Effect of temperature-dependent surface heat transfer coefficient on the maximum surface stress in ceramics during quenching

Abstract

We study the difference in the maximum stress on a cylinder surface σ _max using the measured surface heat transfer coefficient h _m instead of its average value h _a during quenching. In the quenching temperatures of 200, 300, 400, 500, 600 and 800°C, the maximum surface stress σ _mmax calculated by h _m is always smaller than σ _amax calculated by h _a, except in the case of 800°C; while the time to reach σ _max calculated by h _m (f _mmax) is always earlier than that by h _a (f _amax). It is inconsistent with the traditional view that σ _max increases with increasing Biot number and the time to reach σ _max decreases with increasing Biot number. Other temperature-dependent properties also have a small effect on the trend of their mutual ratios with quenching temperatures. Such a difference between the two maximum surface stresses is caused by the dramatic variation of h _m with temperature, which needs to be considered in engineering analysis.

Keywords:

• Thermomechanical
• ceramics
• stress analysis
• thermal shock

Acknowledgement

This work is supported by the National Natural Science Foundation of China [grant number 11102208], [grant number 11232013], [grant number 11472285] and [grant number 11572326].