A Glass-Ceramic Optical Thermal History Sensor for Extreme Environments

This proposal outlines a plan to design, develop and test a prototype glass-ceramic thermal history sensor for use in extreme environments such as encountered in a gas turbine. The proposed sensor is wireless and provides more information than merely the maximum exposure temperature as in the case of a thermal fuse. The sensor will be developed for use in the range of 700 – 1200 degrees centigrade, with a temperature resolution on the order of 30 degrees or better. This is achieved with an array of at least 16 sensor elements with different crystallization rates. The particular innovations outlined in this proposal are: (1) the development of new materials that allow significant increase in sensitivity to time at temperature; (2) an accurate optical sensor readout method that is insensitive to alignment errors and easy to operate; and (3) a data inversion method for reconstruction of the thermal history from a given sensor readout. Several sensor module considerations will be investigated in detail, including sensitivity of crystallization kinetics to moisture in the environment, module assembly, and the effects of thermal and annealing strains. A prototype sensor capable of withstanding prolonged cycling will be developed and tested in a high temperature furnace, and delivered at the end of the Phase II, together with the sensor readout system, for use in further evaluation and experimental demonstrations.