Effect of microstructure on the mechanical, thermal, and electronic property measurement of ceramic coatings

Ceramic materials were investigated as thermal barrier coatings and electrolytes. Electrophoretic deposition (EPD) and physical vapor deposition (PVD) were employed to fabricate samples, and the mechanical properties and microstructure were examined by nanoindentation and microscopy, respectively. Yttria-stabilized zirconia/alumina (YSZ/Al₂O₃) composite coatings, a candidate for thermal barrier coatings, yield a kinky, rather than smooth, load-displacement curve. Scanning electron microscope (SEM) examination reveals that the kinky curve is because of the porous microstructure and cracks are caused by the compression of the indenter. Li_0.34La_0.51TiO_2.94 (LLTO) on Si/SrRuO₃ (Si/SRO) substrates, an ionic conductor in nature, demonstrates electronic performance. Although SEM images show a continuous and smooth microstructure, a close examination of the microstructure by transmission electron microscopy (TEM) reveals that the observed spikes indicate electronic performance. Therefore, we can conclude that ceramic coatings could serve multiple purposes but their properties are microstructure-dependent.