High-pressure-corrosion-resistant hard alloy material as well as preparation method and application thereof

Abstract

The invention 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 strength, toughness and corrosion resistance of the material are improved by constructing a hard phase of titanium boride, silicon carbide and chromium diboride, high-temperature compact coating is achieved by introducing a multi-phase composite binder composed of an aluminum iron alloy, a high-entropy alloy and cerium hexaboride, and the asymmetric gradient paving and sintering technology is adopted for cooperation; a gradient structure with the surface layer high in hardness, the core high in toughness and the transition layer capable of relieving stress concentration is constructed, meanwhile, the surface hardness and sealing performance are strengthened through powder burying and calcination, and the abrasion resistance, corrosion resistance and impact resistance of the material are comprehensively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy materials and relates to a high-pressure corrosion-resistant hard alloy material and a preparation method and application thereof. Background Art

[0002] Cemented carbide is a composite material made of high-hardness metal carbides and a metal binder through a powder metallurgy process. Due to its exceptional hardness and wear resistance, it is widely used in cutting tools and mining. In deep-sea environments, cemented carbide is subject to extremely high water pressure and corrosive media, making its insufficient high-pressure fatigue resistance and corrosion resistance a key issue that needs to be addressed.

[0003] First, cemented carbide's shortcomings in high-pressure fatigue resistance are primarily reflected in its relatively low toughness. In deep-sea environments, such as those in the Mariana Trench, where water pressure can reach approximately 1,100 atmospheres, such extreme pressures can cause brittle fractures in cemented carbide materials at points of stress concentration. Furthermore, long-term high-pressure cyclic loading can cause the expansion of microcracks within the material, further impacting its service life. Although cemented carbide possesses excellent compressive strength, its performance is less than ideal under complex dynamic loading environments, particularly under high-frequency fatigue loading conditions.

[0004] Secondly, cemented carbide also has shortcomings in its corrosion resistance. Most cemented carbides use cobalt or nickel as a binder phase, and these metals are susceptible to corrosion in high-salinity and high-chloride ion environments. The penetration of chloride ions will lead to the degradation of the binder phase, which in turn causes the shedding of carbide particles and a decrease in the structural integrity of the cemented carbide. This corrosion phenomenon is particularly severe in deep-sea environments and may lead to the failure and performance degradation of cemented carbide. In addition, the high potential characteristics of cemented carbide may accelerate the corrosion of other metal materials when in contact with other metal materials such as titanium and stainless steel, further exacerbating the risk of degradation of the overall system. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to provide a high-pressure corrosion-resistant cemented carbide material and its preparation method and application. This application improves the strength, toughness and corrosion resistance of the material by constructing a hard phase of titanium boride, silicon carbide and chromium diboride, introduces a multiphase composite binder composed of aluminum-iron alloy, high entropy alloy and cerium hexaboride to achieve high-temperature dense coating, and uses asymmetric gradient paving and sintering process to construct a gradient structure with high hardness on the surface, high toughness in the core, and stress concentration relief in the transition layer. At the same time, the surface hardness and sealing are enhanced by buried powder calcination, and the wear resistance, corrosion resistance and impact resistance of the material are comprehensively improved.

[0006] To achieve this object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a method for preparing a high-pressure corrosion-resistant cemented carbide material, the method comprising: S1: titanium dioxide, silicon powder, boron carbide, chromium powder and anhydrous ethanol are mixed and ball-milled, and uniaxially pressed to obtain a green body, which is reacted at a first temperature to obtain a crude product, which is then treated and reacted at a second temperature to obtain a hard phase; S2: keeping the aluminum-iron alloy powder at a third temperature to obtain an aluminum-iron alloy matrix powder; mixing cobalt powder, chromium powder, nickel powder, aluminum powder, and titanium powder, and high-energy ball milling to obtain mixed powder A; immersing the mixed powder A in a cleaning solution for ultrasonic cleaning, and filtering to obtain a high-entropy alloy powder; and ball milling the aluminum-iron alloy matrix powder, the high-entropy alloy powder, and cerium hexaboride to obtain a binder phase; S3: Laying the surface layer, the middle layer and the core in the mold in sequence; sintering and cooling to obtain a sintered part; S4: Silicon powder, carbon powder, yttrium oxide, aluminum oxide and calcium fluoride are mixed to obtain a mixed powder B, a sintered part is buried in the mixed powder B, the mixture is kept at a fourth temperature, and cooled to obtain a high-pressure corrosion-resistant cemented carbide material.

