A superhard ceramic infiltration layer on a metal tantalum surface, a preparation method and a metal tantalum material

Abstract

The application discloses a metal tantalum surface superhard ceramic permeation layer, a preparation method and a metal tantalum material. The metal tantalum substrate is embedded into a permeation agent, and a boron tantalum compound is generated on the surface of the metal tantalum by heat preservation in a vacuum or a protective atmosphere at 1200-1600 DEG C, so that a wear-resistant and corrosion-resistant superhard ceramic phase boride permeation layer is obtained. The permeation layer has excellent comprehensive performance and superhigh surface hardness, and the surface hardness can reach HV1520-HV3200. The thickness of the superhard ceramic permeation layer can be adjusted in the range of 10-100 microns. The bonding strength between the boron permeation layer and the substrate is high, and the bonding force is in the range of 20-35 N. In addition, the permeation layer has superior corrosion resistance, and the corrosion rate in a high-temperature molten cerium is in the range of 0.0630-0.0885 microns / h.

Description

Technical Field

[0001] This invention belongs to the field of metal material surface treatment technology, specifically relating to an ultra-hard ceramic diffusion layer on the surface of tantalum metal, its preparation method, and tantalum metal material. Background Technology

[0002] Tantalum metal possesses high density, high melting point, excellent high-temperature strength, good machinability, weldability, and superior mechanical properties, making it widely used in the electronic capacitor industry, biomedicine, chemical corrosion protection equipment, aerospace engine components, and weaponry. However, tantalum metal has low surface hardness, poor wear resistance, and poor resistance to high-temperature oxidation, which affects its performance during high-temperature service and limits its application range.

[0003] Tantalum boride (TaB2) is a boride of the transition metal tantalum, belonging to the hexagonal AlB2 crystal structure. As an excellent ultra-high temperature ceramic (UHTC) material, it has a melting point of around 3200℃, high hardness, high strength at high temperatures, good heat resistance and oxidation resistance, as well as good electrical and thermal conductivity, high chemical stability, high thermal shock resistance, and good wear and corrosion resistance. It has been used in thermal protection systems for spacecraft, refractory crucibles, plasma arc electrodes, and rocket engines. However, the preparation process of bulk tantalum boride is complex. Due to its high melting point, it requires high sintering temperatures and long preparation cycles, and there is a difficulty in obtaining dense, large-sized components, which limits its application in harsh operating environments.

[0004] Methods for preparing tantalum boride composite coatings include pressureless sintering, vapor deposition, in-situ reaction, and thermal spraying. However, the hardness of tantalum boride composite coatings prepared using these methods is not high. For example, the hardness of TaB ceramics recorded in Chen Haihua et al.'s "Study on the Hardness of High-Temperature and High-Pressure Sintered Tantalum Boride (TaB) Body" is only 7.7-11 GPa. Moreover, the bonding between the tantalum boride composite coating prepared using these methods and the substrate is not tight enough, which to some extent affects the material's performance and service life. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides an ultra-hard ceramic diffusion layer on the surface of tantalum metal, its preparation method, and tantalum metal material, specifically including the following:

[0006] A superhard ceramic infiltration layer on the surface of tantalum metal comprises TaB, Ta3B4 and TaB2 phases, wherein the mass ratio of the three phases TaB, Ta3B4 and TaB2 is (1.5-2.5):(0.8-1.2):(0.8-1.2); the surface hardness of the superhard ceramic infiltration layer is HV1520~HV3200, and the thickness of the superhard ceramic infiltration layer is 10μm~100μm. Specifically, the ratio of the TaB, Ta3B4, and TaB2 phases can be 1.5:0.8:0.8, 2:1:1, 2.1:1.1:1.1, 2.3:1.2:1.2, etc.; the surface hardness can reach HV1550, HV2000, HV2500, HV3000, HV3200, etc.; the thickness can be 10μm, 20μm, 50μm, 80μm, 90μm, 100μm, etc. It should be noted that the tantalum metal described in this invention is preferably pure tantalum metal.

