Influence of mechanical stresses on thermal properties of ceramic blankets

events hall

Mr. Ohad Amram Shkury, M.Sc. Candidate

30.01.2022

The Auditorium, Meidan, for green pass holders, or via ZOOM

14:30

As a part of the assembly process of the battery, the components are subjected to different pressing forces. We report on the design of a new test setup that enables us perform thermal diffusivity measurements under uniaxial pressure in the normal direction. The samples’ surface and cross sections were characterized using scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDS) for elemental analysis, followed by measurement of the sample’s relative density. Further investigations were conducted applying additional methods: mercury porosimetry to estimate the gas/solid ratio in the samples, differential scanning calorimetry (DSC) to measure the heat capacity, and thermal gravimetric analysis (TGA) to ensure chemical integrity of the isolation at elevated temperatures up to 500°C.

An interesting finding inferred from the mercury porosimetry experiment indicates that the average diameter of open pores evaluated for the majority of the samples is in the nanometric scale, which fits for the mean free path of air at room temperature. One of our main conclusions is linear correlation between the thermal conductivity and the mechanical strain, which can be observed after surpassing an initial threshold in the applied strain. Additionally, a reversible compliance of the sample’s thermal properties as a function of the applied stress was observed, implying on the absence of any hysteresis effect or deformation. This study provides us with predictive tools of the thermal conductivity of thermal blankets subjected to pressure during the device operation.

Supervisor: Prof. Yaron Amouyal

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