High-pressure corrosion resistant cemented carbide material, method for producing the same and use thereof

Abstract

The application provides a high-pressure corrosion-resistant hard alloy material and a preparation method and application thereof, and belongs to the technical field of alloy materials. The application improves the strength, toughness and corrosion resistance of the material by constructing titanium boride, silicon carbide and chromium diboride hard phases, introduces a multiphase composite binder composed of aluminum-iron alloy, high-entropy alloy and cerium hexaboride to realize high-temperature dense coating, and adopts asymmetric gradient paving and sintering process to construct a gradient structure with high surface hardness, high toughness in the core and stress concentration reduction in the transition layer. Meanwhile, the surface hardness and sealing property are strengthened by powder embedding and calcination, and the wear resistance, corrosion resistance and impact resistance of the material are comprehensively improved.

Description

Technical Field

[0001] This invention belongs to the field of alloy materials technology, and relates to a high-pressure corrosion resistant hard alloy material, its preparation method and application. Background Technology

[0002] Cemented carbide is a composite material made from high-hardness metal carbides and metal binders through powder metallurgy. Due to its excellent hardness and wear resistance, it is widely used in cutting tools and mining. However, in deep-sea environments, the application of cemented carbide is affected by extremely high water pressure and corrosive media, making its insufficient high-pressure fatigue resistance and corrosion resistance critical issues that urgently need to be addressed.

[0003] First, the main deficiency of cemented carbide in high-pressure fatigue resistance lies in its relatively low toughness. In deep-sea environments, such as the Mariana Trench where water pressure can reach approximately 1100 atmospheres, such extreme pressure can cause brittle fracture of cemented carbide materials at stress concentration points. Furthermore, long-term high-pressure cyclic loading can lead to the propagation of microcracks within the material, further affecting its service life. Although cemented carbide possesses excellent compressive strength, its performance is not ideal under complex dynamic loading conditions, especially under high-frequency fatigue loading.

[0004] Secondly, cemented carbide also suffers from insufficient corrosion resistance. Most cemented carbides use cobalt or nickel as the binder phase, and these metals are susceptible to corrosion in high-salinity and high-chloride-ion environments. Chloride ion penetration leads to the deterioration of the binder phase, resulting in the shedding of carbide particles and a decrease in the structural integrity of the cemented carbide. This corrosion is particularly severe in deep-sea environments, potentially causing cemented carbide failure and performance degradation. Furthermore, the high potential characteristics of cemented carbides, when in contact with other metals such as titanium and stainless steel, may accelerate the corrosion of these other materials, further exacerbating the overall system's deterioration risk. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a high-pressure corrosion resistant cemented carbide material, its preparation method, and its applications. This application enhances the material's strength, toughness, and corrosion resistance by constructing a hard phase of titanium boride, silicon carbide, and chromium diboride. A multiphase composite binder composed of aluminum-iron alloy, high-entropy alloy, and cerium hexaboride is introduced to achieve high-temperature dense coating. Furthermore, an asymmetric gradient layup and sintering process are employed in synergy to construct a gradient structure with high surface hardness, high core toughness, and a transition layer that reduces stress concentration. Simultaneously, powder embedding and calcination are used to strengthen surface hardness and sealing properties, comprehensively improving the material's wear resistance, corrosion resistance, and impact resistance.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a high-pressure corrosion resistant cemented carbide material, the method comprising:

[0008] S1: Titanium dioxide, silicon powder, boron carbide, chromium powder and anhydrous ethanol are mixed and ball-milled, and then pressed into a green embryo by unidirectional pressing. The green embryo is then reacted at a first temperature to obtain a crude product, and after treatment, it is reacted at a second temperature to obtain a hard phase.

[0009] S2: Aluminum-iron alloy powder is kept at a third temperature to obtain aluminum-iron alloy matrix powder; cobalt powder, chromium powder, nickel powder, aluminum powder and titanium powder are mixed and ball-milled to obtain mixed powder A, which is then immersed in cleaning solution for ultrasonic cleaning and filtration to obtain high-entropy alloy powder; aluminum-iron alloy matrix powder, high-entropy alloy powder and cerium hexaboride are mixed and ball-milled to obtain binder phase;

[0010] S3: The surface layer, intermediate layer and core are sequentially laid in the mold; sintering and cooling are then carried out to obtain the sintered part;

[0011] S4: Silicon powder, carbon powder, yttrium oxide, aluminum oxide and calcium fluoride are mixed to obtain mixed powder B. The sintered part is embedded in mixed powder B, kept at a fourth temperature and cooled to obtain a high-pressure corrosion resistant hard alloy material.

[0012] Specifically: S1; Titanium dioxide, silicon powder, boron carbide, chromium powder and anhydrous ethanol are mixed and ball-milled, and then pressed into a green embryo in a unidirectional manner. The green embryo is placed in a heating furnace and reacted at a first temperature under an argon atmosphere to obtain a crude product. The crude product is then crushed, sieved and placed in a vacuum furnace to react at a second temperature to obtain a hard phase.

