A TiB2-based cermet resistant to molten aluminum corrosion, and its preparation method and application

Abstract

The present invention discloses a TiB2-based cermet resistant to molten aluminum corrosion, and its preparation method and application, belonging to the technical field of corrosion-resistant cermet materials. The preparation method of the present invention adds TaC, Mo2C and WC ternary mixed carbide powder as a sintering aid, mixes it with a TiB2 matrix and performs high-temperature discharge plasma sintering, and prepares a TiB2-based cermet material resistant to molten aluminum corrosion through the synergistic effect of solid solution strengthening and densification and the formation of a chemically inert barrier. The relative density of the TiB2-based cermet resistant to molten aluminum corrosion prepared in the present invention can reach 99%. At the same time, the material has excellent mechanical properties and resistance to molten aluminum corrosion, and the average corrosion rate can be as low as 0.115μm / h. It can be widely used in the preparation of key components in high-temperature molten aluminum processing equipment, significantly improving the service life and production efficiency of the equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of corrosion-resistant metal ceramic materials, and in particular relates to a TiB2-based metal ceramic resistant to molten aluminum corrosion, and a preparation method and application thereof. Background Art

[0002] In modern advanced manufacturing, aluminum and its alloys, thanks to their low density, high specific strength, good formability, and excellent comprehensive corrosion resistance, have become key foundational materials in industries such as transportation, building structures, and surface engineering. Hot-dip aluminum coating technology, in particular, significantly improves the substrate's high-temperature oxidation resistance, electrochemical corrosion resistance, and mechanical performance by depositing a continuous, dense aluminum-based composite coating on the metal surface. However, during the aluminum casting and hot-dip coating industrial processes, high-temperature liquid aluminum (660-1000°C) is highly chemically aggressive toward equipment components. Violent metallurgical reactions with the metal substrate occur through interfacial diffusion and dissolution-reprecipitation mechanisms, leading to severe corrosion, wear, dimensional degradation, and mechanical property degradation in key components such as sinking rollers, pull rollers, and guide plates, ultimately leading to premature equipment failure. Statistics show that the average service life of these components is less than six months. Frequent replacement not only significantly increases maintenance costs but also severely restricts production continuity and product quality stability, becoming a technical bottleneck hindering the efficient development of the industry.

[0003] Traditional refractory aluminum corrosion materials face significant limitations. For example, alumina ceramics, despite their high melting point (2054°C) and good chemical inertness, can provide effective protection at room temperature. However, in high-temperature molten aluminum, the interface reaction between Al2O3 and liquid aluminum causes the structural destruction of their protective layer. At the same time, their intrinsic brittleness (fracture toughness of only 3-4 MPa·m 1 / 2 ) makes it extremely susceptible to crack propagation under thermal stress and mechanical impact, making it difficult to meet service requirements under complex operating conditions. Therefore, developing new structural materials with high resistance to molten aluminum corrosion, excellent fatigue resistance, and good high-temperature mechanical stability has become a core research direction to break through industrial technical bottlenecks and improve production efficiency and economic benefits.

[0004] TiB2-based cermets have shown broad application prospects due to their high hardness, high melting point, and excellent chemical stability. However, due to their intrinsic covalent bond characteristics, traditional single sintering aid modification strategies have significant limitations. Existing studies have shown that relying solely on single additives (such as oxides, carbides, etc.) can promote particle rearrangement or inhibit grain growth to a certain extent, but it is difficult to simultaneously achieve increased material density, enhanced mechanical properties, and optimized corrosion resistance. In addition, advanced densification technologies such as hot pressing (HP), hot isostatic pressing (HIP), and spark plasma sintering (SPS) can improve material density by precisely controlling the temperature and pressure fields. However, they still face technical bottlenecks such as uneven grain size, residual stress accumulation, and high process costs.

