Production and characterization of MgO partially stabilized zirconia dental ceramics

There are three types of zirconium containing ceramic systems in literature for dental applications. These are classified as yittrium tetragonal zirconia polycrystals (3Y-TZP), magnesium partial stabilized zirconia (Mg-KSZ) and zirconia toughened alumina (ZTA). MgO is an additive in partial stabilized ZrO2 based ceramics, which is widely studied. This study consists of three steps. In the first step. Mg-partial stabilized zirconia (Mg-PSZ) powder was prepared with the addition of magnesium cloride and calcium oxide to the monoclinic zirconia powder. Further step involves dry pressing and cold isostatic pressing of the powders obtained and sintering process of the compacts at three different temperature. Percentages of apparent porosity, closed porosity, total porosity of the samples were calculated. Phase analysis and microstructure investigations were also evaluated by XRD and SEM and mechanical properties were measured by 3-point bending tests and microhardness tests. A commercially available powder stabilized with %3 mol yttria was prepared and sintered in the same conditions by the aim of comparison. As a result, zirconia powder prepared by magnesium cloride and calcium oxide contain a high amount of cubic zirconia with tetragonal phase and calcium zirconate phases. The results showed that the samples synthesized in this study contain high porosity accordingly, two more recipes were prepared by adding magnesium cloride and magnesium nitrate and these powder mixtures were attrition milled before sintering. Consequently, fine grained microstructures and high densities were obtained. Key Words: Mg-PSZ, cold isostatic pressing, sintering, characterization