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CN-121974705-A - Self-healing high-entropy silicide and preparation method and application thereof

CN121974705ACN 121974705 ACN121974705 ACN 121974705ACN-121974705-A

Abstract

The invention discloses a self-healing high-entropy silicide and a preparation method and application thereof, and belongs to the technical field of high-entropy ceramics. The invention discloses a self-healing high-entropy silicide which is formed by preparing NbSi 2 、MoSi 2 、TaSi 2 、VSi 2 and CrSi 2 powder according to an equimolar ratio and sintering the powder by a hot-pressing sintering process. The obtained material has a stable single-phase HCP structure and shows excellent oxidation resistance and self-repairing capability in high-temperature environments such as 1100 ℃. The mechanism is that the fluid SiO 2 generated at high temperature can effectively fill microcracks and interweave with the synergistic oxidation products of Nb, ta and Cr to form a compact composite framework supporting layer. The preparation process is simple, and the obtained material has extremely high structural integrity and reliability under extreme working conditions and has wide industrial application potential.

Inventors

  • YIN BINGBING
  • YU YAJIE
  • YANG YI
  • WANG XIAOXUE

Assignees

  • 湘潭大学

Dates

Publication Date
20260505
Application Date
20260407

Claims (10)

  1. 1. A self-healing high-entropy silicide, wherein the self-healing high-entropy silicide has a molecular formula of (Nb 0.2 Mo 0.2 Ta 0.2 V 0.2 Cr 0.2 )Si 2 or (Nb 0.3 Mo 0.2 Ta 0.2 V 0.1 Cr 0.2 )Si 2 ).
  2. 2. The method for preparing self-healing high-entropy silicide according to claim 1, comprising the following steps: (1) Mixing, namely mixing NbSi 2 、MoSi 2 、TaSi 2 、VSi 2 and CrSi 2 , performing ball milling, taking out powder, drying to obtain mixed powder, and then preserving the mixed powder at 60-80 ℃ for 20-30h under vacuum condition; (2) Sintering, namely sintering the mixed powder obtained in the step (1) under a vacuum condition, and cooling to room temperature along with a furnace to obtain the self-healing high-entropy silicide.
  3. 3. The method of claim 2, wherein the molar ratio of NbSi 2 、MoSi 2 、TaSi 2 、VSi 2 to CrSi 2 is 0.2:0.2:0.2:0.2:0.2 or 0.3:0.2:0.2:0.1:0.2.
  4. 4. The preparation method according to claim 3, wherein the particle sizes of NbSi 2 、MoSi 2 、TaSi 2 、VSi 2 and CrSi 2 are 1-10 μm, and the purities are not less than 99wt%.
  5. 5. The preparation method according to claim 2, wherein the vacuum condition in the step (1) is-0.08 to-0.1 Mpa, and the vacuum condition in the step (2) is 1×10 -4 ~1×10 -2 Pa.
  6. 6. The preparation method of claim 2, wherein the ball-milling in the step (1) has a ball-to-material ratio of 5-8:1, a ball-milling rotation speed of 200-400 r/min and a ball-milling time of 6-18 h.
  7. 7. The method according to claim 2, wherein the sintering temperature in step (2) is 1000-1400 ℃, the time is 15-30min, and the pressure is 20-40 mpa.
  8. 8. The use of the self-healing high-entropy silicide according to claim 1 in the preparation of self-healing high-entropy silicide ceramics.
  9. 9. A self-healing high entropy silicide ceramic comprising the self-healing high entropy silicide of claim 1.
  10. 10. The use of the self-healing high entropy silicide ceramic of claim 9 in the preparation of heat insulating parts, protective housings or structural members of complex structure.

