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CN-121974665-A - Preparation method of alumina fiber interfacial phase coating

CN121974665ACN 121974665 ACN121974665 ACN 121974665ACN-121974665-A

Abstract

A preparation method of an alumina fiber interfacial phase coating belongs to the technical field of continuous ceramic fiber surface modification and interfacial phase design, and particularly relates to a multilayer interfacial phase coating structure for alumina fibers and a low-temperature preparation method based on self-limiting adsorption cycle. The multi-layer structure of the first spinel transition protective layer/the second weak monazite interface layer is constructed by using a magnesium source, an aluminum source, a lanthanum source and a phosphorus source, so that the protection of the preparation process of the alumina fiber and the cooperation of the subsequent interface regulation and control functions are realized. The process is simple, can ensure the uniformity and the repeatability of the coating, has accurate and controllable coating thickness, can adjust the structure according to the requirement, and has important significance for engineering application of the alumina fiber reinforced ceramic matrix composite.

Inventors

  • HU PENG
  • DONG HONGPENG
  • ZHENG YONGZHI
  • ZHOU QINQIN

Assignees

  • 北京工业大学

Dates

Publication Date
20260505
Application Date
20260206

Claims (10)

  1. 1. The alumina fiber with the interfacial phase coating is characterized in that a first transition protective layer is arranged on the surface of the alumina fiber, a second weak interfacial layer is arranged outside the first transition protective layer, the first transition protective layer is a compact continuous oxide layer and is firmly combined with the surface of the fiber to protect the fiber and provide a blocking effect, and the second weak interfacial layer is a rare earth phosphate layer or a complex phase layer thereof to realize interfacial debonding and sliding in subsequent application.
  2. 2. An alumina fibre with an interfacial phase coating according to claim 1, wherein said first transitional protective layer is preferably a MgAl 2 O 4 spinel layer or a MgAl 2 O 4 spinel/alumina complex phase compact layer, with a thickness of 10-800 nm, preferably 100-600 nm.
  3. 3. An alumina fiber having an interfacial phase coating according to claim 1, wherein said second weak interfacial layer is a rare earth phosphate layer, preferably LaPO 4 、CePO 4 or (La, ce) PO 4 , having a thickness of 50-1000 nm, preferably 200-800 nm.
  4. 4. A method for preparing an alumina fiber having an interfacial phase coating as claimed in any one of claims 1 to 3, comprising the steps of: (1) The fiber pretreatment and surface activation, namely cleaning, rinsing and drying the alumina fiber, and activating the surface of the fiber to improve the consistency of hydroxyl sites and adsorption sites on the surface of the fiber; (2) Constructing a first transition protective layer, namely constructing a Mg-Al-O system precursor layer on the surface of the alumina fiber in a self-limiting adsorption cycle mode, and forming the first transition protective layer through solidification and heat treatment; (3) And constructing a second weak interface layer, namely constructing a rare earth phosphate precursor layer outside the first transition protective layer in a self-limiting adsorption cycle mode, and forming the second weak interface layer through solidification and heat treatment.
  5. 5. The method of claim 4, wherein the self-limiting adsorption cycle comprises an alternating process of adsorption-rinse-adsorption/reaction-rinse, wherein the adsorption amount is limited by the number of adsorption sites on the fiber surface, the adsorption amount tends to be stable after site saturation, and the layer-by-layer construction is realized by superposition of a plurality of cycle alternating processes, and the coating thickness is mainly determined by the number of cycles.
  6. 6. The method of claim 5, wherein the self-limiting adsorption cycle in step (2) is comprised of alternating adsorption of Mg 2+ adsorption liquid and Al 3+ adsorption liquid, further comprising alternating adsorption/reaction-flushing of Mg 2+ adsorption-flushing-Al 3+ adsorption/reaction-flushing, wherein the Mg 2+ adsorption liquid is formulated with magnesium salts selected from one or more of magnesium nitrate, magnesium chloride, magnesium acetate, wherein the Mg 2+ concentration is 1-50 mmol/L, preferably 5-20 mmol/L, wherein the solution pH is adjusted to 3-7, preferably 4-6, using dilute acid/dilute base, wherein the Al 3+ adsorption liquid is formulated with aluminum salts selected from one or more of aluminum nitrate, aluminum chloride, aluminum acetate dissolved in deionized water, and wherein a complexing agent is added to inhibit Al 3+ hydrolysis. The complexing agent is one or more selected from citric acid, tartaric acid, lactic acid and acetic acid, the concentration of the complexing agent is 0.01-0.5 mol/L, preferably 0.05-0.2 mol/L, calculated by Al, and the pH value of the Al 3+ adsorption liquid is 3-7, preferably 4-6.
  7. 7. The method according to claim 5, wherein the self-limiting adsorption cycle in the step (3) is formed by alternately adsorbing/reacting an adsorption solution of rare earth cations La 3+ or La 3+ /Ce 3+ with a phosphate reaction solution, wherein the rare earth salt is selected from one or more of nitrate, chloride and acetate, the concentration of rare earth ions (La 3+ and/or Ce 3+ ) is 1-50 mmol/L, preferably 5-20 mmol/L, and the phosphate reaction solution is prepared by dissolving phosphate in deionized water, and the phosphate is selected from one or more of sodium dihydrogen phosphate, potassium dihydrogen phosphate and ammonium dihydrogen phosphate, and the concentration of the phosphate in PO 4 3- is 1-100 mmol/L, preferably 10-50 mmol/L.
  8. 8. The method according to claim 5, wherein the curing and phase-forming heat treatment in the step (2) comprises heating to 300-350 ℃ at 0.5-2 ℃ per minute under an air atmosphere and maintaining the temperature at 0.5-1.5 h for curing. And then heating to 800-900 ℃ at 1-5 ℃ per minute and preserving heat for 1-2 h to form a phase, wherein the curing and crystallization heat treatment in the step (3) comprises heating to 300-350 ℃ at 0.5-2 ℃ per minute and preserving heat for 0.5-1.5 h in an air atmosphere for curing. Then heating to 700-850 ℃ at 1-5 ℃ per min and preserving heat for 1-2 h to crystallize.
  9. 9. The method of claim 5, wherein the alumina fibers are continuous alumina fiber bundles. The surface activation treatment is selected from one of ozone activation, ultraviolet activation and plasma activation.
  10. 10. Use of the alumina fiber with interfacial phase coating according to any one of claims 1-3 for fiber reinforced ceramic matrix composites.

