Over the past forty years, zirconia has been developed into a highly sophisticated advanced ceramic material that is utilized in many important applications via the exploitation of its superior mechanical and unique functional properties.
The exceptional mechanical properties of zirconia are mainly based on the phenomenon of transformation toughening. The delayed martensitic transformation of the tetragonal high - temperature modification into the monoclinic low- temperature modification by adding stabilizing oxides leads to increased stress intensity factors KIc and also R - curve behavior. Hence, appropriately stabilized zirconia has been dubbed “ ceramic steel ”.
The functional properties of fully stabilized zirconia ( FSZ ) and partially stabilized zirconia ( PSZ ) are based largely on the material ’s ionic conductivity at elevated temperatures – a property which is utilized in gas sensors and electrolytes for high - temperature solid oxide fuel cell s ( SOFCs). High - temperature ionic conductivity is based on the existence of vacancies in the oxygen ion lattice caused by the addition of stabilizing cations with valencies lower than that of the zirconium matrix cation. Furthermore, the low thermal conductivity of zirconia has led to applications in thermal barrier coatings for gas turbine vanes and blades. The bio-inert properties of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), coupled to its high strength and toughness, are currently utilized in femoral heads for hip endoprostheses.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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