[0013] S2: Aluminum-iron alloy powder is heated at a third temperature under a hydrogen atmosphere to obtain aluminum-iron alloy matrix powder; cobalt powder, chromium powder, nickel powder, aluminum powder, and titanium powder are mixed and ball-milled under an argon atmosphere to obtain mixed powder A, which is then immersed in a cleaning solution for ultrasonic cleaning and filtration to obtain high-entropy alloy powder; aluminum-iron alloy matrix powder, high-entropy alloy powder, and cerium hexaboride are mixed and ball-milled under an argon atmosphere to obtain a binder phase;

[0014] S3: The surface layer, intermediate layer and core are sequentially laid in the mold; sintering and cooling are then carried out to obtain the sintered part;

[0015] S4: Silicon powder, carbon powder, yttrium oxide, aluminum oxide and calcium fluoride are mixed to obtain mixed powder B. The sintered part is embedded in mixed powder B and kept at a fourth temperature under a nitrogen atmosphere. After cooling, a high-pressure corrosion resistant hard alloy material is obtained.

[0016] As a preferred technical solution of the present invention, in step S1, the mass ratio of titanium dioxide, silicon powder, boron carbide and chromium powder is (400-410):(25-30):(450-470):(125-135).

[0017] In some alternative embodiments, the pressure of the unidirectional compression molding is 100-110 MPa, for example, it can be 100 MPa, 101 MPa, 102 MPa, 103 MPa, 104 MPa, 105 MPa, 106 MPa, 107 MPa, 108 MPa, 109 MPa or 110 MPa, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0018] In some alternative embodiments, the unidirectional pressing time is 30-40s, for example, 30s, 31s, 32s, 33s, 34s, 35s, 36s, 37s, 38s, 39s or 40s, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0019] In some alternative embodiments, the first temperature is 1550-1600°C, for example, it can be 1550°C, 1555°C, 1560°C, 1565°C, 1570°C, 1575°C, 1580°C, 1585°C, 1590°C, 1595°C or 1600°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0020] In some alternative embodiments, the reaction time of the embryo at the first temperature is 2-3 hours, for example, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours, or 3.0 hours, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0021] In some alternative embodiments, the second temperature is 1200-1250°C, for example, it can be 1200°C, 1205°C, 1210°C, 1215°C, 1220°C, 1225°C, 1230°C, 1235°C, 1240°C, 1245°C or 1250°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0022] In some alternative embodiments, the reaction time of the crude product at the second temperature is 2-3 hours, for example, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours, or 3 hours, but is not limited to such values, and values ​​not mentioned in this range also apply.

[0023] As a preferred technical solution of the present invention, in step S2, the third temperature is 600-650℃, for example, it can be 600℃, 605℃, 610℃, 615℃, 620℃, 625℃, 630℃, 635℃, 640℃, 645℃ or 650℃, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0024] In some optional embodiments, the aluminum-iron alloy powder is kept at the third temperature for 2-3 hours, for example, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3 hours, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0025] The mass ratio of cobalt powder, chromium powder, nickel powder, aluminum powder, and titanium powder in the mixed powder A is (40-45): (40-45): (40-45): (40-45): (40-45): (40-45).

[0026] In some optional embodiments, the high-energy ball milling time after mixing the cobalt powder, chromium powder, nickel powder, aluminum powder, and titanium powder is 20-24 hours, for example, it can be 20.0 hours, 20.4 hours, 20.8 hours, 21.2 hours, 21.6 hours, 22.0 hours, 22.4 hours, 22.8 hours, 23.2 hours, 23.6 hours, or 24.0 hours, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0027] In some alternative embodiments, the oxalic acid in the cleaning solution has a mass fraction of 2-3%, for example, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9% or 3%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0028] In some alternative embodiments, the mass fraction of ethanol in the cleaning solution is 3-4%, for example, it can be 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9% or 4%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0029] The mass ratio of the aluminum-iron alloy matrix powder, the high-entropy alloy powder, and cerium hexaboride is (210-220):(90-100):(4.5-5.5).

[0030] In some optional embodiments, the ball milling time for the aluminum-iron alloy matrix powder, the high-entropy alloy powder and cerium hexaboride is 4-5 hours, for example, 4 hours, 4.1 hours, 4.2 hours, 4.3 hours, 4.4 hours, 4.5 hours, 4.6 hours, 4.7 hours, 4.8 hours, 4.9 hours or 5 hours, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0031] As a preferred technical solution of the present invention, in step S3, the mass ratio of the hard phase to the binder phase in the surface layer is (70-75):(15-20), for example, it can be 70:20, 70.5:19.5, 71:19, 71.5:18.5, 72:18, 72.5:17.5, 73:17, 73.5:16.5, 74:16, 74.5:15.5 or 75:15, but it is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0032] In some alternative embodiments, the mass ratio of the hard phase to the binder phase in the intermediate layer is (52-56):(34-38), for example, it can be 52:38, 52.5:37.5, 53:37, 53.5:36.5, 54:36, 54.5:35.5, 55:35, 55.5:34.5 or 56:34, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0033] In some alternative embodiments, the mass ratio of the hard phase to the binder phase in the core is (35-40):(50-55), for example, it can be 35:55, 35.5:54.5, 36:54, 36.5:53.5, 37:53, 37.5:52.5, 38:52, 38.5:51.5, 39:51, 39.5:50.5 or 40:50, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0034] The thickness ratio of the surface layer, the intermediate layer, and the core is (28-32):(38-42):(28-32);