[0005] From the analysis of the nature of the material, the densification process of TiB2 is subject to multiple constraints such as low atomic diffusion rate, high energy barrier for grain boundary migration and weak interfacial bonding. At the same time, the crack sensitivity caused by its intrinsic brittleness further limits the improvement of the overall performance of the material. Therefore, it is urgent to construct an innovative modification strategy based on the synergistic mechanism of multiple additives. By designing a multi-scale microstructure control system, the kinetic barriers and intrinsic brittleness problems of TiB2 sintering densification can be effectively solved, and the performance breakthrough of the material in extreme service environments such as molten aluminum corrosion resistance can be achieved. This research direction has important scientific significance and engineering value for expanding the application of TiB2-based cermets in metallurgy, aerospace and other fields. Summary of the Invention

[0006] In response to the above-mentioned prior art, the present invention discloses a TiB2-based cermet resistant to molten aluminum corrosion and its preparation method and application, in order to solve the technical problems of low density, weak mechanical properties and corrosion resistance of molten aluminum corrosion resistant materials in the prior art.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is: to provide a method for preparing TiB2-based cermets resistant to molten aluminum corrosion, which comprises the following steps:

[0008] S1: Prepare TiB2 powder and carbide mixed powder; the mass percentage of TiB2 powder is 70-90%, and the balance is carbide powder; the carbide mixed powder is TaC, Mo2C and WC mixed powder, and the mass ratio of TaC, Mo2C and WC is 1:1:1;

[0009] S2: placing TiB2 powder and carbide mixed powder in a ball mill for ball milling, and then drying the ball-milled mixed powder;

[0010] S3: The dried mixed powder is subjected to spark plasma sintering to obtain the obtained product; the sintering method is spark plasma sintering, the sintering temperature is 1800~2000℃, the holding time is 5~10min, and the applied pressure value is 30~50MPa.

[0011] On the basis of the above technical solution, the present invention can also be improved as follows.

[0012] Furthermore, the mass percentage of TiB2 powder is 80%.

[0013] Furthermore, the purity of the TiB2 powder is ≥99.5%, and the particle size of the TiB2 powder is 3~5μm; the purity of the carbide mixed powder is ≥99.9%, and the particle size of the carbide mixed powder is 4~5μm.

[0014] Furthermore, in step S2, the ball-to-material ratio during ball milling is 5:1, the ball milling speed is 280-320 rpm, and the ball milling time is 22-24 h.

[0015] Furthermore, in step S2, the drying temperature is 70-90° C., and the drying time is 22-26 hours.

[0016] Furthermore, in step S3, the sintering heating rate is 100° C. / min.

[0017] The invention also discloses the application of the TiB2-based cermet resistant to molten aluminum corrosion in the preparation of industrial aluminum melting equipment.

[0018] The beneficial effects of the present invention are:

[0019] 1. When preparing the TiB2-based cermet material in the present invention, a TiB2 matrix and carbide powder (sintering aid) are mixed and subjected to high-temperature spark plasma sintering, so that the material can achieve extremely high density, with a relative density of up to 99%. The extremely high density effectively minimizes the internal porosity. The in-situ generated (Ti, W, Mo, Ta) B2 high-entropy diboride solid solution shell has excellent chemical stability and constructs a dense, chemically inert microscopic barrier on the surface and grain boundaries of the material, which can effectively prevent the penetration and erosion of molten aluminum. The average corrosion rate of the material in a 700°C molten aluminum environment is as low as 0.115 μm / h (compared with materials commonly used in industry today, this exhibits unparalleled performance advantages. For example, the average corrosion rate of cast iron in 700°C molten aluminum is approximately 850 μm / h, and the corrosion rate of 316L stainless steel is approximately 11 μm / h).

[0020] 2. The TiB2-based cermet prepared in the present invention has excellent mechanical properties. While maintaining good hardness, it achieves multiple solid solution strengthening effects by forming a (Ti, W, Mo, Ta) B2 high-entropy solid solution shell and a (W, Mo, Ta, Ti) C high-entropy carbide interstitial phase, significantly improving the density and fracture toughness of the material, thereby achieving an optimal balance between hardness, toughness and density, and providing a more durable material for high-temperature applications.

