Preparation method of high-entropy oxide ceramic fiber material
阅读说明：本技术 一种高熵氧化物陶瓷纤维材料的制备方法 (Preparation method of high-entropy oxide ceramic fiber material ) 是由 闫森旺 孙小飞 王刚 张雷 李虹屿 李红霞 于 2021-09-30 设计创作，主要内容包括：本发明属于陶瓷纤维材料技术领域,公开了一种高熵氧化物陶瓷纤维材料的制备方法,制备方法采用模板浸渍法制备高熵氧化物陶瓷纤维,以粘胶纤维为模板,将其真空浸渍于金属硝酸盐混合溶液中,其中,金属硝酸盐混合溶液中的金属硝酸盐由硝酸铈、硝酸锆、硝酸钇、硝酸铪、硝酸钛、硝酸镧中的至少四种等摩尔质量混合而成,浸渍后经水洗、离心、烘干、热处理之后高熵氧化物陶瓷纤维。本发明采用液相配料,可确保多种金属元素混合均匀,所制备的高熵氧化物陶瓷纤维材料形貌均匀,相结构为萤石型,所含元素比例接近等摩尔。(The invention belongs to the technical field of ceramic fiber materials, and discloses a preparation method of a high-entropy oxide ceramic fiber material. The invention adopts liquid-phase ingredients, can ensure that a plurality of metal elements are uniformly mixed, and the prepared high-entropy oxide ceramic fiber material has uniform appearance, fluorite phase structure and nearly equimolar proportion of the contained elements.)
1. A preparation method of a high-entropy oxide ceramic fiber material is characterized by comprising the following steps: the preparation method adopts a template dipping method to prepare the high-entropy oxide ceramic fiber, takes viscose fiber as a template, and vacuum-dips the viscose fiber in a metal nitrate mixed solution, wherein the metal nitrate in the metal nitrate mixed solution is formed by mixing at least four of cerium nitrate, zirconium nitrate, yttrium nitrate, hafnium nitrate, titanium nitrate and lanthanum nitrate according to equal molar mass, and the high-entropy oxide ceramic fiber is washed by water, centrifuged, dried and thermally treated after dipping, and the preparation method comprises the following specific steps:
(1) putting metal nitrate into deionized water, and stirring to completely and uniformly dissolve the metal nitrate to obtain a metal nitrate mixed solution;
(2) dipping viscose fibers in the mixed solution prepared in the step (1) in vacuum;
(3) after the dipping, washing the viscose fibers by using deionized water, and then centrifugally dewatering;
(4) putting the viscose fiber washed and centrifugally dewatered in the step (3) into a drying oven for drying;
(5) and (3) putting the dried viscose fibers into a high-temperature electric furnace for heat treatment to obtain the high-entropy oxide ceramic fibers.
2. A method of preparing a high entropy oxide ceramic fibre material as claimed in claim 1, characterized in that: the molar concentration of the metal nitrate mixed solution is 1-3 mol/L.
3. The preparation method of the high-entropy oxide ceramic fiber material as claimed in claim 1, wherein the dipping time of the viscose fiber in the metal nitrate mixed solution is 6-24 hours, and the dipping temperature is 20-60 ℃.
4. The method for preparing a high-entropy oxide ceramic fiber material according to claim 1, wherein the washing and centrifuging times are 3 to 5 times.
5. The method for preparing a high-entropy oxide ceramic fiber material according to claim 1, wherein the drying temperature is 40-60 ℃ and the drying time is 6-8 h.
6. A method of preparing a high entropy oxide ceramic fibre material as claimed in claim 1, characterized in that: the heat treatment temperature is 1000-1500 ℃, and the heat preservation time is 2-5 h; during heat treatment, the heat treatment is carried out slowly before 500 ℃, the decomposition rate of organic matters in the viscose fibers is slowed down, the sintered fibers are uniformly shrunk and leveled, the warping phenomenon of the fibers is avoided, and the temperature rising system is as follows: the heating rate is 0.5 ℃/min before 500 ℃, and the temperature is kept for 2h at 250 ℃; the rate of temperature rise after 500 ℃ was 2 ℃/min.
Technical Field
The invention belongs to the technical field of ceramic fiber materials, and particularly relates to a preparation method of a high-entropy oxide ceramic fiber material.
Background
The high-entropy oxide is an oxide having a single structure obtained by a method in which five or more kinds of metal or nonmetal oxides are solid-dissolved with each other at an equimolar or near molar ratio. The high-entropy oxide has multiple main elements, is in disordered arrangement among the main elements, has a high entropy value and large lattice distortion, is easy to form solid solution structures such as rock salt type, fluorite type, spinel type and perovskite type, and thus shows excellent performances such as unique mechanical, electrical and optical performances, and has very wide application prospects in the fields of aerospace, solar cells, photocatalytic materials, nuclear reactors and the like. In recent years, high-entropy oxides have received much attention from researchers at home and abroad because of their simple structure, excellent properties, and the like. The existing preparation method of the high-entropy oxide mainly comprises a solid phase method, a pyrolysis method, a coprecipitation method, a hydrothermal synthesis method, a liquid phase combustion synthesis method and the like.
