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技术制备了功能性纳米粉体。采用固体和液体前驱体氧化法制备了纳米二氧化钛粉体。等离子体法合成的TiO_2纳米粒子表现出与传统湿法合成不同的物相选择性。通过反应热等离子体处理，一步形成了高结晶度和非平衡化学组成的纳米颗粒。此外，等离子体合成的纳米粉体的高分散行为被认可。超声辐照的悬浮液显示聚集体尺寸接近通过图像分析评价的初级颗粒尺寸。超声波辐射被证明是一个强大的方式来分散纳米粒子，即使在浓缩的水悬浮液。

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.