[0021] 3. The TiB2-based cermet prepared in this invention, which is resistant to molten aluminum corrosion, is suitable for key components in high-temperature molten aluminum processing equipment, such as molds, crucibles, and guide plates. Its enhanced durability and corrosion resistance are expected to significantly extend the service life of equipment, significantly reduce maintenance costs, and improve overall production efficiency, thereby bringing considerable economic benefits and broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the SEM image of the sample in Example 1;

[0023] Figure 2 This is the SEM image of the sample in Example 2;

[0024] Figure 3 This is the SEM image of the sample in Example 3;

[0025] Figure 4 is the SEM image of the sample of Comparative Example 1;

[0026] Figure 5 is the XRD diffraction pattern of the sample in Example 1;

[0027] Figure 6 The graph shows the corrosion depth test results of samples in Examples 1 to 3 and Comparative Example 1 at different times. DETAILED DESCRIPTION

[0028] The specific implementation methods of the present invention are described in detail below with reference to the embodiments.

[0029] Example 1

[0030] A TiB2-based cermet resistant to molten aluminum corrosion, the preparation method of which comprises the following steps:

[0031] S1: Accurately weigh 80g of TiB2 powder and 20g of carbide mixed powder (TaC powder, Mo2C powder, and WC powder are mixed in a mass ratio of 1:1:1); the purity of TiB2 powder is ≥99.5%, and the particle size of TiB2 powder is 3~5μm; the purity of TaC powder, Mo2C powder, and WC powder is ≥99.9%, and the particle size of TaC powder, Mo2C powder, and WC powder is 4~5μm;

[0032] S2: Place the above powder in a planetary ball mill, then add an appropriate amount of anhydrous ethanol as a medium. The amount of anhydrous ethanol added should just cover the powder. Then, planetary ball milling is performed at a ball-to-material ratio of 5:1 and a rotation speed of 300 rpm for 24 hours. The ball-milled mixed powder is then placed in a vacuum drying oven and vacuum dried at 80°C for 24 hours to remove the anhydrous ethanol.

[0033] S3: The dried mixed powder is placed into a graphite mold and sintered in a spark plasma sintering furnace. The obtained product is cooled after sintering. The sintering process parameters are: heating rate 100°C / min, sintering temperature 1900°C, holding time 10min, and axial applied pressure value 50MPa.

[0034] Example 2

[0035] A TiB2-based cermet resistant to molten aluminum corrosion, the preparation method of which comprises the following steps:

[0036] S1: Accurately weigh 90g TiB2 powder and 10g carbide mixed powder (TaC powder, Mo2C powder and WC powder are mixed in a mass ratio of 1:1:1); the purity of TiB2 powder is ≥99.5%, and the particle size of TiB2 powder is 3~5μm; the purity of TaC powder, Mo2C powder and WC powder is ≥99.9%, and the particle size of TaC powder, Mo2C powder and WC powder is 4~5μm;

[0037] S2: Place the above powder in a planetary ball mill, then add an appropriate amount of anhydrous ethanol as a medium. The amount of anhydrous ethanol added should just cover the powder. Then, planetary ball milling is performed at a ball-to-material ratio of 5:1 and a rotation speed of 300 rpm for 24 hours. The ball-milled mixed powder is then placed in a vacuum drying oven and vacuum dried at 80°C for 24 hours to remove the anhydrous ethanol.

[0038] S3: The dried mixed powder is placed into a graphite mold and sintered in a spark plasma sintering furnace. The obtained product is cooled after sintering. The sintering process parameters are: heating rate 100°C / min, sintering temperature 1900°C, holding time 10min, and axial applied pressure value 50MPa.

