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CN-121976143-A - Method for preparing high-entropy silicide composite coating on Nb521 alloy surface by single-step slurry sintering method and application thereof

CN121976143ACN 121976143 ACN121976143 ACN 121976143ACN-121976143-A

Abstract

The invention discloses a method for preparing a high-entropy silicide composite coating on the surface of Nb521 alloy by a single-step slurry sintering method and application thereof, and relates to the technical field of high-temperature alloy heat protection. The method comprises the steps of uniformly mixing refined Nb powder, mo powder, cr powder, ta powder, W powder, zr powder, hf powder, Y powder, ge powder and a cosolvent through ball milling to obtain slurry I, uniformly mixing Si powder, cr powder, V powder, fe powder and Ti powder through ball milling to obtain slurry II, sequentially brushing or dip-coating the slurry I and the slurry II on the surface of a Nb521 alloy matrix through a separation coating method, and performing heat treatment at 1450-1550 ℃ for 30-90 min to obtain the high-entropy silicide composite coating on the surface of the Nb521 alloy. The refractory high-entropy metal silicide composite protective coating with metallurgical bonding and high compactness is prepared by adopting a staged slurry infiltration sintering method of a metal framework and a silicon source.

Inventors

  • QIAO YANQIANG
  • JIANG HAO
  • GUO XIPING

Assignees

  • 西北工业大学

Dates

Publication Date
20260505
Application Date
20260115

Claims (10)

  1. 1. A method for preparing a high-entropy silicide composite coating on the surface of an Nb521 alloy by a single-step slurry sintering method, which is characterized by comprising the following steps of: The refined Nb powder, mo powder, cr powder, ta powder, W powder, zr powder, hf powder, Y powder, ge powder and cosolvent are subjected to ball milling and uniformly mixed to obtain slurry I; Uniformly ball-milling Si powder, cr powder, V powder, fe powder and Ti powder to obtain slurry II; Sequentially brushing or dip-coating slurry I and slurry II on the surface of an Nb521 alloy matrix by adopting a separation coating method, and performing heat treatment at 1450-1550 ℃ for 30-90 min to obtain a high-entropy silicide composite coating on the Nb521 alloy surface; wherein the cosolvent is mixed powder of B 2 O 3 , al and Si.
  2. 2. The method for preparing the high-entropy silicide composite coating on the surface of the Nb521 alloy by a single-step slurry sintering method as claimed in claim 1, wherein the Nb powder, the Mo powder, the Cr powder, the Ta powder, the W powder, the Zr powder, the Hf powder, the Y powder and the Ge powder are weighed in equal atomic percentages.
  3. 3. The method for preparing the high-entropy silicide composite coating on the Nb521 alloy surface by a single-step slurry sintering method as claimed in claim 2, wherein the slurry I is prepared by adding a binder and a solvent during ball milling and mixing; when the slurry I is prepared, 40-50% of alloy powder, 0-10% of cosolvent, 0.5-2% of binder and 40-50% of solvent are weighed according to mass percentage, wherein the mass percentage of each component is 100%, and the components are uniformly mixed by ball milling; The alloy powder is obtained by ball milling and mixing the Nb powder, the Mo powder, the Cr powder, the Ta powder, the W powder, the Zr powder, the Hf powder, the Y powder and the Ge powder uniformly, and the grain size of the alloy powder is 2-10 mu m.
  4. 4. The method for preparing the high-entropy silicide composite coating on the Nb521 alloy surface by a single-step slurry sintering method as claimed in claim 3, wherein the cosolvent comprises the following components in percentage by mass, 0-10% of B 2 O 3 , 0-20% of Al, 60-80% of Si, and the total mass percentage of the components is 100%; the binder is polyvinyl butyral, and the solvent is ethanol.
  5. 5. The method for preparing the high-entropy silicide composite coating on the Nb521 alloy surface by the single-step slurry sintering method according to claim 1, wherein in the process of obtaining slurry II, 30-50% of Si powder, 10-20% of Cr powder, 0-10% of V powder, 0-10% of Fe powder, 0-10% of Ti powder, 0.5-2% of binder and 45-65% of solvent are weighed according to mass percentage, wherein the mass percentage of each component is 100%, the components are uniformly mixed by ball milling, and the binder is polyvinyl butyral, and the solvent is ethanol.
  6. 6. The method for preparing the high-entropy silicide composite coating on the surface of the Nb521 alloy by a single-step slurry sintering method as claimed in claim 1, wherein the slurry I is coated on the surface of the Nb521 alloy substrate by a brushing method, and the brushing thickness of the slurry I is 100-300 mu m.
  7. 7. The method for preparing the high-entropy silicide composite coating on the Nb521 alloy surface by a single-step slurry sintering method as claimed in claim 1, wherein the Nb521 alloy substrate coated with the slurry I is immersed in the slurry II for 3-8 seconds by adopting a dip coating method, and is repeated for 1-3 times.
  8. 8. A high entropy silicide composite coating prepared on the surface of Nb521 alloy by the method of any one of claims 1 to 7.
  9. 9. The high-entropy silicide composite coating of claim 8, wherein the high-entropy silicide composite coating comprises an outer layer, an intermediate layer and a transition layer sequentially disposed on the Nb521 alloy surface; The transition layer is a Nb 5 Si 3 layer, the middle layer is a NbSi 2 layer, and the outer layer is an AB 2 -A 5 B 3 layer, wherein A= Nb, mo, cr, ta, W, zr, hf, Y, ge, and B=Si, al and B; the thickness of the transition layer is 8-16 mu m, the thickness of the intermediate layer is 40-60 mu m, and the thickness of the outer layer is 80-120 mu m; The Nb 5 Si 3 layer and the NbSi 2 layer are formed by the diffusion reaction of Si to a matrix, and the AB 2 -A 5 B 3 layer is formed by the reaction of Si and multi-element alloy powder.
  10. 10. Use of the high entropy silicide composite coating of claim 8 or 9 in Nb521 alloy for high temperature oxidation resistance.

