Fabrications of spherical alumina particles by controlling process parameters in a transferred arc plasma system

Abstract

Aerosol processing is gaining much interest in fabricating particles for various applications due to its easy application and good control of particle characteristics. In this study, spherical alumina particles were prepared using a transferred arc plasma aerosol system with argon shield gas and nitrogen carrier gas. The operating conditions for spheroidization were controlled by comparing the particle heating and particle residence times in plasma to obtain the calculated critical particle size. Nitrogen fractions (10%–63%) and plasma powers (1–2.5 kW) were used as control parameters to verify the process design for the average injected particle sizes of 10 μm and 100 μm. The spherical particle sizes were examined by using field-emission scanning electron microscopy. Results showed that the particle size limits for melting(dP,LM) and vaporization (dP,LV) increased with increasing plasma power. Higher plasma power is required to fabricate spherical shapes from larger injected particles at nitrogen fractions of 10% and 63% because of the longer residence time needed to reach the melting state of the raw materials.