Plasma dynamic synthesis of ultradisperse aluminum oxide in carbon dioxide medium

Abstract

High stable interest in aluminum oxide as one of the most widespread functional materials andconstant expansion of its possible applications cause significant production volumes, as well as thesearch for new synthesis methods. Potentially, aluminum oxide can be produced by applying carbondioxide (CO2) as a cheap and available source of oxygen. However, the use of CO2 as an oxidizingagent requires breaking the bonds of the CO2 molecule, which is a very energy-consuming process.This paper presents a fundamentally new approach to the synthesis of aluminum oxide when applyingCO2 as a gaseous precursor and oxidizer, based on the application of pulsed arc discharge plasmaof the electric erosion type. The implementation of the proposed method, called plasma dynamicsynthesis, results in producing ultradisperse aluminum oxide. The influence of the plasma jet outflowmode on the composition and morphology of the synthesized materials is investigated. The multipulseoperation mode in the considered system provides obtaining of almost complete oxidation ofsynthesis products and high productivity (up to 15 g per cycle), as well as allows achieving the CO2conversion rate of up to 14.5%. The plasma dynamic synthesis implementation is found to result inalmost completely oxidized and highly dispersed product with minimum content of metal phase andparticle sizes in the range from 50 nm to 1 μm.