[0007] Preferably, the corrosion rate of the ultra-hard ceramic diffusion layer in high-temperature molten cerium is 0.0630-0.0885 μm / h (e.g., 0.0650 μm / h, 0.0700 μm / h, 0.0750 μm / h, 0.0800 μm / h, 0.0850 μm / h, etc.). The method for determining the corrosion rate of boron-dipped tantalum in high-temperature molten cerium is as follows: based on the sample's weight loss m, sample surface area s, diffusion layer density ρ, and corrosion time t, the corrosion rate of the boron-dipped tantalum sample is calculated using the formula η = m / s / ρ / t, and is within the range of 0.0630-0.0885 μm / h.

[0008] A method for preparing an ultra-hard ceramic infiltration layer on a tantalum metal surface includes embedding a tantalum metal substrate in an infiltration agent, and then holding it at a temperature in a vacuum or protective atmosphere; the infiltration agent can be selected from one or more combinations of the following four:

[0009] The first type: (20-25 wt% B4C) + (3-5 wt% KBF4) + (70-77 wt% SiC) (e.g., 21 wt% B4C + 3.5 wt% KBF4 + 72 wt% SiC, 23 wt% B4C + 4.5 wt% KBF4 + 75 wt% SiC, 24 wt% B4C + 4.8 wt% KBF4 + 76 wt% SiC, etc.);

[0010] The second type: (3-5 wt% B4C) + (3-5 wt% KBF4) + (90-94 wt% SiC) (e.g., 3.5 wt% B4C + 3.5 wt% KBF4 + 91 wt% SiC, 4.5 wt% B4C + 4.5 wt% KBF4 + 92 wt% SiC, 4.8 wt% B4C + 4.8 wt% KBF4 + 93 wt% SiC, etc.);

[0011] The third type: (3-5 wt% B4C) + (3-5 wt% KBF4) + (90-94 wt% Al2O3) (e.g., 3.5 wt% B4C + 3.5 wt% KBF4 + 91 wt% Al2O3, 4.5 wt% B4C + 4.5 wt% KBF4 + 92 wt% Al2O3, 4.8 wt% B4C + 4.8 wt% KBF4 + 93 wt% Al2O3, etc.);

[0012] The fourth type: (3-5 wt% B4C) + (3-5 wt% NH4Cl) + (90-94 wt% Al2O3) (e.g., 3.5 wt% B4C + 3.5 wt% NH4Cl + 91 wt% Al2O3, 4.5 wt% B4C + 4.5 wt% NH4Cl + 92 wt% Al2O3, 4.8 wt% B4C + 4.8 wt% NH4Cl + 93 wt% Al2O3, etc.).

[0013] Preferably, the method for preparing the ultra-hard ceramic infiltration layer on the tantalum metal surface includes the following steps:

[0014] (1) Substrate pretreatment: The surface of the tantalum substrate is polished and then ultrasonically cleaned;

[0015] (2) Preparation of the penetrant: Prepare the penetrant according to the proportion, and then mix the penetrant evenly;

[0016] (3) Boronizing: The tantalum metal substrate treated in step (1) is embedded in the homogeneous boronizing agent mixed in step (2) and kept at 1200-1600℃ (e.g., 1250℃, 1300℃, 1400℃, 1500℃, etc.) under vacuum conditions or a protective atmosphere for 3-8 hours (e.g., 4 hours, 5 hours, 6 hours, 7 hours, etc.). ， The processed tantalum metal is obtained;

[0017] (4) Post-processing: Take out the tantalum metal after step (3) and remove the residual permeating agent on the surface.

[0018] Preferably, the polishing method in step (1) is to polish with 200-2000 grit sandpaper or polish with polishing material, and the cleaning agent used for ultrasonic cleaning is acetone or alcohol. Using the substrate pretreatment method disclosed in this invention can make the surface of the tantalum metal substrate smoother and cleaner, which is beneficial to improving the adhesion between the diffusion layer and the substrate.

[0019] Preferably, the method for mixing the penetrant in step (2) is to use a ball mill. Using a ball mill can ensure that the penetrant is mixed evenly and can also crush the penetrant into fine and uniform powder, which is beneficial to improving the reaction efficiency of the encapsulation penetrant step, as well as improving the hardness and uniformity of the penetrant layer.

[0020] Preferably, the method for removing residual penetrant from the surface in step (4) is to ultrasonically clean the tantalum metal in water and alcohol in sequence.

