The effect of ceramic surface structure modification method on the ignition and combustion behavior of non-metallized and metallized gel fuel particles exposed to conductive heating

Abstract

The study explores the effect of roughness characteristics of ceramic surfaces processed by diamond abrasives (ground and polished) and laser radiation on the consistent patterns and characteristics of the ignition and combustion of non-metallized and metallized gel fuel (GF) particles based on oil-filled cryogels exposed to conductive heating. Ceramics were produced from SiC F1200 powder using spark plasma sintering. It was established that when combustible liquid droplets in a normal state, as well as metallized and non-metallized GF particles are ignited and burned on a ceramic surface, the ignition delay times can be controlled by the characteristics of the heating surface roughness. Laser surface treatment of ceramics was shown to be a high-potential technique to control the ignition delay times of combustible liquid droplets (±48 %), as well as metallized and non-metallized GF particles (±35 %). A reduction in the ignition delay times of liquid fuels, when using laser surface treatment of ceramics, calls for developed, multi-level roughness with Sdr more than 6.3 %. To decrease the ignition delay times of GF on a ceramic surface by using laser treatment, it is necessary to create a texture with roughness parameters Sdr, Sq, Sz close to the respective characteristics of a polished (molecularly-smooth) heating surface. Evidence was provided that laser surface treatment of ceramics is more promising than mechanical processing using diamond abrasives, which is the most common method currently used in mechanical engineering. This is explained by the fact that laser surface treatment of ceramics creates conditions for enhancing the dispersion of GF melt droplets when ignited, as well as reduces the burnout time by creating a layered multimodal texture of the heating surface, characterized by more developed roughness as compared with the texture resulting from the mechanical processing by means of diamond abrasives.