Improvement of standard ceramic technology for producing YTZP ceramics using hydrothermal synthesis

Abstract

YTZP ceramics, due to their excellent mechanical properties, corrosion resistance and biocompatibility, are a promising material in many areas of industry and technology. Currently, one of the most popular methods for producing YTZP ceramics is standard ceramic technology, which includes many technological stages. In turn, using ZrO₂ – Y₂O₃ nanoparticles obtained by hydrothermal synthesis as the starting material can significantly simplify the production process of YTZP ceramics. In this article, ZrO₂ – Y₂O₃ nanoparticles were synthesized by a hydrothermal method from ZrO(NO₃)₂·2H₂O and Y(NO)₃·2H₂O salts at a temperature of 130 ⁰C for 12 hours. From X-ray diffraction and Raman spectroscopy data, the obtained particles are characterized by the presence of exclusively c – ZrO₂ phase. Analysis of TEM images showed that the particles are nanosized conglomerates of spherical shape with an average size in the range of 4–14 nm. The TGA results indicate that the obtained powders contain residual synthesis products. Short-term exposure to temperature of 1300 ⁰C leads to the incorporation of Y³⁺ ions into the ZrO₂ crystal lattice and the formation of the t-ZrO₂ phase. The bulk ceramic sample synthesized from the obtained nanoparticles is characterized by high values of volume shrinkage (50%) and, at the same time, high porosity due to the evaporation of residual synthesis products under thermal influence. The synthesized sample consists of t – ZrO₂ phase (99%) and m – ZrO₂ phase (less than 1%). Due to the use of nanoparticles synthesized by the hydrothermal method as the starting material, it was possible to exclude the stages of mixing and grinding, manufacturing of press powder, and preliminary annealing from the standard ceramic technology.