Novel oxide coatings on single-crystal sapphire and sintered ceramics

The formation of the protective and hardening oxide coatings on the surface of the single-crystal sapphire and sintered corundum (ceramics) is studied. Corundum systems with oxide coatings are as yet unknown and our studies are original. The compositions of the coating based on the mixture of Al$_{2}$O$_{3}$ + В$_{2}$О$_{3}$ oxides and a technique of their deposition on the samples are worked out. The strength of the samples during the bending test is studied. It is shown that the hardening of several samples achieves $\sim$30% and microhardness (HV) reaches 30 GPa. Basing on the results of an investigation of the significant number of the samples obtained under different conditions, it is concluded that the developed method of the protection and hardening of the corundum products is promising.