B4.1 - Carbon-containing High Temperature Piezoresistive Materials
- Event
- AMA Conferences 2013
2013-05-14 - 2013-05-16
Nürnberg - Band
- Proceedings SENSOR 2013
- Chapter
- B4 - Sensor Materials
- Author(s)
- E. Ionescu, H. Kleebe, K. Krause, N. Nicoloso, R. Riedel - Technische Universität Darmstadt (Germany), L. Toma - Fraunhofer-Institut für Silicatforschung ISC, Bayreuth (Germany)
- Pages
- 252 - 256
- DOI
- 10.5162/sensor2013/B4.1
- ISBN
- 978-3-9813484-3-9
- Price
- free
Abstract
Silicon oxycarbide-based ceramics (SiOC) with contents of segregated carbon in the range from 9 to 33 vol% have been synthesized by pyrolysis of polysiloxanes (1100 °C) and subsequent annealing at high temperatures (1400-1600 °C). The samples annealed at 1400 and 1600 °C were found to exhibit piezoresistivity with room temperature gauge factors 102 < k < 3x103, two to three orders of magnitude higher than those of conventional pressure sensors; whereas the sample synthesized at 1100 °C did not show any piezoresistive effect. X-ray and TEM-analysis of the prepared materials indicate that the piezoresistive behaviour strongly depends on the microstructure of the compounds, most likely . on the presence and nature of the segregated carbon phase. The thermal stability and microstructure of the carbon phase has been assessed by means of temperature-dependent Raman spectroscopy (25 < T < 600 °C). Within the investigated temperature range the microstructure of the carbon phase is essentially unaltered, suggesting that the piezoresistive effect seen at RT will persist up to high temperatures, i.e. up to the thermal stability limit of SiOC (T 1400 °C). Due to their other outstanding properties, e.g. thermal and chemical stability as well as excellent creep resistance, the SiOC compounds allow a substantial extension of the operation pressure and temperature range of piezoresistive sensors beyond the current state-of-the-art.