| 02 Jan 2026
Nascent Titanium/Silicon-Containing Particle Formation in Corona Discharge Assisted Combustion
Abstract. Plasma-assisted combustion (PAC) is a technology that introduces high concentrations of charges, ions, and radicals, making the flame more stable and efficient. At the same time, PAC has also been shown to alter particle formation during combustion. Here, we investigate the effect of a high-frequency (~ 21 kHz) alternating current (AC) corona discharge on particle formation and growth in a premixed flame, especially at the initial stages (with particle sizes below 10 nm). We first examined the mobility size distribution of ions generated from non-plasma combustion and corona discharge-assisted combustion. The mobility size for positive ions does not change with the introduction of plasma. However, the negative ions change towards a larger size, likely due to different ion chemistry from plasma. We then introduced corona discharge with varying powers into the flame that contains titanium isopropoxide (TTIP) or tetraethyl orthosilicate (TEOS) and obtained the size distribution of the synthesized nanoparticles. We found that particle growth is suppressed by the corona discharge under relatively higher precursor feed rates (above ~ 29 mg h-1 for TTIP and above ~ 60 mg h-1 for TEOS). The mobility diameter is suppressed by up to 12 % for TTIP and by up to 20 % for TEOS. We further used different charging models to examine the impact of plasma on particle formation. In the case of higher precursor feed rates, the incipient particle concentration is high within the flame region. As higher number of charges accumulated on particles from negative charge carriers (including electrons and negative ions) than positive ions, the particles are preferentially charged negative. Such preferential charging results in particle-particle repulsion which suppresses coagulation particle growth. The findings of this study can guide nanoparticle synthesis and particulate matter control using PAC.
This work clearly illustrates the transformation process of precursors in a plasma flame. It investigates the effects of feed rate on the formation of nanoparticles. The study provides guidance for the synthesis of nanoparticles in flames and for controlling the morphology of particulate matter. The research content and conclusions are consistent with the standards of AR journals, and it is recommended for publication after appropriate revisions.
1. The authors could consider increasing the testing and evaluation of the product nanoparticles to enhance the contribution and impact in the field of nanomaterials synthesis.
2. The evaluation methods in this work all use organic sources as raw materials. It could be worthwhile to explore whether similar conclusions hold when using volatile inorganic precursors, which could appropriately expand the application scope of this work.