[0007] Specifically: S1; titanium dioxide, silicon powder, boron carbide, chromium powder and anhydrous ethanol are mixed and ball-milled, and uniaxially pressed to obtain a green body, which is placed in a heating furnace under an argon atmosphere and reacted at a first temperature to obtain a crude product, which is crushed, sieved, and placed in a vacuum furnace and reacted at a second temperature to obtain a hard phase; S2: Preserving aluminum-iron alloy powder at a third temperature under a hydrogen atmosphere to obtain an aluminum-iron alloy matrix powder; mixing cobalt powder, chromium powder, nickel powder, aluminum powder, and titanium powder, and subjecting the mixture to high-energy ball milling under an argon atmosphere to obtain a mixed powder A, which is then ultrasonically cleaned in a cleaning solution and filtered to obtain a high-entropy alloy powder; mixing the aluminum-iron alloy matrix powder, the high-entropy alloy powder, and cerium hexaboride, and subjecting the mixture to ball milling under an argon atmosphere to obtain a binder phase; S3: Laying the surface layer, the middle layer and the core in the mold in sequence; sintering and cooling to obtain a sintered part; S4: Silicon powder, carbon powder, yttrium oxide, aluminum oxide and calcium fluoride are mixed to obtain a mixed powder B, a sintered part is buried in the mixed powder B, the mixture is kept at the fourth temperature under a nitrogen atmosphere, and cooled to obtain a high-pressure corrosion-resistant cemented carbide material.

[0008] 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); In some optional embodiments, the pressure of the unidirectional pressing 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 numerical range are also applicable.

[0009] In some optional embodiments, the unidirectional pressing time is 30-40s, for example, it can be 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 numerical range are also applicable.

[0010] In some optional 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 numerical range are also applicable.

[0011] In some optional embodiments, the reaction time of the green 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 these values, and values ​​not mentioned in this numerical range are also applicable.

[0012] In some optional 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 numerical range are also applicable.

[0013] In some optional embodiments, the crude product is reacted at the second 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 numerical range are also applicable.

[0014] As a preferred technical solution of the present invention, in step S2, the third temperature is 600-650°C, for example, it can be 600°C, 605°C, 610°C, 615°C, 620°C, 625°C, 630°C, 635°C, 640°C, 645°C or 650°C, but is not limited to such values, and values ​​not mentioned in this numerical range are also applicable.

[0015] In some optional embodiments, the aluminum-iron alloy powder is kept at the third temperature for 2-3 hours, for example, 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3h, but is not limited to such values, and values ​​not mentioned in this numerical range are also applicable.

[0016] 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); 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 numerical range are also applicable.

[0017] In some optional embodiments, the mass fraction of oxalic acid in the cleaning solution is 2-3%, for example, it can be 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 numerical range are also applicable.

[0018] In some optional embodiments, the mass fraction of ethanol in the cleaning liquid 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 numerical range are also applicable.

[0019] The mass ratio of the aluminum-iron alloy matrix powder, the high entropy alloy powder and the cerium hexaboride is (210-220): (90-100): (4.5-5.5); In some optional embodiments, the time for ball milling the mixed aluminum-iron alloy matrix powder, high entropy alloy powder and cerium hexaboride is 4-5h, for example, it can be 4h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5h, but is not limited to such values, and values ​​not mentioned in this numerical range are also applicable.

[0020] As a preferred technical solution of the present invention, in step S3, the mass ratio of the hard phase to the binding 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 is not limited to such values, and values ​​not mentioned in this numerical range are also applicable.

[0021] In some optional embodiments, the mass ratio of the hard phase to the binding 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 numerical range are also applicable.

[0022] In some optional embodiments, the mass ratio of the hard phase to the binding 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 numerical range are also applicable.

[0023] The thickness ratio of the surface layer, the middle layer and the core is (28-32): (38-42): (28-32); In some optional embodiments, the temperature of the pre-firing stage in the sintering is 800-850°C, for example, it can be 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 numerical range are also applicable.

[0024] In some optional embodiments, the pressure in the pre-firing stage of the sintering is 10-12 MPa, for example, it can be 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 numerical range are also applicable.

[0025] In some optional embodiments, the time of the pre-firing stage in the sintering is 30-40 min, for example, it can be 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min or 40 min, but is not limited to such values, and values ​​not mentioned in this numerical range are also applicable.

[0026] In some optional 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 numerical range are also applicable.

[0027] In some optional embodiments, the pressure in 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 numerical range are also applicable.

[0028] In some optional embodiments, the time of the transition stage in the 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 numerical range are also applicable.

[0029] In some optional embodiments, the temperature of the final sintering stage in the sintering is 1300-1350°C, for example, it can be 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 numerical range are also applicable.

[0030] In some optional embodiments, the pressure in the final sintering stage is 50-55 MPa, for example, it can be 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 numerical range are also applicable.

[0031] In some optional embodiments, the time of the final sintering stage in the sintering is 120-130 min, for example, it can be 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 numerical range are also applicable.

