High rate synthesis of nano-size powders at non-equilibrium conditions by controlled thermal plasma processing and the complete dispersion of the powders

利用反应热等离子体加工技术合成了功能纳米结构粉末。采用固体和液体前驱体氧化法制备了纳米氧化钛粉体。等离子体合成的TiO_2纳米颗粒表现出不同于常规湿法合成的相偏好。采用反应热等离子体工艺一步制备了高结晶度、化学成分不平衡的纳米级颗粒。此外，还发现了等离子体合成纳米粉体的高分散特性。超声照射后的悬浮液显示出接近于通过图像分析评估的原始颗粒大小的集合尺寸。超声辐照被证明是一种有效的分散纳米颗粒的方法，即使是在浓水悬浮液中。

Synthesis of functional nano-structured powders has been developed through reactive thermal plasma processing. Nano-sized titanium oxide powders has been prepared by the oxidation of solid and liquid precursors. The plasma-synthesized TiO_2 nano-particles showed phase preferences different from those synthesized by conventional wet processes. Nano-sized particles of high crystallinity and non-equilibrium chemical composition were formed by one-step via reactive thermal plasma processing. Also, high dispersion behavior of plasma-synthesized nanopowders was recognized. The ultrasonically irradiated suspensions show aggregate sizes close to the primary particle sizes evaluated by an image analysis. Ultrasonic irradiation was shown to be a powerful way to disperse nanoparticles even in concentrated aqueous suspensions.