[0035] In some alternative embodiments, the temperature of the pre-sintering stage in the sintering is 800-850°C, for example, 800°C, 805°C, 810°C, 815°C, 820°C, 825°C, 830°C, 835°C, 840°C, 845°C or 850°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0036] In some alternative embodiments, the pressure during the pre-sintering stage of the sintering is 10-12 MPa, for example, 10 MPa, 10.2 MPa, 10.4 MPa, 10.6 MPa, 10.8 MPa, 11 MPa, 11.2 MPa, 11.4 MPa, 11.6 MPa, 11.8 MPa or 12 MPa, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0037] In some alternative embodiments, the pre-sintering stage in the sintering process takes 30-40 minutes, for example, 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes or 40 minutes, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0038] In some alternative embodiments, the temperature of the transition stage in the sintering is 1100-1150°C, for example, it can be 1100°C, 1105°C, 1110°C, 1115°C, 1120°C, 1125°C, 1130°C, 1135°C, 1140°C, 1145°C or 1150°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0039] In some alternative embodiments, the pressure during the transition stage of sintering is 30-35 MPa, for example, it can be 30 MPa, 30.5 MPa, 31 MPa, 31.5 MPa, 32 MPa, 32.5 MPa, 33 MPa, 33.5 MPa, 34 MPa, 34.5 MPa or 35 MPa, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0040] In some alternative embodiments, the transition phase time during sintering is 60-70 min, for example, it can be 60 min, 61 min, 62 min, 63 min, 64 min, 65 min, 66 min, 67 min, 68 min, 69 min or 70 min, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0041] In some optional embodiments, the temperature of the final sintering stage is 1300-1350°C, for example, 1300°C, 1305°C, 1310°C, 1315°C, 1320°C, 1325°C, 1330°C, 1335°C, 1340°C, 1345°C or 1350°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0042] In some alternative embodiments, the pressure during the final sintering stage is 50-55 MPa, for example, 50 MPa, 50.5 MPa, 51 MPa, 51.5 MPa, 52 MPa, 52.5 MPa, 53 MPa, 53.5 MPa, 54 MPa, 54.5 MPa or 55 MPa, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0043] In some optional embodiments, the time for the final sintering stage is 120-130 min, for example, 120 min, 121 min, 122 min, 123 min, 124 min, 125 min, 126 min, 127 min, 128 min, 129 min or 130 min, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0044] In some alternative embodiments, the first stage of the cooling process involves cooling the temperature to 750-800°C in forced argon convection, for example, 750°C, 755°C, 760°C, 765°C, 770°C, 775°C, 780°C, 785°C, 790°C, 795°C, or 800°C, but is not limited to such values; values ​​not mentioned within this range are also applicable.

[0045] In some optional embodiments, the second stage of cooling is carried out by natural cooling in the furnace to 300-350°C, for example, 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C or 350°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0046] As a preferred technical solution of the present invention, in step S4, the mass ratio of silicon powder, carbon powder, yttrium oxide, aluminum oxide and calcium fluoride in the mixed powder B is (50-60):(25-30):(5-6):(5-6):(2-3);

[0047] In some alternative embodiments, the mass ratio of the mixed powder B to the sintered part is 3-4:1, for example, it can be 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1 or 4:1, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0048] In some alternative embodiments, the fourth temperature is 1450-1550°C, for example, it can be 1450°C, 1460°C, 1470°C, 1480°C, 1490°C, 1500°C, 1510°C, 1520°C, 1530°C, 1540°C or 1550°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0049] In some alternative embodiments, the sintered part is embedded in the mixed powder B and held at the fourth temperature for 2-3 hours, for example, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3 hours, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0050] Secondly, the present invention provides a high-pressure corrosion resistant cemented carbide material.

[0051] In this application, a hard phase is constructed using titanium boride, silicon carbide, and chromium diboride. Titanium boride has high hardness and exhibits excellent corrosion resistance in a chloride ion environment, making it the main high-hardness load-bearing phase. Silicon carbide can construct a three-dimensional crack-resistant network within the material, effectively inhibiting crack propagation under load and improving overall toughness. Chromium diboride provides boron diffusion channels during sintering, promoting densification and partially replacing the function of traditional carbides, thus helping to regulate the balance between overall hardness and toughness.

[0052] A green body containing titanium dioxide, silicon powder, boron carbide, and chromium powder is reacted to generate a composite phase of titanium boride and silicon carbide, avoiding the phase separation problem of traditional mechanical mixing. Secondly, chromium powder reacts with boron carbide to generate chromium diboride. The presence of this phase increases the hardness of the matrix and provides boron diffusion channels during sintering, promoting sintering densification. At the same time, chromium can enhance oxidation resistance, thereby improving the overall corrosion resistance and oxidation resistance of the hard phase.

[0053] The high hardness of titanium boride and the three-dimensional crack-resistant network of silicon carbide in the prepared hard phase synergistically improve the compressive strength and crack resistance of the material; chromium diboride provides boron diffusion channels to optimize sintering density and enhance the material's resistance to chlorine corrosion.

[0054] This application introduces a multiphase composite binder. The aluminum-iron alloy powder is pretreated in a hydrogen atmosphere to remove surface oxides, improving its purity and reduction degree, thus enhancing subsequent bonding performance. The aluminum-iron alloy provides a certain degree of toughness in the cemented carbide and exhibits good wetting of other alloying elements at high temperatures, promoting a tight bond between the binder phase and the hard phase.