[0021] A tantalum material with an ultra-hard ceramic infiltration layer on the surface of tantalum metal.

[0022] The beneficial effects of this invention are:

[0023] (1) The superhard ceramic phase boride diffusion layer disclosed in this invention comprises TaB, Ta3B4 and TaB2 phases in a mass ratio of (1.5-2.5):(0.8-1.2):(0.8-1.2). Through the rational design of the diffusion layer composition, the hardness of the boride diffusion layer and its bonding force with the substrate are effectively improved. Its surface hardness is HV1520~HV3200, and the bonding strength between the boride diffusion layer and the substrate is 20N~35N, thereby improving the wear resistance and corrosion resistance of the tantalum metal surface. According to the test, the corrosion rate of the superhard ceramic phase boride diffusion layer in high-temperature molten cerium metal is 0.0630-0.0885μm / h.

[0024] (2) The preparation method of the superhard ceramic infiltration layer on the surface of tantalum metal disclosed in this invention (3) The equipment for high-temperature treatment is a vacuum heat treatment furnace. By setting the conditions for embedding and infiltration treatment as follows: 1200-1600℃ vacuum or protective atmosphere for 3-8h, a superhard ceramic layer can be formed on the surface of tantalum metal. Moreover, the preparation method is very convenient for mass production, the product quality is easy to control, the required equipment is simple, and the investment is low.

[0025] (3) This invention utilizes a solid-entrapment infiltration method to obtain a wear-resistant and corrosion-resistant ultra-hard ceramic phase boride infiltrated layer. The infiltrated layer exhibits excellent comprehensive properties, including extremely high surface hardness, reaching HV1520–HV3200. The thickness of the ultra-hard ceramic infiltrated layer is adjustable within the range of 10–100 μm. Furthermore, the bonding strength between the boride-infiltrated layer and the substrate is high, with a bonding force ranging from 20 to 35 N. In addition, the infiltrated layer possesses superior corrosion resistance, exhibiting a corrosion rate in high-temperature molten cerium metal within the range of 0.0630–0.0885 μm / h. Attached Figure Description

[0026] Figure 1 Photographs of the surface morphology of tantalum metal after boronizing with the first formulation;

[0027] Figure 2 Photographs of the cross-sectional morphology of tantalum metal after boronizing with the first formulation;

[0028] Figure 3 Photographs of the cross-sectional morphology of tantalum metal after boronizing with the second ratio;

[0029] Figure 4 Photographs of the cross-sectional morphology of tantalum metal after boronizing with the third formulation;

[0030] Figure 5 Photographs of the cross-sectional morphology of tantalum metal after boronizing with the fourth ratio. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments shown below do not limit the scope of the invention as described in the claims. Furthermore, the complete contents of the configurations illustrated in the following embodiments are not limited to those necessary for the solution of the invention as described in the claims.

[0032] Example 1

[0033] The surface of the tantalum sample was degreased, then polished with sandpaper of different grits (200#, 400#, 600#, 800#, 1000#, 1500#, 2000#) from low to high grit to break the surface oxide layer. Finally, the sample was ultrasonically cleaned in acetone and alcohol for 10 minutes and then sealed for storage. B4C, KBF4, and SiC powders in a mass ratio of 25:5:70 were placed in a ball mill jar. Eight to ten grinding balls with diameters of 8 mm and 3 mm were added to the jar, which was then sealed. The powders were mixed in a ball mill for 30 minutes at a frequency of 30 Hz. The mixed infiltration powder was spread evenly in an alumina crucible to a thickness of 2 / 3 of the crucible depth. The tantalum sample was then embedded in the powder, ensuring the sample was at least 10 mm from the crucible edge. The powder was then continued to be spread evenly in the crucible until it was completely filled. The crucible lid and crucible were sealed with refractory clay and placed in a vacuum furnace. The furnace was evacuated to below 1 Pa and held at 1600℃ for 4.5 hours. Afterward, the furnace was cooled to room temperature. The infiltrated tantalum sample was then ultrasonically cleaned in water and alcohol to obtain a wear-resistant and corrosion-resistant infiltrated layer with ultra-high hardness on the tantalum surface. The sample surface included a compound layer containing TaB, Ta3B4, and TaB2 phases. The adhesion between the infiltrated layer and the substrate was 30.2 N, and the corrosion rate in molten cerium at high temperature was 0.0687 μm / h. The surface hardness of the infiltrated layer was HV2754, and the surface morphology was as follows. Figure 1 As shown, its infiltration layer thickness is as follows Figure 2 As shown, it is approximately 68 μm.