[0032] In some optional embodiments, the first stage of cooling is cooling to a temperature of 750-800°C in argon forced convection, for example, it can be 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, and values ​​not mentioned in this numerical range are also applicable.

[0033] In some optional embodiments, the second stage of cooling is naturally cooled to 300-350°C with the furnace, for example, it can be 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 numerical range are also applicable.

[0034] 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); In some optional 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 numerical range are also applicable.

[0035] In some optional 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 numerical range are also applicable.

[0036] In some optional embodiments, the sintered part is buried in the mixed powder B and kept warm at the fourth temperature for 2-3 hours, for example, it can be 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3h, but is not limited to such values, and values ​​not mentioned in this numerical range are also applicable.

[0037] In a second aspect, the present invention provides a high-pressure corrosion-resistant cemented carbide material.

[0038] In this application, a hard phase is constructed by 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 build a three-dimensional crack-resistant network within the material, effectively preventing crack propagation during loading and improving overall toughness; and chromium diboride can provide a boron diffusion channel during the sintering process, promoting densification and partially replacing the functions of traditional carbides, helping to regulate the overall hardness and toughness balance.

[0039] The green body containing titanium dioxide, silicon powder, boron carbide and chromium powder reacts 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 a boron diffusion channel during sintering, promoting sintering densification. At the same time, the chromium element can enhance oxidation resistance, thereby improving the overall corrosion resistance and oxidation resistance of the hard phase.

[0040] 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 a boron diffusion channel to optimize sintering density, while enhancing the material's resistance to chlorine corrosion.

[0041] This application introduces a multiphase composite binder. The aluminum-iron alloy powder is pretreated in a hydrogen atmosphere to remove surface oxides, improve its purity and reduction, and enhance subsequent bonding performance. The aluminum-iron alloy provides a certain degree of toughness in the cemented carbide and exhibits good wettability for other alloying elements at high temperatures, promoting a close bond between the bonding phase and the hard phase.

[0042] High-entropy alloys (HEAs) are prepared from cobalt, chromium, nickel, aluminum, and titanium powders. These alloys exhibit high component mixing entropy, large lattice distortion, and high diffusion resistance, enabling them to maintain high strength and toughness at high temperatures and in harsh environments. The addition of HEAs to the binder phase further enhances the alloy's stability and corrosion resistance at high temperatures, while also enabling the manipulation of microstructure and properties (e.g., providing dispersion strengthening at grain boundaries and resistance to oxidative corrosion).

[0043] The bonding phase of the present invention adopts a ternary combination of "aluminum-iron alloy, high entropy alloy and cerium hexaboride", which takes into account the toughness of traditional cobalt or nickel bonding phases and the strength, corrosion resistance and stability of high entropy alloys. The multiphase bonding agent can fully wet and coat the main hard phase during high-temperature sintering; the intermetallic compound properties of aluminum-iron alloy combined with the passivation mechanism of high entropy alloy give the bonding phase excellent protection in corrosive environments such as oxidation and chloride ions; nanoparticle dispersion strengthening can maintain the strength required for high-pressure service, and the certain ductility of the aluminum-iron alloy matrix provides impact toughness for the overall material. Cerium hexaboride is added to the bonding phase, which is distributed in the material matrix as a high-hardness second-phase particle, inhibiting excessive grain growth through physical hindrance, while directly improving the wear resistance of the material.

[0044] This application uses asymmetric gradient paving in conjunction with sintering processes. Through a layered paving design, a gradient structure with high surface hardness, a transitional middle layer, and high toughness in the core is achieved: the high hard phase content in the surface layer improves wear and corrosion resistance; the high binder phase content in the core enhances overall toughness and impact resistance; and the middle layer acts as a "transition" between hardness and toughness, reducing stress concentration and cracking at the interlayer interface.

[0045] The temperature in the pre-firing stage during sintering is relatively low, which can remove the volatile components in 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 bonding of the hard phase and the generation of the liquid phase when the bonding phase meets, so that the hard phase is fully wetted and tightly bonded in the bonding phase; the final firing stage is fully densified under high temperature and high pressure to form a stable metal-ceramic composite phase structure, suppress pores, and improve high-pressure resistance.

[0046] The layered gradient structure combined with the high-entropy alloy bonding phase enables the material to form a more stable interface bond while achieving both high hardness and high toughness, thereby reducing the risk of cracking on the hard and brittle phase surface and enhancing overall impact resistance.

[0047] This application uses a staged cooling process. In the first stage, forced convection cooling with argon gas can rapidly reduce the temperature and inhibit excessive grain growth, while relieving internal stress. In the second stage, natural cooling with the furnace can prevent thermal stress cracking caused by excessive temperature differences.

