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High-entropy carbide ultrahigh temperature ceramic powder and preparation method thereof

A technology for ultra-high temperature ceramics and ceramic powders, applied in the field of carbide ceramics, can solve the problems of low purity of carbide ceramic powders, long sol-gel reaction period, high mixing uniformity requirements, etc. control, short preparation time and high antioxidant properties

Active Publication Date: 2019-01-11
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The patent "CN1128012A" reports the preparation method of submicron carbide and submicron carbide solid solution, using at least one metal oxide and carbon as raw materials, mixing them uniformly and reacting at 1400-2400°C to form a solid solution precursor, and then adding After the carbon is mixed evenly, it is refined at 1200-1400°C to form a carbide solid solution. The preparation process requires two uniform mixing of raw materials, and the process is relatively complicated.
In general, the carbothermal reduction method requires high mixing uniformity of raw material powder. If the uniformity is not ideal, the purity of the synthesized carbide ceramic powder is not high.
Yan Y and others from Shanghai Institute of Ceramics published the paper "Yan Y, Huang Z, Liu X, et al.Carbothermal synthesis of ultra-finezirconium carbide powders using inorganic precursors via sol-gel method[J].Journal of Sol-Gel Science and Technology, 2007,44(1):81-85."Using sol-gel method to ZrOCl 2 ·8H 2 O and phenolic resin are used as raw materials, the binary gel is first synthesized and then heat-treated to obtain ZrC powder, the average particle size is less than 200nm, and the oxygen content is less than 1.0wt%. However, the sol-gel reaction cycle is long, the operation is complicated, and the product is usually Residual carbon and pores, and the method does not involve the preparation of high-entropy carbide ultra-high temperature ceramic powder

Method used

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  • High-entropy carbide ultrahigh temperature ceramic powder and preparation method thereof

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Experimental program
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Embodiment 1

[0034] The Zr powder, Ti powder, and C powder are ball milled on a planetary ball mill for 2 hours according to the molar ratio of 0.8:0.2:0.9, wherein the particle size of the Zr powder and Ti powder is -300 mesh, and the C powder is -4000 mesh, with a purity of ≥99%. The ball milling medium is ethanol, the rotation speed is 100rpm, the ball-to-material ratio is 5:1, after ball milling, it is taken out and dried at 40°C, and the mixed powder is obtained after sieving;

[0035] Place the mixed powder in a graphite mold for pressureless discharge plasma sintering for pressureless discharge plasma sintering. The vacuum degree in the furnace is less than 5Pa, and the temperature is raised to 1300°C for 30 minutes, and the heating rate is 100°C / min. Then cool to room temperature and take out the sintered ceramics The block is crushed and then manually ground in an agate mortar to obtain carbide ceramic powder. Such as figure 1 As shown, the carbide ceramic powder exhibits typical...

Embodiment 2

[0038] The Zr powder, Ti powder, and C powder are ball milled on a planetary ball mill for 2 hours according to the molar ratio of 0.8:0.2:0.8, wherein the particle size of the Zr powder and Ti powder is -300 mesh, and the C powder is -4000 mesh, with a purity of ≥99%. The ball milling medium is ethanol, the speed is 100rpm, and the ball-to-material ratio is 5:1. After ball milling, it is taken out and dried at 40°C, and the mixed powder is obtained after sieving;

[0039] Place the mixed powder in a graphite mold for pressureless discharge plasma sintering for pressureless discharge plasma sintering. The vacuum degree in the furnace is less than 5Pa, and the temperature is raised to 1600°C for 15min at a heating rate of 100°C / min, and then cooled to room temperature to take out the sintered ceramics The block is crushed and then manually ground in an agate mortar to obtain carbide ceramic powder. Such as Figure 1-4 As shown, the carbide ceramic powder presents a typical ZrC...

Embodiment 3

[0042] The Hf powder, Zr powder, Ti powder, and C powder are ball milled on a planetary ball mill for 0.5h according to the molar ratio of 0.5:0.3:0.2:0.8, wherein the Hf powder, Zr powder, and Ti powder have a particle size of -300 mesh, and the C powder is -4000 mesh, purity ≥ 99%, the ball milling medium is ethanol, the rotation speed is 200rpm, the ball-to-material ratio is 5:1, after the ball milling, it is taken out and dried at 40°C, and the mixed powder is obtained after sieving;

[0043] Place the mixed powder in a graphite mold for pressureless discharge plasma sintering for pressureless discharge plasma sintering. The vacuum degree in the furnace is less than 5Pa, and the temperature is raised to 1600°C for 15min at a heating rate of 100°C / min, and then cooled to room temperature to take out the sintered ceramics The block is crushed and then manually ground in an agate mortar to obtain carbide ceramic powder. Such as Figure 5-7 As shown, the carbide ceramic powde...

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Abstract

The invention belongs to the technical field of carbide ceramics, and concretely relates to a high-entropy carbide ultrahigh temperature ceramic powder and a preparation method thereof. The molecularformula of the ceramic powder is XCy, wherein X is at least two of Zr, Ti, Hf, V, Nb, Ta, Cr, Mo and W, and y is equal to or more than 0.6 and less 1.0. The ceramic powder has a single phase face-centered cubic structure, and has a free carbon content of 0.035 wt% or below. The ceramic powder is prepared through the steps of ball-milling mixing of at least two metal powders and C powder, and pressureless plasma sintering. The high-entropy carbide ultrahigh temperature ceramic powder is a single-phase solid solution, has the single phase face-centered cubic structure, and also has the advantages of low free carbon content, high purity, loose structure, fragility, and facilitation of post-processing applications.

Description

technical field [0001] The invention belongs to the technical field of carbide ceramics, and in particular relates to a high-entropy carbide ultra-high temperature ceramic powder and a preparation method thereof. Background technique [0002] With the rapid development of space shuttles, recyclable rockets, supersonic space vehicles, etc., higher requirements are put forward for the anti-ablation and anti-oxidation properties of the thermal protection system materials, especially for long-term resistance under the condition of up to 3000 °C. Ablation and oxidation resistance, at present, traditional binary ultra-high temperature ceramics (ZrB 2 , HfB 2 , ZrC, HfC, TaC, HfN, etc.) are difficult to meet this demand. [0003] The current concept of high-entropy mainly involves alloy materials. The idea of ​​high-entropy alloys is an alloy formed by mixing multiple elements in equimolar or near equimolar ratios. It has high thermodynamic mixing entropy and forms a single cryst...

Claims

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Application Information

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IPC IPC(8): C04B35/56C04B35/65C04B35/626
CPCC04B35/5607C04B35/62665C04B35/65C04B2235/666
Inventor 曾毅熊翔伦惠林孙威王雅雷陈招科
Owner CENT SOUTH UNIV
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