LONG-TERM ABLATION-RESISTANT NITROGEN-CONTAINING CARBIDE ULTRA-HIGH TEMPERATURE CERAMIC WITH ULTRA-HIGH MELTING POINT AND APPLICATION THEREOF

Abstract

A long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with an ultra-high melting point is prepared as follows: preparing the HfC powder and the HfN powder according to a mass ratio of HfC:HfN=(1-7):1; uniformly mixing the HfC powder and the HfN powder with the carbon powder and the carbon nitride powder to obtain a mixed powder, wherein the amount of the carbon powder and the amount of the carbon nitride powder do not exceed 8.0 wt. % and 5.0 wt. %, respectively, of the mixed powder mass; and performing spark plasma sintering on the mixed powder to produce the ceramic with the ultra-high melting point, a density ≥98%, and a uniform C/N content distribution. The ultra-high temperature ceramic is suitable for ultra-high temperature ablation-resistant protection at ≥3000° C. The ceramic maintains a close to zero ablation rate and a continuously stable oxidation-resistant protective structure after ablation for 300 s.

Claims

1. A long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with an ultra-high melting point, prepared by the following steps: step 1: preparing a HfC powder and a HfN powder according to a mass ratio of HfC:HfN=(1-7):1, uniformly mixing the HfC powder and the HfN powder with a carbon powder and a carbon nitride powder to obtain a mixed powder, wherein an amount of the carbon powder does not exceed 8.0 wt. % of a mass of the mixed powder, and an amount of the carbon nitride powder does not exceed 5.0 wt. % of the mass of the mixed powder; and step 2: performing a spark plasma sintering on the mixed powder obtained in step 1 to produce the long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point, wherein conditions of the spark plasma sintering are: a temperature in a sintering furnace is 1500-2400° C., a holding time is 5-60 minutes, a heating rate is 5-150° C./min, a cooling rate is 5-150° C./min, a pressure is 20-60 Mpa, and a vacuum degree is less than 5 Pa.

2. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 1, wherein in step 1, the HfC powder and the HfN powder are prepared according to a mass ratio of HfC:HfN=(1-3):1; the HfC powder and the HfN powder are mixed with the carbon powder and the carbon nitride powder uniformly to obtain the mixed powder, wherein the amount of the carbon powder is greater than 0 and does not exceed 8.0 wt. % of the mass of the mixed powder, and the amount of the carbon nitride powder is greater than 0 and does not exceed 5.0 wt. % of the mass of the mixed powder.

3. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 1, wherein the HfC powder and the HfN powder in step 1 are nano-sized powders or micro-sized powders; wherein a particle size of the HfC powder and the HfN powder is less than or equal to 10 microns, a particle size of the carbon powder is less than or equal to 10 microns, and a particle size of the carbon nitride powder is less than or equal to 10 microns.

4. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 1, wherein a purity of the HfC powder and the HfN powder in step 1 is greater than or equal to 99.9%.

5. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 1, wherein raw material powders consisting of the HfC powder, the HfN powder, the carbon powder, and the carbon nitride powder are uniformly mixed by a wet ball milling; and in the wet ball milling, a ball milling speed is controlled to be 200-400 r/min, a ball milling time is 12-24 h, and a mass ratio of a ball milling medium to the raw material powders is (3-10):1.

6. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 5, wherein in the wet ball milling, the ball milling medium is organic, and the ball milling medium is ethanol; and after the wet ball milling, drying is performed at 50-150° C. for 8-12 h in a vacuum atmosphere, then the mixed powder is screened with a 325-mesh sieve, and a screen underflow is taken as a spare material for the spark plasma sintering.

7. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 1, wherein a density of the long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point is greater than or equal to 98% and a C/N content distribution is uniform.

8. The long-term ablation-resistant)gen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 1, wherein after an ablation is performed on the long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point for 300 s in an oxyacetylene flame environment at 3000° C., a mass ablation rate is 8×10.sup.−3-9×10.sup.4 mg/s, and a linear ablation rate is 1×10.sup.−5 mm/s-3×10.sup.−3 mm/s.

9. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 7, wherein in step 1, when the HfC powder and the HfN powder are prepared according to the mass ratio of HfC:HfN=3:1, a mass ablation rate and a linear ablation rate of the long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point after an ablation for 300 s in an oxyacetylene flame environment at 3000° C. are 8×10.sup.−3 mg/s and 1×10.sup.−5 mm/s, respectively.

10. A method of an ultra-high temperature ablation-resistant protection at 3000° C. or above, comprising the step of applying the long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 1 to the ultra-high temperature ablation-resistant protection at 3000° C. or above.

11. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 2, wherein after an ablation is performed on the long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point for 300 s in an oxyacetylene flame environment at 3000° C., a mass ablation rate is 8×10.sup.−3-9×10.sup.−1 mg/s, and a linear ablation rate is 1 ×10.sup.−5 mm/s-3×10.sup.−3 mm/s.

12. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 3, wherein after an ablation is performed on the long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point for 300 s in an oxyacetylene flame environment at 3000° C., a mass ablation rate is 8×10.sup.−3-9×10.sup.−1 mg/s, and a linear ablation rate is 1×10.sup.−5 mm/s-3×10.sup.−3 mm/s.

13. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 4, wherein after an ablation is performed on the long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point for 300 s in an oxyacetylene flame environment at 3000° C., a mass ablation rate is 8×10.sup.−3-9×10.sup.−1 mg/s, and a linear ablation rate is 1×10.sup.−5 mm/s-3×10.sup.−3 mm/s.

14. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 5, wherein after an ablation is performed on the long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point for 300 s in an oxyacetylene flame environment at 3000° C., a mass ablation rate is 8×10.sup.−3-9×10.sup.−1 mg/s, and a linear ablation rate is 1×10.sup.−5 mm/s-3×10.sup.−3 mm/s.

15. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 6, wherein after an ablation is performed on the long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point for 300 s in an oxyacetylene flame environment at 3000° C., a mass ablation rate is 8×10.sup.−3-9×10.sup.−1 mg/s, and a linear ablation. rate is 1×10.sup.−5 mm/s-3×10.sup.−3 mm/s.

16. The long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point of claim 7, wherein after an ablation is performed on the long-term ablation-resistant nitrogen-containing carbide ultra-high temperature ceramic with the ultra-high melting point for 300 s in an oxyacetylene flame environment at 3000° C., a mass ablation rate is 8×10.sup.−3-9×10.sup.−1 mg/s, and a linear ablation rate is 1×10.sup.−5 mm/s-3×1.0.sup.−3 mm/s.

17. The method according to claim 10, wherein in step 1, the HfC powder and the HfN powder are prepared according to a mass ratio of HfC:HfN=(1-3):1; the HfC powder and the HfN powder are mixed with the carbon powder and the carbon nitride powder uniformly to obtain the mixed powder, wherein the amount of the carbon powder is greater than 0 and does not exceed 8.0 wt. % of the mass of the mixed powder, and the amount of the carbon nitride powder is greater than 0 and does not exceed 5.0 wt. % of the mass of the mixed powder.

18. The method according to claim 10, wherein the HfC powder and the HfN powder in step 1 are nano-sized powders or micro-sized powders; wherein a particle size of the HfC powder and the HfN powder is less than or equal to 10 microns, a particle size of the carbon powder is less than or equal to 10 microns, and a particle size of the carbon nitride powder is less than or equal to 10 microns.

19. The method according to claim 10, wherein a purity of the HfC powder and the HfN powder in step 1 is greater than or equal to 99.9%.

20. The method according to claim 10, wherein raw material powders consisting of the HfC powder, the HfN powder, the carbon powder, and the carbon nitride powder are uniformingly mixed by a wet ball milling; and in the wet ball milling, a ball milling speed is controlled to be 200-400 r/min, a ball milling time is 12-24 h, and a mass ratio of a ball milling medium to the raw material powders is (3-10):1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 presents an X-ray diffraction pattern of the HfC.sub.xN.sub.y ceramic surfaces in Examples 1, 2 and 3.

