【摘要】：低地球軌道環(huán)境中的原子氧(AO)具有強氧化性,其高能碰撞會導(dǎo)致聚合物材料性能退化,嚴重影響航天器的正常工作。本文借助溶膠-凝膠(Sol-gel)法和濕化學(xué)改性法在聚酰亞胺薄膜(Kapton)和硅橡膠(SR)表面制備無機氧化物涂層,通過AO模擬試驗評價其防護效果。同時研究了聚合物基體表面改性的微觀變化、涂層與基體的界面結(jié)合狀態(tài)等問題。主要研究工作如下:1.SiO_2溶膠體系研究:為制備適宜鍍膜的溶膠體系,本文研究了乙醇用量、酸堿催化劑、陳化溫度等條件對SiO_2溶膠體系的穩(wěn)定性和粒徑的影響。結(jié)果表明:溶膠濃度較小時,粒徑普遍較小,溶膠的凝膠時間延長。此外酸催化的溶膠體系粒徑普遍較大,溶膠的穩(wěn)定性也較差,接近凝膠時粒徑急劇增大。而相同實驗條件下,堿催化的SiO_2溶膠體系粒徑較小,穩(wěn)定性較高。陳化溫度也對溶膠穩(wěn)定性產(chǎn)生較大的影響,隨著溫度的升高,酸催化溶膠的穩(wěn)定性降低。2.堿液刻蝕與硅烷偶聯(lián)劑相結(jié)合的表面改性方法研究:用低濃度堿液刻蝕去除Kapton基材的表面鈍化層,再用硅烷偶聯(lián)劑進行改性。改性后的Kapton基材表面親水性顯著增加,SnO_2/SiO_2溶膠很容易在其表面鋪展形成均勻的液膜。采用這種方法制得的涂層與基材之間粘附牢固。AO輻照試驗后,涂層依然均勻致密,具有很好的抗AO能力,AO的侵蝕效應(yīng)僅相當(dāng)于原始Kapton的4.1%,且賦予樣品良好的抗靜電能力。3.柔性SR表面涂層易開裂問題研究:本文對SR基體和表面改性過程進行了研究。研究發(fā)現(xiàn):硅烷偶聯(lián)劑KH-550改性后的SR樣品表面已產(chǎn)生不規(guī)則裂紋。SR基體與改性層之間的應(yīng)力是導(dǎo)致裂紋的主要原因,彎曲變形等外力加劇應(yīng)力累積,造成更多裂紋。采用有機溶劑適度溶脹SR,可有效緩解SR基體與表面改性層之間的應(yīng)力,從而大幅減少了改性過程以及鍍膜過程所產(chǎn)生的裂紋。4.SiO_2摻雜對提高柔性SR抗AO性能研究:研究表明,適宜濃度的SiO_2溶膠加入SR基膠中,能夠?qū)崿F(xiàn)SiO_2在SR中均勻分散。AO輻照試驗后,摻雜SiO_2溶膠的樣品相比于原始SR,表面依然平整致密,裂紋較少,AO侵蝕危害有所緩解。同時SR的機械性能得到提高。
[Abstract]:Atomic oxygen (AO) in low Earth orbit environment has strong oxidization and its high energy collision will degrade the properties of polymer materials and seriously affect the normal operation of spacecraft. Inorganic oxide coatings were prepared on the surface of polyimide film (Kapton) and silicone rubber (SR) by sol-gel (Sol-gel) method and wet chemical modification method. The protective effect was evaluated by AO simulation test. At the same time, the microcosmic change of polymer matrix surface modification and the interfacial bonding state between coating and substrate were studied. The main research work is as follows: the study of 1.SiO_2 sol system: in order to prepare the suitable sol system, the effects of the amount of ethanol, acid base catalyst and aging temperature on the stability and particle size of SiO_2 sol system were studied in this paper. The results show that the particle size is generally smaller and the gel time is prolonged when the concentration of sol is small. In addition, the particle size of the acid-catalyzed sol system is generally larger, and the stability of the sol is also poor. The particle size increases sharply when the gel is close to the gel. Under the same experimental conditions, the SiO_2 sol system catalyzed by alkali has smaller particle size and higher stability. Aging temperature also had a great effect on the stability of the sol. With the increase of the temperature, the stability of the acid catalyzed sol decreased. 2. Study on the Surface Modification method of Alkali etching combined with Silane Coupling Agent: the surface passivation layer of Kapton substrate was etched with low concentration alkali solution and then modified with silane coupling agent. The surface hydrophilicity of the modified Kapton substrate was significantly increased, and the SnO_2/SiO_2 sol could easily spread on the surface to form a uniform liquid film. The coating prepared by this method adheres firmly to the substrate. After AO irradiation, the coating is still uniform and compact, and has good ability to resist AO. The corrosion effect of AO is only 4.1 of that of the original Kapton. And gives the sample good antistatic ability. 3. Study on the easy cracking of flexible SR Surface coating: the SR substrate and surface modification process were studied in this paper. It is found that the surface of SR samples modified by silane coupling agent KH-550 has produced irregular cracks. The stress between the SR matrix and the modified layer is the main cause of the cracks. The external forces such as bending deformation aggravate the accumulation of stress and cause more cracks. The stress between the SR matrix and the surface modified layer can be effectively alleviated by moderate swelling of SR, in organic solvent. Thus, the cracks produced by the modification process and the coating process were greatly reduced. The study on the improvement of AO resistance of flexible SR by 4.SiO_2 doping showed that the appropriate concentration of SiO_2 sol was added to SR base adhesive. After AO irradiation, the samples doped with SiO_2 sol were still flat and compact compared with the original SR, surface, the cracks were less, and the corrosion damage of AO was alleviated. At the same time, the mechanical properties of SR are improved.
【學(xué)位授予單位】：煙臺大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB306

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