[0048] In this application, the surface of the sintered component is strengthened through powder embedding calcination. Silicon powder and carbon powder react to form silicon carbide, which coats the surface. Yttrium oxide and aluminum oxide form a composite crystalline phase at high temperatures, filling the micropores of the silicon carbide layer. Silicon carbide provides surface hardness and resistance to abrasive wear, while the yttrium-aluminum-oxygen composite crystalline phase seals the pores, preventing the penetration of high-pressure corrosive media.

[0049] Calcium fluoride's fluxing or diffusion-promoting effect on the embedded powder at high temperature helps to remove residual oxides on the surface. On the other hand, it can cooperate with yttrium oxide and aluminum oxide to form a denser or tougher glass phase / nitride covering layer, thereby further improving surface sealing and corrosion resistance.

[0050] In a third aspect, the present invention provides a high-pressure corrosion-resistant cemented carbide material for use in deep-sea environments.

[0051] Compared with the prior art, the present invention has the following beneficial effects: This application constructs a hard phase by combining titanium boride, silicon carbide, and chromium diboride. Titanium boride provides high hardness and corrosion resistance, silicon carbide builds a three-dimensional crack-resistant network to enhance toughness, and the presence of chromium diboride increases matrix hardness while providing a boron diffusion channel and enhancing oxidation resistance during sintering. At a first temperature, titanium dioxide, silicon powder, boron carbide, and chromium powder react to form a titanium boride and silicon carbide composite phase. Simultaneously, chromium powder and boron carbide react to form chromium diboride, avoiding phase separation issues and ultimately synergistically improving the material's strength, toughness, and corrosion resistance.

[0052] This application introduces a multiphase composite binder composed of an aluminum-iron alloy, a high-entropy alloy, and cerium hexaboride. The aluminum-iron alloy undergoes hydrogen pretreatment to enhance purity and bonding properties, providing toughness and wettability at high temperatures. The high-entropy alloy exhibits high strength, toughness, and corrosion resistance, and its microstructure can be regulated through dispersion strengthening. The cerium hexaboride inhibits excessive grain growth through physical hindrance, while also directly improving the material's wear resistance. This 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 imparting the material with exceptional strength, toughness, and corrosion resistance.

[0053] This application uses asymmetric gradient paving and sintering processes to create a gradient structure with high surface hardness, high core toughness, and a transition layer that mitigates stress concentration, achieving balanced wear resistance, corrosion resistance, and impact resistance. Sintering is performed in stages to achieve densification and stable microstructure formation, while segmented cooling suppresses grain growth and thermal stress cracking, ultimately improving overall performance and interface stability.

[0054] This application strengthens the surface of the sintered part by burying powder and calcining. The silicon carbide generated by silicon powder and carbon powder improves the surface hardness. Yttrium oxide and aluminum oxide form a composite crystal phase to fill the micropores and block the penetration of corrosive media. Calcium fluoride removes residual oxides on the surface through fluxing and diffusion, and cooperates with the oxide to form a dense glass phase or nitride covering layer, further enhancing the surface sealing and corrosion resistance. DETAILED DESCRIPTION

[0055] The technical solutions of the present invention are described in detail below with reference to specific embodiments. The embodiments described herein are specific embodiments 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 understood as limiting the embodiments of the present invention and 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 contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications made to the embodiments described herein.

[0056] The chemical reagents used in the examples and comparative examples of the present invention are all commercially available products without further purification or treatment. Example 1

[0057] This embodiment provides a high-pressure corrosion-resistant cemented carbide material and a preparation method thereof. The preparation method of the high-pressure corrosion-resistant cemented carbide material specifically comprises the following steps: S1: 408 g of titanium dioxide, 27 g of silicon powder, 465 g of boron carbide, and 132 g of chromium powder were mixed with anhydrous ethanol and then ball-milled. The green body was uniaxially pressed at a pressure of 100 MPa for 30 seconds. The green body was placed in a heating furnace under an argon atmosphere and reacted at a first temperature of 1580° C. for 2.5 hours to obtain a crude product. The product was crushed, sieved, and placed in a vacuum furnace at a second temperature of 1230° C. for 2.5 hours to obtain a hard phase. S2: The aluminum-iron alloy powder is kept at a third temperature of 620° C. under a hydrogen atmosphere for 2 h to obtain an aluminum-iron alloy matrix powder; 43 g of cobalt powder, 42 g of chromium powder, 44 g of nickel powder, 40 g of aluminum powder, and 45 g of titanium powder are mixed, and high-energy ball milling is performed under an argon atmosphere for 22 h to obtain a mixed powder A, which is ultrasonically cleaned in a cleaning solution and filtered to obtain a high-entropy alloy powder; 215 g of the aluminum-iron alloy matrix powder, 90 g of the high-entropy alloy powder, and 5.2 g of cerium hexaboride are mixed, and the mixture is ball milled under an argon atmosphere for 4 h to obtain a binder phase; S3: laying a surface layer, an intermediate layer and a core in the mold in sequence, wherein the thickness ratio of the surface layer, the intermediate layer and the core is 30:40:30, the mass ratio of the hard phase to the binding phase in the surface layer is 72:18, the mass ratio of the hard phase to the binding phase in the intermediate layer is 53:37, and the mass ratio of the hard phase to the binding phase in the core is 35:55; sintering is performed, wherein the temperature of the pre-sintering stage in the sintering is 800°C, the pressure is 11 MPa, and the time is 30 min; the temperature of the transition stage is 1120°C, the pressure is 33 MPa, and the time is 60 min; the temperature of the final sintering stage is 1300°C, the pressure is 52 MPa, and the time is 120 min, and cooling is performed, wherein the temperature of the first cooling stage is cooled to 750°C in argon forced convection; and the second stage is naturally cooled to 300°C in the furnace to obtain a sintered part; S4: Mix 55g of silicon powder, 27g of carbon powder, 5.8g of yttrium oxide, 5.4g of aluminum oxide and 2g of calcium fluoride to obtain a mixed powder B, bury the sintered part in the mixed powder B, wherein the mass ratio of the mixed powder B to the sintered part is 3.7:1, and keep it at a fourth temperature of 1520°C under a nitrogen atmosphere for 2h, and cool to obtain a high-pressure corrosion-resistant cemented carbide material. Example 2