[0028] FIG. 2 presents a macro morphology of the surface of the HfC.sub.0.76N.sub.0.24 solid solution in Example 2.

[0029] FIG. 3 presents a micro morphology of the surface of the HfC.sub.0.76N.sub.0.24 solid solution in Example 2. It can be seen that the sample is dense without apparent holes, and the phase composition is uniform.

[0030] FIG. 4 presents a macro ablation morphology of the HfC.sub.0.76N.sub.0.24 sample in Example 2 after ablation with an oxyacetylene flame at 3000° C. for 300 s. No apparent ablation pits are seen after long-term ablation at ultra-high temperature, which proves that the HfC.sub.0.76N.sub.0.24 sample has excellent ablation resistance.

[0031] FIG. 5 presents a surface microstructure in the central area of the HfC.sub.0.76N.sub.0.24 sample in Example 2 after ablation.

[0032] FIG. 6 presents a cross-sectional microstructure in the central area of the HfC.sub.0.76N.sub.0.24 sample in Example 2 after ablation.

[0033] FIG. 7 presents a surface micro morphology of HfC in Comparative Example 1. It can be seen that the sample has apparent holes.

[0034] FIG. 8 presents a macro ablation morphology of HfC ceramics in Comparative Example 1 after ablation with an oxyacetylene flame at 3000° C. for 60 s. There are apparent ablation pits in the ablation central area.

DETAILED DESCRIPTION OF THE EMBODIMENTS

EXAMPLE 1

[0035] HfC and HfN powders in a mass ratio of 3:2, carbon powder with an addition amount of 5% of the total mass of the powder, and carbon nitride with an addition amount of 5% of the total mass of the powder were ball milled on a planetary ball mill for 15 h, where the powders had a particle size of 1 μm and a purity of greater than 99.9%, the ball milling medium was ethanol solution, the rotation speed was 200 r/min, and the mass ratio of ball milling medium to material was 8:1. Then the powder was dried in a drying oven at 80° C. for 10 hours and sieved to obtain a mixed powder.

[0036] The mixed powder was placed in a graphite mold for performing spark plasma sintering. The vacuum degree in the furnace was less than 5 Pa. The temperature was raised to 2100° C. at a heating rate of 100° C./min and kept for 15 minutes, and the pressure was 45 Mpa. Then the temperature was decreased to room temperature at a cooling rate of 100° C./min. The sintered ceramic block was characterized by an electron probe and showed that the atomic ratio of C to N was 0.60:0.40, and a homogeneous HfC.sub.0.60N.sub.0.40 solid solution (with a density of 99.8%) was obtained. Ablation test was performed with reference to the ablation experimental equipment described in the National Standard GJB323A-96. After ablation for 300 s in an oxyacetylene flame environment at 3000° C., the mass ablation rate was 9×10.sup.−1 mg/s, and the linear ablation rate was 3×10.sup.−3 mm/s.

EXAMPLE 2

[0037] HfC and HfN powders in a mass ratio of 3:1, carbon powder with an addition amount of 4% of the total mass of the powder, and carbon nitride with an addition amount of 6% of the total mass of the powder were ball milled on a planetary ball mill for 20 h, where the powders had a particle size of 1 μm and a purity of greater than 99.9%, the ball milling medium was ethanol solution, the rotation speed was 200 r/min, and the mass ratio of ball milling medium to material was 8:1. Then the powder was dried in a drying oven at 50° C. for 10 hours and sieved to obtain a mixed powder.

