• Lube, Tanja
• Danzer, R.
• Sestakova, Lucie
• Bermejo, Raúl

Abstract

<p>The size and type processing and/or machining defects in monolithic ceramic materials determine the mechanical strength of components, thus yielding a statistically variable brittle fracture which limits their use for load-bearing applications. Layered ceramics have been proposed as an alternative choice for the design of structural ceramics with improved fracture toughness and reliability. The use of tailored residual compressive stresses in the layers is the key parameter to improve the strength as well as the crack resistance of the material during crack growth, yielding in some particular cases a minimum mechanical resistance (threshold strength below which the material does not fail. In this work two multilayer ceramics based on the alumina-zirconia system, designed with external (ECS-laminatesand internal (ICS-laminatescompressive stresses, have been investigated using a fracture mechanics and weight function analysis. An optimal multilayer architecture that maximises material toughness and strength has been found for each design as a function of geometry and material properties. From a flaw tolerant viewpoint, ECS-laminates are suitable for ceramic components which contain small cracks or flaws. On the other hand, the existence of large cracks or defects suggests the use of ICS-laminates to attain a more reliable mechanical response. This analysis can be extended to other multilayer ceramic systems.</p>

Topics

• impedance spectroscopy
• crack
• strength
• layered
• ceramic
• fracture toughness
• ion chromatography
• electron coincidence spectroscopy