本文關(guān)鍵詞： 碳纖維 聚合物前驅(qū)體 Si-O-C氣凝膠 抗氧化性能　出處：《哈爾濱工業(yè)大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著航天航空技術(shù)的快速發(fā)展,對(duì)新型超輕質(zhì)、耐高溫、抗氧化復(fù)合材料需求越來越迫切。但是碳纖維的抗氧化性能較低,在高溫條件復(fù)合材料會(huì)因?yàn)榈涂寡趸远鴮?dǎo)致綜合性能下降,限制了碳纖維高性能的發(fā)揮,因而有必要對(duì)碳纖維的抗氧化性進(jìn)行改善,碳纖維的表面抗氧化改性研究一直是研究的重點(diǎn)之一。本文以二甲基二甲氧基硅烷、正硅酸乙酯作為前驅(qū)體,乙醇和蒸餾水為溶劑,采用溶膠凝膠法制備Si-C-O凝膠,浸漬碳纖維,氬氣保護(hù)氣氛下燒結(jié)制備Si-C-O結(jié)構(gòu)涂層。前驅(qū)體在鹽酸作為催化劑的酸性環(huán)境下(p H=3)發(fā)生水解反應(yīng),然后在氨水作為催化劑的堿性環(huán)境下(p H=8)發(fā)生聚合反應(yīng)改性剛性碳纖維多孔材料;前驅(qū)體在不加入鹽酸下水解,在氨水作為催化劑的堿性環(huán)境下(p H=8)發(fā)生聚合反應(yīng)改性柔性碳纖維多孔材料,并研究二者的結(jié)構(gòu)和成分,在熱處理前后都為無定型結(jié)構(gòu),表面涂層含有Si-C鍵、Si-O鍵。重點(diǎn)研究剛性碳纖維多孔材料改性,通過XRD,SEM,TEM等分析測(cè)試方法,研究前驅(qū)體配比、醇/水比對(duì)涂層形貌結(jié)構(gòu)的影響;探究熱處理溫度、前驅(qū)體配比、涂覆次數(shù)對(duì)碳纖維抗氧化性能的影響,優(yōu)化碳纖維表面改性的制備工藝,分析改性后碳纖維的抗氧化行為。前驅(qū)體配比、醇/水比影響溶膠粘度,粘度過大涂層過后易開裂,粘度過小不利于形成均勻的涂層,正硅酸乙酯/二甲基二甲氧基硅烷質(zhì)量比小于1:4、醇/水比為5:1,制備的凝膠適合應(yīng)用于碳纖維表面改性;不同配比中,以不加入正硅酸乙酯,以二甲基二甲氧基硅烷作為前驅(qū)體制備Si-C-O結(jié)構(gòu)涂層改性碳纖維的抗氧化性能最好,氧化起始溫度提高了200℃;在不同溫度熱處理后,發(fā)現(xiàn)改性后碳纖維的氧化起始溫度隨著熱處理燒結(jié)溫度的升高而升高。以二甲基二甲氧基硅烷為前驅(qū)體,1200℃熱處理,在碳纖維表面制備不同層數(shù)Si-C-O結(jié)構(gòu)涂層,研究發(fā)現(xiàn)涂覆二層的碳纖維抗氧化性能最好,樣品氧化初始溫度提高了500℃,且熱震性能良好,800℃熱震5次后,失重1.8%;1000℃靜態(tài)氧化實(shí)驗(yàn)6h前涂層抗氧化性能良好,6h后失重明顯,10h后涂層失效。
[Abstract]:With the rapid development of aerospace technology, the demand for new super lightweight, high temperature and oxidation resistant composite materials is becoming more and more urgent, but the oxidation resistance of carbon fiber is relatively low. Under high temperature conditions, the composite materials will have lower comprehensive properties due to low oxidation resistance, which limits the high performance of carbon fiber, so it is necessary to improve the oxidation resistance of carbon fiber. In this paper, Si-C-O gel was prepared by sol-gel method with dimethyl dimethoxy silane, ethyl orthosilicate as precursor, ethanol and distilled water as solvent. The Si-C-O coating was sintered in argon atmosphere. The precursor was hydrolyzed in acidic environment with hydrochloric acid as catalyst. Then the rigid carbon fiber porous material was modified by polymerization in alkaline environment with ammonia water as catalyst, and the precursor was hydrolyzed without hydrochloric acid. The flexible carbon fiber porous material was modified by polymerization in alkaline environment with ammonia water as catalyst. The structure and composition of the two materials were studied, and the structure was amorphous before and after heat treatment. The surface coating contains Si-C bond and Si-O bond. The modification of rigid carbon fiber porous material is studied. The influence of precursor ratio and alcohol / water ratio on the morphology and structure of the coating is studied by means of XRDX SEMTEM, and the heat treatment temperature and precursor ratio are investigated. The influence of coating times on the oxidation resistance of carbon fiber, the preparation process of carbon fiber surface modification was optimized, the oxidation resistance behavior of modified carbon fiber was analyzed. The precursor ratio and the ratio of alcohol to water affected the sol viscosity, and the coating was easy to crack after the viscosity was too large. The viscosity is too small to form a uniform coating. The mass ratio of ethyl orthosilicate to dimethyl dimethoxy silane is less than 1: 4 and the ratio of alcohol to water is 5: 1.The gel prepared is suitable for the surface modification of carbon fiber. The oxidation resistance of carbon fiber modified by Si-C-O structure coating prepared by dimethyl dimethoxy silane as precursor is the best, and the initial oxidation temperature of carbon fiber is increased by 200 鈩，

本文編號(hào)：1541242