Processing and MD Analyses of Mechanical Properties of Ceramics Coated Materials

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A commercial borosilicate glass was coated with an alumina of 99.99% purity or a silicon carbide of 99.60% purity by an RF magnetron sputtering method under several conditions. In coating the silicon carbide successfully, the glass substrate was required to be pre-heated. Three-point bending tests of coated materials and the glass substrate were conducted under a constant stress rate. The strength of coated materials was improved in comparison with that of the glass substrate. However, no significant effect of the sputtering condition on the strength was identified in both coated materials. Although the strength of monolithic alumina was clarified to be less than that of monolithic silicon carbide, alumina coated materials were found to be stronger than silicon carbide coated materials in sputtering situations examined in this work. The aforementioned contradiction was attributed to a tensile thermal stress generated in silicon carbide coated materials which were processed by pre-heating substrate.The formation of amorphous ceramic film in sputtering process was simulated by using the dynamics of rigid spheres on the basis of some empirical facts. The structure of simulated film was investigated and a columnar structure associated with the shadowing effect was found to be formed. Simulated results showed that the volume fraction of deposited spheres defined for a simulated film increased as the sphere size is increased, According to an empirical fact, a larger sphere size was assumed to correspond to a higher RF output in sputtering. A larger value of the sphere volume fraction, implying a higher density, was supposed to correspond to a higher resistance to compressive deformation, i.e. a higher hardness. On the assumptions, the dependence of the sphere volume fraction on the sphere size was found to qualitatively agree with the dependence of the film hardness on the RF output as observed experimentally.