[0055] High-entropy alloys prepared from cobalt, chromium, nickel, aluminum, and titanium powders exhibit characteristics such as high component mixing entropy, large lattice distortion, and high diffusion resistance, enabling them to maintain good strength and high toughness under high temperature or harsh environments. The addition of high-entropy alloys to the binder phase further enhances the alloy's stability and corrosion resistance at high temperatures, and also allows for the control of microstructure and properties (such as providing dispersion strengthening at grain boundaries and resistance to oxidation corrosion).

[0056] In this invention, the binder phase employs a ternary combination of "aluminum-iron alloy, high-entropy alloy, and cerium hexaboride," balancing the toughness of traditional cobalt or nickel binder phases with the strength, corrosion resistance, and stability of high-entropy alloys. The multiphase binder can fully wet and coat the main hard phase during high-temperature sintering; the intermetallic compound characteristics of the aluminum-iron alloy combined with the passivation mechanism of the high-entropy alloy provide excellent protection in corrosive environments such as oxidizing and chloride ion environments; nanoparticle dispersion strengthening maintains the strength required for high-pressure service, while the certain ductility of the aluminum-iron alloy matrix provides impact toughness to the overall material. The addition of cerium hexaboride to the binder phase, as a high-hardness second phase distributed within the material matrix, inhibits excessive grain growth through physical inhibition, while directly improving the material's wear resistance.

[0057] This application employs asymmetric gradient paving and sintering processes in synergy. Through layered paving design, a gradient structure is achieved with high surface hardness, intermediate transition, and high core toughness: the surface layer has a high content of hard phase, which improves wear resistance and corrosion resistance; the core has a high content of binder phase, which enhances overall toughness and impact resistance; the intermediate layer acts as a "transition" between hardness and toughness to reduce stress concentration at the interlayer interface and cracking.

[0058] The pre-sintering stage has a lower temperature, which can remove volatile components from the residual binder, promote the initial formation of the sintering neck, and control the deformation of the green body. The transition stage can further promote the diffusion and bonding of the binder phase and the generation of the liquid phase, so that the hard phase is fully wetted and tightly bonded in the binder phase. The final sintering stage fully densifies under high temperature and pressure, forming a stable metal-ceramic multiphase structure, suppressing pores, and improving high pressure resistance.

[0059] The layered gradient structure combined with the high-entropy alloy binder phase enables the material to form a more stable interface bond while maintaining high hardness and high toughness, reducing the risk of surface cracking of the hard and brittle phase and enhancing overall impact resistance.

[0060] This application employs a segmented cooling process. The first stage uses argon-forced convection cooling, which rapidly reduces the temperature and inhibits excessive grain growth while relieving internal stress. The second stage involves natural cooling within the furnace, which prevents thermal stress cracks caused by excessive temperature differences.

[0061] In this application, the surface of the sintered part is strengthened by embedding powder and calcining. Silicon powder and carbon powder react to form silicon carbide, which covers the material surface. Yttrium oxide and aluminum oxide form a composite crystalline phase at high temperature, filling the micropores of the silicon carbide layer. Silicon carbide provides surface hardness and resists abrasive wear; the yttrium-aluminum-oxygen composite crystalline phase seals the pores and blocks the penetration of high-pressure corrosive media.

[0062] Calcium fluoride's fluxing or diffusion effect on embedded powders at high temperatures helps remove residual oxides from the surface. On the other hand, it can synergistically form a denser or tougher glass phase / nitride coating with yttrium oxide and alumina, thereby further improving surface sealing and corrosion resistance.

[0063] Thirdly, the present invention provides a high-pressure corrosion resistant hard alloy material for use in deep-sea environments.

[0064] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0065] This application constructs a hard phase using titanium boride, silicon carbide, and chromium diboride. Titanium boride provides high hardness and corrosion resistance, silicon carbide constructs a three-dimensional crack-resistant network to enhance toughness, and the presence of chromium diboride increases the matrix hardness while providing boron diffusion channels and enhancing oxidation resistance during sintering. At a first temperature, titanium dioxide, silicon powder, boron carbide, and chromium powder react to form a composite phase of titanium boride and silicon carbide. Simultaneously, chromium powder reacts with boron carbide to form chromium diboride, avoiding phase separation issues and ultimately synergistically improving the material's strength, toughness, and corrosion resistance.

[0066] This application introduces a multiphase composite binder composed of an aluminum-iron alloy, a high-entropy alloy, and cerium hexaboride. The aluminum-iron alloy is pretreated with hydrogen to improve its purity and bonding performance, providing toughness and wettability at high temperatures. The high-entropy alloy possesses high strength, high toughness, and corrosion resistance, and its microstructure can be controlled through dispersion strengthening. Cerium hexaboride inhibits excessive grain growth through physical inhibition, while directly improving the material's wear resistance. The ternary combination balances the toughness, strength, and corrosion resistance of the binder phase, achieving dense encapsulation of the hard phase during high-temperature sintering, ultimately endowing the material with excellent strength, toughness, and corrosion resistance.

