Modeling of the microstructure of ancient functional ceramics and assessment of their performance

Over millennia, ceramics were deployed as quasi universal materials serving diverse functions, such as cooking, storage, transport, construction or pyrotechnical processing. The reasons were that raw materials were ubiquitously available, objects of practically any shape could be moulded from the unfired clay paste and after firing the material presented adequate resistance against mechanical and thermal loads. Nevertheless, different functions required different material properties and the ceramic production process was accordingly adapted, as it has been observed in many studies of functional ceramics for diverse use, such as storage, transport, food processing, pyrotechnology or construction. Apart from the composition of the ceramics, the material properties depended on the ceramics’ microstructure, in terms of pore structure, non-plastic inclusions and vitrification. The performance characteristics of ceramic materials can be tested with specimens cut from the ancient ceramics or by using laboratory specimens replicating the basic characteristics of archaeological ceramics. In the present paper an alternative approach will be introduced, generating 3-dimensional computer models of the ceramics’ microstructure. These are evaluated for their performance under simulated mechanical or thermal loads using the finite element method (FEM). The approach allows for assessing specific parameters of the microstructure in a systematic way. The simulation results are verified with material testing of, among others, specimens of pyrotechnical ceramics. Scope of the study is to identify the most decisive parameters of the microstructure in terms of their effect on the materials performance and to assess technological choices of ancient craftspeople.