Carbon content control in plasma carburizing using process parameter and probe methods

Low carbon steel foil specimen was plasma carburized in methane/hydrogen mixed gas. In this study carbon content was controlled using process parameter and probe methods. As the plasma current, plasma voltage and/or treating time increases, the carbon content increases. An equation, by which carbon content was accurately estimated with respect to process parameters, was obtained. Using this equation along with variables such as treating time, plasma current and plasma voltage, the carbon content can be predicted using the treating parameters. In the plasma carburizing process, the influence of electron temperature and electron density measured by the Langmuir probe, on carbon content was studied on low carbon steel foils of 0.25 mm in thickness. Increases in plasma current and plasma voltage lead to decrease in electron temperature. The carbon content decreases curvilinearly as the electron temperature increases.