Low sintering temperature transition metal boride ceramics and methods of making the same

Abstract

The application discloses a kind of low sintering temperature transition metal boride ceramics and preparation method thereof, which comprises: three to five kinds of boride ceramic powders TaB2, TiB2, ZrB2, VB2, HfB2, ZrB2, NbB2, CrB2, WB2 are weighed according to different mole ratio;The obtained boride ceramic powder is placed in a ball mill tank and ball milled for 4-24h at a speed of 150-360r / min;0.1-15 vol% of metal Co and 0.1-25 vol% of silicon carbide are added to the obtained boride ceramic powder as sintering aids, and then placed in a ball mill tank and ball milled for 4-24h at a speed of 150-360r / min;The obtained mixture powder is subjected to spark plasma sintering, and the sintering conditions are as follows: first, heat to 1450-1800℃ at a heating rate of 80-120℃ / min, and keep for 5-15 minutes, then apply a uniaxial load of 30-50MPa when the temperature reaches 800-1000℃;Finally, cool to room temperature at a cooling rate of 80-120℃ / min.The low sintering temperature transition metal boride ceramic prepared by the application has higher hardness and wear resistance than the boride ceramic without introducing metal Co and silicon carbide.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic preparation, and particularly relates to a low-sintering-temperature transition metal boride ceramic and a preparation method thereof. BACKGROUND

[0002] Initially, borides can only be prepared by reducing boron oxide with light metals, and the performance is poor. With the deepening of research, the preparation technology and performance of borides have been greatly improved. With the continuous expansion and perfection of boride systems, ternary borides, quaternary borides and high-entropy borides have emerged in succession. As one of the important refractory materials, borides have high melting point, strong corrosion resistance, high hardness and good wear resistance, and thus are concerned by researchers. However, the poor sintering property and single type of borides limit their development. Until the 1980s, the birth of multi-component borides changed this situation. Through the doping of elements and the reconstruction of boride crystals, the certain specific performance of boride ceramics is adjusted, and the application range also becomes more extensive. Boride ceramics and multi-component boride materials gradually become a popular material due to their good performance, and continuously meet the development needs of the fields of aerospace, nuclear industry and the like.

[0003] In recent years, three to five component transition metal borides have attracted widespread attention due to their high melting point, high hardness, good thermal shock resistance and corrosion resistance. However, the preparation temperature requirement is extremely high, and a sintering temperature of 2000 degrees Celsius or higher is required in the process of spark plasma sintering, which inevitably causes the problem of coarse grains, which also leads to a significant decrease in mechanical properties. Meanwhile, this harsh condition also seriously restricts the engineering application of borides.

[0004] At present, the research on borides mainly focuses on one to two component borides. The synthesis and performance of three to five component boride ceramics (medium / high entropy borides) are rarely reported. SUMMARY

[0005] In view of the problems existing in the prior art, the present application takes three to five component boride ceramics as the matrix, and introduces metal cobalt and silicon carbide as sintering agents to greatly reduce the sintering temperature of three to five component boride ceramics. This application can explore new boride ceramics and their mechanical properties on the one hand, and also can reduce the high cost caused by the preparation of boride ceramics, which has good engineering application value. Through the present application, three to five component boride ceramics with single phase, high relative density, high hardness and excellent wear resistance can be prepared at a sintering temperature much lower than the reported 2000 degrees Celsius.

[0006] Specifically, the first aspect of the present application provides a low sintering temperature transition metal boride ceramic, comprising three to five transition metal borides, metal Co and silicon carbide; wherein the volume ratio of the metal Co to the three to five transition metal borides is 0.1-15 vol%; and the volume ratio of the silicon carbide to the three to five transition metal borides is 0.1-25 vol%.

[0007] As a further illustration of the present application, the molecular formula of the three to five transition metal borides is (A a B b C c D d E e )B2, wherein ABCDE are mutually different elements selected from Ta, Ti, Zr, V, Hf, Zr, Nb, Cr or W, abcde is 0-1 / 3, and a+b+c+d+e=2.

[0008] As a further illustration of the present application, the relative density of the transition metal boride ceramic is 95-100%, the hardness of the transition metal boride ceramic is 22-27 GPa, and the fracture toughness of the transition metal boride ceramic is 3-7 MPa•m 1 / 2 .

