Logo: to the web site of the Swedish Defence University

In aerospace applications, but also in manufacturing, mining, energy industry and natural hazards, high temperature, corrosion, erosion and radiation, challenge the performance and being of hardware.

In this work, high-temperature co-fired ceramic (HTCC) alumina and platinum have been used for a range of devices intended for aerospace applications at up to 1000°C.

The thermomechanics of a pressure sensor was investigated, and the interfacing was attained by wireless powering and reading. However, read range was limited and sensitivity decreased with temperature. Silver, electroplated after sintering, was found to remedy this until it eventually alloyed with platinum.

Copper was electroplated and oxidized for oxygen storage in a microcombustor, intended for sample preparation for optogalvanic spectroscopy (OGS) to indicate extraterrestrial life. Despite delamination, caused by residual stresses, the device operated successfully.

Conversely, pre-firing metallization by integration of platinum wires was studied. Freely suspended, and despite heat-induced shape irregularities, these were found advantageous over screen printed elements for gas heating, and temperature and pressure sensing. By fusing off the wires, spherical tips, allowing for impedance monitoring of microplasma sources in, e.g., OGS, were formed.

Microplasma sources can also be used for gas heating. This, together with screen printed and suspended resistive heaters, was evaluated in a microthruster, showing that plasma heating is the most effective, implying fuel consumption reduction in satellite propulsion.

In conclusion, HTCC alumina microdevices are thermally stable and could benefit several aerospace applications, especially with the complementary metallization schemes devised here.

Future developments are expected to include both processing and design, all with the intention of sensing, actuating and surviving in high-temperature environments.