稻殼以水熱法合成碳化矽-氮化矽
複合材料之研究

稻殼(RHs)在經過600℃與800℃、持溫3小時的燃燒後，可以移除大部分的雜質及金屬性物質，殘留下來的稻殼灰(RHAs)主要成份為二氧化矽(cristobalite phase; 白矽石)和微量有機及金屬性物質。此研究中利用稻殼灰為原料，另添加氫氟酸溶液(HF)作為礦化劑以溶解二氧化矽，並使用氨水 (NH4OH) 當作氮氣及部分水蒸氣壓之來源，而後控制反應溫度、時間，嘗試合成出碳氮化矽 (Silicon Carbonitride, SiCN) 以及氮化矽 (Silicon Nitride, Si3N4)晶體。此篇研究顯示出於[(p-RHA + HF + C + H2O) + NH4OH] 反應系統中，最終產物由原本的白矽石相經由重構相變 (Reconstructive Phase Transformation)以及位移相變(Displacive Phase Transformation)過程轉變為低溫石英相 (Quartz low phase)。而在 [(RHA + HF) + NH4OH (600RHA or 800RHA)] 反應系統中，至目前為止，再反應溫度與時間達到250oC, 24hrs以上時便開始有碳氮化矽之結晶相產生，且其結晶強度隨著反應溫度及持續時間升高而上升。然而，將反應時間拉長雖然有助於SiCN相的生成但也會使得氧及氮原子有更多的機率鑲崁進已生成的碳氮化矽或氮化矽晶體而產生晶格扭曲現象。因此，於研究中之最佳化反應條件為[(800RHA + HF) + NH4OH] 300oC- 24 小時。

關鍵字

稻殼；碳化矽；氮化矽；矽氧氮化物；水熱法

並列摘要

The rice husks (RHs) could remove most of impurities and metallic contents by undergoes thermal decomposed under 600oC and 800oC with 3 hours duration, and the residual rice husk ashes (RHAs) contained silicon dioxide (cristobalite phase) as a main phase with trace organic and metallic matters. In this study we used rice husks as raw materials, and added hydrofluoric acid (HF) solution as mineralizer for silica dissolved, ammonium hydroxide (NH4OH) was used as a source of nitrogen gas and partial water vapor pressure. Therefore, we tried to synthesized silicon carbonitride and silicon nitride crystalline by controlled reaction temperature, duration and additives. In the study of [(p-RHA + HF + C + H2O) + NH4OH] parts, that shows the final low quartz phase transformed from cristobalite phase through Reconstructive Phase Transformation (RPT) processes and followed Displacive Phase Transformation (DPT). In the other hand, in the study of [(RHA + HF) + NH4OH (600RHA or 800RHA)] parts, as present, the silicon carbonitride crystallized started at reaction temperature and duration achieved to 250oC with 24 hours, and then the intensity of crystallize increased with reaction temperature and duration increase. However, increased the reaction temperature not only helps crystallized of SiCN but also provided more probability of embedded of oxygen and nitrogen atoms in silicon carbonitride or silicon nitride and resulted in lattice twisted. Consequently, the optimal reaction condition is [(800RHA + HF) + NH4OH] under 300oC for 24 hours.

並列關鍵字

Rice husks ； Silicon carbide ； Silicon nitride ； Silicon oxynitride ； Hydrothermal method

參考文獻

[2] Yung-Jen Lin, Chia-Ping Tsang, Ceramics International 29 (2003) 69–75, The effects of starting precursors on the carbothermal synthesis of SiC powders

[5] R.V. Krishnarao, Y.R. Mahajan, and T.J. Kumar, Journal of the European Ceramic Society 18 (1998) 147-152, Conversion of raw rice husks to SiC by pyrolysis in nitrogen atmosphere

[6] Hsiung-Wen Han, Hok-Shing Liu, Ceramics International 25 (1999) 631-637, Characterization of vapour deposited products in furnace tube during SiC synthesis from carbonized rice hulls

[7] G.W. Meng, Z. Cui, L.D. Zhang, F. Phillipp, Journal of Crystal Growth 209 (2000) 801-806, Growth and characterization of nanostructured β-SiC via carbothermal reduction of SiO2 xerogels containing carbon nanoparticles

[8] L. Z. Pei, Y. H. Tang, Y. W. Chen, C. Guo, X. X. Li, Y. Yuan, Y. Zhang, Journal of Applied Physics 99, 114306 (2006), Preparation of silicon carbide nanotubes by hydrothermal method

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稻殼以水熱法合成碳化矽-氮化矽複合材料之研究

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