臺灣博碩士論文加值系統

本研究係以鹼土氟化物為添加劑，進行矽粉直接氮化反應，在研
究過程中利用熱重分析反應系統進行矽粉氮化反應，由氮化反應前後的重
量變化求得矽粉的轉化率，來探討各項操作變數對氮化反應的影響。
本文中主要探討的影響因素包括有添加劑、氣體流率、氟化鋇添加量、壓
結壓力、氮氣濃度及反應溫度等。研究中並配合物性測試 （X-射線繞射
儀、掃描式電子顯微鏡等），作為各項實驗結果的證明，並進行一系列動
力學的分析及探討。實驗結果顯示，在分別添加0.5 wt%和1 wt%的氟化鋇
、氟化鎂及氟化鈣進行氮化反應之後，發現氟化鋇對於矽粉轉化率的提升
最有效；氣體流率對於提高矽粉的轉化程度並無明顯的影響；添加適量的
氟化鋇於矽粉中，可明顯地提升氮化反應速率及產率；而減小壓結壓力、
提高氮氣濃度及反應溫度皆可提升矽粉的轉化率。而研究結果也發現氮化
反應的進行主要是以氣/固反應為主，而產物是以鬚晶狀的氮化矽居多。
動力學的分析所得到氮化反應的反應級數為 1.47 ± 0.05，而活化能為
559.2 ± 7 kJ/mol。

The nitridation of alkaline earth fluoride added silicon
powder compacts to produce silicon nitride in a flowing 5%
hydrogen / 95% nitrogen stream was investigated by a thermal
gravimetric analysis (TGA)technique. The effect of operating
variables, including kinds of alkalineearth fluorides added,
gaseous flow rate, amount of barium fluoride added,compact
forming pressure, nitrogen concentration and reaction
temperatureon the nitridation were extensively examined. The
analysis of the experiment was conducted by X-ray diffraction
(XRD) and scanning electron microscope.(SEM). Experimental
results indicated that the order of three alkaline
earthfluorides added effect on the nitridation rate is BaF2>
MgF2>CaF2.Changing the gaseous flow rate had no influence on the
reaction. The proper barium fluoride added in silicon powder
would singnificantly promote the nitridation rate and the yield
of silicon nitride. In addition, thereaction rate could be
increased by decreasing the compact forming pressure, increasing
the nitrogen concentration and the reaction temperautre.
Moreover, the primary progress of nitridation was thegas/solid
reaction and the major product of silicon nitride was in the
formof fine whiskers. From the kinetic analysis, we found that
the reaction order of the nitridation was 1.47 ± 0.05 and the
activation energy of thereaction was 559.2 ± 7 kJ/mol.