[0009] The second aspect of the present application provides a preparation method of the above-mentioned low sintering temperature transition metal boride ceramic, comprising the following steps:

[0010] Step 1: three to five kinds of boride ceramic powders selected from TaB2, TiB2, ZrB2, VB2, HfB2, ZrB2, NbB2, CrB2 and WB2 are weighed according to different molar ratios;

[0011] Step 2: the boride ceramic powders obtained in step 1 are placed in a ball mill tank for ball milling for 4-24 hours at a rotation speed of 150-360 r / min;

[0012] Step 3: 0.1-15 vol% of metal Co and 0.1-25 vol% of silicon carbide are added to the boride ceramic powders obtained in step 2 as sintering aids, and then the mixture is placed in a ball mill tank for ball milling for 4-24 hours at a rotation speed of 150-360 r / min;

[0013] Step 4: the mixture powder obtained in step 3 is subjected to spark plasma sintering, and the sintering conditions are as follows: first, the temperature is raised to 1450-1800℃ at a temperature rising rate of 80-120℃ / min, and then the temperature is kept for 5-15 minutes; then, when the temperature reaches 800-1000℃, a uniaxial load of 30-50 MPa is applied; finally, the temperature is cooled to room temperature at a cooling rate of 80-120℃ / min.

[0014] As a further illustration of the present application, the purity of the TaB2, TiB2, ZrB2, VB2, HfB2, ZrB2, NbB2, CrB2, WB2 powder in step 1 is 98-99.99%, and the particle size is 1-3 um.

[0015] As a further illustration of the present application, the molecular formula of the transition metal boride ceramic powder prepared in step 2 is (A a B b C c D d E e )B2, wherein ABCDE are mutually different elements selected from Ta, Ti, Zr, V, Hf, Zr, Nb, Cr or W, and abcde is 0-1 / 3, and a+b+c+d+e=2.

[0016] As a further illustration of the present application, the ball milling tank in step 2 is a tungsten carbide tank containing 1wt% of stearic acid; the ball milling tank in step 3 is a tungsten carbide tank; and the ball powder ratio during the ball milling process in steps 2 and 3 is 2-5:1.

[0017] As a further illustration of the present application, the boride ceramic powder obtained in step 2 needs to be stored and dried in a vacuum drying box.

[0018] As a further illustration of the present application, the sample loading process in steps 1, 2 and 3 is completed in an argon atmosphere glove box to prevent oxidation.

[0019] As a further illustration of the present application, in step 4, the mixture powder obtained in step 3 is loaded into a graphite mold, and then placed into a spark plasma sintering furnace for sintering, wherein the atmosphere in the spark plasma sintering furnace is argon to prevent oxidation during the process.

[0020] Compared with the prior art, the present application has the following beneficial technical effects:

[0021] The present application is directed to three to five element transition metal boride ceramics, and the sintering temperature of the three to five element transition metal boride is greatly reduced by adding metal Co and silicon carbide. The introduction of metal Co can react to generate Co-B based liquid to accelerate the sintering of the three to five element transition metal boride and reduce the sintering temperature, and can also segregate Co on the grain boundary to inhibit grain growth. The introduction of silicon carbide as a second phase can inhibit the growth of boride grains and improve the density. Therefore, the three to five element transition metal boride added with Co and silicon carbide shows finer grains, and the mechanical properties are improved, which provides a new scheme for improving the sintering behavior of the three to five element transition metal boride ceramics. The preparation method provided by the present application can significantly reduce the sintering cost, and at the same time optimize the performance of the three to five element transition metal boride.

[0022] The low sintering temperature transition metal boride ceramic prepared by the application has higher hardness and wear resistance than the boride ceramic without introducing metal Co and silicon carbide. The low sintering temperature transition metal boride ceramic can be applied to the field of wear-resistant materials, and the processing performance is significantly better than that of monoboride ceramic. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 XRD patterns of boride powder and boride ceramic after SPS sintering;

[0024] Figure 2 SEM and EDS element distribution patterns of boride ceramic matrix composite sintered at 1450 degrees (MEB-1450);

[0025] Figure 3 SEM and EDS element distribution patterns of boride ceramic matrix composite sintered at 1600 degrees (MEB-1600);

[0026] Figure 4 Friction coefficient curve of boride ceramic matrix composite sintered at 1450 degrees (MEB-1450) under 0.5N load with time;

[0027] Figure 5 Friction coefficient curve of boride ceramic matrix composite sintered at 1450 degrees (MEB-1450) under 1N load with time;

[0028] Figure 6 Friction coefficient curve of boride ceramic matrix composite sintered at 1450 degrees (MEB-1450) under 5N load with time;

