni2Cu1.5Co0.5Cr, and the remaining operation steps and technical parameters are the same as those in Example 1.

[0132] Comparative Example 7

[0133] The main difference between this comparative example and Example 1 lies in that the alloy design components (wt%) are 93W3Ni2Cu2Co, and the remaining operation steps and technical parameters are the same as those in Example 1.

[0134] Density test method

[0135] Density determination and relative density calculation were carried out on the tungsten-based high-density alloy blank entities prepared in the examples and comparative examples. The density determination was carried out by the Archimedes drainage method and measured and calculated according to the density determination method of dense sintered metal materials and cemented carbides (GBT 3850-2015). The relative density calculation method is as follows:

[0136] Relative density = solid density / theoretical density × 100%.

[0137] Performance test

[0138] Sampling and processing were carried out on the tungsten-based high-density alloy blanks prepared in the examples and comparative examples, and room temperature tensile property tests (GB / T 228.1-2021), damp heat tests (GJB 150.9A-2009) and salt spray tests (GJB150.11A-2009) were carried out respectively. The test results are shown in Table 1.

[0139] Effect data

[0140] Table 1

[0141]

[0142] As shown in Table 1, in Comparative Example 1, since the W content is greater than 95% and does not contain Co and Cr elements, the damp heat resistance and salt spray resistance of the tungsten-based high-density alloy decrease, resulting in the alloy failing the damp heat test and salt spray test. Moreover, the too high W content leads to insufficient liquid phase sintering, which in turn affects the mechanical properties of the alloy.

[0143] As shown in Table 1, in Comparative Example 2, since it does not contain Co and Cr elements, the damp heat resistance and salt spray resistance of the tungsten-based high-density alloy decrease, resulting in the alloy failing the damp heat test and salt spray test.

[0144] As shown in Table 1, in Comparative Example 3, due to the omission of the last step of solution quenching treatment, the hard and brittle second phase generated during the sintering and cooling process of the material and the impurity segregation at the grain boundaries are not fully dissolved into the bonding phase, resulting in a decrease in the mechanical properties of the material.

[0145] As shown in Table 1, in Comparative Example 4, since its alloy design components (wt%) are 93W2.5Ni2.5Cu1.9Co0.1Cr and its Ni / Cu ratio is 1, which is not within the scope defined by the present invention, difficulties may occur during the liquid-phase sintering process of the material, and the dissolution and precipitation of the W element are blocked, resulting in low density and poor mechanical properties of the material.

[0146] As shown in Table 1, in Comparative Example 5, since its alloy design components (wt%) are 90W6.8Ni1.2Fe1.8Co0.2Cr and its Ni / Cu ratio is 5.67, which is not within the scope defined by the present invention, brittle and hard secondary phase structures such as Ni4W appear in the material, resulting in a serious decline in mechanical properties.

[0147] As shown in Table 1, in Comparative Example 6, since its alloy design components (wt%) are 93W3Ni2Cu1.5Co0.5Cr and the content of Cr is ≥20% of the Co content, the addition amount of the Cr element is relatively excessive. After sintering treatment, the Cr element is not completely dissolved in the binder phase, affecting the mechanical properties of the material.

[0148] As shown in Table 1, in Comparative Example 7, since its alloy design components (wt%) are 93W3Ni2Cu2Co and do not contain the Cr element, the moisture and heat resistance and salt spray resistance of the material are significantly reduced, resulting in the material failing the moisture and heat test and the salt spray test.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features. These modifications or replacements 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 corrosion-resistant tungsten-based high-density alloy material, characterized in that: It comprises the following components by mass percentage: 89% ≤ W ≤ 95%, 0 < Ni ≤ 8%, 0 < Cu ≤ 4%, 0 < Co ≤ 4% and 0 < Cr ≤ 0.5%; Among them, the content ratio of Ni / Cu is 1.5 - 4; The Co content < the Ni content; The content of Cr ≤ 20% of the Co content.