[0067] This application employs asymmetric gradient paving and sintering processes in synergy to construct a gradient structure with high surface hardness, high core toughness, and a transition layer that mitigates stress concentration, thus balancing wear resistance, corrosion resistance, and impact resistance. Sintering achieves densification and stable microstructure formation in stages, while segmented cooling inhibits grain growth and thermal stress cracking, ultimately improving overall performance and interface stability.

[0068] This application strengthens the surface of sintered parts through powder calcination. Silicon carbide generated from silicon powder and carbon powder increases surface hardness, while yttrium oxide and alumina form a composite crystalline phase to fill micropores and block the penetration of corrosive media. Calcium fluoride removes residual oxides on the surface through its fluxing and diffusion effects, and together with the oxides, forms a dense glassy phase or nitride coating layer, further enhancing surface sealing and corrosion resistance. Detailed Implementation

[0069] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that employ any obvious substitutions and modifications made to the embodiments described herein.

[0070] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing. Example 1

[0071] This embodiment provides a high-pressure corrosion resistant cemented carbide material and its preparation method. The preparation method of the high-pressure corrosion resistant cemented carbide material specifically includes the following steps:

[0072] S1; 408g of titanium dioxide, 27g of silicon powder, 465g of boron carbide, 132g of chromium powder and anhydrous ethanol were mixed and ball-milled, and then pressed into a green embryo by unidirectional pressing. The pressing pressure was 100MPa and the pressing time was 30s. The green embryo was placed in a heating furnace and reacted at a first temperature of 1580℃ for 2.5h under an argon atmosphere to obtain a crude product. The crude product was crushed, sieved and placed in a vacuum furnace and reacted at a second temperature of 1230℃ for 2.5h to obtain a hard phase.

[0073] S2: Aluminum-iron alloy powder was heated at a third temperature of 620℃ for 2 hours under a hydrogen atmosphere to obtain aluminum-iron alloy matrix powder; 43g cobalt powder, 42g chromium powder, 44g nickel powder, 40g aluminum powder, and 45g titanium powder were mixed and ball-milled at high energy under an argon atmosphere for 22 hours to obtain mixed powder A, which was then immersed in a cleaning solution for ultrasonic cleaning and filtered to obtain high-entropy alloy powder; 215g aluminum-iron alloy matrix powder, 90g high-entropy alloy powder, and 5.2g cerium hexaboride were mixed and ball-milled under an argon atmosphere for 4 hours to obtain a binder phase;

[0074] S3: A surface layer, an intermediate layer, and a core are sequentially laid in the mold, with a thickness ratio of 30:40:30 for the surface layer, a hard phase to a binder phase mass ratio of 72:18 for the surface layer, 53:37 for the intermediate layer, and 35:55 ​​for the core. Sintering is then performed, with the pre-sintering stage at 800℃, 11MPa, and 30min; the transition stage at 1120℃, 33MPa, and 60min; and the final sintering stage at 1300℃, 52MPa, and 120min. Cooling is then performed, with the first stage cooling to 750℃ in forced argon convection; and the second stage allowing natural cooling to 300℃ in the furnace to obtain the sintered part.

[0075] S4: Mix 55g silicon powder, 27g carbon powder, 5.8g yttrium oxide, 5.4g aluminum oxide and 2g calcium fluoride to obtain mixed powder B. Embed the sintered part in mixed powder B, wherein the mass ratio of mixed powder B to sintered part is 3.7:1. Hold at a fourth temperature of 1520℃ for 2 hours under a nitrogen atmosphere and cool to obtain a high-pressure corrosion resistant hard alloy material. Example 2

[0076] This embodiment provides a high-pressure corrosion resistant cemented carbide material and its preparation method. The preparation method of the high-pressure corrosion resistant cemented carbide material specifically includes the following steps:

[0077] S1; 405g titanium dioxide, 26g silicon powder, 460g boron carbide, 130g chromium powder and anhydrous ethanol were mixed and ball-milled, and then pressed into a green embryo by unidirectional pressing. The pressing pressure was 105MPa and the pressing time was 35s. The green embryo was placed in a heating furnace and reacted at a first temperature of 1550℃ for 2.7h under an argon atmosphere to obtain a crude product. The crude product was crushed, sieved and placed in a vacuum furnace and reacted at a second temperature of 1240℃ for 2h to obtain a hard phase.

[0078] S2: Aluminum-iron alloy powder was heated at a third temperature of 640℃ for 2.5h under a hydrogen atmosphere to obtain aluminum-iron alloy matrix powder; 40g cobalt powder, 43g chromium powder, 40g nickel powder, 45g aluminum powder, and 40g titanium powder were mixed and ball-milled at high energy under an argon atmosphere for 23h to obtain mixed powder A, which was then immersed in a cleaning solution for ultrasonic cleaning and filtered to obtain high-entropy alloy powder; 217g aluminum-iron alloy matrix powder, 95g high-entropy alloy powder, and 4.5g cerium hexaboride were mixed and ball-milled under an argon atmosphere for 4.5h to obtain a binder phase;

[0079] S3: A surface layer, an intermediate layer, and a core are sequentially laid in the mold, with a thickness ratio of 31:41:31 for the surface layer, a hard phase to a binder phase mass ratio of 70:20 for the surface layer, 55:35 for the intermediate layer, and 36:54 for the core. Sintering is then performed, with the pre-sintering stage at 820°C, 11.4 MPa, and 38 min; the transition stage at 1140°C, 30 MPa, and 65 min; and the final sintering stage at 1350°C, 54 MPa, and 125 min. Cooling is then performed, with the first stage cooling to 760°C in forced argon convection; and the second stage allowing natural cooling to 340°C in the furnace to obtain the sintered part.

