Gakuji Tsukada1, Hidekazu Sueyoshi2, Hiroki Kamibayashi2, Masayuki Tokuda3, Mitsuo Torii3. 1. Department of Restorative Dentistry and Endodontology, Kagoshima University Graduate School of Medical and Dental Sciences, Sakuragaoka, Kagoshima, Japan. Electronic address: tsukada@dent.kagoshima-u.ac.jp. 2. Department of Mechanical Engineering, Graduate School of Science and Engineering, Kagoshima University, Korimoto, Kagoshima, Japan. 3. Department of Restorative Dentistry and Endodontology, Kagoshima University Graduate School of Medical and Dental Sciences, Sakuragaoka, Kagoshima, Japan.
Abstract
OBJECTIVES: The purpose of this study was to fabricate functionally graded materials (FGMs) consisting of yttria-stabilised tetragonal zirconia polycrystal (Y-TZP) and porcelain using spark plasma sintering (SPS) and examine the influence of their microstructures and thermal stress on their bending strengths. METHODS: Two types of four-layered Y-TZP/porcelain FGMs having a constant layer thickness and a varying layer thickness, Y-TZP/porcelain composite materials having a microstructure corresponding to each layer in FGMs and monolithic materials of Y-TZP and porcelain were fabricated by SPS. The Y-TZP/porcelain volume fraction of each layer in FGMs was varied over 100/0-70/30. Three-point bending test, X-ray diffraction, density measurement, microstructure observation, and thermal stress estimation were performed to characterise the materials. RESULTS: The bending strength of the Y-TZP/porcelain composite materials decreased with the volume fraction of the porcelain. About FGMs, when the 100%Y-TZP layer was on the tensile stress side during the bending test, the bending strength was almost the same as that of the 100%Y-TZP monolithic material. On the other hand, when the 100%Y-TZP layer was on the compressive stress side, the bending strength of FGM having a constant layer thickness was almost the same as that of the 70%Y-TZP+30%porcelain composite material, while the bending strength of FGM with a varying layer thickness was significantly higher than that of the 70%Y-TZP+30%porcelain composite material. CLINICAL SIGNIFICANCE: The FGMs prepared and analyzed in this research can potentially be used for crowns and bridges as well as for inlays and onlays. CONCLUSION: The SPS method could effectively fabricate the Y-TZP/porcelain FGMs, and the bending strength results revealed that the graded structure was very efficient to raise the bending strength.
OBJECTIVES: The purpose of this study was to fabricate functionally graded materials (FGMs) consisting of yttria-stabilised tetragonal zirconia polycrystal (Y-TZP) and porcelain using spark plasma sintering (SPS) and examine the influence of their microstructures and thermal stress on their bending strengths. METHODS: Two types of four-layered Y-TZP/porcelain FGMs having a constant layer thickness and a varying layer thickness, Y-TZP/porcelain composite materials having a microstructure corresponding to each layer in FGMs and monolithic materials of Y-TZP and porcelain were fabricated by SPS. The Y-TZP/porcelain volume fraction of each layer in FGMs was varied over 100/0-70/30. Three-point bending test, X-ray diffraction, density measurement, microstructure observation, and thermal stress estimation were performed to characterise the materials. RESULTS: The bending strength of the Y-TZP/porcelain composite materials decreased with the volume fraction of the porcelain. About FGMs, when the 100%Y-TZP layer was on the tensile stress side during the bending test, the bending strength was almost the same as that of the 100%Y-TZP monolithic material. On the other hand, when the 100%Y-TZP layer was on the compressive stress side, the bending strength of FGM having a constant layer thickness was almost the same as that of the 70%Y-TZP+30%porcelain composite material, while the bending strength of FGM with a varying layer thickness was significantly higher than that of the 70%Y-TZP+30%porcelain composite material. CLINICAL SIGNIFICANCE: The FGMs prepared and analyzed in this research can potentially be used for crowns and bridges as well as for inlays and onlays. CONCLUSION: The SPS method could effectively fabricate the Y-TZP/porcelain FGMs, and the bending strength results revealed that the graded structure was very efficient to raise the bending strength.
Authors: Bruno Henriques; Douglas Fabris; Júlio C M Souza; Filipe S Silva; Joana Mesquita-Guimarães; Yu Zhang; Márcio Fredel Journal: Mater Sci Eng C Mater Biol Appl Date: 2016-11-25 Impact factor: 7.328
Authors: Douglas Fabris; Júlio C M Souza; Filipe S Silva; Márcio Fredel; Joana Mesquita-Guimarães; Yu Zhang; Bruno Henriques Journal: Ceram Int Date: 2016-04-01 Impact factor: 4.527
Authors: Douglas Fabris; Júlio C M Souza; Filipe S Silva; Márcio Fredel; Joana Mesquita-Guimarães; Yu Zhang; Bruno Henriques Journal: Ceram Int Date: 2016-12-01 Impact factor: 4.527
Authors: Regina Furbino Villefort; Marina Amaral; Gabriel Kalil Rocha Pereira; Tiago Moreira Bastos Campos; Yu Zhang; Marco Antonio Bottino; Luiz Felipe Valandro; Renata Marques de Melo Journal: Dent Mater Date: 2017-01-21 Impact factor: 5.304