Atomic layer deposition (ALD) is uniquely capable of providing uniform thin-film coatings on powder substrates, but powder processing has historically required an ALD reactor designed specifically for powders—e.g., a fluidized bed. Tubular hot-walled viscous-flow reactors commonly employed in laboratory-scale ALD research for coating planar substrates such as silicon have been employed previously to coat gram quantities of powder spread out in a thin layer on a tray, but larger quantities of powder introduce long diffusion pathways where reactants are unable to percolate to the bottom of the powder bed to provide uniform coating in reasonable time periods. In this work, we report a rotary drum with a capacity of 100s of grams that is compatible with conventional tubular hot-walled ALD reactors and provides uniform coatings on powders in viscous flow operation. We benchmark this system using Al₂O₃ ALD with trimethylaluminum and water. We examine the effect of rotation speed and powder quantity on saturation time via in situ quadrupole mass spectroscopy measurements and gravimetric analysis. The rotary drum we report is able to provide homogenous coating of up to 75 g of silica gel powder with a total surface area of ∼1500 m² in viscous flow operation with precursor utilization as high as 70%.

中文翻译：

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大容量旋转鼓，用于在热壁粘性流动反应器中将原子层沉积到粉末和小型机械零件上

原子层沉积（ALD）独特地能够在粉末基材上提供均匀的薄膜涂层，但是历史上，粉末加工一直需要专门为粉末设计的ALD反应器，例如流化床。通常在实验室规模的ALD研究中通常使用的管状热壁粘性流反应器，用于涂覆诸如硅之类的平面基板，以前曾用于涂覆散布在托盘上的薄层中的克数的粉末，但是大量的粉末会引入很长的时间反应物无法渗透到粉末床底部的扩散途径，无法在合理的时间内提供均匀的涂层。在这项工作中 我们报道了一种容量为100s克的转鼓，该转鼓与传统的管状热壁ALD反应器兼容，并在粘性流动操作中在粉末上提供均匀的涂层。我们使用Al对这个系统进行基准测试₂ O ₃ ALD与三甲基铝和水。通过原位四极杆质谱测量和重量分析，我们研究了转速和粉末量对饱和时间的影响。我们报道的旋转鼓能够在粘性流动操作中提供高达75 g的硅胶粉末均匀涂层，总表面积约为1500 m ²，前体利用率高达70％。