Synthesis of ultrafine particles by surface discharge-induced plasma chemical process (SPCP) and its application

A comparison was made between the present surface discharged-induced plasma chemical process (SPCP) approach to chemical vapor deposition (CVD) and another type of cold plasma CVD using a silent glow discharge (GPCP). In the GPCP CVD system, two coaxial cylindrical electrodes are used in combination with two coaxial quartz tubes spaced at a small gap to generate silent discharge in the gap. In the SPCP CVD system, a ceramic-made electrode assembly is used, and a high frequency and a high voltage are applied to form an energetic and stable surface discharge. Both of the methods can produce ultrafine particles of silicone dioxide and titanium dioxide under room temperature and atmospheric pressure. However, SPCP CVD has a great advantage over GPCP CVD in that it permits further electrostatic processing in the same reaction region. For example, a very peculiar ceramic membrane could be produced with SPCP CVD by depositing electrostatically the ultrafine particles on a ceramic substrate and sintering the deposited layer