本文關(guān)鍵詞：藍(lán)寶石紅外窗口用碳納米管薄膜的制備及其性能調(diào)控研究　出處：《哈爾濱工業(yè)大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 碳納米管薄膜 化學(xué)氣相沉積法 鎳催化劑 鎢鐵催化劑 光電性能

【摘要】：藍(lán)寶石紅外窗口的電磁屏蔽防護(hù),有著重要的理論研究和實際應(yīng)用價值。碳納米管薄膜尤其是單一手性單壁碳納米管薄膜,具有良好的紅外透過率和較好的理論導(dǎo)電性能,在紅外窗口電磁屏蔽領(lǐng)域有著較好的應(yīng)用前景。本論文基于碳納米管氣-液-固(VLS)和氣-固-固(VSS)兩種生長原理,分別以金屬Ni和W-Fe合金為催化劑,在藍(lán)寶石基底和鍍有SiO_2層的藍(lán)寶石基底上,采用化學(xué)氣相沉積法(CVD)制備了一系列碳納米管薄膜。主要采用掃描電子顯微術(shù)(SEM)、拉曼光譜和透射電子顯微術(shù)(TEM)表征和分析碳納米管薄膜的生長形貌及結(jié)晶質(zhì)量;采用紅外光譜法測試薄膜的紅外透過率;采用霍爾效應(yīng)法測試其導(dǎo)電性能以評估其電磁屏蔽性能。以金屬Ni為催化劑,CVD制備碳納米管薄膜的實驗表明,使用Ni催化劑制備碳納米管薄膜時,Ni催化劑濺射時間不能太長,否者退火后Ni顆粒會發(fā)生重疊,不利于碳納米管薄膜的生長。CVD法制備碳納米管時,反應(yīng)溫度升高能夠提高Ni催化劑活性,使碳納米管薄膜質(zhì)量變好,但是過高的溫度也會讓催化劑中毒失效;實驗通入CH_4/H_2的流量隨著H_2比例的增加,碳納米管薄膜的質(zhì)量慢慢變好,但是過量的H_2會降低反應(yīng)速率使碳納米管密度下降;Ar流量對反應(yīng)的影響效果不大,當(dāng)Ar流量過大時,碳納米管團(tuán)聚會變得嚴(yán)重;碳納米管薄膜的厚度隨反應(yīng)時間延長而增加,但生長30min后碳納米管開始停滯生長。此外,還通過對比藍(lán)寶石鍍制SiO_2層前后碳納米管薄膜光電性能變化,研究了SiO_2層的作用,分析了SiO_2層提高碳納米管光電性能的原因。制備新型W-Fe合金,并以其為催化劑制備碳納米管薄膜的實驗結(jié)果表明:W48Fe28Ox在高溫H_2環(huán)境下退火才能形成W-Fe催化劑;W-Fe催化劑具有非常高的熔點,反應(yīng)溫度要達(dá)到850℃以上W-Fe催化劑才具有活性;高溫下CH_4容易裂解,CH_4流量不能太大,H_2流量可適當(dāng)增加來改善碳納米管薄膜質(zhì)量。比較以SiO_2為過渡層使用Ni催化劑和直接基于藍(lán)寶石以W-Fe為催化劑制備的碳納米管,采用拉曼散射光譜和TEM分析表明,W-Fe催化劑制備的碳納米管直徑比Ni催化劑制備的碳納米管要小且無定形碳雜質(zhì)少。因而使用W-Fe催化劑制備碳納米管薄膜質(zhì)量更好,將具有更高紅外透過率和導(dǎo)電性能,在紅外窗口電磁屏蔽領(lǐng)域具有更好的應(yīng)用前景。
[Abstract]:The electromagnetic shielding of sapphire infrared window has important theoretical research and practical application value. Carbon nanotube thin film, especially single chiral single-walled carbon nanotube film. It has good infrared transmittance and good theoretical conductivity. This thesis is based on the two growth principles of carbon nanotube gas-liquid-solid VLS and gas-solid-solid VSS. Metal Ni and W-Fe alloys were used as catalysts on sapphire substrate and sapphire substrate coated with SiO_2 layer respectively. A series of carbon nanotube films were prepared by chemical vapor deposition (CVD), mainly by scanning electron microscopy (SEM). Raman spectroscopy and transmission electron microscopy (TEM) were used to characterize and analyze the morphology and crystallization quality of carbon nanotube films. Infrared transmittance was measured by infrared spectroscopy. Hall effect method was used to test its electrical conductivity to evaluate its electromagnetic shielding performance. The experimental results of carbon nanotube films prepared by CVD using Ni as catalyst show that when Ni catalysts are used to prepare carbon nanotubes films. The sputtering time of Ni catalyst can not be too long, and the Ni particles will overlap after annealing, which is not conducive to the growth of carbon nanotube thin films. The increase of reaction temperature can improve the activity of Ni catalyst and improve the quality of carbon nanotube film, but too high temperature will also make the catalyst toxic. The mass of carbon nanotube films gradually improved with the increase of the ratio of H _ 2 to CH_4/H_2, but excessive H _ (2) decreased the reaction rate and decreased the density of carbon nanotubes. The effect of ar flux on the reaction is not obvious. When ar flow is too large, the CNTs congregation becomes serious. The thickness of carbon nanotube films increased with the increase of reaction time, but the growth of carbon nanotubes began to stagnate after 30 minutes of growth. The role of SiO_2 layer was studied by comparing the photoelectric properties of carbon nanotube films before and after sapphire SiO_2 coating. The reasons for improving the photoelectric properties of carbon nanotubes by SiO_2 layer were analyzed and a new W-Fe alloy was prepared. The experimental results show that the W-Fe catalyst can be formed only by annealing at high temperature under the condition of H _ (2) _ (2) at 1: W _ (48) Fe _ (28) O _ (x). The W-Fe catalyst has a very high melting point, and the reaction temperature is more than 850 鈩，

本文編號：1377025