Porosity study of zirconia doped yttrium synthesized by Pechini method

Full text: The use of zirconia for the production of dental materials have been employed, due to the need to obtain materials with high mechanical properties and excellent aesthetic conditions. In order to minimize the effects of volume expansion upon transformation of tetragonal-monoclinic phase during cooling of Zirconia, various dimensional stabilizers have been used, highlighting the Yttria (Y₂O₃ ), which produces a metastable tetragonal crystals in matrix of Zirconia, conferring wear resistance, fracture toughness and flexural strength [1]. To ensure that these materials submit a high densification, is important, since the presence of pores acts as stress concentrators and under cyclic stages may develop faults failures and consequently, collapse of structure. The Pechini is a simple method using temperatures varied, allowing synthesize materials with compositional [2]. Therefore, this work aims to evaluate parameters of porosity, from the stoichiometric change of the content of yttrium in zirconia. The resin formed with 3, 4 e 5% Yttria were pre-calcined at 350°C/2h and calcined at 1000°C/4h. The samples were characterized by XRD, XRF and Archimedes Method.The XRD showed the formation of tetragonal zirconia, indicated by reflections (111), (200) e (220), respectively. In XRF results showed agreement with the stoichiometry preliminary established. The Archimedes Method indicates that the materials presented high porosity between 76,4 and 57,8%, independent of the dopant amount introduced. References: [1] THOMPSON, J. et al. Adhesion/cementation to zirconia and other non-silicate ceramics: Where are we now? Elsevier. Dental Materials 27, 71-82, 2011. [2] PECHINI, M.P., Patent, 3, 330, 697, July 11 1967. (author)