title: Evaporation kinetics of laser heated silica in reactive and inert gases based on near-equilibrium dynamics.
abstract: Evaporation kinetics of fused silica were measured up to ≈3000K using CO(2) laser heating, while solid-gas phase chemistry of silica was assessed with hydrogen, air, and nitrogen. Enhanced evaporation in hydrogen was attributed to an additional reduction pathway, while oxidizing conditions pushed the reaction backwards. The observed mass transport limitations supported use of a near-equilibrium analysis for interpreting kinetic data. A semi-empirical model of the evaporation kinetics is derived that accounts for heating, gas chemistry and transport properties. The approach described should have application to materials laser processing, and in applications requiring knowledge of thermal decomposition chemistry under extreme temperatures.
authors.affiliation: Lawrence Livermore National Laboratory Department, Livermore, California 94550, USA. Elhadj2@llnl.gov
authors.forename: Selim
authors.initials: S
authors.lastname: Elhadj
authors.forename: Manyalibo J
authors.initials: MJ
authors.lastname: Matthews
authors.forename: Steven T
authors.initials: ST
authors.lastname: Yang
authors.forename: Diane J
authors.initials: DJ
authors.lastname: Cooke
mesh_terms: D000388:Air; D019277:Entropy; D004867:Equipment Design; D005336:Fiber Optic Technology / Q000379:methods*; D006358:Hot Temperature; D006859:Hydrogen / Q000737:chemistry; D007700:Kinetics; D054020:Lasers, Gas; D008956:Models, Chemical; D009584:Nitrogen / Q000737:chemistry; D005741:Noble Gases / Q000737:chemistry*; D044367:Phase Transition; D012822:Silicon Dioxide / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D005741:Noble Gases; D012822:Silicon Dioxide; D006859:Hydrogen; D009584:Nitrogen