Description

Preparation method of alumina fiber interfacial phase coating Technical Field The invention belongs to the technical field of continuous ceramic fiber surface modification and interfacial phase design, and particularly relates to a multilayer interfacial phase coating structure for aluminum oxide fibers and a low-temperature preparation method based on self-limiting adsorption cycle. Background The continuous alumina fiber has excellent high temperature resistance, oxidation resistance and chemical stability, has important application value in alumina fiber reinforced ceramic matrix composite, and has been used in various ground tests and engineering demonstration applications on aerospace high temperature components such as combustion chamber bushings, exhaust mixers, tail nozzles, central bodies and the like of aeronautical engines. However, alumina fibers are susceptible to surface activity enhancement, grain coarsening or local defect expansion during service in high temperature treatment and subsequent water vapor environments, resulting in reduced fiber strength retention. Meanwhile, the fiber and surrounding oxide materials in the oxide system have stronger chemical compatibility and sintering activity, and the interface is easy to form strong combination, so that the subsequent mechanisms such as interfacial debonding, fiber and crack deflection and the like are not facilitated to be exerted. To achieve interfacial designability of the fibers, interfacial phase coatings are often introduced into the fiber surface to regulate interfacial shear strength and damage evolution pathways. The existing single-layer interfacial phase scheme is difficult to simultaneously satisfy multiple requirements, namely, on one hand, the protection and the blocking of the fiber are required to be realized in the high-temperature preparation or service process of the fiber-reinforced ceramic matrix composite. On the other hand, it is desirable to provide a moderately weak interface in subsequent applications to induce interfacial debonding and pullout to improve the toughness of the composite. If the single-layer coating is too dense or too strong in combination with the fiber, the weak interface function is insufficient. If loose or too weak a bond, it tends to flake off and affect the surface integrity of the fiber, resulting in an inability to protect the fiber. In addition, for continuous fiber bundles or fabric reinforcements, the problems of excessively thick outer layers, insufficient inner layers, local agglomeration, sudden increase deposition, drying cracking and the like easily occur in the traditional dip-coating mode, and the batch stability and engineering amplification are affected. Vapor deposition in turn places high demands on sample shape and size and is costly. Therefore, a multilayer interfacial phase coating structure and a preparation method capable of realizing functional delamination of a protective layer/a weak interfacial layer, with controllable thickness and low cost are needed. Disclosure of Invention The invention aims to provide an alumina fiber interface phase coating and a preparation method thereof, which realize the cooperation of the preparation process protection and the subsequent interface regulation function of alumina fibers by constructing a multi-layer structure of a first transition protection layer/a second weak interface layer. Meanwhile, a precursor layer is built layer by adopting self-limiting adsorption circulation, so that the thickness of the coating is mainly determined by the circulation times, and the uniformity and reproducibility of continuous fiber bundle coating are improved. The alumina fiber with the interfacial phase coating is characterized in that a first transition protective layer is arranged on the surface of the alumina fiber, a second weak interfacial layer is arranged outside the first transition protective layer, and the first transition protective layer is a compact continuous oxide layer and is firmly combined with the surface of the fiber to protect the fiber and provide a barrier effect. The second weak interface layer is a rare earth phosphate layer or a complex phase layer thereof and is used for realizing interface debonding and sliding in subsequent application so as to induce crack deflection and maintain load transmission. The first transition protective layer is preferably a MgAl 2O4 spinel layer or a MgAl 2O4 spinel/alumina complex phase compact layer, and the thickness is 10-800 nm, preferably 100-600 nm. The second weak interface layer is a rare earth phosphate layer, preferably LaPO 4、CePO4 or (La, ce) PO 4, and has a thickness of 50-1000 nm, preferably 200-800 nm. The invention relates to a preparation method of an alumina fiber interfacial phase coating, which comprises the following steps: (1) The fiber pretreatment and surface activation, namely cleaning, rinsing and drying the alumina fiber, and activating the surface of the fiber