[0039] Example 3

[0040] A TiB2-based cermet resistant to molten aluminum corrosion, the preparation method of which comprises the following steps:

[0041] S1: Accurately weigh 70g TiB2 powder and 30g carbide mixed powder (TaC powder, Mo2C powder and WC powder are mixed in a mass ratio of 1:1:1); the purity of TiB2 powder is ≥99.5%, and the particle size of TiB2 powder is 3~5μm; the purity of TaC powder, Mo2C powder and WC powder is ≥99.9%, and the particle size of TaC powder, Mo2C powder and WC powder is 4~5μm;

[0042] S2: Place the above powder in a planetary ball mill, then add an appropriate amount of anhydrous ethanol as a medium. The amount of anhydrous ethanol added should just cover the powder. Then, planetary ball milling is performed at a ball-to-material ratio of 5:1 and a rotation speed of 300 rpm for 24 hours. The ball-milled mixed powder is then placed in a vacuum drying oven and vacuum dried at 80°C for 24 hours to remove the anhydrous ethanol.

[0043] S3: The dried mixed powder is placed into a graphite mold and sintered in a spark plasma sintering furnace. The obtained product is cooled after sintering. The sintering process parameters are: heating rate 100°C / min, sintering temperature 1900°C, holding time 10min, and axial applied pressure value 50MPa.

[0044] Example 4

[0045] A TiB2-based cermet resistant to molten aluminum corrosion, the preparation method of which comprises the following steps:

[0046] S1: Accurately weigh 80g of TiB2 powder and 20g of carbide mixed powder (TaC powder, Mo2C powder, and WC powder are mixed in a mass ratio of 1:1:1); the purity of TiB2 powder is ≥99.5%, and the particle size of TiB2 powder is 3~5μm; the purity of TaC powder, Mo2C powder, and WC powder is ≥99.9%, and the particle size of TaC powder, Mo2C powder, and WC powder is 4~5μm;

[0047] S2: Place the above powder in a planetary ball mill, then add an appropriate amount of anhydrous ethanol as a medium. The amount of anhydrous ethanol added should just cover the powder. Then, planetary ball milling is performed at a ball-to-material ratio of 5:1 and a rotation speed of 280 rpm for 24 hours. The ball-milled mixed powder is then placed in a vacuum drying oven and vacuum dried at 70°C for 26 hours to remove the anhydrous ethanol.

[0048] S3: The dried mixed powder is loaded into a graphite mold and sintered in a spark plasma sintering furnace. The obtained product is cooled after sintering. The sintering process parameters are: heating rate 100°C / min, sintering temperature 1800°C, holding time 10min, and axial applied pressure value 30MPa.

[0049] Example 5

[0050] A TiB2-based cermet resistant to molten aluminum corrosion, the preparation method of which comprises the following steps:

[0051] S1: Accurately weigh 80g of TiB2 powder and 20g of carbide mixed powder (TaC powder, Mo2C powder, and WC powder are mixed in a mass ratio of 1:1:1); the purity of TiB2 powder is ≥99.5%, and the particle size of TiB2 powder is 3~5μm; the purity of TaC powder, Mo2C powder, and WC powder is ≥99.9%, and the particle size of TaC powder, Mo2C powder, and WC powder is 4~5μm;

[0052] S2: Place the above powder in a planetary ball mill, then add an appropriate amount of anhydrous ethanol as a medium. The amount of anhydrous ethanol added should just cover the powder. Then, planetary ball milling is performed at a ball-to-material ratio of 5:1 and a rotation speed of 320 rpm for 22 hours. The ball-milled mixed powder is then placed in a vacuum drying oven and vacuum dried at 90°C for 22 hours to remove the anhydrous ethanol.

[0053] S3: The dried mixed powder is placed into a graphite mold and sintered in a spark plasma sintering furnace. The obtained product is cooled after sintering. The sintering process parameters are: heating rate 100°C / min, sintering temperature 2000°C, holding time 5min, and axial applied pressure value 40MPa.

