This work presents the scale-up of room-temperature mechanochemical synthesis of nanocorundum (high-surface-area α-Al₂O₃) from boehmite (γ-AlOOH). This transformation on the 1 g scale using a laboratory shaker mill had previously been reported. High-energy Simoloyer ball mills equipped with milling chambers of sizes ranging from 1 to 20 L were used to scale up the mechanochemical nanocorundum synthesis to the 50 g to 1 kg scale, which paves the way to further increase batch size. Milling chambers made of steel and lined with silicon nitride (Si₃N₄) and milling balls made of steel, zirconia (ZrO₂), and silicon nitride (Si₃N₄) were investigated to address the abrasion problem, leading to contamination of the alumina. Furthermore, several other process parameters, such as ball-to-powder ratio, degree of chamber filling, and milling speed, were optimized to find the conditions for efficient formation of nanocorundum with minimum contamination. Impact forces were found to be decisive in driving the transformation from boehmite to corundum. The nanocorundum produced in the scaled-up experiments has a high specific surface area >110 m²/g with an average particle size of ∼13 nm at a low level of contamination. The optimal sample was also shown to possess improved stability of surface area when exposed to temperatures up to 1200 °C. These results successfully demonstrate the scale-up of 1 g scale results to up to the 1 kg scale and may serve as a blueprint for scaling up also other mechanochemistry processes.

中文翻译：

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通过勃姆石的机械化学脱水放大纳米刚玉合成的规模化


本工作介绍了从勃姆石 （γ-AlOOH） 中制备纳米刚玉 （高表面积 α-Al₂O₃） 的室温机械化学合成的放大。以前曾报道过使用实验室振动研磨机在 1 g 尺度上进行这种转变。配备 1 至 20 L 研磨室的高能 Simoloyer 球磨机用于将机械化学纳米刚玉合成放大到 50 g 至 1 kg 的规模，这为进一步增加批量铺平了道路。研究了由钢制成并衬有氮化硅 （Si₃N₄） 的铣削室和由钢、氧化锆 （ZrO₂） 和氮化硅 （Si₃N₄） 制成的铣削球，以解决导致氧化铝污染的磨损问题。此外，还优化了其他几个工艺参数，例如球粉比、腔室填充程度和研磨速度，以找到有效形成纳米刚玉且污染最小的条件。研究发现，冲击力在推动从勃姆石到刚玉的转变中起着决定性的作用。在放大实验中产生的纳米刚玉具有高比表面积 >110 m²/g，平均粒径为 ∼13 nm，污染水平低。研究还显示，最佳样品在暴露于高达 1200 °C 的温度下时具有更高的表面积稳定性。 这些结果成功地证明了从 1 g 规模的结果放大到 1 kg 规模，并可能作为扩大其他机械化学工艺的蓝图。