Early stages of oxidation observed by in situ thermogravimetry in low pressure atmospheres

Abstract A highly sensitive set-up for in situ mass-gain measurements during high temperature reaction is presented. By removing the inert gas components of a corrosive atmosphere and keeping the flows and partial pressures of the reactive species constant, the experiment is preformed in a low-pressure environment. A better signal-to-noise ratio which increases sensitivity down to 10 μg/cm 2 is achieved. The random behaviour of the mass-gain signal, caused by turbulences in the gas stream, could be reduced by a factor of 10. Compared to theoretical simulations, the mass-change during oxidation in binary iron-based model alloys is slower than expected from pure bulk diffusion behaviour.