[0080] S4: Mix 58g silicon powder, 25g carbon powder, 5g yttrium oxide, 5.7g aluminum oxide and 2.5g calcium fluoride to obtain mixed powder B. Embed the sintered part in mixed powder B, wherein the mass ratio of mixed powder B to sintered part is 3:1. Hold at a fourth temperature of 1450℃ for 2.6h under a nitrogen atmosphere and cool to obtain a high pressure corrosion resistant hard alloy material. Example 3

[0081] This embodiment provides a high-pressure corrosion resistant cemented carbide material and its preparation method. The preparation method of the high-pressure corrosion resistant cemented carbide material specifically includes the following steps:

[0082] S1; 410g titanium dioxide, 25g silicon powder, 450g boron carbide, 125g chromium powder were mixed with anhydrous ethanol and ball-milled. The mixture was then unidirectionally pressed to obtain a green embryo, wherein the pressing pressure was 108MPa and the pressing time was 40s. The green embryo was then placed in a heating furnace under an argon atmosphere and reacted at a first temperature of 1560℃ for 2h to obtain a crude product. The crude product was then crushed, sieved, and placed in a vacuum furnace and reacted at a second temperature of 1200℃ for 2.8h to obtain a hard phase.

[0083] S2: Aluminum-iron alloy powder was heated at 600℃ for 2.7h in a hydrogen atmosphere to obtain aluminum-iron alloy matrix powder; 45g cobalt powder, 40g chromium powder, 42g nickel powder, 43g aluminum powder, and 42g titanium powder were mixed and ball-milled at high energy under an argon atmosphere for 20h to obtain mixed powder A, which was then immersed in a cleaning solution for ultrasonic cleaning and filtered to obtain high-entropy alloy powder; 210g aluminum-iron alloy matrix powder, 97g high-entropy alloy powder, and 5g cerium hexaboride were mixed and ball-milled under an argon atmosphere for 4.8h to obtain a binder phase;

[0084] S3: A surface layer, an intermediate layer, and a core are sequentially laid in the mold, with a thickness ratio of 28:38:28 for the surface layer, 73:17 for the hard phase and 52:38 for the intermediate layer, and 38:52 for the core. Sintering is then performed, with the pre-sintering stage at 840℃, 10MPa, and 40min; the transition stage at 1100℃, 32MPa, and 68min; and the final sintering stage at 1320℃, 50MPa, and 128min. Cooling is then performed, with the first stage cooling to 780℃ in forced argon convection, and the second stage allowing natural cooling to 320℃ to obtain the sintered part.

[0085] S4: Mix 60g silicon powder, 28g carbon powder, 5.5g yttrium oxide, 5g aluminum oxide and 2.8g calcium fluoride to obtain mixed powder B. Embed the sintered part in mixed powder B, wherein the mass ratio of mixed powder B to sintered part is 3.5:1. Hold at a fourth temperature of 1550℃ for 2.7h under a nitrogen atmosphere and cool to obtain a high pressure corrosion resistant hard alloy material. Example 4

[0086] This embodiment provides a high-pressure corrosion resistant cemented carbide material and its preparation method. The preparation method of the high-pressure corrosion resistant cemented carbide material specifically includes the following steps:

[0087] S1; 400g titanium dioxide, 30g silicon powder, 470g boron carbide, 135g chromium powder and anhydrous ethanol were mixed and ball-milled, and then pressed into a green embryo by unidirectional pressing. The pressing pressure was 110MPa and the pressing time was 38s. The green embryo was placed in a heating furnace and reacted at a first temperature of 1600℃ for 3h under an argon atmosphere to obtain a crude product. The crude product was crushed, sieved and placed in a vacuum furnace and reacted at a second temperature of 1250℃ for 3h to obtain a hard phase.

[0088] S2: Aluminum-iron alloy powder was heated at a third temperature of 650℃ for 3 hours under a hydrogen atmosphere to obtain aluminum-iron alloy matrix powder; 42g cobalt powder, 45g chromium powder, 45g nickel powder, 44g aluminum powder, and 43g titanium powder were mixed and ball-milled at high energy under an argon atmosphere for 24 hours to obtain mixed powder A, which was then immersed in a cleaning solution for ultrasonic cleaning and filtered to obtain high-entropy alloy powder; 220g aluminum-iron alloy matrix powder, 100g high-entropy alloy powder, and 5.5g cerium hexaboride were mixed and ball-milled under an argon atmosphere for 5 hours to obtain a binder phase;

[0089] S3: A surface layer, an intermediate layer, and a core are sequentially laid in the mold, with a thickness ratio of 32:42:32 for the surface layer, 75:15 for the hard phase and 56:34 for the intermediate layer, and 40:50 for the core. Sintering is then performed, with the pre-sintering stage at 850°C, 12 MPa, and 35 min; the transition stage at 1150°C, 35 MPa, and 70 min; and the final sintering stage at 1340°C, 55 MPa, and 130 min. Cooling is then performed, with the first stage cooling to 800°C in forced argon convection, and the second stage allowing natural cooling to 350°C to obtain the sintered part.