[0029] Figure 7 Friction coefficient curve of boride ceramic matrix composite sintered at 1450 degrees (MEB-1450) under 10N load with time;

[0030] Figure 8 Friction coefficient curve of boride ceramic matrix composite sintered at 1600 degrees (MEB-1600) under 0.5N load with time;

[0031] Figure 9 Friction coefficient curve of boride ceramic matrix composite sintered at 1600 degrees (MEB-1600) under 1N load with time;

[0032] Figure 10 Friction coefficient curve of boride ceramic matrix composite sintered at 1600 degrees (MEB-1600) under 5N load with time;

[0033] Figure 11The friction coefficient of boride ceramic matrix composite (MEB-1600) fired at 1600 degrees versus time under a 10N load. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0035] Embodiment 1

[0036] The (Ta 1 / 3 Ti 1 / 3 Zr 1 / 3 )B2 ternary boride ceramic is processed by the process, and the specific processing system is as follows:

[0037] TaB2, TiB2 and ZrB2 boride powders are weighed according to an equimolar ratio, and then placed in a tungsten carbide tank containing 1wt% of stearic acid for ball milling at 180r / min for 4h. The ball-to-powder ratio is 2:1 during the ball milling process.

[0038] 10vol% of metal Co and 20vol% of silicon carbide are added to the obtained boride powder as sintering aids, and then the mixture is placed in a tungsten carbide tank for ball milling at 150r / min for 4h. The ball-to-powder ratio is 2:1 during the ball milling process.

[0039] The mixture powder is respectively loaded into a graphite mold (25mm in diameter), and then heated to 1800℃ at a heating rate of 100℃ / min in a spark plasma sintering furnace, and kept for 10min. When the temperature reaches 800℃, a uniaxial load of 35MPa is applied. Finally, the temperature is cooled to room temperature at a cooling rate of 100℃ / min.

[0040] The polished boride ceramic is detected by X-ray diffraction (XRD, Bruker D8 ADVANCE, λ = 1.5404 Å).

[0041] The (Ta 1 / 3 Ti 1 / 3 Zr 1 / 3 )B2 ternary boride ceramic is processed by the process, and the specific processing system is as follows: Figure 1 As shown in the XRD image of the (Ta 1 / 3 Ti 1 / 3 Zr 1 / 3B2 ternary boride. The hardness of this boride ceramic was measured using a Vickers hardness tester with a force of 4.9 N for 15 seconds. Its Vickers hardness, as shown in Table 1, is 21.11 ± 0.77 GPa.

[0042] Example 2

[0043] To (Ta) 1 / 3 Ti 1 / 3 Zr 1 / 3 The B2 ternary boride ceramics are treated using this process, and the specific treatment regime is as follows:

[0044] TaB2, TiB2, and ZrB2 boride powders were weighed in an equimolar ratio and placed in a tungsten carbide jar containing 1 wt% stearic acid for ball milling for 4 hours at a speed of 180 r / min. The ball-to-powder ratio during ball milling was 2:1.

[0045] The obtained boride powder was mixed with 10 vol% metallic Co and 20 vol% silicon carbide as sintering aids, and then placed in a tungsten carbide jar for ball milling for 4 hours at a speed of 150 r / min. The ball-to-powder ratio during ball milling was 2:1.

[0046] The mixed powder was loaded into graphite molds (25 mm in diameter) and heated to 1450 °C in a spark plasma sintering furnace at a heating rate of 100 °C / min and held for 10 minutes. When the temperature reached 800 °C, a uniaxial load of 35 MPa was applied. Finally, it was cooled to room temperature at a cooling rate of 100 °C / min.

[0047] The polished boride ceramics were examined by X-ray diffraction (XRD, Bruker D8 ADVANCE, λ = 1.5404 Å) and the microstructure of the polished samples was studied by scanning electron microscopy (SEM, FEI Helios G4CX).

[0048] The (Ta) 1 / 3 Ti 1 / 3 Zr 1 / 3 XRD pattern of B2 ternary boride ceramics as shown in the figure. Figure 1 As shown in the figure, it can be seen that all phases were detected; and based on their SEM images ( Figure 2 It can be seen that a single phase (Ta) has been formed. 1 / 3 Ti 1 / 3 Zr 1 / 3 (Ta2) ternary borides were successfully prepared, but segregation occurred in some regions. SEM and XRD analysis showed that (Ta2) ternary borides were successfully prepared. 1 / 3 Ti 1 / 3 Zr 1 / 3)B2 ternary boride. The hardness of this boride ceramic was measured using a Vickers hardness tester with an applied load of 4.9 N. The Vickers hardness was 19.75 ± 1.54 GPa as shown in Table 1.