Description

Self-healing high-entropy silicide and preparation method and application thereof Technical Field The invention relates to the technical field of silicide ceramics, in particular to a self-healing high-entropy silicide and a preparation method and application thereof. Background With the continuous improvement of the flight Mach number of the novel hypersonic aircraft, the performance requirements of people on the hot end protection system of the hypersonic aircraft are also higher and higher, for example, higher oxidation resistance and ablation resistance temperature, longer service life and the like are required. The high-entropy silicide ceramic has the characteristics of high hardness, high melting point, low heat conductivity, excellent corrosion resistance and the like, is suitable for being used as a hot end part protection material of a hypersonic aircraft, and has very wide application prospect. Silicide ceramics are regarded as promising high temperature structural materials in aerospace and advanced energy fields by virtue of high melting point, excellent oxidation resistance and excellent heat conduction characteristics. However, its lower fracture toughness makes it extremely sensitive to microscopic defects. In actual production, microcracks are inevitably introduced in the machining process, and the initial damage is easy to evolve into a stress concentration source and unstably expand in a complex service environment, so that the material is finally invalid, and the large-scale application of the material is severely restricted. Disclosure of Invention In order to solve the defects in the prior art, the invention aims to provide a self-healing high-entropy silicide and a preparation method and application thereof, so as to solve the problem of brittle failure of the conventional silicide ceramics. The technical scheme for solving the technical problems is as follows, and the self-healing high-entropy silicide has a molecular formula (Nb 0.2Mo0.2Ta0.2V0.2Cr0.2)Si2 or (Nb 0.3Mo0.2Ta0.2V0.1Cr0.2)Si2). The invention provides a preparation method of the self-healing high-entropy silicide, which comprises the following steps: (1) Mixing, namely mixing NbSi 2、MoSi2、TaSi2、VSi2 and CrSi 2, performing ball milling, taking out powder, drying to obtain mixed powder, and then preserving the mixed powder at 60-80 ℃ for 20-30h under vacuum condition; (2) Sintering, namely sintering the mixed powder obtained in the step (1) under a vacuum condition, and cooling to room temperature along with a furnace to obtain the self-healing high-entropy silicide. Further, the molar ratio of NbSi 2、MoSi2、TaSi2、VSi2 to CrSi 2 is 0.2:0.2:0.2:0.2:0.2 or 0.3:0.2:0.2:0.1:0.2. Further, the particle sizes of NbSi 2、MoSi2、TaSi2、VSi2 and CrSi 2 are 1-10 μm, and the purities are not less than 99wt%. Further, the vacuum condition in the step (1) is-0.08 to-0.1 MPa, and the vacuum condition in the step (2) is 1X 10 -4~1×10-2 Pa. Further, the ball-milling material ratio in the step (1) is 5-8:1, the ball-milling rotating speed is 200-400 r/min, and the ball-milling time is 6-18 h. Further, in the step (2), the sintering temperature is 1000-1400 ℃, the time is 15-30 min, and the pressure is 20-40 MPa. The invention provides an application of the self-healing high-entropy silicide in preparing self-healing high-entropy silicide ceramics. The invention provides self-healing high-entropy silicide ceramic, which comprises the self-healing high-entropy silicide. The invention provides application of the self-healing high-entropy silicide ceramic in preparation of heat-insulating parts, protective shells or structural members with complex structures. The invention has the following beneficial effects: 1. Compared with the method for adopting simple substance powder for reaction sintering, the method directly adopts five metal silicides as the initial raw materials, avoids the severe heat release and microcosmic loosening caused by the volume effect during simple substance combination reaction, and can obtain the single-phase close-packed Hexagonal (HCP) solid solution with high compactness and more uniform component distribution under lower pressure (20-40 MPa). The invention also introduces Cr (chromium), which is the core of the self-healing high-entropy silicide with self-healing capability. The oxide of W (WO 3) is extremely volatile at high temperature, so that loose holes can be generated on the oxide layer, and the Cr oxide in the self-healing high-entropy silicide can be used for 'locking' the glassy SiO 2 with an oxide framework formed by Nb and Ta, so that the real crack filling is realized. Therefore, the self-healing high-entropy silicide prepared by the method has good mechanical property, self-healing capacity at high temperature, and can automatically repair cracks generated after abrasion. 2. In the five-membered system, mo and V belong to elements which are easy to form low-melting-point oxides, oxidation products of the M