Low-cost SiZrOC ceramic material and preparation method thereof
阅读说明：本技术 一种低成本SiZrOC陶瓷材料及其制备方法 (Low-cost SiZrOC ceramic material and preparation method thereof ) 是由 郭蕾 马青松 于 2020-07-10 设计创作，主要内容包括：本发明公开了一种低成本SiZrOC陶瓷材料及其制备方法,以小分子量的硅树脂为原料,采用溶胶-凝胶的方法将无机锆盐引入形成含Zr的PSO先驱体,通过先驱体交联、高温裂解得到SiZrOC陶瓷,该过程中采用的硅树脂为甲基硅树脂,溶于乙醇,无机锆盐为氯氧化锆(ZrOCl<Sub>2</Sub>·8H<Sub>2</Sub>O),溶于乙醇,加入少量螯合剂、空间位阻剂后混合制备溶胶,静置后形成凝胶。本发明的制备方法,具有成本低廉、耐高温性能好且工艺简单、对设备要求低等优点。(The invention discloses a low-cost SiZrOC ceramic material and a preparation method thereof, wherein silicon resin with small molecular weight is used as a raw material, inorganic zirconium salt is introduced into a PSO precursor containing Zr by adopting a sol-gel method, SiZrOC ceramic is obtained by precursor crosslinking and high-temperature cracking, the silicon resin used in the process is methyl silicon resin and is dissolved in ethanol, and the inorganic zirconium salt is zirconium oxychloride (ZrOCl) 2 ·8H 2 O), dissolving in ethanol, adding a small amount of chelating agent and a steric inhibitor, mixing to prepare sol, and standing to form gel. The preparation method has the advantages of low cost, good high-temperature resistance, simple process, low requirement on equipment and the like.)
1. A preparation method of a low-cost SiZrOC ceramic material is characterized by comprising the following steps: the method comprises the following steps:
1) preparing zirconium sol: ZrOCl is added under the constant temperature condition of 40-50 DEG C2·8H2O in ethanol, ZrOCl2·8H2The mass ratio of O to ethanol is 2-5:10, a chelating agent is added, and the chelating agent and ZrOCl are added2·8H2The mass ratio of O is 1-4: 1, stirring to obtain zirconium sol; the chelating agent is acetylacetone;
2) preparing a gel: mixing the zirconium sol obtained in the previous step with a silicone resin ethanol solution, adding a spatial resistance agent, and uniformly stirring, wherein the spatial resistance agent comprises silicone resin and ZrOCl in mass2·8H25-20% of the sum of the mass of O, standing to form gel; the steric position resisting agent is polyethylene glycol;
3) preparing a precursor: heating the gel obtained in the previous step to 150-220 ℃, and fully drying to obtain a zirconium modified polysiloxane precursor;
4) preparing a SiZrOC ceramic material: and (3) carrying out high-temperature cracking on the zirconium modified polysiloxane precursor obtained in the previous step in an inert atmosphere by using a precursor conversion method, wherein the high-temperature cracking temperature is 1000-1200 ℃, the high-temperature cracking time is 60-90min, and the SiZrOC ceramic material is obtained after the cracking is finished.
2. The method for preparing a low-cost SiZrOC ceramic material as claimed in claim 1, wherein: the stirring in the step 1) is magnetic stirring for 10-20 min.
3. The method for preparing a low-cost SiZrOC ceramic material as claimed in claim 1, wherein: mixing the solution obtained in step 2) with the zirconium sol obtained in the previous step, wherein ZrOCl is added2·8H2The mass ratio of O to silicone resin is 1-10: 10, the mass concentration of the silicon resin ethanol solution is 30-50%.
4. The method for preparing a low-cost SiZrOC ceramic material as claimed in claim 1, wherein: the silicone resin in the step 2) is selected from methyl silicone resin.
5. The method for preparing a low-cost SiZrOC ceramic material as claimed in claim 1, wherein: the gel is formed after standing in the step 2), and the gel is formed after standing for 6-28 h.
6. The method for preparing a low-cost SiZrOC ceramic material as claimed in claim 1, wherein: and 2) fully drying for 4-10 h.
7. A low-cost SiZrOC ceramic material is characterized in that: the use of a low cost SiZrOC ceramic material as claimed in any of the claims 1-6 for the preparation thereof.
Technical Field
The invention belongs to the technical field of high-temperature structural ceramics, and particularly relates to a low-cost SiZrOC ceramic material and a preparation method thereof.
Background
Low-cost high-temperature ceramics and ceramic matrix composites have been the focus and hot spot areas of concern for aerospace surface thermal protection systems and propulsion systems. SiOC ceramics can be regarded as SiO2The oxygen atoms in the network are replaced by a portion of the carbon atoms. Because more carbon atoms replace oxygen to enter SiO4In the structure, the mechanical property, high-temperature stability, chemical stability and the like of the SiOC ceramic are obviously superior to those of quartz ceramic; therefore, it is considered to be a very good lightweight, high temperature resistant structural material.