[0054] Comparative Example 1

[0055] A metal ceramic, the preparation method of which comprises the following steps:

[0056] S1: Accurately weigh 80g of TiB2 powder (the purity of the TiB2 powder should be ≥99.5% and the particle size of the TiB2 powder should be 3-5μm) and place it in a planetary ball mill. Then, add an appropriate amount of anhydrous ethanol as the medium. The amount of anhydrous ethanol added should just cover the powder. Then, planetary ball milling is performed at a ball-to-material ratio of 5:1 and a rotation speed of 300rpm for 24 hours. The ball-milled powder is then placed in a vacuum drying oven and vacuum dried at 80℃ for 24 hours to remove the anhydrous ethanol.

[0057] S2: The dried powder is loaded into a graphite mold and sintered in a spark plasma sintering furnace. The obtained product is cooled after sintering. The sintering process parameters are: heating rate 100°C / min, sintering temperature 1900°C, holding time 10min, and axial applied pressure value 50MPa.

[0058] The performance of the TiB2-based cermets resistant to molten aluminum corrosion prepared in the embodiments of the present invention is similar. Taking embodiments 1 to 3 as examples, the performance of the related products will be described below.

[0059] Experimental example

[0060] 1. Structural testing

[0061] The samples prepared in Examples 1 to 3 and Comparative Example 1 were scanned by electron microscope, and the SEM images were as follows: Figures 1 to 4 As shown. Figure 1 It can be seen that the sample has a relatively dense and flat microstructure, the number of pores is significantly reduced, the contrast of its grain boundaries is significantly reduced, and the boundary features tend to be blurred, indicating that the full penetration and reaction of the sintering aids make the structure more uniform and dense. The light gray sintered solid solution phase is evenly filled around the polygonal TiB2 particles, forming a complete ceramic core-shell structure. Figure 2 It can be seen from the figure that the sample shows a relatively smooth surface, the number of pores is reduced, TiB2 is distributed in blocks, and Ta, W, and Mo elements are evenly distributed, indicating that a solid solution phase has been formed. Figure 3 It can be seen that the sample structure is dense and flat, the number of pores is slightly reduced, and the TiB2 grain boundary is no longer visible, indicating that the sintered sample has been clearly dissolved.

[0062] Figure 4The sample without the addition of a sintering aid exhibited a mottled surface morphology, with a large number of pores in the reaction layer. The TiB2 particles were distributed as independent small particles, rather than forming a dense continuous network. This high porosity significantly reduced the material's compactness, providing an easy penetration path for molten aluminum, leading to a significant decrease in its corrosion resistance.

[0063] The sample in Example 1 was subjected to X-ray diffraction, and the obtained XRD diffraction pattern was as follows: Figure 5 To accurately analyze the phase composition of this composite material, it is necessary to correlate XRD crystallographic information with scanning electron microscopy (SEM) microstructural information and energy dispersive spectroscopy (EDS) local elemental composition information. Comprehensive analysis results show that this material is not a simple physical mixture of initial powders, but rather a complex in-situ reaction during the high-temperature SPS process, forming a three-phase composite ceramic with a unique microstructure. Its final phase composition is:

[0064] 1. TiB2 Core Phase: The spectrum contains a series of strongest diffraction peaks with no shift in peak position, which perfectly match the standard card of hexagonal TiB2 (e.g. PDF# 85-2083). These peaks originate from the incompletely reacted core of the original TiB2 powder particles, corresponding to the SEM image ( Figure 1 ) The darker grey polygonal grain core region in the image.

[0065] 2. (Ti,W,Mo,Ta)B2 high-entropy diboride solid solution shell phase: A set of "shoulder" or "ghost peaks" are observed at low angles to the main TiB2 diffraction peak. These peak positions are systematically shifted, sharing the same crystal structure (hexagonal P6 / mmm space group) as the main TiB2 diffraction peak. This peak shift is direct crystallographic evidence for the formation of a solid solution and conforms to Vegard's law. This occurs during high-temperature sintering, where the additive elements W, Mo, and Ta diffuse onto the TiB2 particle surface and replace some Ti atoms, forming the (Ti,W,Mo,Ta)B2 high-entropy diboride solid solution. This solid solution shell corresponds to the lighter gray region surrounding the TiB2 core in SEM images. The presence of both the unshifted "core peak" and the shifted "shell peak" in the XRD pattern perfectly confirms the presence of this core-shell microstructure.

