SiO2 coated CNT films for regulated laser ablation plasma dynamics

SiO 2 　coating enhanced the thermal stability and oxidation resistance of CNTF with suppressed thermal-affected zones. • SiO 2 incorporation reduceｓ C 2 plume emission intensity and plume expansion velocity. • The SiO 2 coating increases C m 　of CNTF by 29.2%, attributed to improved thermal confinement and reduced excessive mass ejection. Carbon nanotube films (CNTFs) hold considerable potential as carbon-based propellants; however, their energy-conversion efficiency is constrained by rapid heat diffusion and inefficient utilization of ablation products. Herein, we report a surface-engineering approach employing SiO 2 -mediated thermal confinement to modulate the ablation characteristics of CNTFs. CNTF/SiO 2 composite films with varying SiO 2 contents are fabricated via vacuum-assisted infiltration followed by thermal conversion. Comprehensive structural characterization confirms the formation of a relatively continuous SiO 2 coating with interfacial SiC x O y species on the CNTF scaffold. Time-resolved plasma imaging reveals that SiO 2 incorporation suppresses C 2 plume expansion velocity from 13,448 ± 6 to 9703 ± 30 m/s and extends the characteristic decay time from 24.4 ± 0.6 to 32.3 ± 3.1 ns, evidencing moderated plasma relaxation dynamics. Thermogravimetric analysis shows that the SiO 2 coating elevates the oxidation onset temperature from ~500 to 600 °C, while post-ablation SEM observations reveal substantially reduced ablation crater dimensions and heat-affected zones. The optimized CNTF/SiO 2 -3 achieves an impulse coupling coefficient of 31 μN⋅W −1 , representing a 29.2% improvement over pristine CNTF. This improvement is attributed primarily to the SiO 2 thermal confinement which is consistent with a more controlled ablation process and reduced C 2 emission. A more efficient conversion of laser energy into directed momentum is proposed as an interpretation. Our results demonstrate that inorganic oxide coatings offer a promising strategy for designing high-performance carbon-based propellants for laser ablation propulsion. Download: Download high-res image (649KB) Download: Download full-size image