Vertically aligned carbon nanotube carpets/carbon nanocoils: Synthesis, Electrothermal Properties and Devices

本論文主要針對奈米碳管叢與奈米碳螺旋線圈成長、基材效應、電熱性質與電熱元件方面做相關的研究與討論。本研究利用自行組裝可個別控制溫度之三段溫度式化學氣相沉積系統，以粉末二茂鐵為催化劑，藉由控制催化劑重量、碳源氣體流率、氬氣氣體流率、成長時間和成長溫度，最終可在金屬與絕緣基材上成長多壁奈米碳管叢。其結果顯示三段式高溫爐管可延長碳源裂解時間與可維持催化劑之使用壽命而增加奈米碳管叢成長效率，使得能在各種基板上成長奈米碳管叢。 奈米碳管除了以筆直的形態呈現外，也可以三維立體的螺旋狀來表現，本研究在不?袗?線表面添加微量錫奈米粒子，同時配合適當的退火溫度，能有效地提升奈米碳螺旋線圈在金屬線上的產率，奈米碳螺旋線圈佔所有碳產物之比例高達80%。此外本文也利用二茂鐵與三段高溫爐管之製程於金屬線與金屬網上成長奈米碳螺旋線圈與奈米碳管叢，此製程能降低成長溫度與有效提升奈米碳螺旋線圈與奈米碳管叢在金屬線與金屬網上之產率。本研究之結果未來可用於大量生產奈米碳螺旋線圈與奈米碳管叢，提升奈米碳螺旋線圈與奈米碳管叢之應用性。 本文也在撓性金屬鋁箔紙上成長奈米碳管叢，且能直接製作撓性應變感測器，簡化撓性應變感測器之製程，其具有高靈敏度，能在微小應變下有高電阻變化率，其應變靈敏度0.0028%，應變規因子可達296．此外奈米碳管叢間存在接觸電阻，使得電流通過有熱效應產生，並且當電流傳輸方向與奈米碳管叢垂直時，奈米碳管叢具有高發熱效率與高溫度變化靈敏度，可即時且穩定發熱，熱阻可達400℃/W以上，其可應用於發熱器等相關產品生產，商機無限。而奈米碳管叢除可發熱外則還具有儲熱保溫之特性。This dissertation reports on the synthesis of vertically aligned carbon nanotube carpets/carbon nanocoils, the measurement of their electro and electro-thermal properties, and some of their electro-thermal applications. Vertically aligned multi-walled carbon nanotube (VACNT) carpets have been synthesized on metal thin films and isolating substrates without the use of a pre-deposited catalyst. We used ferrocene as precursor powder catalyst and acetylene as a carbon source to grow VACNT carpets using three-temperature-zone chemical vapor deposition (TTZ-CVD). Tuning the carrier gas Ar flow rate and the sublimation time of ferocene in the TTZ-CVD extended the lifetime of the catalyst, increasing the efficiency of growth. By controlling the growth parameters, the growth of VACNT carpets on selective substrate can be controlled. Radial growth of carbon nanocoils (R-CNCs) on stainless steel (SS) wire has been achieved using thermal chemical vapor deposition from acetylene. A solution of tin acetate in ethanol with molarities of 0.01-0.2 M was coated on SS wire and oxidized as an active catalyst in air at 600-1000ºC. It was found that SS wire oxidized at 900ºC for 30 min with a tin solution of 0.1M exhibited the highest catalytic activity. Growing R-CNCs on metal wire provides excellent electrical contact, good alignment, and ease of handling and manipulation. VACNT carpets have been synthesized onto commercially available aluminum foil without the use of a pre-deposited catalyst. A high-sensitivity flexible strain sensor is used Al foils and VACNT carpets. The sensor allows change in contact resistance between the VACNT carpets to detect lengthwise strain. Experimental results show the sensor measures a strain as small as 0.0028%. The measured gauge factor of the sensor is 296. The demonstrated flexible sensors have high sensitivity and quality, which is beneficial in mass production. VACNT carpets were existed a high heating efficiency using the low power. A heating-resistance device of VACNT carpets has a heating efficiency higher than that of a heating device having a different shape and materials, which can be fabricated in a simple process. On the other hand, this work has a high heating efficiency using a low power. The heating-resistance can achieve over 400℃/W. Moreover, the heating device of VACNT carpets can be easily transferred onto any kind of substrate for wide applications, which is a material that converts electric energy to heat energy and transfers energy by radiating the heat to the objects. The heating device of VACNT carpets is widely used for various home appliances or general industrial fields