Ceramic Alumina Substrates for High-temperature Gas Sensors – Implications for Applicability

Abstract

In the field of gas sensors and high temperature flow sensors, thick-film based structures play a key role, particularly in harsh environments. Their substrates have to be electrically insulating and chemically inert. Alumina substrates are often considered as ideal sensor substrates. However, neither their electrical resistivity nor their chemical inertness is ideal. Even the thermal conductivity is that temperature dependent that one has to consider it when modeling temperature profiles. Measurements on the resistivity and the thermal conductivity between room temperature and 800 oC of alumina substrates are presented in this contribution together with data how the resistance of naked alumina substrates is affected by NO2.