Thermal history sensor based on glass-ceramics

The degradation of mechanical properties of materials during service is strongly dependent on the history of thermal exposure resulting from thermally activated microstructural processes. This degradation can lead to catastrophic failure of engineering components; consequently, knowledge of the thermal history of a component is crucial to predicting the degradation of properties and anticipating/preventing failures. In this work, a thermal history sensor capable of operating wirelessly in severe environments has been developed which functions as much more than a thermal fuse, but less than a computer-monitored thermocouple. The sensor utilizes the thermally activated crystallization of glass-ceramics to record a thermal history fingerprint in an array of glass-ceramic substrates. Computer modeling as well as experimental results are presented as proof of concept for the sensor. Degradation state sensing as well as the effects of environmental moisture on the operation of the sensor will also be discussed. The end product will employ a pattern-matching algorithm to characterize instantly the thermal exposure by comparing to a database of thermal history fingerprints. The thermal history sensor is expected to be useful in a variety of high temperature, severe environment applications. (C) 2007 Elsevier B.V. All rights reserved.