Mechanical properties of highly textured porous Ni - YSZ and Co - YSZ cermets produced from Directionally Solidified Eutectics

It is well known that several ceramic materials develop an usual; and sometimes unique; combination of properties as a result of mixing different phases with similar expansion coefficients. Sometimes they are elastically stiff, have relatively low thermal expansion coefficients, good thermal and electrical conductivities, and are resistant to chemical attack. As this paper will show, their mechanical properties are also enhanced. Nanoindentation technique is used to measure the mechanical properties for each phase of NiO-YSZ and CoO-YSZ eutectics produced by the laser floating zone technique, and also the analogues Ni-YSZ and Co-YSZ cermets produced by reduction from the eutectics precursors. The different tests have been performed at a constant indentation depth of 100nm, in order to obtain a residual imprint lower than the size of the secondary phase and extract the hardness and Young’s modulus using the Oliver and Pharr approach. Moreover, several tests have been