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  • Küçük Resim
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    Hardness Behavior of Alumina-Zirconia Nanocomposites Synthesized by Gel Process
    (Polish Acad Sciences Inst Physics, 2013) Sahin, O.; Hasde, A.; Gocmez, H.; Tuncer, M.; Cetinkara, H. Ali; Guder, H. Salih; Sahin, E.
    The alumina-zirconia composites are one of the relatively good and promising candidates for biomaterials application, due to biocompatibility and their mechanical properties that combines high flexural strength with a high toughness. The aim of the present work is to analyze the mechanical properties of these composites, where zirconia content was varied from 5 to 50 wt%. The citrate gel method, similar to the polymerized complex method, was used to synthesize these ceramics. Scanning electron microscopy, X-ray diffraction and microhardness tests are used to characterize synthesized materials. The examined material exhibits the behaviour of indentation size effect. Modified proportional resistance model are used to analyze the load dependence of the microhardness. X-ray diffraction analysis was used to calculation of the grain size and dislocation density. It is found that hardness is decreased when the zirconia content increases with enlargement of grain size. DOI: 10.12693/APhysPolA.123.299
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    Mechanical Properties of Nanocrystalline Tetragonal Zirconia Stabilized with CaO, MgO and Y2O3
    (Polish Acad Sciences Inst Physics, 2013) Sahin, O.; Demirkol, I.; Gocmez, H.; Tuncer, M.; Cetinkara, H. Ali; Guder, H. Salih; Sahin, E.
    The citrate gel method, similar to the polymerized complex method, was used to synthesize homogeneous tetragonal zirconia at 1000 degrees C. Nanocrystalline tetragonal phase has been fully stabilized at wide temperature range with 10 mol.% CaO, MgO, and Y2O3 addition. Scanning electron microscopy, X-ray diffraction, and microhardness tests are used to characterize synthesized materials. The grain size and dislocation density were calculated from X-ray diffraction data. The examined material exhibits indentation size effect behavior. Results revealed that the Vickers and Knoop microhardness are dependent on indentation test load. Geometrically necessary dislocation model and modified proportional resistance model are used to analyze the load dependence of the microhardness. The highest hardness values were obtained for the samples with CaO addition; however the lowest values were acquired for sample stabilized with Y2O3 by using both Knoop and Vickers techniques. This situation might be explained using the Hall-Fetch relation. DOI: 10.12693/APhysPolA.123.296