Understanding ceramics upon exposure to extreme environments

In materials science, a detailed study of the microstructural characteristics, from the micro- down to the nano-scale, is fundamental for the identification of particular features, deriving from processing, which are responsible of specific thermo-mechanical behaviors. Only with an overall understanding of the microstructure evolution and behavior under extreme environment, corrective actions can be taken and materials performance ameliorated beyond current state of art. Extreme environment has a broad meaning, that might imply high-speed rate impact, corrosion, high temperature and ablation or a combination thereof. Here, the focus is on those structural ceramic materials that must withstand high thermo-mechanical loads at temperature above 1500°C. Thinking about the fields of machining and mining, WC-based ceramics play a major role, but are rarely used above 1000-1200°C due to the common addition of metallic phases. Moving then to the aero-space and hypersonic fields, the family of materials known as ultra-high temperature ceramics (UHTC) is the most suitable candidate. Each of the identified environment imposes a set of different structural requirements that are achievable only upon a careful tailoring of components, synthesis and processing. A series of ceramics and their unique microstructural features are presented and correlated to the observed specific properties.