Etude de l'amélioration de l'état de surface d'un spinelle MgAl2O4 transparent par dépot de couche en oxyde métallique

Abstract

Transparent materials in contact with aggressive environments such as sandstorms are exposed to surface damage. The transparent MgAl2O4 spinel used as protective window, lens or laser exit port etc. is one of those materials affected by natural aggressions. The impact of the sand particle can cause significant defects on the exposed surface by affecting its optical and mechanical effectiveness. The aim of this work is to study the improvement of the surface state of a spinel damaged surface by the deposition of a thin layer of SiO2-ZrO2 elaborated by sol-gel process. For this purpose, spinel samples of different chemical compositions sintered at different temperatures was sandblasted. Then, they were coated with thin layers. The results indicated that sandblasting strongly affects the surface morphology and therefore the optical transmission except in the case of samples with a small grain size. Also, it has been reported that the deposition of a SiO2-ZrO2 layer clearly improves the surface state and the optical properties of the sandblasted samples and even the mechanical properties expressed by the hardness.