Fracture Strength of Ultra-High Temperature Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 1785-1787
Author(s):  
Tao Zeng ◽  
Dai Ning Fang ◽  
Xia Mei Lu ◽  
Fei Fei Zhou
Keyword(s):  
High Temperature ◽  
Theoretical Model ◽  
High Temperatures ◽  
Fracture Strength ◽  
Environmental Temperature ◽  
Ultra High Temperature Ceramics ◽  
Temperature Range ◽  
Effects Of Temperature ◽  
Ultra High Temperature

This paper presents a theoretical model to predict the fracture strength of ultra-high temperature ceramics (UHTCs). According to different mechanisms, the environmental temperature is divided into four ranges. Effects of temperature and oxidation on the fracture strength of UHTCs are investigated in each temperature range. The results show that oxidation plays an important role in enhancing the fracture strength of UHTCs at high temperatures.

A THERMO-DAMAGE STRENGTH MODEL FOR THE SiC-DEPLETED LAYER OF ULTRA-HIGH-TEMPERATURE CERAMICS ON HIGH TEMPERATURE OXIDATION

2013 ◽  
Vol 05 (03) ◽  
pp. 1350026 ◽  
Author(s):  
RUZHUAN WANG ◽  
WEIGUO LI ◽  
DAINING FANG
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Fracture Strength ◽  
High Temperature Oxidation ◽  
Oxidation Process ◽  
High Porosity ◽  
Strength Model ◽  
Temperature Oxidation ◽  
Ultra High Temperature Ceramics ◽  
Ultra High Temperature

At high temperatures above 1650°C, the SiC -depleted layer of ultra-high-temperature ceramics which has high porosity appears during the oxidation process. In this present paper, based on the studies of the oxidative mechanisms and the fracture mechanisms of ultra-high-temperature ceramics under normal and high temperatures, a thermo-damage strength model for the SiC -depleted layer on high temperature oxidation was proposed. Using the model, the phase transformation, microstructure development and fracture performance in the SiC -depleted layer on high temperature oxidation were studied in detail. The study showed that the porosity is mainly related to the oxidation of SiC . And while the SiC is substantially completely oxidized, only a very small part of matrix is oxidized. The fracture strength of the SiC -depleted layer degrades seriously during the high temperature oxidation process. And the bigger the initial volume fraction of SiC , the lower the fracture strength of the SiC -depleted layer is. This layer may become the origin of failure of material, thus the further researches should be undertaken to improve the oxidation behavior for the ultra-high-temperature ceramics in a wider temperature range.

Temperature and Microstructures Dependent Thermal Shock Resistance Models for Ultra-High-Temperature Ceramics Considering Effect of Residual Stress

2013 ◽  
Vol 29 (4) ◽  
pp. 695-702 ◽  
Author(s):  
R. Z. Wang ◽  
S. G. Ai ◽  
W. G. Li ◽  
J. Zheng ◽  
C. Z. Zhang
Keyword(s):  
Residual Stress ◽  
High Temperature ◽  
Thermal Shock ◽  
Fracture Strength ◽  
Thermal Shock Resistance ◽  
Temperature Dependent ◽  
Ultra High Temperature Ceramics ◽  
Micro Cracks ◽  
Shock Resistance ◽  
Ultra High Temperature

ABSTRACTBased on the researches on the temperature and microstructures dependent fracture strength and temperature dependent thermal shock resistance, the new thermal shock resistance models for ultra-high-temperature ceramics were proposed. The effect of density on the fracture strength of material was investigated. A damage term was introduced to reveal the effects of uncertain factors on fracture strength. The roles of residual stress and microstructure sizes at different initial thermal shock temperatures in the thermal shock resistance were studied using the models. The study showed that the models can reveal the relationships among the residual stress, microstructure sizes and the temperature dependent thermal shock resistance well. The better thermal shock resistance is found for ultra-high-temperature ceramics having small SiC grains and relatively large micro-cracks around SiC grains. Large enhancement in thermal shock resistance can be achieved through our studies.

Ultra High Temperature Ceramics

2013 ◽  
pp. 49-99 ◽  
Author(s):  
Amartya Mukhopadhyay ◽  
G. B. Raju ◽  
Bikramjit Basu
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Ceramic Materials ◽  
Considerable Extent ◽  
Present Review ◽  
Engineering Applications ◽  
Ultra High Temperature Ceramics ◽  
Mechanical And Physical Properties ◽  
Near Future ◽  
Ultra High Temperature

Most engineering applications concerned with exposure to extremely high temperatures, (>2000°C), and harsh environmental conditions require the use of ceramic materials possessing melting points in excess of ~ 3000°C. Such ceramics, more commonly referred to as ultra high temperature ceramics (UHTCs), are required to possess a desired combination of mechanical and physical properties, which are retained despite the extremely high temperatures as demanded by their applications. However, there are some drawbacks of such materials, with respect to both their processing as well as their properties, which limit their applications to a considerable extent and demand careful engineering of their composition and microstructure to circumvent those limitations. Continuing research efforts have been focused on addressing such issues. Against this backdrop, the present review summarizes the various properties possessed by the UHTCs and critically analyzes the issues concerned with such materials. Through such analysis, an overview of the more recent research efforts that have been conducted to solve the various issues related to this material class is presented. This also highlights the difficulties associated with experimental assessments of the various properties of such materials. Lastly, the various existing applications and potential future applications for such materials are mentioned, with an outlook towards the issues that need to be addressed in the near future.

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