Surface solar treatment of materials under high solar flux densities : Two examples on a small-scale facility

Abstract
Surface solar treatments of materials using solar furnaces have been investigated by various teams, showing promising results. Concentrated solar energy can compete with conventional radiant sources, like lasers. Two examples of solar surface treatments under elevated flux densities are presented. The re-melting of zirconia-based plasma-sprayed thermal barrier coating was investigated, resulting in transformations equivalent to the ones obtained with laser processing. The porosity is drastically decreased, without morphological transformations in the subsurface, while the chemical composition and the microstructure are unchanged. The solar surface hardening of carbon-steel was also investigated, leading to the increase of the hardness in a layer of controlled thickness, and achieving compressive stresses in this thermally affected area. No tensile peak was observed at the interface with the bulk of the specimens. In both cases, the processing operated were either single spot or continuous scanning.