[0058] This embodiment provides a high-pressure corrosion-resistant cemented carbide material and a preparation method thereof. The preparation method of the high-pressure corrosion-resistant cemented carbide material specifically comprises the following steps: S1: 405 g of titanium dioxide, 26 g of silicon powder, 460 g of boron carbide, and 130 g of chromium powder were mixed with anhydrous ethanol, ball-milled, and uniaxially pressed to obtain a green body, wherein the pressing pressure was 105 MPa and the pressing time was 35 s. The green body was placed in a heating furnace under an argon atmosphere and reacted at a first temperature of 1550° C. for 2.7 h to obtain a crude product, which was crushed, sieved, and placed in a vacuum furnace at a second temperature of 1240° C. for 2 h to obtain a hard phase; S2: The aluminum-iron alloy powder is kept at a third temperature of 640° C. under a hydrogen atmosphere for 2.5 hours to obtain an aluminum-iron alloy matrix powder; 40 g of cobalt powder, 43 g of chromium powder, 40 g of nickel powder, 45 g of aluminum powder, and 40 g of titanium powder are mixed, and high-energy ball milling is performed under an argon atmosphere for 23 hours to obtain a mixed powder A, which is immersed in a cleaning solution for ultrasonic cleaning and filtered to obtain a high-entropy alloy powder; 217 g of the aluminum-iron alloy matrix powder, 95 g of the high-entropy alloy powder, and 4.5 g of cerium hexaboride are mixed, and the mixture is ball milled under an argon atmosphere for 4.5 hours to obtain a binder phase; S3: laying the surface layer, the middle layer and the core in the mold in sequence, wherein the thickness ratio of the surface layer, the middle layer and the core is 31:41:31, the mass ratio of the hard phase to the binding phase in the surface layer is 70:20, the mass ratio of the hard phase to the binding phase in the middle layer is 55:35, and the mass ratio of the hard phase to the binding phase in the core is 36:54; sintering is performed, wherein the temperature of the pre-sintering stage in the sintering is 820°C, the pressure is 11.4MPa, and the time is 38min; the temperature of the transition stage is 1140°C, the pressure is 30MPa, and the time is 65min; the temperature of the final sintering stage is 1350°C, the pressure is 54MPa, and the time is 125min, and cooling is performed, wherein the temperature of the first cooling stage is cooled to 760°C in argon forced convection; and the second stage is naturally cooled to 340°C in the furnace to obtain a sintered part; S4: Mix 58g of silicon powder, 25g of carbon powder, 5g of yttrium oxide, 5.7g of aluminum oxide and 2.5g of calcium fluoride to obtain a mixed powder B, bury the sintered part in the mixed powder B, wherein the mass ratio of the mixed powder B to the sintered part is 3:1, and keep it at a fourth temperature of 1450°C in a nitrogen atmosphere for 2.6h. Cool it to obtain a high-pressure corrosion-resistant cemented carbide material. Example 3

