The role of interfaces in advanced ceramic composites

Reference	Presenter	Authors (Institution)	Abstract
09-064	Piotr Wiecinski	Wiecinski, P.(Warsaw University of Technology, Faculty of Chemistry); Wieclaw-Midor, A.(Warsaw University of Technology, Faculty of Chemistry); Smolik, J.(Institute for Sustainable Technology – National Research Institute); Garbacz, H.(Warsaw University of Technology, Faculty of Materials Science and Engineering);	The interfaces play important role in providing high mechanical properties and fracture toughness of ceramics materials. In composite ceramic coatings the interfaces dissipate fracture energy and change the direction of crack propagation. They also can split a crack into smaller cracks. These phenomena decrease the possibility of microcrack propagation and decrease the energy of cracks. The interfaces interact also with dislocations and defects. They can act as sources and sinks of defects, barriers to defects and storage sites for defects. The interfaces in the composite coatings can influence mechanisms of grow, grain size, mechanical properties and fracture behaviour. In bulk ceramic materials interfaces between grains (grain boundaries) also determine mechanical properties. The reduction of grain size (increase of interface surface) leads to significant increase of mechanical properties, including facture toughness which, due to low value, very often limits applications of ceramic materials. By applying appropriate modification of the grain boundaries it is possible to reduce the grain growth during sintering as well as modify functional properties of ceramic materials. In this work the influence of the type of interface on the mechanism of growth and grain size in composite multilayer ceramic coatings (Cr/CrN, TiN/CrN) was analyzed. The effect of layer thickness and number of interfaces on mechanical properties, mechanisms of failure (crack initiation and propagation during mechanical loading) in ceramics composite coatings was also examined. In case of bulk ceramic materials, the possible use of metal salts as additives to control the grain size in ZnO based ceramics as well as to change the properties of the grain boundaries (interfaces) is discussed. This work was financially supported by the National Science Centre, Poland (Agreement No. UMO-2016/23/D/ST8/02687).
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