Ceramics International｜英国正版365官方网站 顧曉華 開創實現工業廢矽鋁凝膠低溫合成晶須産業化

  近日，英国正版365官方网站顧曉華課題組在Ceramics International的Top頂刊上發表了題為Industrial waste silica-alumina gel recycling: low-temperature synthesis of mullite whiskers for mass production的研究論文。該研究開創實現工業廢矽鋁凝膠成功回收，揭示了由工業廢矽鋁凝膠低溫合成晶須産業化過程及制備機理，發現了一個新穎的低溫合成晶須的綠色制備方法。研究結果顯示以工業廢矽鋁凝膠和硫酸鋁為原料，AlF₃·3H₂O和Na₂SO₄為助劑，采用氣-液-固(V-L-S)法制備了高純度莫來石晶須（圖1）。采用XRD、TG-DTA、SEM等手段研究了燒結溫度對莫來石化反應和莫來石形貌的影響（圖2-圖7）。結果表明:AlF₃·3H₂O和Na₂SO₄的引入改變了莫來化反應的路徑，使莫來化反應的初始溫度達到720℃；SEM結果表明，當燒結溫度從720℃升高到825℃時，莫來石晶須由二次生長向各向異性生長轉變。

  通過分析，提出了以Na₂SO₄為液相模闆的AlF₃輔助莫來石晶須生長的“溶解-沉澱”過程機理（圖8）。

  該研究成果不僅成功探索了綠色低溫固廢膠渣制備莫來石晶須的制備方法，而且揭示了熔鹽法制備莫來石晶須的機理。本研究提出了一種新穎可行的富矽工業廢棄物回收利用方案，為工業廢棄物的高附加值回收利用提供了新的簡單見解，為莫來石晶須的實際批量生産提供了新的思路。

  本文的工作受到中石化齊魯催化劑公司的支持。晶須掃描和衍射數據測試得到了上海交大測試工作人員的幫助。

Fig. 1 The preparation process of the mullite whisker.

Fig. 2 XRD patterns of samples sintering at different temperatures. (a) shows the full temperature change; (b) and (c) shows a representative change. (d) Rietveld refinement of X-ray powder diffraction data for E sample showing the observed (red circle) and calculated (solid black line) intensities, the calculated Bragg reflections (green tick marks), and the difference (solid blue line).

Fig. 3 SEM micrographs of samples sintering at different temperatures (A1-700 °C, A2-700 °C, A3 EDS analysis spectrum of the whisker from A2; B1-720 °C, B2 are the magnified SEM images of B1, B3 EDS analysis spectrum of the whisker from B2; C1-750 °C, C2 are the magnified SEM images of C1; C3 SEM shows the fine mullite whiskers that have been decomposed from the coarse whiskers; D1-800 °C, D2-800 °C, D3-800 °C; E1−825 °C, E2 and E3 are the magnified SEM images of E1.

Fig. 4 SEM micrographs of samples sintering at different temperatures (F-850 °C, G-875 °C, H-900 °C, I-950 °C, J−1000 °C).

Fig. 5 The morphological evolution model of mullite whiskers at different sintering temperatures.

Fig. 6 TEM characterization of mullite whiskers of sintered samples at 800 °C. (a, d) TEM image of a single mullite whisker; (b) HRTEM image; (c) The SAED of mullite whiskers. (e) shows the crystal structure of mullite along the [001] direction.

Fig. 7 TG-DTA curve of the samples in nitrogen atmosphere.

Fig. 8 The scheme of vapor-liquid-solid (V-L-S) growth mechanism of mullite using AlF₃·3H₂O assisted Na₂SO₄ molten salt method.

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