Year: 2026
Type: article
Abstract: Onion-like carbons (OLCs) show promise in lubrication, thermal management, and energy storage, but adoption is limited by the absence of continuous, scalable synthesis routes. This work reports continuous plasma processing of aerosolized N234 carbon black in an atmospheric-pressure three-phase (3φ) argon arc reactor operated for more than 100 cumulative hours at approximately 5 kW. A 3 × 3 factorial design varied argon flow rate (12, 15, 18 SLPM) and carbon feed rate (1, 2.25, 3.5 g min⁻¹). Structural evolution was assessed by transmission electron microscopy, first-order Raman spectroscopy (633 nm), and thermogravimetric analysis in air, benchmarked against untreated N234 and commercially graphitized LITX 50. Plasma treatment raised the baseline-corrected Raman intensity ratio I(G)/I(D) from 1.23 ± 0.01 to 1.25–1.35, with the maximum at 1 g min⁻¹ and 12 SLPM approaching the LITX 50 benchmark (1.41 ± 0.04), and narrowed the fitted D-band width from 157 to 79–134 cm⁻¹; I(D)/I(D′) (2.4–4.2) is consistent with boundary-type defects. Oxidation resistance increased in parallel: the 5% mass-loss temperature rose from 549°C to 553–625°C, and the best condition reached a peak mass-loss (DTG) temperature of 726°C (N234: 614°C; LITX 50: 796°C). Within every feed-rate series, both metrics increased with decreasing gas flow rate, consistent with longer plasma residence time; decreasing feed rate additionally improved bulk oxidation metrics, consistent with a larger graphitized fraction at higher thermal dose per unit mass. These results establish 3φ arc processing as a viable continuous route to OLC with predictable process control over graphitization.
Source: Carbon Trends
Institution: University of New Brunswick
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,000
OpenAlex ID: W7223173682