[0034] Example 2

[0035] The surface of the tantalum sample was degreased, then polished with an industrial scouring pad to break the oxide layer. Finally, the sample was ultrasonically cleaned in acetone and alcohol for 10 minutes and then sealed for storage. B4C, KBF4, and SiC powders in a mass ratio of 3:5:92 were placed in a ball mill jar. Eight to ten grinding balls with diameters of 8 mm and 4 mm were added to the jar, which was then sealed. The powders were mixed in a ball mill for 30 minutes at a frequency of 40 Hz. The mixed infiltration agent powder was spread evenly in an alumina crucible to a thickness of 2 / 3 of the crucible depth. A tantalum sample was then embedded in the powder, ensuring the sample was at least 10 mm from the crucible edge. The powder was then continued to be spread evenly in the crucible until it was completely filled. The crucible lid and crucible were sealed with refractory clay and placed in a vacuum furnace. The furnace was evacuated to below 1 Pa, and then high-purity argon gas was introduced to maintain the furnace pressure within the range of 500–800 Pa. The furnace was held at 1400℃ for 5 hours, and then cooled to room temperature with the furnace. The infiltrated tantalum sample was then ultrasonically cleaned in water and alcohol, resulting in a wear-resistant and corrosion-resistant infiltrated layer with ultra-high hardness on the tantalum surface. The sample surface included a compound layer containing TaB, Ta3B4, and TaB2 phases. The adhesion between the infiltrated layer and the substrate was 27.1 N, and the corrosion rate in molten cerium at high temperature was 0.0715 μm / h. The surface hardness of the infiltrated layer was HV2147, and its thickness was as follows. Figure 3 As shown, it is approximately 41 μm.

[0036] Example 3

[0037] The surface of the tantalum sample was degreased, then polished with sandpaper of different grits (200#, 400#, 600#, 800#, 1000#, 1500#, 2000#) from low to high grit to break the surface oxide layer. Finally, the sample was ultrasonically cleaned in acetone and alcohol for 10 minutes and then sealed for storage. B4C, KBF4, and Al2O3 powders in a mass ratio of 5:5:90 were placed in a ball mill jar. Eight to ten grinding balls with diameters of 8 mm and 3 mm were added to the jar, which was then sealed. The powders were mixed in a ball mill for 25 minutes at a frequency of 30 Hz. The mixed infiltration agent powder was spread evenly in a corundum crucible to a thickness of 2 / 3 of the crucible depth. The tantalum sample was then embedded in the powder, ensuring the sample was at least 10 mm from the crucible edge. The powder was then continued to be spread evenly in the crucible until it was completely filled. The crucible lid and crucible were sealed with refractory clay and placed in a vacuum furnace. The furnace was evacuated to below 1 Pa and held at 1300℃ for 6 hours. Afterward, the furnace was cooled to room temperature. The infiltrated tantalum sample was then ultrasonically cleaned in water and alcohol to obtain a wear-resistant and corrosion-resistant infiltrated layer with ultra-high hardness on the tantalum surface. The sample surface included a compound layer containing TaB, Ta3B4, and TaB2 phases. The adhesion strength between the infiltrated layer and the substrate was 24.3 N, and the corrosion rate in molten cerium was 0.0774 μm / h. The surface hardness of the infiltrated layer was HV1966, and its thickness was as follows. Figure 4 As shown, it is approximately 31 μm.