[0038] The mixed powder was placed in a graphite mold for performing spark plasma sintering. The vacuum degree in the furnace was less than 5 Pa. The temperature was raised to 2000° C., at a heating rate of 100° C./min and kept for 10 minutes, and the pressure was 40 Mpa. Then the temperature was decreased to room temperature at a cooling rate of 100° C./min, and a high-purity single-phase face-centered cubic structured ceramic was obtained. The sintered ceramic block was characterized by an electron probe and showed that the atomic ratio of C to N was 0.76:0.24, and a HfC.sub.0.76N.sub.0.24 solid solution (with a density of 99.6%) was formed. Ablation test was performed with reference to the ablation experimental equipment described in the National Standard GJB323A-96. After ablation for 300 s in an oxyacetylene flame environment at 3000° C., the mass ablation rate and the linear ablation rate were only 8×10.sup.−3 mg/s and 1×10.sup.−5 mm/s.

EXAMPLE 3

[0039] HfC and HfN powders in a mass ratio of 7:1, carbon powder with an addition amount of 5% of the total mass of the powder, and carbon nitride with an addition amount of 5% of the total mass of the powder were ball milled on a planetary ball mill for 20 h, where the powders had a particle size of 1 μm and a purity of greater than 99.9%, the ball milling medium was ethanol solution, the rotation speed was 200 r/min, and the mass ratio of ball milling medium to material was 8:1. Then the powder was dried in a drying oven at 70° C. for 10 hours and sieved to obtain a mixed powder.

[0040] The mixed powder was placed in a graphite mold for performing spark plasma sintering. The vacuum degree in the furnace was less than 5 Pa. The temperature was raised to 2000° C. at a heating rate of 100° C./min and kept for 10 minutes, and the pressure was 45 Mpa. Then the temperature was decreased to room temperature at a cooling rate of 100° C./min, and a high-purity single-phase face-centered cubic structured ceramic was obtained. The sintered ceramic block was characterized by an electron probe and showed that the atomic ratio of C to N was 0.88:0.12, and a HfC.sub.0.83N.sub.0.12 solid solution (with a density of 98%) was formed. Ablation test was performed with reference to the ablation experimental equipment described in the National Standard GJB323A-96. After ablation for 300 s in an oxyacetylene flame environment at 3000° C., the mass ablation rate was 6×10.sup.−1 mg/s, and the linear ablation rate was 2×10.sup.−3 mm/s.

EXAMPLE 4

[0041] HfC and HfN powders in a mass ratio of 4:1, carbon powder with an addition amount of 6% of the total mass of the powder, and carbon nitride with an addition amount of 5% of the total mass of the powder were ball milled on a planetary ball mill for 17 h, where the powders had a particle size of 1 μm and a purity of greater than 99.9%, the ball milling medium was ethanol solution, the rotation speed was 200 r/min, and the mass ratio of ball milling medium to material was 8:1. Then the powder was dried in a drying oven at 70° C. for 10 hours and sieved to obtain a mixed powder.

[0042] The mixed powder was placed in a graphite mold for performing spark plasma sintering. The vacuum degree in the furnace was less than 5 Pa. The temperature was raised to 2100° C., at a heating rate of 100° C./min and kept for 10 minutes, and the pressure was 45 Mpa. Then the temperature was decreased to room temperature at a cooling rate of 100° C./min, and a high-purity single-phase face-centered cubic structured ceramic was obtained. Ablation test was performed with reference to the ablation experimental equipment described in the National Standard GJB323A-96. After ablation for 300 s in an oxyacetylene flame environment at 3000° C., the mass ablation rate was 7×10.sup.−1 mg/s, and the linear ablation rate was 4×10.sup.−3 mm/s.

EXAMPLE 5

[0043] HfC and HfN powders in a mass ratio of 5:2, carbon powder with an addition amount of 4% of the total mass of the powder, and carbon nitride with an addition amount of 5% of the total mass of the powder were ball milled on a planetary ball mill for 16 h, where the powders had a particle size of 1 μm and a purity of greater than 99.9%, the ball milling medium was ethanol solution, the rotation speed was 200 r/min, and the mass ratio of ball milling medium to material was 8:1. Then the powder was dried in a drying oven at 70° C. for 10 hours and sieved to obtain a mixed powder.