[0059] This embodiment provides a high-pressure corrosion-resistant cemented carbide material and a preparation method thereof. The preparation method of the high-pressure corrosion-resistant cemented carbide material specifically comprises the following steps: S1: 410 g of titanium dioxide, 25 g of silicon powder, 450 g of boron carbide, and 125 g of chromium powder were mixed with anhydrous ethanol and then ball-milled. The green body was uniaxially pressed at a pressure of 108 MPa for 40 seconds. The green body was placed in a heating furnace under an argon atmosphere and reacted at a first temperature of 1560° C. for 2 hours to obtain a crude product. The product was crushed, sieved, and placed in a vacuum furnace at a second temperature of 1200° C. for 2.8 hours to obtain a hard phase. S2: The aluminum-iron alloy powder is kept at a third temperature of 600° C. under a hydrogen atmosphere for 2.7 hours to obtain an aluminum-iron alloy matrix powder; 45 g of cobalt powder, 40 g of chromium powder, 42 g of nickel powder, 43 g of aluminum powder, and 42 g of titanium powder are mixed, and high-energy ball milling is performed under an argon atmosphere for 20 hours to obtain a mixed powder A, which is immersed in a cleaning solution for ultrasonic cleaning and filtered to obtain a high-entropy alloy powder; 210 g of the aluminum-iron alloy matrix powder, 97 g of the high-entropy alloy powder, and 5 g of cerium hexaboride are mixed, and the mixture is placed in an argon atmosphere for ball milling for 4.8 hours to obtain a binder phase; S3: laying a surface layer, an intermediate layer and a core in the mold in sequence, wherein the thickness ratio of the surface layer, the intermediate layer and the core is 28:38:28, the mass ratio of the hard phase to the binding phase in the surface layer is 73:17, the mass ratio of the hard phase to the binding phase in the intermediate layer is 52:38, and the mass ratio of the hard phase to the binding phase in the core is 38:52; sintering is performed, wherein the temperature of the pre-sintering stage in the sintering is 840°C, the pressure is 10 MPa, and the time is 40 min; the temperature of the transition stage is 1100°C, the pressure is 32 MPa, and the time is 68 min; the temperature of the final sintering stage is 1320°C, the pressure is 50 MPa, and the time is 128 min, and cooling is performed, wherein the temperature of the first cooling stage is cooled to 780°C in argon forced convection; and the second stage is naturally cooled to 320°C in the furnace to obtain a sintered part; S4: 60g of silicon powder, 28g of carbon powder, 5.5g of yttrium oxide, 5g of aluminum oxide and 2.8g of calcium fluoride were mixed to obtain a mixed powder B, and a sintered part was buried in the mixed powder B, wherein the mass ratio of the mixed powder B to the sintered part was 3.5:1. The mixture was kept at a fourth temperature of 1550°C under a nitrogen atmosphere for 2.7h, and cooled to obtain a high-pressure corrosion-resistant cemented carbide material. Example 4

[0060] This embodiment provides a high-pressure corrosion-resistant cemented carbide material and a preparation method thereof. The preparation method of the high-pressure corrosion-resistant cemented carbide material specifically comprises the following steps: S1: 400 g of titanium dioxide, 30 g of silicon powder, 470 g of boron carbide, and 135 g of chromium powder were mixed with anhydrous ethanol and then ball-milled. The green body was uniaxially pressed at a pressure of 110 MPa for 38 seconds. The green body was placed in a heating furnace under an argon atmosphere and reacted at a first temperature of 1600° C. for 3 hours to obtain a crude product. The crude product was crushed, sieved, and placed in a vacuum furnace at a second temperature of 1250° C. for 3 hours to obtain a hard phase. S2: The aluminum-iron alloy powder is kept at a third temperature of 650° C. under a hydrogen atmosphere for 3 h to obtain an aluminum-iron alloy matrix powder; 42 g of cobalt powder, 45 g of chromium powder, 45 g of nickel powder, 44 g of aluminum powder, and 43 g of titanium powder are mixed, and high-energy ball milling is performed under an argon atmosphere for 24 h to obtain a mixed powder A, which is immersed in a cleaning solution for ultrasonic cleaning and filtered to obtain a high-entropy alloy powder; 220 g of the aluminum-iron alloy matrix powder, 100 g of the high-entropy alloy powder, and 5.5 g of cerium hexaboride are mixed, and the mixture is ball milled under an argon atmosphere for 5 h to obtain a binder phase; S3: laying a surface layer, an intermediate layer and a core in a mold in sequence, wherein the thickness ratio of the surface layer, the intermediate layer and the core is 32:42:32, the mass ratio of the hard phase to the binding phase in the surface layer is 75:15, the mass ratio of the hard phase to the binding phase in the intermediate layer is 56:34, and the mass ratio of the hard phase to the binding phase in the core is 40:50; sintering is performed, wherein the temperature of the pre-sintering stage in the sintering is 850°C, the pressure is 12 MPa, and the time is 35 min; the temperature of the transition stage is 1150°C, the pressure is 35 MPa, and the time is 70 min; the temperature of the final sintering stage is 1340°C, the pressure is 55 MPa, and the time is 130 min, and cooling is performed, wherein the first stage of cooling is cooling to 800°C in argon forced convection; the second stage is naturally cooling to 350°C in the furnace to obtain a sintered part; S4: Mix 50g of silicon powder, 30g of carbon powder, 6g of yttrium oxide, 6g of aluminum oxide and 3g of calcium fluoride to obtain a mixed powder B, bury the sintered part in the mixed powder B, wherein the mass ratio of the mixed powder B to the sintered part is 4:1, and keep it at a fourth temperature of 1500°C for 3h in a nitrogen atmosphere, and cool it to obtain a high-pressure corrosion-resistant cemented carbide material.

