本文選題：碳纖維 + 表面改性　； 參考：《國防科學(xué)技術(shù)大學(xué)》2015年碩士論文

【摘要】：C_f/SiO_2復(fù)合材料在理論上具有熱導(dǎo)率低、耐高溫性能優(yōu)異、耐燒蝕、密度低、高溫力學(xué)性能好的優(yōu)點(diǎn),在高溫材料領(lǐng)域具有非常好的發(fā)展前景。本論文針對(duì)采用溶膠凝膠法制備復(fù)合材料時(shí),二氧化硅溶膠與碳纖維表面不浸潤的問題,開展了對(duì)碳纖維表面改性方法的研究,并使用改性后的碳纖維為原料通過溶膠凝膠法制備復(fù)合材料。首先,實(shí)驗(yàn)研究了兩種氧化方法對(duì)碳纖維表面結(jié)構(gòu)的影響,并分析其對(duì)纖維力學(xué)性能的影響及作用機(jī)理。結(jié)果表明,氧化法能明顯改善纖維表面的浸潤性。該法能增多纖維表面的官能團(tuán),并對(duì)纖維表面產(chǎn)生刻蝕作用,使纖維表面產(chǎn)生溝壑。結(jié)果表明,采用450℃氧化碳纖維,氧化反應(yīng)發(fā)生較為劇烈,同時(shí),纖維表面微晶被氧化為細(xì)晶,活性比表面積增大,纖維表面浸潤性改善明顯。第二,在上述氧化纖維基礎(chǔ)上,探索了高溫?zé)崽幚韺?duì)碳纖維的影響。實(shí)驗(yàn)通過對(duì)比空氣氧化纖維在熱處理后的形貌、組成、比表面積和浸潤性,發(fā)現(xiàn)高溫?zé)崽幚頃?huì)使纖維表面不浸潤,因?yàn)楦邷叵绿祭w維碳化表面官能團(tuán)脫去水分子,且碳原子發(fā)生重排,形成六元環(huán)結(jié)構(gòu),使纖維不親水,同時(shí),水分子逸出時(shí)在纖維表面留下孔洞,對(duì)纖維強(qiáng)度造成損傷。第三,采用溶膠凝膠法,使用氧化前后的纖維經(jīng)多次氧化-浸漬-燒結(jié)反應(yīng)制備C_f/SiO_2復(fù)合材料,研究了復(fù)合材料的性能,并對(duì)復(fù)合材料的結(jié)構(gòu)、物相進(jìn)行評(píng)價(jià),分析了復(fù)合材料在高溫下碳熱還原反應(yīng)的發(fā)生情況。最后,分析了制備工藝,包括纖維表面處理、燒結(jié)工藝和纖維體積分?jǐn)?shù)對(duì)復(fù)合材料性能的影響。結(jié)果表明,在纖維能夠承受的范圍內(nèi),使用過高的燒結(jié)溫度會(huì)導(dǎo)致復(fù)合材料中缺陷增多,纖維性能下降。纖維編織物較疏松有利于溶膠對(duì)預(yù)浸布的浸潤,控制纖維體積分?jǐn)?shù),使其在一定區(qū)間內(nèi),可以得到性能較高的復(fù)合材料�；w并不致密,不能有效保護(hù)纖維不被氧化,需要對(duì)纖維進(jìn)行抗氧化處理或?qū)に囘M(jìn)一步優(yōu)化使材料致密。對(duì)碳纖維進(jìn)行表面氧化改性處理后,C_f/SiO_2復(fù)合材料的性能有良好的提升,復(fù)合材料的抗彎強(qiáng)度與彈性模量都得到較大的提升,碳纖維對(duì)石英基體有良好的增強(qiáng)增韌效果。
[Abstract]:In theory, C_f/SiO_2 composites have the advantages of low thermal conductivity, excellent high temperature resistance, good ablation resistance, low density and good mechanical properties at high temperature. In this paper, the surface modification of silica sol and carbon fiber was studied in order to solve the problem that the surface of silica sol and carbon fiber was not soaking when the composites were prepared by sol-gel method. The composites were prepared by sol-gel method using modified carbon fiber as raw material. Firstly, the effects of two oxidation methods on the surface structure of carbon fiber were studied experimentally, and the effects and mechanism of the two methods on the mechanical properties of carbon fiber were analyzed. The results show that oxidation method can obviously improve the wettability of fiber surface. The method can increase the number of functional groups on the surface of the fiber and etch the surface of the fiber, resulting in a gully on the surface of the fiber. The results showed that the oxidation reaction of carbon fiber at 450 鈩，

本文編號(hào)：1785527