The properties of nanostructured ceramics or engineering applications: the example of silica carbide and alumina/silica carbide compounds

摘要

Over the last years, interest has grown in the development and experimentation of nanostructured ceramic materials. Scientific literature seems to indicate there is a possibility indeed, to obtain ceramics with a nanometric structure with certain advantages in terms of some specific properties, like for example superplasticity, wear resistance and functional properties (electric, thermal, optical, etc.) which would result improved or however different from what observed so far in ceramics with a micrometric structure. The transition from micrometric to nanometric structures (grain size approximately below 200 nm} implies a deep re-examination of the production process, for what concerns powder treatments, moulding and sintering, the potential benefits in terms of properties and performance, can in fact be evaluated ad exploited only if it possible to realise finished items with a high density value and free from defects. In the article, two typical types of ceramics are illustrated, which are especially interest for structural applications: a monolithic ceramic and a compound with a nanometric strengthening phase. The microstructure of these two materials is observed, as well as their specific properties. These properties are then compared with those measured in the same materials with a micrometric structure, to highlight any behaviour difference.