[0066] 3. (W,Mo,Ta,Ti)C High-Entropy Carbide Solid Solution Interstitial Phase: After deducting the diffraction peaks of the two boride phases mentioned above, the remaining major diffraction peaks in the spectrum can be uniquely and perfectly calibrated to a single phase with a cubic rock salt structure (space group Fm3-m). This phase is a (W,Mo,Ta,Ti)C high-entropy carbide solid solution formed by the initial WC, Mo2C, and TaC carbide additives, along with some Ti that participates in the reaction. This phase corresponds to the brightest white interstitial region in the SEM image, filling the gap between the core-shell grains.

[0067] 4. Trace amounts of free graphite and titanium dioxide (TiO2): These are trace impurities or by-products produced by complex physical and chemical processes at high temperatures. Their content is extremely low and does not affect our core conclusion that the material is composed of three main phases: a TiB2 core, a (Ti, W, Mo, Ta)B2 shell, and a (W, Mo, Ta, Ti)C interstitial phase.

[0068] In summary, the key technical effect of the present invention lies in the in-situ synthesis of an advanced high-entropy ceramic composite material with a hierarchical "core-shell-interstitial" three-phase structure, rather than forming multiple independent borides and carbides, through a specific SPS process. This structure is composed of an unreacted TiB2 core, a high-entropy boride solid solution shell, and a high-entropy carbide solid solution interstitial phase. This unique microstructure is the fundamental reason for the material's excellent mechanical properties and resistance to molten aluminum corrosion.

[0069] 2. Mechanical properties test

[0070] The samples prepared in Examples 1 to 3 and Comparative Example 1 were cut and surface polished, and surface defects and scratches were removed using 40# and 180# sandpaper. Finally, the surface was polished using diamond polishing paste until a mirror effect was achieved. The mechanical properties were then tested, and the results are shown in Table 1.

[0071] Table 1

[0072]

[0073] From the mechanical properties data in Table 1, it can be seen that compared with the comparative example 1 without adding additives, the samples prepared in the embodiment of the present invention have achieved significant synergistic improvement in performance. Although the Vickers hardness of comparative example 1 (pure TiB2) is the highest (2249 MPa), its fracture toughness is extremely low (5.63 MPa·m 1 / 2), and the relative density is only 94.44%, showing typical hard and brittle characteristics, which is difficult to meet the needs of practical applications. In contrast, the sample of Example 1 has a slightly lower hardness (1962 MPa), while its fracture toughness has achieved a huge improvement of nearly double (10.55 MPa·m 1 / 2 ), and the relative density reaches an excellent 99.04%. This balance of sacrificing a small amount of hardness in exchange for significantly improved toughness, density, and overall performance is the core advantage of the technical solution of this invention.

[0074] The fundamental mechanism of this invention lies in the fact that the introduced TaC, Mo2C, and WC powders are not simply "sintering aids" but instead undergo a profound and complex in-situ chemical reaction with the TiB2 matrix during the high-temperature spark plasma sintering (SPS) process. Based on precise analysis of the microstructure and phases, the resulting composite material is not a simple mixture of discrete phases, but rather an advanced high-entropy ceramic composite with a hierarchical "core-shell-interstitial" structure. Its phase composition is: a TiB2 core phase, a (Ti, W, Mo, Ta)B2 high-entropy diboride solid solution shell phase, and a (W, Mo, Ta, Ti)C high-entropy carbide solid solution interstitial phase, along with trace amounts of free graphite and titanium dioxide (TiO2).