Description

Method for preparing high-entropy silicide composite coating on Nb521 alloy surface by single-step slurry sintering method and application thereof Technical Field The invention relates to the technical field of high-temperature alloy heat protection, in particular to a method for preparing a high-entropy silicide composite coating on the surface of Nb521 alloy by a single-step slurry burning method and application thereof. Background Niobium alloys have demonstrated great potential for use in hot-end components of aerospace devices due to their high melting point, good high temperature strength, and excellent processability. However, niobium alloys can undergo severe oxidation at temperatures above 500 ℃ to form a loosely porous Nb 2O5/NbO oxide film, resulting in diffusion of oxygen atoms along the grain boundaries causing matrix embrittlement failure. The alloying method has a certain help to improve the oxidation resistance of the niobium alloy, however, the improvement effect has obvious limitation. In addition, the addition of too many alloying elements also risks reducing the mechanical properties of the alloy. Surface coating technology is a method of modifying the surface of a material to achieve desired properties. The method can not only not damage the mechanical properties of the alloy, but also greatly improve the high-temperature oxidation resistance of the alloy. The silicide coating forms a SiO 2 protective film with self-healing capability in the high-temperature process. The most widely used silicide coatings on niobium alloys today are composite silicide coatings, typified by Si-Cr-Ti and Si-Cr-Fe systems, and disilicides of refractory alloys, such as NbSi 2、MoSi2. Recently, a developed high-entropy silicide material based on the design concept of high-entropy alloy is considered as a novel hot-end component protection material with great potential. High entropy suicides have more excellent properties than conventional suicides, such as high melting point, high fracture toughness, high hardness, high temperature oxidation, corrosion resistance and creep resistance. In addition, the high-entropy silicide still maintains excellent oxidation resistance at low temperature, and overcomes the defect of single silicide in the field of low-temperature oxidation resistance. The high entropy silicide not only forms amorphous SiO 2 to isolate the entry of oxygen in the oxidation process, but also generates various metal oxides. The metal oxides are dispersed in the SiO 2 oxide film, so that the oxygen permeability can be reduced, the stability of the oxide film can be improved, and the formation and diffusion of oxide film cracks can be prevented. The "high entropy effect" created by the interaction of the various oxides can bring about unexpected effects on the performance of the coating. The slurry burning method has the advantages of simple equipment, low cost, convenient operation and the like, can prepare the coating on the substrate with complex shape, and can accurately control the components of the coating by adjusting the components of the slurry. At present, researchers have adopted a slurry sintering method to realize the preparation of a high-entropy silicide coating on the surface of the niobium alloy and show effective oxidation protection. However, the refractory high-entropy metal silicide coating prepared by the method has higher porosity and poorer interface bonding. The presence of voids in the coating can greatly reduce the high temperature oxidation resistance of the coating. And poor interfacial bonding can lead to easier flaking and rapid failure during oxidation of the coating. Therefore, the design of the single-step slurry sintering method for preparing the refractory high-entropy metal silicide composite coating with metallurgical bonding and high compactness has important significance. Disclosure of Invention Aiming at solving the defects existing in the background technology, the invention aims at the problems of low density and poor interface bonding of the refractory high-entropy metal silicide composite coating on the surface of the Nb521 alloy prepared by a slurry sintering method. The invention provides a method for preparing a high-entropy silicide composite coating on the surface of Nb521 alloy by a single-step slurry sintering method and application thereof. The method realizes the preparation of the refractory high-entropy silicide composite coating with metallurgical bonding and high compactness on the surface of the niobium alloy by a single-step slurry sintering method. The preparation method has the advantages of simple and clear operation, low cost and high material utilization rate, can be used for actual industrial production, and can obtain the refractory high-entropy metal silicide coating with excellent oxidation resistance. The first object of the invention is to provide a method for preparing a high-entropy silicide composite coating on the surface of