Crystalline Structure and Grain Size of an Experimental Zirconium-Oxide-Ceramic

Objectives: Characterizing the crystalline structure and the grain size of yttria-stabilzed zirconium-oxide-ceramic (Y-TZP) produced without the use of high pressure and compare with a conventionally produced Y-TZP.
Methods: Seven samples in rod, cylindrical and disk shapes were sintered. Selected surfaces were polished. ATZ-20 (conventional standard Y-TZP) was used as a control. X-ray diffraction (XRD) was performed on two samples per batch with a XPERT-Pro diffractometer (Kα, Cu, 45kV, 40mA; 20.0040-100.008°, step-size 0.0167°, for 10.16s). The data were subsequently submitted to Rietveld analysis. Sub-samples of nine polished specimens were thermally etched (Δt: 10°C/min; 30min at 1350°C), sputtered with AuPd and analyzed using a scanning electron microscope (SEM) (T-Scan-Mira-3-SEM (83’000x) and a ZEISS-Ultra-Plus-SEM (10000x, 25000x)). Optical Granulometry (grain-size-distribution-analysis) was done digitally with the software (ImageJ, NIH) according to ISO 13383-1:2012. Grain size distributions were analyzed using one-way ANOVA (α=0.05, ß=0.2).
Results: XRD data showed that the ATZ-20 samples contained only 2 % of monoclinic phase, but 28% Al₂O₃, which was confirmed in the SEM analyses, while the experimental Y-TZP samples contained 98% tetragonal phase of zirconium oxide. Polishing did not increase the monoclinic phase content. In the ATZ-20 ceramic some pores were identified, however this was not the case for the experimental material. The mean grain size was: ATZ-20: 311±9nm (ZrO₂) and experimental Y-TZP: 322±32nm The geometrical SD was 1.46±0.17nm and 1.40±0.05nm, respectively. No statistical differences were found between the two materials.
Conclusions: The experimental Y-TZP showed the typical zirconium oxide ceramic structure. Based on the crystallinity and grain size distribution, similar mechanical properties should be expected for the experimental Y-TZP.