[0038] Example 4

[0039] The surface of the tantalum sample was degreased, then polished with a resin grinding disc to break the surface oxide layer. Finally, the sample was ultrasonically cleaned in acetone and alcohol for 10 minutes and then sealed for storage. B4C, NH4Cl, and Al2O3 powders in a mass ratio of 5:4:91 were placed in a ball mill jar. Eight to ten grinding balls with diameters of 6 mm and 3 mm were added to the jar, which was then sealed. The powders were mixed in a ball mill for 30 minutes at a frequency of 30 Hz. The mixed infiltration agent powder was spread evenly in a corundum crucible to a thickness of 2 / 3 of the crucible depth. The tantalum sample was then embedded in the powder, ensuring the sample was at least 10 mm from the edge of the crucible. The powder was then continued to be spread evenly in the crucible until it was completely filled. The crucible lid and crucible were sealed with refractory clay and placed in a vacuum furnace. The furnace was evacuated to below 1 Pa, and then high-purity argon gas was introduced to maintain the furnace pressure within the range of 200–400 Pa. The furnace was held at 1200℃ for 4.5 hours, and then cooled to room temperature with the furnace. The infiltrated tantalum sample was then ultrasonically cleaned in water and alcohol, resulting in a wear-resistant and corrosion-resistant infiltrated layer with ultra-high hardness on the tantalum surface. The sample surface included a compound layer containing TaB, Ta3B4, and TaB2 phases. The adhesion strength between the infiltrated layer and the substrate was 22.5 N, and the corrosion rate in molten cerium at high temperature was 0.0816 μm / h. The surface hardness of the infiltrated layer was HV1667, and its thickness was as follows. Figure 5 As shown, it is approximately 21.3 μm.

[0040] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A superhard ceramic infiltration layer on the surface of tantalum metal, characterized in that, It includes TaB, Ta3B4 and TaB2 phases, with the mass ratio of the three phases being (1.5-2.5):(0.8-1.2):(0.8-1.2); the surface hardness of the superhard ceramic infiltrated layer is HV1520~HV3200, and the thickness of the superhard ceramic infiltrated layer is 10~100μm.

2. The ultra-hard ceramic infiltration layer on the surface of tantalum metal according to claim 1, characterized in that, The corrosion rate of the superhard ceramic infiltration layer in high-temperature molten cerium is 0.0630-0.0885 μm / h.

3. A method for preparing an ultra-hard ceramic infiltration layer on a tantalum metal surface as described in claim 1 or 2, characterized in that, The method involves embedding a tantalum metal matrix in a diffusion agent and then heat-insulating it in a vacuum or protective atmosphere; the diffusion agent is one of (20~25wt%B4C)+(3~5wt%KBF4)+(70~77wt%SiC), (3~5wt%B4C)+(3~5wt%KBF4)+(90~94wt%SiC), (3~5wt%B4C)+(3~5wt%KBF4)+(90~94wt%Al2O3), or (3~5wt%B4C)+(3~5wt%NH4Cl)+(90~94wt%Al2O3).

4. The method for preparing an ultra-hard ceramic infiltration layer on a tantalum metal surface according to claim 3, characterized in that, Includes the following steps: (1) Substrate pretreatment: The surface of the tantalum metal substrate is polished and then ultrasonically cleaned; (2) Preparation of the penetrant: Prepare the penetrant according to the proportion, and then mix the penetrant evenly; (3) Boronizing: The tantalum metal substrate treated in step (1) is embedded in the homogeneous infiltrator mixed in step (2) and kept at 1200-1600℃ under vacuum or protective atmosphere for 3-8 hours to obtain the treated tantalum metal. (4) Post-processing: Take out the tantalum metal processed in step (3) and remove the residual permeating agent on the surface.

5. The method for preparing an ultra-hard ceramic infiltration layer on a tantalum metal surface according to claim 4, characterized in that, The grinding method in step (1) is to grind with 200-2000 grit sandpaper or polish with polishing material. The cleaning agent used in the ultrasonic cleaning is acetone or alcohol.

6. The method for preparing an ultra-hard ceramic infiltration layer on a tantalum metal surface according to claim 4, characterized in that, The method for mixing the penetrant in step (2) is to use a ball mill.

7. The method for preparing an ultra-hard ceramic infiltration layer on a tantalum metal surface according to claim 4, characterized in that, The method for removing residual penetrant from the surface in step (4) is to ultrasonically clean the tantalum metal in water and alcohol in sequence.

8. A tantalum metal material having an ultra-hard ceramic infiltration layer on the surface of the tantalum metal as described in claim 1 or 2.

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