At present, the methods for preparing the high-entropy oxide ceramics are more or solid-phase sintering methods, and the high-entropy oxide ceramics are prepared by uniformly mixing a plurality of oxide powders in equal proportion and then sintering the mixture at high temperature, wherein the solid-phase sintering generally needs higher temperature and longer time. Rost et al prepared the first example of high-entropy oxide (Mg, Ni, Co, Cu, Zn) O in 2015 by a solid-phase sintering method, and the preparation method adopts mechanical grinding, easily causes uneven mixing of raw materials, is difficult to realize a designed stoichiometric ratio, and has high energy consumption for high-temperature calcination. Patent publication No. CN110204328A discloses a method for preparing high-entropy oxide ceramics, which comprises the steps of ball-milling, drying, granulating and pressing a plurality of metal oxide powders mixed according to an equal molar ratio to obtain a green body, then carrying out heat treatment on the green body, and then preparing the high-entropy oxide ceramics by flash firing. Patent publication No. CN112159234A discloses a preparation method of high-entropy ceramic powder, which is characterized in that a plurality of metal nitrates and amorphous boron are mixed, absolute ethyl alcohol and a dispersing agent are added, pH is adjusted, stirring and heating are carried out, dried gel is prepared, grinding is carried out after drying, heat treatment is carried out at 600-800 ℃ in a protective atmosphere, a blank is pressed after grinding and sieving and is calcined at 1400-1600 ℃ in the protective atmosphere, and high-entropy ceramic powder is obtained after grinding and sieving. At present, the preparation of the high-entropy oxide ceramic fiber material is not reported.
Disclosure of Invention
The invention aims to provide a preparation method of a high-entropy oxide ceramic fiber material. The invention uses the template dipping method to prepare the high-entropy oxide ceramic fiber, uses the viscose fiber as the template, adopts the liquid-phase burdening method, does not introduce impurities, has simple and convenient process, and is green and environment-friendly.
The invention adopts the following technical scheme for achieving the purpose:
a preparation method of a high-entropy oxide ceramic fiber material is characterized by comprising the following steps: the preparation method adopts a template dipping method to prepare the high-entropy oxide ceramic fiber, takes viscose fiber as a template, and vacuum-dips the viscose fiber in a metal nitrate mixed solution, wherein the metal nitrate in the metal nitrate mixed solution is formed by mixing at least four of cerium nitrate, zirconium nitrate, yttrium nitrate, hafnium nitrate, titanium nitrate and lanthanum nitrate according to equal molar mass, and the high-entropy oxide ceramic fiber is washed by water, centrifuged, dried and thermally treated after dipping, and the preparation method comprises the following specific steps:
(1) putting metal nitrate into deionized water, and stirring to completely and uniformly dissolve the metal nitrate to obtain a metal nitrate mixed solution;
(2) dipping viscose fibers in the mixed solution prepared in the step (1) in vacuum;
(3) after the dipping, washing the viscose fibers by using deionized water, and then centrifugally dewatering;
(4) putting the viscose fiber washed and centrifugally dewatered in the step (3) into a drying oven for drying;
(5) and (3) putting the dried viscose fibers into a high-temperature electric furnace for heat treatment to obtain the high-entropy oxide ceramic fibers.
The molar concentration of the metal nitrate mixed solution is 1-3 mol/L.
The dipping time of the viscose fiber in the metal nitrate mixed solution is 6-24 hours, and the dipping temperature is 20-60 ℃.
The washing centrifugation times are 3-5.
The drying temperature is 40-60 ℃, and the drying time is 6-8 h.
The heat treatment temperature is 1000-1500 ℃, and the heat preservation time is 2-5 h; during heat treatment, the heat treatment is carried out slowly before 500 ℃, the decomposition rate of organic matters in the viscose fibers is slowed down, the sintered fibers are uniformly shrunk and leveled, the warping phenomenon of the fibers is avoided, and the temperature rising system is as follows: the heating rate is 0.5 ℃/min before 500 ℃, and the temperature is kept for 2h at 250 ℃; the rate of temperature rise after 500 ℃ was 2 ℃/min.
The preparation method of the high-entropy oxide ceramic fiber material provided by the invention adopts the technical scheme, and has the beneficial effects that: (1) the ceramic fiber is prepared by adopting a template dipping method, so that the method is simple and convenient to operate; (2) the invention adopts liquid-phase ingredients, the stoichiometric specific volume is easy to control, the metal ions have better dispersion effect in the liquid phase, and a plurality of metal elements can be uniformly mixed under the liquid-phase condition; (3) the high-entropy oxide ceramic fiber material prepared by the invention has uniform appearance, a fluorite phase structure and approximately equimolar proportion of contained elements; (4) the method has the advantages of low energy consumption, mild reaction conditions, green and environment-friendly reaction process, and almost no pollution and waste generation.