2. A method for preparing the corrosion-resistant tungsten-based high-density alloy material according to claim 1, characterized in that: It includes the following steps: S1. Tungsten alloy powder mixing: Mix tungsten powder, nickel powder, copper powder, cobalt powder and chromium powder, and then screen the mixed powder to obtain the undersize powder; S2. Powder pretreatment: Perform high-energy ball milling on the undersize powder obtained in step S1 to obtain pretreated powder; S3. Compression molding: Load the pretreated powder obtained in step S2 into a designed mold for compression molding to obtain a corrosion-resistant tungsten-based high-density alloy green compact; S4. Sintering treatment: Perform sintering treatment on the corrosion-resistant tungsten-based high-density alloy green compact obtained in step S3 to obtain a sintered compact; S5. Vacuum heat treatment: Perform vacuum heat treatment on the sintered compact obtained in step S4 to obtain a heat-treated sintered compact; S6. Solution quenching treatment: Perform solution quenching treatment on the heat-treated sintered compact obtained in step S5 to obtain a corrosion-resistant tungsten-based high-density alloy material.

3. The method for preparing the corrosion-resistant tungsten-based high-density alloy material according to claim 2, characterized in that: In step S1, the tungsten powder is industrial tungsten powder with a particle size of 2.0 - 4.0 μm; the nickel powder is electrolytic nickel powder or carbonyl nickel powder; the copper powder is electrolytic copper powder; both the cobalt powder and chromium powder are industrial powders.

4. The method for preparing the corrosion-resistant tungsten-based high-density alloy material according to claim 2, characterized in that: In step S1, the mixing refers to mixing on a three-dimensional mixer; The mixing time is 6 - 12 h and the rotation speed is 20 - 80 r / min. And / or, in step S1, the mesh number of the sieve through which the mixed powder passes is: 80 - 140 mesh. After screening, take the undersize powder for subsequent treatment.

5. The method for preparing the corrosion-resistant tungsten-based high-density alloy material according to claim 2, characterized in that: In step S2, in the high-energy ball milling treatment, the ball-to-powder ratio of the grinding balls and the raw material powder during the high-energy ball milling process is 1:1 - 5:1, the rotation speed of the ball mill is 50 - 120 r / min, and the high-energy ball milling duration is 6 - 12 h.

6. The method for preparing the corrosion-resistant tungsten-based high-density alloy material according to claim 2, characterized in that: In step S3, loading the pretreated powder obtained in step S2 into a designed mold means loading the pretreated powder obtained in step S2 into a rubber sleeve and sealing it, immersing it in an oil cylinder, and performing cold isostatic pressing and molding in an isotropic pressure manner; Preferably, in the cold isostatic pressing and molding treatment, the pressing pressure is 180 - 250 MPa and the pressure holding time is 30 - 120 min.

7. The method for preparing the corrosion-resistant tungsten-based high-density alloy material according to claim 2, characterized in that: In step S4, the sintering treatment refers to liquid-phase sintering treatment; Preferably, in the liquid-phase sintering treatment, the atmosphere in the sintering furnace is hydrogen, the sintering temperature is 1350 - 1420 °C, and the holding time is 0.5 - 4 h.

8. The method for preparing the corrosion-resistant tungsten-based high-density alloy material according to claim 2, characterized in that: In step S5, during the vacuum heat treatment, the vacuum degree is less than 10 -1 Pa, the temperature of vacuum heat treatment is 900-1250°C, and the time of vacuum heat treatment is 4-8h.

9. The method for preparing the corrosion-resistant tungsten-based high-density alloy material according to claim 2, characterized in that: In step S6, in the solution quenching treatment, the protective atmosphere for solution quenching is an inert gas or a vacuum state; Preferably, the protective atmosphere includes nitrogen or argon; Preferably, the solution quenching treatment temperature is 1000 - 1250 °C, and the solution quenching holding time is 1 - 3 h; Preferably, the quenching medium is quenching oil.

10. The method for preparing the corrosion-resistant tungsten-based high-density alloy material according to claim 2, characterized in that: The preparation method further includes machining treatment, shaping the blank after cold isostatic pressing and molding and performing finished product processing on the sintered blank after vacuum heat treatment respectively.

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