[0075] From the perspective of microstructural evolution, this unique core-shell-interstitial structure is the key to achieving high performance. Its densification and toughening mechanisms can be summarized as follows:

[0076] 1. Formation of a core-shell structure and grain boundary toughening: The in-situ generated (Ti, W, Mo, Ta) B2 high-entropy solid solution shell and (W, Mo, Ta, Ti) C high-entropy carbide interstitial phase form new interfaces on the surface and grain boundaries of the TiB2 grains. These new phases not only effectively inhibit the abnormal growth of TiB2 at high temperatures through a "pinning effect," achieving grain refinement, but more importantly, as tough phases, they effectively prevent crack propagation through crack deflection and bridging mechanisms, thereby significantly improving the material's fracture toughness.

[0077] 2. Reaction-driven, efficient densification: The high-temperature in-situ reaction itself, particularly the transient liquid phase that may form, greatly promotes atomic diffusion and material transport, accelerating particle rearrangement and the elimination of pores. This is the core kinetic reason for achieving a high relative density exceeding 99%. Unlike the "graphite filling pores" mentioned in the original analysis, the material's high density stems primarily from the efficient sintering and reaction mechanisms of the SPS process, rather than the physical filling effect of trace impurities.

[0078] In summary, the key to the success of this invention lies not in simply introducing a sintering aid, but in the ingenious design of ingredients and process control that drives a series of in-situ reactions, resulting in the successful construction of a three-phase synergistic strengthening system consisting of a TiB2 core, a high-entropy boride shell, and a high-entropy carbide interstitial structure. This system, through the synergistic effect of multiple mechanisms, including the toughening mechanism provided by the core-shell structure, the solid solution strengthening effect of the high-entropy phase, and the grain refinement and efficient densification promoted by the reaction, perfectly resolves the inherent contradiction of pure TiB2 materials, which have high hardness but poor toughness and difficulty in densification. Ultimately, an advanced composite ceramic material with high density, high fracture toughness, and excellent overall performance is obtained.

[0079] The sample material in the embodiment has extremely low internal porosity, a highly dense structure, and exhibits excellent mechanical strength and wear resistance, and also has good performance in resisting crack propagation. However, the relative density of the sample in Comparative Example 1 is only 94.44%, which is much lower than that of the sample with additives, indicating the presence of significant residual porosity, and the fracture toughness is 5.63 MPa·m 1 / 2 , which is significantly lower than that of the embodiments of the present invention, indicating that it is relatively brittle and has poor resistance to crack propagation. Its Vickers hardness is 2249 MPa. Although it is higher than that of Example 1, this high hardness is accompanied by low density and poor corrosion resistance. If a single high hardness is accompanied by high porosity, it cannot meet the comprehensive requirements of corrosion resistance and wear resistance of materials in practical applications.

[0080] 3. Corrosion resistance test

[0081] The samples prepared in Examples 1 to 3 and Comparative Example 1 were subjected to corrosion experiments in molten aluminum at 700°C. The corrosion depth test results of the samples at different times are shown in FIG. Figure 6 The average corrosion rate of the samples is shown in Table 2.

[0082] Table 2

[0083]