[0061] Comparative Example 1 This comparative example provides a high-pressure corrosion-resistant cemented carbide material, which differs from Example 1 in that, in S1, chromium powder is removed, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0062] Comparative Example 2 This comparative example provides a high-pressure corrosion-resistant cemented carbide material, which differs from Example 1 in that, in S2, no high-entropy alloy is added to the binder phase, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0063] Comparative Example 3 This comparative example provides a high-pressure corrosion-resistant cemented carbide material. The difference from Example 1 is that no cerium hexaboride is added to S2, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0064] Comparative Example 4 This comparative example provides a high-pressure corrosion-resistant cemented carbide material. The difference from Example 1 is that homogeneous structure sintering is adopted in S3, that is, all layers use the same ratio, and other operating steps and process parameters are exactly the same as Example 1.

[0065] Comparative Example 5 This comparative example provides a high-pressure corrosion-resistant cemented carbide material, which differs from Example 1 in that, in S3, only single-stage sintering (final sintering stage) is used during sintering, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0066] Comparative Example 6 This comparative example provides a high-pressure corrosion-resistant cemented carbide material, which differs from Example 1 in that the surface treatment in step S4 is omitted, and the other operating steps and process parameters are exactly the same as those in Example 1.

[0067] The performance test of the high pressure corrosion resistant cemented carbide materials of Examples 1-4 and Comparative Examples 1-6 was carried out, and the specific process is as follows: Test the hardness of the sample according to GB / T230.1-2018; The compressive strength of the samples was tested according to GB / T7314-2017; High-pressure fatigue life of test samples according to GB / T3075-2021; Corrosion resistance testing: The corrosion behavior of each sample group was tested in a seawater environment (3.5% sodium chloride aqueous solution, 5-10°C) using an electrochemical workstation. An Ag / AgCl electrode was used as the working electrode, and a platinum foil electrode was used as the counter electrode. The corrosion potential of the samples was analyzed in the range of -1.0 to 1 V at a scan rate of 1 mV / s.

[0068] The test results are shown in Table 1.

[0069] Table 1: Test results of high pressure corrosion resistant cemented carbide materials of Examples 1-4 and Comparative Examples 1-6 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 The test results of Example 1 and Comparative Example 1 indicate that after removing the chromium powder, the hard phase lacks chromium boride phases, resulting in reduced material density, hardness, and compressive strength. The absence of chromium prevents the material from forming an effective chromium protective film, exacerbating chloride ion penetration, shifting the corrosion potential negatively, and deteriorating corrosion resistance. Furthermore, the hard phase exhibits increased porosity, making cracks more susceptible to initiation and propagation under high-pressure cyclic loading, shortening fatigue life.

[0070] The test results of Example 1 and Comparative Example 2 indicate that omitting the high-entropy alloy leaves the binder phase solely dependent on the aluminum-iron alloy matrix, which is highly brittle and lacks solid solution strengthening, resulting in decreased toughness and compressive strength. The synergistic passivation effect of chromium and aluminum in the high-entropy alloy is lost, leading to a negative shift in the corrosion potential. Although the surface hard phase maintains a high hardness, the lack of internal toughness causes fatigue cracks to propagate rapidly in stress concentration areas, shortening fatigue life.

[0071] The test results of Example 1 and Comparative Example 3 indicate that without the addition of cerium hexaboride, the interfacial bond strength between the hard phase and the binder phase weakens, resulting in a decrease in compressive strength. The lack of cerium oxide's purifying effect at the grain boundaries leads to impurity accumulation, increasing intergranular corrosion susceptibility and negatively shifting the corrosion potential. Microcracks are more likely to initiate along the grain boundaries, reducing fatigue life. However, the hard phase composition remains unchanged, and hardness is largely maintained.

[0072] The test results of Example 1 and Comparative Example 4 indicate that a homogeneous structure fails to balance surface hardness with core toughness. Stress concentrates at the interface between the hard and adhesive phases, resulting in decreased compressive strength and an increased risk of delamination. This conflicting performance between the surface and core reduces overall hardness, rapidly propagates fatigue cracks along the interface, and shortens service life. Although the corrosion potential is similar to that of the examples, internal stress concentration may indirectly accelerate localized corrosion.

