本研究為以矽粉為添加劑，在氮氣環境下進行二氧化矽的碳熱還原反應，探討矽粉添加劑對反應產物的形態與反應速率等之影響，並深入研究矽粉添加劑於反應中所扮演之角色。研究中使用直立式管狀高溫爐，由反應前後之重量變化求得二氧化矽之轉化率，以探討各項操作變數對反應之影響。 本文主要探討的因素包括：氮氣流率、矽粉添加量、C/SiO2莫耳數比、樣品載量及反應溫度等。研究中並做各種物性分析（感應耦合電漿質譜分析儀、比表面積測定儀、X-射線繞射儀、低真空掃描式電子顯微鏡等）來提供各項實驗結果之佐證。 實驗結果顯示，增大氮氣流率可增加二氧化矽之轉化率，當氣體流率大於500 ml/min時，則影響並不明顯；添加矽粉可增加二氧化矽之轉化率；過量的碳可提高二氧化矽的轉化率，當C/SiO2莫耳數比大於5時，影響漸減；而減小反應物載量亦可增加二氧化矽之轉化率；升高反應溫度則可明顯的促進反應速率。添加矽粉氮化反應的產物為碳化矽，其型態主要為纖維狀的結晶。推測矽粉添加造成一氧化矽的大量生成與一氧化矽是經由矽粉還原二氧化矽而來，是碳化矽成長的重要機制。 The carbothermal reduction and nitridation of silicon dioxide with silicon powder addition was investigated by weight gain measurement. The reaction were carried out in a vertical reaction tube heated by a tubular furnace. In this study, the operating variables have been discussed included: nitrogen flow rate, amount of silicon powder added in the reactant, silicon dioxide/carbon molar ratio, sample weight, and reaction temperature. The analysis of this experiment is conducted by X-ray diffraction (XRD), scanning electron microscope (SEM), BET surface area, and inductively coupled plasma-mass spectrometer (ICP-MS). The experimental results indicated that the conversion of silicon dioxide is increased with an increasing nitrogen flow rate and the effect is not appreciable when the flow rate exceeds 500ml/min. The conversion of silicon dioxide is increased with an increasing amount of silicon powder added in the reactant. An excess of carbon powder and decrease of the sample weight are required to promote the conversion, however, the effect is not appreciable when the molar ratio is above 5 and sample weight is below 0.3g. Moreover, the reaction rate and the conversion of silicon dioxide is significantly increased with higher reaction temperature. The reaction product is fibrous shape β-SiC with silicon powder addition. We conjectured that the large formation of gaseous SiO is an important way for β-SiC growth.
