A Cascaded Microwave Plasma Source for Synthesis of Ceramic Nanocomposite Powders

Abstract

ABSTRACTBased on the experience of the synthesis of nanophased ceramic powders with particle size in the range of a few nanometers, a new device for the synthesis of ceramic nanocomposite powders was designed. The new equipment is based on a 915 MHz microwave system built of IEC 153 R9 waveguide elements. The microwaves coming from the magnetron are split up in two branches using an E-plane power splitter. The reaction tube, made of quartz, passes consecutively both branches of the wave-guide system. Behind the applicators with the reaction tube, the waveguides are terminated with sliding shorts. These sliding shorts are adjusted in a way to ignite and operate a plasma in both branches of the waveguide system simultaneously. The system allows the production of homogeneous powders for nanocomposites. “Nanocoated particles” can be obtained in some special cases;for example ZrO2 particles synthesized with sizes in the range between 4 and 5 nm can be coated with a 1 to 2 nm layer of Al2O3 or vice versa. Metal chlorides are selected as precursors for the reactions. A mixture of, argon with 20 vol% oxygen is used as a plasma gas.