Stress design of the ceramic grain boundary

摘要

The trend in the development of ceramic materials has been towards various forms of multiphase composites, or, more exactly, multiphase composed ceramics, which include: fibre (or whisker) enhanced ceramic composites, second-phase particulate dispersed multiphase composed ceramics, self-enhanced multiphase composed ceramics, gradient multiphase composed ceramics, etc. Bonding between different phases is important with regard to some of the properties of multiphase composites. The difference between 'interface' and 'interphase' should be clarified. Only the physical matches of the former need to be considered, but the chemical compatibility between two phases is more important in the latter. Hence, it has been suggested that the grain boundary area should be considered as an independent phase, which is also made to fit the three principles of ceramic design. In this paper, stress design of the ceramic grain boundary is proposed, based on the interface and interphase studies of multiphase composed ceramics. It is expected that, through stress design of the boundary, ceramic composite materials may be obtained which possess the ability to transfer, consume or absorb the applied loading energy so as to achieve ceramic strengthening and toughening, and even to combat the problem of ceramic brittleness.