The organic Polymer Derived Ceramics (PDCs) technology realizes the revolutionary breakthrough of the science and technology of ceramic preparation and becomes one of the mainstream preparation technologies of ceramic materials. Organic polymers are the source of PDCs technology and largely determine the composition, structure and properties of the target ceramic derived from cracking. Since the advent of PDCs technology, a wide variety of series of organic polymers have been developed. Polysiloxane (PSO) is an important member, is commercialized, has multiple varieties, low price, high ceramic yield, excellent physical and chemical properties, high stability in air and good operation safety, and is considered as an ideal raw material for preparing a ceramic material with high cost performance. Depending on the composition and microstructure, Polysiloxane (PSO) derived SiOC ceramics may also exhibit functional properties such as electrical, optical, magnetic, electrochemical, and the like under certain conditions, and may be used as optical materials, electronic packaging ceramic substrate materials, lithium ion battery electrode materials, and the like. Therefore, the SiOC ceramic has some functional characteristics while having excellent mechanical properties, and can be used as a candidate material for structural and functional integration.
However, the SiOC ceramic has a unique ternary metastable structure, and can generate phase separation and carbothermic reduction reaction at high temperature, so that the service temperature of the SiOC ceramic is not more than 1250 ℃. Therefore, the high temperature resistance of the SiOC ceramic needs to be further improved for increasingly demanding high temperature structure application requirements, so that the application range can be widened.
At present, the high temperature resistance of SiOC ceramics can be improved by adding a foreign element, and the cracking behavior of PSO and the phase splitting and crystallization behaviors of SiOC can be changed by introducing the foreign element into the PSO molecular structure, so that the high temperature resistance is influenced, which is one direction of industrial research.
Disclosure of Invention
The invention aims to solve the technical problem of providing a low-cost SiZrOC ceramic material and a preparation method thereof aiming at the defect of poor thermal stability of SiOC ceramic materials in the prior art, and the preparation method is a preparation method of the SiZrOC ceramic material with simple process method, convenient operation and low cost.
A preparation method of a low-cost SiZrOC ceramic material comprises the following steps:
1) preparing zirconium sol: ZrOCl is added under the constant temperature condition of 40-50 DEG C2·8H2O in ethanol, ZrOCl2·8H2The mass ratio of O to ethanol is (2-5):10, chelating agent and ZrOCl are added2·8H2The mass ratio of O is (1-4): 1, stirring to obtain zirconium sol; the chelating agent is acetylacetone;
2) preparing a gel: mixing the zirconium sol obtained in the previous step with a silicone resin ethanol solution, adding a spatial resistance agent, and uniformly stirring, wherein the spatial resistance agent comprises silicone resin and ZrOCl in mass2·8H25-20% of the sum of the mass of O, standing to form gel; the steric position resisting agent is polyethylene glycol;
3) preparing a precursor: heating the gel obtained in the previous step to 150-220 ℃, and fully drying to obtain a zirconium modified polysiloxane precursor;
4) preparing a SiZrOC ceramic material: and (3) carrying out high-temperature cracking on the zirconium modified polysiloxane precursor obtained in the previous step in an inert atmosphere by using a precursor conversion method, wherein the high-temperature cracking temperature is 1000-1200 ℃, the high-temperature cracking time is 60-90min, and the SiZrOC ceramic material is obtained after the cracking is finished.
The stirring in the step 1) of the invention adopts magnetic stirring for 10-20 min.
Mixing the solution obtained in step 2) with the zirconium sol obtained in the previous step, wherein ZrOCl is added2·8H2The mass ratio of O to the silicone resin is (1-10): 10, the mass concentration of the silicon resin ethanol solution is 30-50%.
The silicone resin of step 2) is selected from low molecular weight methyl silicone resin (MK), MK is methyl silicone resin dissolved in toluene, and the resin has high SiO2Content, after complete oxidation, 80% SiO2Calculated as solid resin content.
The gel is formed after standing in the step 2), and the gel is formed after standing for 6-28 h.
And 2) fully drying for 4-10 h.
The invention also relates to the SiZrOC ceramic material obtained by the preparation method of the low-cost SiZrOC ceramic material, wherein heterogeneous elements are introduced into the PSO molecular structure, so that the cracking behavior of PSO and the phase splitting and crystallization behaviors of SiOC can be changed, the high temperature resistance is influenced, and Zr is introduced into the PSO molecules to generate ZrO2Or ZrSiO4And the high-temperature resistance of the SiZrOC ceramic is better, the high-temperature resistance of the SiOC ceramic can be improved, and the SiZrOC ceramic with better high-temperature resistance can be prepared by introducing more Zr on the premise of keeping or even improving the advantage of low cost through the micromolecular silicon resin and the inorganic zirconium salt with simple structures.
Compared with the prior art, the invention has the following advantages:
1. the invention takes methyl silicone resin with simple molecular structure and inorganic zirconium salt which is low in price and easy to obtain as raw materials, utilizes a sol-gel method to synthesize Zr-doped PSO, and adopts the technical scheme that SiZrOC ceramic is prepared by a precursor conversion cracking method, thus obtaining the SiZrOC ceramic with low cost and better high temperature resistance.
2. The preparation method is simple, the operation is convenient, the cost is low, the problem that the SiZrOC ceramic generates the carbothermic reduction reaction at 1250 ℃ is solved, and the high temperature resistance of the SiOC ceramic can be effectively improved.
Drawings
FIG. 1 shows the XRD spectrum of the SiOC ceramic material prepared in example 1 of the present invention after high temperature heat treatment.
FIG. 2 shows the XRD spectrum of the SiZrOC ceramic material obtained in example 1 of the present invention after high temperature heat treatment.
Detailed Description
The present invention is described in further detail below by way of examples, which should not be construed as limiting the invention thereto.