Manufacture and performance of diamond-coated thermocouples

Diamond-coated thermocouples were prepared with the aim of measuring the te mperature at the interface between a grinding wheel and workpiece material. Thermocouples with K-type, R-type and G-type alloy combinations were prepa red. Continuous diamond films were grown on each type of thermocouple using hot filament chemical vapour deposition techniques. The resulting diamond films were characterised using Raman spectroscopy and scanning electron mic roscopy. Diamond deposition was found to be particularly successful, in ter ms of quality and adhesion, with the G-type thermocouple. Diamond-coated G- type thermocouples, with varying diamond thickness, were then prepared and characterised with respect to their thermoelectric voltage response. Such m easurements were performed under static conditions, where the thermocouple joint had been allowed to reach a thermal equilibrium with its environment, and under dynamic conditions, where a pulse of heat was applied to the the rmocouple at various intensities and frequencies. (C) 1999 Published by Els evier Science S.A. All rights reserved.