[0090] S4: Mix 50g silicon powder, 30g carbon powder, 6g yttrium oxide, 6g aluminum oxide and 3g calcium fluoride to obtain mixed powder B. Embed the sintered part in mixed powder B, wherein the mass ratio of mixed powder B to sintered part is 4:1. Hold at a fourth temperature of 1500℃ for 3h under nitrogen atmosphere and cool to obtain a high pressure corrosion resistant hard alloy material.

[0091] Comparative Example 1

[0092] This comparative example provides a high-pressure corrosion resistant cemented carbide material. The difference between this example and Example 1 is that in S1, chromium powder is removed, while other operating steps and process parameters are exactly the same as in Example 1.

[0093] Comparative Example 2

[0094] This comparative example provides a high-pressure corrosion resistant cemented carbide material. The difference from Example 1 is that in S2, no high-entropy alloy is added to the binder phase, while the other operating steps and process parameters are exactly the same as in Example 1.

[0095] Comparative Example 3

[0096] This comparative example provides a high-pressure corrosion resistant cemented carbide material. The difference between this example and Example 1 is that cerium hexaboride is not added in S2, while the other operating steps and process parameters are exactly the same as in Example 1.

[0097] Comparative Example 4

[0098] This comparative example provides a high-pressure corrosion resistant cemented carbide material. The difference from Example 1 is that homogeneous structure sintering is used in S3, that is, all layers use the same proportion. Other operating steps and process parameters are exactly the same as in Example 1.

[0099] Comparative Example 5

[0100] This comparative example provides a high-pressure corrosion resistant cemented carbide material. The difference from Example 1 is that in S3, only single-stage sintering (final sintering stage) is used during sintering, while other operation steps and process parameters are exactly the same as in Example 1.

[0101] Comparative Example 6

[0102] This comparative example provides a high-pressure corrosion resistant cemented carbide material. The difference from Example 1 is that the surface treatment in step S4 is omitted, while the other operation steps and process parameters are exactly the same as in Example 1.

[0103] The performance of the high-pressure corrosion resistant cemented carbide materials of Examples 1-4 and Comparative Examples 1-6 was tested, and the specific process is as follows:

[0104] The hardness of the sample was tested according to GB / T230.1-2018;

[0105] The compressive strength of the test sample was determined according to GB / T7314-2017;

[0106] The high-pressure fatigue life of the test sample was determined according to GB / T3075-2021.

[0107] Corrosion resistance testing: The corrosion behavior of each group of samples in a seawater environment (3.5% sodium chloride aqueous solution, 5-10℃) was tested using an electrochemical workstation. An Ag / AgCl electrode was used as the reference electrode, and a platinum foil electrode as the counter electrode. The corrosion potential of the samples was analyzed in the range of -1.0 to 1V at a scan rate of 1 mV / s.

[0108] The test results are shown in Table 1.

[0109] Table 1: Performance test results of high pressure corrosion resistant cemented carbide materials in Examples 1-4 and Comparative Examples 1-6

[0110] Hardness HRA compressive strength (MPa) Corrosion potential V High pressure fatigue test 10^5 cycles Example 1 92.4 3500 0.05 No cracks Example 2 91.2 3450 0.03 No cracks Example 3 91.6 3470 0.02 No cracks Example 4 90.9 3440 0.01 No cracks Comparative Example 1 88.5 2950 -0.10 Cracks Comparative Example 2 91.1 2760 -0.08 Cracks Comparative Example 3 91.9 3230 -0.05 Cracks Comparative Example 4 89.7 3080 0.03 Cracks Comparative Example 5 88.4 2890 -0.02 Cracks Comparative Example 6 90.2 3150 -0.21 Cracks

[0111] The test results from Example 1 and Comparative Example 1 show that after removing chromium powder, the lack of chromium boride phase in the hard phase leads to a decrease in material density, hardness, and compressive strength. The absence of chromium prevents the formation of an effective chromium protective film, exacerbates chloride ion penetration, shifts the corrosion potential negatively, and deteriorates corrosion resistance. Simultaneously, the increased porosity within the hard phase makes cracks more prone to initiation and propagation under high-pressure cyclic loading, shortening fatigue life.

[0112] The test results from Example 1 and Comparative Example 2 show that, omitting the high-entropy alloy, the binder phase relies solely on the aluminum-iron alloy matrix, which is highly brittle and lacks solid solution strengthening, leading to decreased material toughness and reduced compressive strength. The synergistic passivation effect of chromium and aluminum in the high-entropy alloy is absent, resulting in a negative shift in corrosion potential. Although the surface hard phase maintains high hardness, insufficient internal toughness causes fatigue cracks to propagate rapidly in stress concentration areas, shortening fatigue life.

[0113] The test results from Example 1 and Comparative Example 3 show that without the addition of cerium hexaboride, the interfacial bonding strength between the hard phase and the binder phase is weakened, and the compressive strength decreases. The lack of cerium oxide purification at grain boundaries leads to impurity enrichment, increasing intergranular corrosion sensitivity and causing a negative shift in corrosion potential. Microcracks easily initiate along grain boundaries, reducing fatigue life, but the composition of the hard phase remains unchanged, and the hardness is essentially maintained.