[0049] The tribological performance detection method of the present application is as follows:

[0050] The prepared (Ta 1 / 3 Ti 1 / 3 Zr 1 / 3 )B2 ternary boride ceramic was evaluated for its friction and wear performance using a UMT-Tribolab (Bruker, Germany). The counter ball was a GCr15 bearing steel ball, the load was 10 N, the frequency was 3 HZ, and the running time was 20 min. A three-dimensional profilometer was used to detect the wear performance.

[0051] The average friction coefficients of the ternary boride ceramic of Example 2 under loads of 0.5, 1, 5, and 10 N were 0.512, 0.552, 0.704, and 0.6152, respectively, as shown in Table 2. The friction coefficient curve is shown in Figures 4-7 Table 2. The wear rates of the ternary boride ceramic of Example 2 under loads of 0.5, 1, 5, and 10 N were 6.02 x 10 -6 mm 3 / N·m, 4.52 x 10 -6 mm 3 / N·m, 1.25 x 10 -7 mm 3 / N·m, and 1.1 x 10 -8 mm 3 / N·m, respectively.

[0052] Example 3

[0053] The (Ta 1 / 3 Ti 1 / 3 Zr 1 / 3 )B2 ternary boride ceramic was treated by the process, and the specific treatment system was as follows:

[0054] After the TaB2, TiB2, and ZrB2 boride powders were weighed according to an equimolar ratio, they were placed in a tungsten carbide tank containing 1 wt% of stearic acid for ball milling for 4 h at a speed of 180 r / min. The ball-to-powder ratio during the ball milling process was 2:1.

[0055] After 10 vol% of metal Co and 20 vol% of silicon carbide were added to the obtained boride powder as sintering aids, the mixture was again placed in a tungsten carbide tank for ball milling for 4 h at a speed of 150 r / min. The ball-to-powder ratio during the ball milling process was 2:1.

[0056] The mixed powder was loaded into graphite molds (25 mm in diameter) and heated to 1600 °C in a spark plasma sintering furnace at a heating rate of 100 °C / min and held for 10 minutes. When the temperature reached 800 °C, a uniaxial load of 35 MPa was applied. Finally, it was cooled to room temperature at a cooling rate of 100 °C / min.

[0057] The polished boride ceramics were examined by X-ray diffraction (XRD, Bruker D8 ADVANCE, λ = 1.5404 Å) and the microstructure of the polished samples was studied by scanning electron microscopy (SEM, FEI Helios G4CX).

[0058] The (Ta) 1 / 3 Ti 1 / 3 Zr 1 / 3 XRD pattern of B2 ternary boride ceramics as shown in the figure. Figure 1 As shown in the figure, it can be seen that all phases were detected; and based on their SEM images ( Figure 3 It can be seen that a single phase (Ta) has been formed. 1 / 3 Ti 1 / 3 Zr 1 / 3 (Ta2) ternary boride. SEM and XRD analysis showed that (Ta2) ternary boride was successfully prepared. 1 / 3 Ti 1 / 3 Zr 1 / 3 B2 ternary boride. The hardness of this boride ceramic was measured using a Vickers hardness tester with a force of 4.9 N for 15 seconds. The Vickers hardness, as shown in Table 1, is 22.54 ± 0.94 GPa.

[0059] The tribological property testing method of the present invention is as follows:

[0060] Prepared (Ta 1 / 3 Ti 1 / 3 Zr 1 / 3 The tribowear properties of B2 ternary boride ceramics were evaluated using the UMT-Tribolab (Bruker, Germany). The paired balls were GCr15 bearing steel balls, with a load of 10 N, a frequency of 3 Hz, and a running time of 20 min. A three-dimensional profilometer was used to detect their wear performance.