[0084] The average corrosion rate of the samples in the Examples was significantly lower than that in the Comparative Examples, fully demonstrating their excellent resistance to molten aluminum corrosion, particularly in Example 1. While Example 3 exhibited the highest density, its molten aluminum corrosion resistance was slightly inferior to that of Example 1. This phenomenon suggests that excessive additive content may lead to the formation of secondary phases with weaker corrosion resistance or the introduction of other microstructural defects, resulting in suboptimal performance in long-term molten aluminum corrosion. This underscores the importance of striking a balance of properties in material design, rather than simply maximizing a single metric. The average corrosion rate of the Comparative Example 1 sample was 0.228 μm / h, twice that of Example 1, indicating its poor molten aluminum corrosion resistance. The excellent molten aluminum corrosion resistance of the Example materials stems from their unique dual synergistic protective mechanism, comprising both physical and chemical barriers. First, the high-density structure (relative density exceeding 99%) achieved through the spark plasma sintering (SPS) process inherently forms a strong physical barrier. This barrier significantly enhances the material's density, effectively preventing macroscopic penetration of aggressive molten aluminum. Secondly, and more crucially, the chemical barrier formed during the high-temperature in-situ reaction is composed of two high-entropy solid solution phases. The formation mechanism of this barrier is as follows: A high-entropy diboride solid solution shell ((Ti,W,Mo,Ta)B2): During sintering, the added W, Mo, and Ta elements diffuse toward the surface of the original TiB2 particles, forming a (Ti,W,Mo,Ta)B2 high-entropy solid solution "shell" surrounding the TiB2 core. The excellent chemical inertness and thermodynamic stability imparted by the high-entropy effect make this dense shell the first microscopic line of defense against corrosion at the grain scale. A high-entropy carbide solid solution interstitial phase ((W,Mo,Ta,Ti)C): Formed by the reaction of the initial carbides (WC, Mo2C, TaC) with a portion of Ti, the (W,Mo,Ta,Ti)C high-entropy carbide phase fills the gaps between the core-shell grains, forming a continuous grain boundary network. This phase also has excellent chemical stability, further blocking potential corrosion weaknesses such as grain boundaries. These two high-entropy phases together construct a continuous, dense, chemically inert interface network on the surface and internal grain boundaries of the material. This network significantly reduces the activity of wetting and adverse interfacial chemical reactions between the material and molten aluminum, thereby fundamentally improving the material's corrosion resistance in high-temperature molten aluminum environments. In summary, it is this unique dual protection mechanism composed of a "high-density physical barrier" and a "dual high-entropy phase chemical barrier" that has become the key to the present invention's breakthrough in molten aluminum corrosion resistance.

[0085] Although the specific embodiments of the present invention have been described in detail in conjunction with the embodiments, this should not be construed as limiting the scope of protection of this patent. Within the scope described by the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A method for preparing a TiB2-based cermet resistant to molten aluminum corrosion, characterized in that: The following steps are involved: S1: Prepare TiB2 powder and carbide mixed powder; wherein the mass percentage of TiB2 powder is 70-90%, and the balance is carbide powder; the carbide mixed powder is a mixed powder of TaC, Mo2C and WC, and the mass ratio of TaC, Mo2C and WC is 1:1:1; S2: placing TiB2 powder and carbide mixed powder in a ball mill for ball milling, and then drying the ball-milled mixed powder; S3: The dried mixed powder is subjected to spark plasma sintering to obtain the obtained product; the sintering method is spark plasma sintering, the sintering temperature is 1800~2000℃, the holding time is 5~10min, and the applied pressure value is 30~50MPa.

2. The method for preparing the TiB2-based cermet resistant to molten aluminum corrosion according to claim 1, characterized in that: The purity of TiB2 powder is ≥99.5%, and the particle size of TiB2 powder is 3~5μm; the purity of carbide mixed powder is ≥99.9%, and the particle size of carbide mixed powder is 4~5μm.

3. The method for preparing the TiB2-based cermet resistant to molten aluminum corrosion according to claim 1, characterized in that: In step S2, the ball-to-material ratio during ball milling is 5:1, the ball milling speed is 280-320 rpm, and the ball milling time is 22-24 h.

4. The method for preparing the TiB2-based cermet resistant to molten aluminum corrosion according to claim 1, wherein: In step S2, the drying temperature is 70-90° C., and the drying time is 22-26 hours.

5. The method for preparing the TiB2-based cermet resistant to molten aluminum corrosion according to claim 1, characterized in that: The sintering heating rate in step S3 is 100°C / min.

6. A TiB2-based cermet resistant to molten aluminum corrosion, characterized by: The TiB2-based cermet resistant to molten aluminum corrosion is prepared by the preparation method of any one of claims 1 to 5.

7. An application of a TiB2-based cermet resistant to molten aluminum corrosion, characterized by: The TiB2-based cermet resistant to molten aluminum corrosion according to claim 6 is used to prepare industrial aluminum melting equipment.

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