A novel SiC MEMS apparatus for in situ uniaxial testing of microanomaterials at high temperature

摘要

We present a novel silicon carbide MEMS stage for in situ uniaxial test of microanoscale samples at high temperature. The stage, which has a cofabricated temperature sensor, is used as a heat source by Joule heating during in situ tests. We theoretically study the temperature profile of the SiC stage and sample during Joule heating. The results show that sample temperature varies within 3% across the sample length up to 700℃ and is insensitive to sample resistance. We further explore a design parameter space for the SiC stage to minimize the electrical current through the sample and hence prevent potential damages on the sample. For the experimental study, we first present microfabrication and calibration procedures for the SiC MEMS stage and a cofabricated temperature sensor. Then, we experimentally consider the temperature profile of the stage and independently fabricated single crystal silicon (SCS) microsamples by precalibrated temperature sensors. We observe substantial temperature difference between the stage and sample due to the irregular surface contact at the gripping mechanism. Finally, to verify the feasibility of the in situ thermo-mechanical testing method, we obtain stress-strain responses of the SCS microsamples at temperatures from room to 400℃ which matches with the known elastic modulus of SCS in the literature.