[0061] The average friction coefficients of the ternary boride ceramic of Example 3 under loads of 0.5, 1, 5, and 10 N are shown in Table 2, which are 0.515, 0.461, 0.580, and 0.459, respectively. These coefficients are lower than those of the ternary boride ceramic of Example 2. The friction coefficient curves are shown in Table 2. Figures 8-11The wear rates of the ternary boride ceramic of Example 3 at 0.5, 1, 5 and 10 N loads are shown in Table 3, which are 3.07 x 10 -5 mm 3 / N·m, 1.12 x 10 -6 mm 3 / N·m, 4.9 x 10 -7 mm 3 / N·m, 3.03 x 10 -7 mm 3 / N·m, which are lower than the ternary boride ceramic of Example 2 at 0.5 N and 1 N loads, and similar to the ternary boride ceramic of Example 2 at 5 N and 10 N loads.

[0062] Table 1 Vickers hardness (GPa) of MEB-1800, MEB-1450 and MEB-1600 at different loads

[0063] Sample Vickers Hardness MEB-1800 21.11±0.77 MEB-1450 19.75±1.54 MEB-1600 22.54±0.94

[0064] Table 2 Coefficient of friction of MEB-1450 and MEB-1600 at different loads

[0065] Load MEB-1450 MEB-1600 0.5N 0.512 0.515 1N 0.552 0.461 5N 0.704 0.580 10N 0.615 0.459

[0066] Table 3 Wear rate (x 10 -6 mm 3 / N·m) of MEB-1450 and MEB-1600 at different loads

[0067] Load MEB-1450 MEB-1600 0.5N 6.02 3.07 1N 4.52 1.12 5N 0.125 0.490 10N 0 0.303

[0068] It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Pronouns in the masculine form include the feminine form, and vice versa, except as otherwise expressly specifically herein, and the singular form includes the plural form unless the context clearly dictates otherwise.

[0069] While the embodiments of the application have been shown and described, it is to be understood that the application is not limited to these embodiments. Rather, it is the intention that modifications, changes and substitutions be made in view of the scope of the appended claims and their equivalents.

Claims

1. A method for producing a low sintering temperature transition metal boride ceramic, characterized by, The boride ceramic is a (Ta 1 / 3 Ti 1 / 3 Zr 1 / 3 )B2 ternary boride ceramic, the method comprising the steps of: Step 1: According to (Ta 1 / 3 Ti 1 / 3 Zr 1 / 3 The boride powders of TaB2, TiB2, and ZrB2 are weighed according to the equal molar ratio. Step 2: Put the boride ceramic powder weighed in step 1 into a ball mill tank and ball mill for 4-24 hours at a speed of 150-360 r / min; Step 3: Add 10 vol% of metal Co and 20 vol% of silicon carbide as sintering aids to the boride ceramic powder obtained in step 2, and then put it into a ball mill tank and ball mill for 4-24 hours at a speed of 150-360 r / min; Step 4: Put the mixture powder obtained in step 3 into a spark plasma sintering furnace, and the sintering conditions are as follows: first, heat to 1600℃ at a heating rate of 80-120℃ / min, and keep for 5-15 minutes; then, when the temperature reaches 800-1000℃, apply a uniaxial load of 30-50 MPa; finally, cool to room temperature at a cooling rate of 80-120℃ / min.

2. The method of producing a low sintering temperature transition metal boride ceramic according to claim 1, wherein The relative density of the transition metal boride ceramic is 95-100%, the hardness of the transition metal boride ceramic is 22-27 GPa, and the fracture toughness of the transition metal boride ceramic is 3-7 MPa•m 1 / 2 .

3. The method of producing a low sintering temperature transition metal boride ceramic according to claim 1, wherein The purity of TaB2, TiB2, ZrB2 powder in step 1 is 98-99.99%, and the particle size is 1-3 um.

4. The method of producing a low sintering temperature transition metal boride ceramic according to claim 1, wherein The ball mill tank in step 2 is a tungsten carbide tank containing 1wt% of stearic acid; the ball mill tank in step 3 is a tungsten carbide tank; the ball powder ratio during ball milling in steps 2 and 3 is 2-5:

1.

5. The method of producing a low sintering temperature transition metal boride ceramic according to claim 1, wherein The boride ceramic powder obtained in step 2 needs to be stored and dried in a vacuum drying box.

6. The method of producing a low sintering temperature transition metal boride ceramic according to claim 1, wherein The sample loading process in steps 2 and 3 is completed in an argon atmosphere glove box to prevent oxidation.

7. The method of producing a low sintering temperature transition metal boride ceramic according to claim 1, wherein In step 4, the mixture powder obtained in step 3 is loaded into a graphite mold, and then put into a spark plasma sintering furnace for sintering, wherein the atmosphere in the spark plasma sintering furnace is argon to prevent oxidation during the process.

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