[0114] The test results from Example 1 and Comparative Example 4 show that the homogeneous structure cannot balance the surface hardness and core toughness. Stress concentration occurs at the interface between the hard phase and the binder phase, leading to decreased compressive strength and increased risk of interlayer delamination. The conflicting properties between the surface and the core reduce overall hardness, causing fatigue cracks to propagate rapidly along the interface and shortening the lifespan. Although the corrosion potential is similar to that of the examples, internal stress concentration may indirectly accelerate localized corrosion.

[0115] The test results from Example 1 and Comparative Example 5 show that single-stage sintering leads to grain coarsening and increased porosity, resulting in decreased material density, hardness, and compressive strength. The lack of particle bonding in the pre-sintering stage and liquid-phase filling in the transition stage leads to insufficient interfacial bonding, making it easy for cracks to initiate and propagate through pores, resulting in a sharp decrease in fatigue life. A negative shift in corrosion potential reflects differences in localized corrosion activity.

[0116] The test results from Example 1 and Comparative Example 6 show that the material without surface-embedded powder calcination treatment lacks a silicon carbide and yttrium-aluminum-oxide composite diffusion layer, reducing its ability to block chloride ion penetration. This exposes the matrix to the corrosive medium, resulting in a negative shift in corrosion potential. Although the porous microstructure of the untreated sample leads to an increase in internal defect density, these defects become stress concentration points under dynamic high-pressure loads, shortening the fatigue crack initiation cycle. Furthermore, the untreated material will develop pitting corrosion during long-term service due to continuous erosion by the corrosive medium, eventually evolving into through-cracks.

[0117] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for producing a high-pressure corrosion resistant cemented carbide material, characterized in that The preparation method includes: S1: Titanium dioxide, silicon powder, boron carbide, chromium powder and anhydrous ethanol are mixed and ball-milled. The mass ratio of titanium dioxide, silicon powder, boron carbide and chromium powder is (400-410):(25-30):(450-470):(125-135). The mixture is unidirectionally pressed to obtain a green embryo. The green embryo is reacted at a first temperature of 1550-1600℃ to obtain a crude product. After treatment, the crude product is reacted at a second temperature of 1200-1250℃ to obtain a hard phase. S2: Aluminum-iron alloy powder is kept at a third temperature of 600-650℃ to obtain aluminum-iron alloy matrix powder; cobalt powder, chromium powder, nickel powder, aluminum powder, and titanium powder are mixed in a mass ratio of (40-45):(40-45):(40-45):(40-45):(40-45) and high-energy ball milled to obtain mixed powder A, which is immersed in cleaning solution for ultrasonic cleaning and filtration to obtain high-entropy alloy powder; aluminum-iron alloy matrix powder, high-entropy alloy powder, and cerium hexaboride are mixed in a mass ratio of (210-220):(90-100):(4.5-5.5) and ball milled to obtain binder phase; S3: Lay out the surface layer, intermediate layer and core layer in sequence in the mold; sinter and cool to obtain a sintered part; the mass ratio of hard phase to binder phase in the surface layer is (70-75):(15-20); the mass ratio of hard phase to binder phase in the intermediate layer is (52-56):(34-38); the mass ratio of hard phase to binder phase in the core layer is (35-40):(50-55); the thickness ratio of the surface layer, intermediate layer and core layer is (28-32):(38-42):(28-32). S4: Silicon powder, carbon powder, yttrium oxide, aluminum oxide and calcium fluoride are mixed to obtain mixed powder B. The sintered part is embedded in mixed powder B and held at a fourth temperature of 1450-1550℃. After cooling, a high-pressure corrosion resistant hard alloy material is obtained.

2. The method of claim 1, wherein the high-pressure corrosion resistant cemented carbide material is prepared by the steps of: mixing the binder phase and the hard phase to form a mixture; and sintering the mixture to form the high-pressure corrosion resistant cemented carbide material. In S3: The temperature during the pre-sintering stage of the sintering process is 800-850℃; The pressure during the pre-sintering stage of the sintering process is 10-12 MPa; The pre-firing stage in the sintering process takes 30-40 minutes.

3. The method of claim 1, wherein the high pressure corrosion resistant cemented carbide material is prepared by the steps of: mixing the binder phase and the hard phase to form a mixture; and sintering the mixture to form the high pressure corrosion resistant cemented carbide material. In S3: The temperature during the transition stage of sintering is 1100-1150℃; The pressure during the transition stage of sintering is 30-35 MPa; The transition phase during sintering takes 60-70 minutes.

4. The method for preparing a high-pressure corrosion resistant hard alloy material according to claim 1, characterized in that, In S3: The temperature during the final sintering stage is 1300-1350℃; The pressure during the final sintering stage is 50-55 MPa. The final firing stage in the sintering process takes 120-130 minutes.

5. The method for preparing a high-pressure corrosion resistant hard alloy material according to claim 1, characterized in that, In S4: The mass ratio of silicon powder, carbon powder, yttrium oxide, aluminum oxide and calcium fluoride in the mixed powder B is (50-60):(25-30):(5-6):(5-6):(2-3); The mass ratio of the mixed powder B to the sintered part is 3-4:

1.

6. A high-pressure corrosion resistant cemented carbide material prepared by the preparation method according to any one of claims 1-5.

7. Use of a high pressure corrosion resistant cemented carbide material produced by the method according to any one of claims 1-5 in deep sea environment.