[0044] The mixed powder was placed in a graphite mold for performing spark plasma sintering. The vacuum degree in the furnace was less than 5 Pa. The temperature was raised to 2100° C. at a heating rate of 100° C./min and kept for 10 minutes, and the pressure was 45 Mpa. Then the temperature was decreased to room temperature at a cooling rate of 100° C./min, and a high-purity ceramic (with a density of 99.5%) was obtained. Ablation test was performed with reference to the ablation experimental equipment described in the National Standard. GJB323A-96. After ablation for 300 s in an oxyacetylene flame environment at 3000° C., the mass ablation rate was 9×10.sup.2 mg/s, and the linear ablation rate was 9×10.sup.−4 mm/s.

COMPARATIVE EXAMPLE 1

[0045] HfC powder was ball milled on a planetary ball mill for 20 h, where the powders had a particle size of 1 μm and a purity of greater than 99.9%, the ball milling medium was ethanol solution, the rotation speed was 200 r/min, and the mass ratio of ball milling medium to material was 8:1. Then the powder was dried in a drying oven at 60° C. for 10 hours and sieved to obtain a mixed powder.

[0046] The mixed powder was placed in a graphite mold for performing spark plasma sintering. The vacuum degree in the furnace was less than 5 Pa. The temperature was raised to 2000° C. at a heating rate of 100° C./min and kept for 10 minutes, and the pressure was 40 Mpa. Then the temperature was decreased to room temperature at a cooling rate of 100° C./min, and a HfC ceramic (with a density of 90%) was obtained, The HfC ceramic without nitrogen doped had apparent ablation pits after ablation for 60 s in an oxyacetylene flame environment at 3000° C., After ablation for 60 s in the oxyacetylene flame environment at 3000° C., the mass ablation rate was 9 mg/s and the linear ablation rate was 5×10.sup.−2 mm/s. The ablation resistance was not as good as the novel nitrogen-doped carbide ultra-high temperature ceramics in the embodiments.

COMPARATIVE EXAMPLE 2

[0047] HfC and HfN powders in a mass ratio of 10:1 were ball milled on a planetary ball mill for 18 h, where the powders had a particle size of 1 μm and a purity of greater than 99.9%, the ball milling medium was ethanol solution, the rotation speed was 200 r/min, and the mass ratio of ball milling medium to material was 7:1. Then the powder was dried in a drying oven at 60° C. for 10 hours and sieved to obtain a mixed powder.

[0048] The mixed powder was placed in a graphite mold for performing spark plasma sintering. The vacuum degree in the furnace was less than 5 Pa. The temperature was raised to 2100° C. at a heating rate of 100° C./min and kept for 10 minutes, and the pressure was 40 Mpa. Then the temperature was decreased to room temperature at a cooling rate of 100° C./min. After the ceramic sample was subjected to ablation for 60 s in an oxyacetylene flame environment at 3000° C., the mass ablation rate was 8.7 mg/s, and the linear ablation rate was 4×10.sup.−2 mm/s.

COMPARATIVE EXAMPLE 3

[0049] HfN powder was ball milled on a planetary ball mill for 18 h, where the powders had a particle size of 1 μm and a purity of greater than 99.9%, the ball milling medium was ethanol solution, the rotation speed was 200 r/min, and the mass ratio of ball milling medium to material was 7:1. Then the powder was dried in a drying oven at 60° C. for 10 hours and sieved to obtain a mixed powder.

[0050] The mixed powder was placed in a graphite mold for performing spark plasma sintering. The vacuum degree in the furnace was less than 5 Pa. The temperature was raised to 2100° C. at a heating rate of 100° C./min and kept for 10 minutes, and the pressure was 40 Mpa. Then the temperature was decreased to room temperature at a cooling rate of 100° C./min. After the HfN ceramic sample was subjected to ablation for 60 s in an oxyacetylene flame environment at 3000° C., the mass ablation rate was 9.5 mg/s, and the linear ablation rate was 6×10.sup.−2 mm/s.