Detailed Description
The invention is illustrated with reference to the examples given:
example 1: putting cerium nitrate, zirconium nitrate, hafnium nitrate, tin nitrate and titanium nitrate with equal molar mass into deionized water, and stirring to completely and uniformly dissolve the cerium nitrate, the zirconium nitrate, the hafnium nitrate, the tin nitrate and the titanium nitrate to obtain a metal nitrate mixed solution, wherein the molar concentration of the metal nitrate mixed solution is 2 mol/L; mixing viscose fiberEmpty dipping is carried out in the prepared mixed solution, the dipping time is 12 hours, and the dipping temperature is 40 ℃; after dipping, washing and centrifugally dewatering the fabric by deionized water, wherein the washing and centrifuging times are 3 times; then putting the mixture into a drying oven for drying, wherein the drying temperature is 60 ℃, and the drying time is 8 hours; and (3) drying, and then putting the dried product into a high-temperature electric furnace for heat treatment to obtain the high-entropy oxide ceramic fiber, wherein the heat treatment temperature is 1500 ℃, and the heat preservation time is 4 hours. Prepared (Ce)0.2Zr0.2Hf0.2Sn0.2Ti0.2)O2The high-entropy oxide ceramic fiber material has uniform appearance, a phase structure of a single-phase fluorite structure, and lower thermal conductivity.
Example 2: putting zirconium nitrate, hafnium nitrate, cerium nitrate and yttrium nitrate with equal molar mass into deionized water, and stirring to completely and uniformly dissolve the zirconium nitrate, the hafnium nitrate, the cerium nitrate and the yttrium nitrate to obtain a metal nitrate mixed solution, wherein the molar concentration of the metal nitrate mixed solution is 1 mol/L; dipping the viscose fibers in the prepared mixed solution in vacuum for 12 hours at the dipping temperature of 40 ℃; after dipping, washing and centrifugally dewatering the fabric by deionized water, wherein the washing and centrifuging times are 3 times; then putting the mixture into a drying oven for drying, wherein the drying temperature is 60 ℃, and the drying time is 8 hours; and (3) drying, and then placing the dried product into a high-temperature electric furnace for heat treatment to obtain the high-entropy oxide ceramic fiber, wherein the heat treatment temperature is 1500 ℃, and the heat preservation time is 2 hours. Prepared of (Hf)0.25Zr0.25Ce0.25Y0.25)O2-δThe high-entropy oxide ceramic fiber material has uniform appearance, and the phase structure is a single-phase fluorite structure.
Example 3: putting zirconium nitrate, cerium nitrate, tin nitrate and titanium nitrate with equal molar mass into deionized water, and stirring to completely and uniformly dissolve the zirconium nitrate, the cerium nitrate, the tin nitrate and the titanium nitrate to obtain a metal nitrate mixed solution, wherein the molar concentration of the metal nitrate mixed solution is 1 mol/L; dipping the viscose fibers in the prepared mixed solution in vacuum for 12 hours at the dipping temperature of 40 ℃; after dipping, washing and centrifugally dewatering the fabric by deionized water, wherein the washing and centrifuging times are 3 times; then putting the mixture into a drying oven for drying, wherein the drying temperature is 60 ℃, and the drying time is 8 hours; drying, and heat treating in a high temperature electric furnace to obtain high entropy oxide ceramicThe heat treatment temperature of the fiber is 1500 ℃, and the heat preservation time is 4 h. Prepared (Ce)0.25Zr0.25Sn0.25Ti0.25)O2The high-entropy oxide ceramic fiber material has uniform appearance, and the phase structure is a single-phase fluorite structure.
Example 4: weighing zirconium nitrate, cerium nitrate, hafnium nitrate, yttrium nitrate and calcium nitrate according to a molar ratio of 2:2:2:1:1, mixing, placing in deionized water, stirring and dissolving uniformly to obtain a metal nitrate mixed solution, wherein the molar concentration of the metal nitrate mixed solution is 2 mol/L; dipping the viscose fibers in the prepared mixed solution in vacuum for 12 hours at the dipping temperature of 40 ℃; after dipping, washing and centrifugally dewatering the fabric by deionized water, wherein the washing and centrifuging times are 3; then putting the mixture into a drying oven for drying, wherein the drying temperature is 60 ℃, and the drying time is 8 hours; drying, and heat treating in a high temperature furnace at 1500 deg.c for 5 hr to obtain high entropy oxide ceramic fiber with single fluorite structure (Hf)0.25Zr0.25Ce0.25)(Y0.125Ca0.125)O2-δHigh entropy oxide ceramic fiber material.