[0073] The test results of Example 1 and Comparative Example 5 indicate that single-stage sintering leads to grain coarsening and increased porosity, decreased material density, and reduced hardness and compressive strength. The lack of particle bonding during the pre-sintering stage and liquid phase filling during the transition stage results in insufficient interfacial bonding, allowing cracks to easily initiate and propagate through pores, resulting in a sharp decrease in fatigue life. A negative shift in the corrosion potential reflects differences in localized corrosion activity.

[0074] The test results of Example 1 and Comparative Example 6 indicate that the material without surface powder calcination treatment lacks a composite diffusion layer of silicon carbide and yttrium-aluminum-oxide, which reduces the material's ability to resist chloride ion penetration. This exposure of the substrate to corrosive media results in a negative shift in the corrosion potential. Although the loosening of the microstructure of the untreated sample leads to an increase in the density of internal defects in the material, these defects become stress concentration points under dynamic high-pressure loads, shortening the fatigue crack initiation cycle. However, in long-term service, the material without surface treatment will develop pitting pits due to continuous erosion by the corrosive medium, which then evolve into through-cracks.

[0075] 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 thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a high-pressure corrosion-resistant cemented carbide material, characterized in that: The preparation method comprises: S1: titanium dioxide, silicon powder, boron carbide, chromium powder and anhydrous ethanol are mixed and ball-milled, and uniaxially pressed to obtain a green body, which is reacted at a first temperature to obtain a crude product, which is then treated and reacted at a second temperature to obtain a hard phase; S2: keeping the aluminum-iron alloy powder at a third temperature to obtain an aluminum-iron alloy matrix powder; mixing cobalt powder, chromium powder, nickel powder, aluminum powder, and titanium powder, and high-energy ball milling to obtain mixed powder A; immersing the mixed powder A in a cleaning solution for ultrasonic cleaning, and filtering to obtain a high-entropy alloy powder; and ball milling the aluminum-iron alloy matrix powder, the high-entropy alloy powder, and cerium hexaboride to obtain a binder phase; S3: Laying the surface layer, the middle layer and the core in the mold in sequence; sintering and cooling to obtain a sintered part; S4: Silicon powder, carbon powder, yttrium oxide, aluminum oxide and calcium fluoride are mixed to obtain a mixed powder B, a sintered part is buried in the mixed powder B, the mixture is kept at a fourth temperature, and cooled to obtain a high-pressure corrosion-resistant cemented carbide material.

2. The method for preparing a high-pressure corrosion-resistant cemented carbide material according to claim 1, characterized in that: In S1: the mass ratio of the titanium dioxide, silicon powder, boron carbide and chromium powder is (400-410): (25-30): (450-470): (125-135).

3. The method for preparing a high pressure corrosion resistant cemented carbide material according to claim 1, characterized in that: In S2: 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); The mass ratio of the aluminum-iron alloy matrix powder, the high entropy alloy powder and the cerium hexaboride is (210-220): (90-100): (4.5-5.5).

4. The method for preparing a high-pressure corrosion-resistant cemented carbide material according to claim 1, characterized in that: In S3: The mass ratio of the hard phase to the binding phase in the surface layer is (70-75): (15-20); The mass ratio of the hard phase to the binder phase in the intermediate layer is (52-56): (34-38); The mass ratio of the hard phase to the binder phase in the core is (35-40): (50-55); The thickness ratio of the surface layer, the middle layer and the core is (28-32): (38-42): (28-32).

5. The method for preparing a high pressure corrosion resistant cemented carbide material according to claim 1, characterized in that: In S3: The temperature of the pre-sintering stage in the sintering is 800-850°C; The pressure in the pre-sintering stage of the sintering is 10-12 MPa; The time of the pre-firing stage in the sintering is 30-40 minutes.

6. The method for preparing a high-pressure corrosion-resistant cemented carbide material according to claim 1, characterized in that: In S3: The temperature of the transition stage in the sintering is 1100-1150°C; The pressure in the transition stage of sintering is 30-35 MPa; The time of the transition stage in the sintering is 60-70 minutes.

7. The method for preparing a high pressure corrosion resistant cemented carbide material according to claim 1, characterized in that: In S3: The temperature of the final sintering stage in the sintering is 1300-1350°C; The pressure in the final sintering stage of the sintering is 50-55 MPa; The time of the final sintering stage in the sintering is 120-130 minutes.

8. The method for preparing a high-pressure corrosion-resistant cemented carbide 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 composite 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.

9. A high-pressure corrosion-resistant cemented carbide material prepared by the preparation method according to any one of claims 1 to 8.

10. Use of a high-pressure corrosion-resistant cemented carbide material prepared by the preparation method according to any one of claims 1 to 8 in a deep-sea environment.