Characterization of magnesia-doped yttria-stabilized zirconia powders for dental technology applications

Purpose: This paper is focused on the works concerning on preparing zirconium oxide ceramic blocks recommended for CAD/CAM systems used in prosthetic dentistry for manufacturing fixed prosthetic restorations. Methods: Zirconium-yttrium-magnesium mixed ceramic oxides were prepared by sol-gel method via hydrolysis and condensation of zirconium alkoxide precursor (zirconium (IV) propoxide) with yttrium and magnesium nitrates diluted in 2-propanol. The aim of this work it was to obtain 2% mol yttria stabilized zirconia ceramic powders with magnesium as an additional tetragonal ZrO₂ phase stabilizer in amount between 2÷6% mol (with 2% variable). Prepared gels were dried (24 h in 65°C). Obtained powders were mixed with binder (carboxymethyl cellulose) and uniaxial pressed in to a specimens with diameter 38 x 22 x 6 mm. Afterwards green bodies were sintered in range of temperature between 1350-1550°C. Powders and blocks were characterized by Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Specific Area Measurement. Results: Highly homogeneous powders with a low open porosity, was obtained. Prepared blocks after sintering showed numerous cracks. Nevertheless blocks was fine grained and show quite reproducible chemical composition. Conclusion: A sol gel wet chemical route of powder synthesis allow to obtain high homogenous ceramic materials with inconsiderable amount of pores with low variation in a diameter. In spite of a reproducible synthesis methods of a ceramic powders, applied to prepare green bodies procedure and sintering manner do not allowed to obtain free from cracks zirconia ceramics blocks.