THERMAL FRACTURE OF CERAMICS WITH TEMPERATURE-DEPENDENT PROPERnES
نویسندگان
چکیده
Some aspects of thetmal fracture mechanics of ceramics with temperature-dependent properties are studied. It is first shown that the square-root singular field still prevaiLY in the crack tip region. However, the size of the K-dominant zone may be influenced by the effect of temperature-dependent properties. Then the steady thetmal stress intensity factor in an edge-cracked strip is calculated. The results show that the stress intensity factor, which is zero when the temperature dependence of material properties is neglected, can exceed the fracture toughness of the ceramic when the temperature dependence of the material properties is considered. Finally, a temperature-dependent crack-bridging law is proposed to study the R-curoe behavior of polycrystalline ceramics subjected to elevated temperatures.
منابع مشابه
Thermal-stress resistance and fracture toughness of two tool ceramics
The thermal-stress resistance and fracture strength behaviour of two oxide ceramics (a hot-pressed pure AI203 and a composite ceramic NTK-HC2) subjected to severe thermal shocks have been investigated. The damage resistance parameter (Kic/of)2 for both ceramics is also determined for a wide range of temperatures (25 ~ to 800 ~ C) and cross-head rates (10 -2 cm min -1 ~ 2.5 m sec -1 ). Fracture ...
متن کاملFracture toughness and thermal shock of tool and turbine ceramics
The behaviour of some commercial tool carbides and turbine ceramics has been investigated in regard to resistance to crack initiation, crack propagation and retained strength after thermal shock. New data are provided, particularly measurements of the fracture toughness of these materials at actual operating temperatures (up to 1200 ~ C). Many of the materials did not follow the generally accep...
متن کاملreview of the mechanical and thermal properties of high temperature Diboride ceramics
Ceramic borides, carbides and nitrides with high melting point, relatively good resistance to oxidation and corrosive environments are considered by many researchers in various high temperature industries, which is known from the family of materials as high temperature ceramic (UHTC). To be. All UHTCs have very strong bonds that give them structural stability at high temperatures, and among the...
متن کاملMicrostructure, mechanical and thermal properties of chalcogenide glasses and glass-ceramics based on Se-As-Ge system nucleated by Sn
In particular, chalcogenide glasses and glass-ceramics are new materials that exhibit good transparency in infrared region (0.8-12µm). We can overcome the main weakness of these glasses by improving the hardness through controlling crystallization. In this paper, we report results of a study on chalcogenide glasses in the ternary system of As-Se-Ge with nominal composition of Snx (Se...
متن کاملTheoretical Research on Thermal Shock Resistance of Ultra-High Temperature Ceramics Focusing on the Adjustment of Stress Reduction Factor
The thermal shock resistance of ceramics depends on not only the mechanical and thermal properties of materials, but also the external constraint and thermal condition. So, in order to study the actual situation in its service process, a temperature-dependent thermal shock resistance model for ultra-high temperature ceramics considering the effects of the thermal environment and external constr...
متن کامل