Bending strength of borosilicate glass coated with alumina and silicon carbide by RF magnetron sputtering

Bending strength of ceramics coated glass was investigated from two aspects, concerning effects of the sputtering condition and the difference of target material on the strength. In this work, a borosilicate glass was coated with an alumina or a silicon carbide by a radio-frequency magnetron sputtering method under various conditions. Three-point bending tests of coated materials and the glass substrate were carried out. The strength of coated material was improved compared with that of the glass substrate. The scatter in the strength of coated materials appeared to be comparable with or less than the strength scatter of the glass substrate. Although monolithic alumina is usually weaker than monolithic silicon carbide, the strength of alumina coated materials was found to be higher than that of silicon carbide coated materials. This tendency was explained by a tensile thermal stress generated in silicon carbide coated materials, in which substrates were initially pre-heated.