Micropillar compression inside zirconia degraded layer

In the dental field, Yttria-doped Tetragonal Polycrystalline Zirconia (Y-TZP) plays an important role due to its high mechanical properties, good aesthetics and bio-inert behavior. Surface mechanical properties are crucial for Y-TZP especially when it comes to osseointegration or contact loading, since it may undergo a spontaneous aging phenomenon when exposed to humid environment, creating a thin degraded layer that affects surface integrity. In this work, polished samples of Y-TZP have been artificially aged, and micropillars with diameters in the range 3.3–0.3 μm have been milled by FIB inside the degraded layer and in the reference non-aged surface. Reproducible stress–strain curves were obtained by testing the micropillars in compression, demonstrating that this technique is suitable for assessing the degraded surface properties. Mechanical and failure behavior are significantly different for the degraded micropillars due to the presence of microcracks, while important differences are observed when reducing the micropillar diameter.