Influence of mechanical stresses on thermal properties of ceramic blankets

events hall

Mr. Ohad Shkury M.Sc. candidate

08.05.2022

David Wang Auditorium, 3rd floor Dalia Meidan Bldg.

14:30

Thermal insulation is widely used for high-end military and space products such as thermal batteries, which are applied as a sole power source in missiles. The ceramic insulation has a key role in maintaining the active materials of the thermal battery above the solidification temperature of the electrolyte, i.e. 350 – 450°C for several minutes up to an hour. As a part of the assembly process of the battery, the insulating ceramic blankets are subjected to different pressing forces. Although the thermal properties of these materials are well-known, no such data are available regarding their thermal behavior upon such press. The goal of this study is to understand the effects of stress on the thermal properties of the insulation. To this end, we apply the laser flash analysis (LFA) technique.
We design a new test setup that enables us perform thermal diffusivity measurements under uniaxial pressure in the normal direction. It is indicated that the average diameter of open pores is in the nanometric length scale. We observe linear increase of the thermal conductivity from ca. 0.20 up to 0.35 W/mK upon increase of the strain up to 27%, which can be observed after an initial threshold of 12% in the applied strain associated to interface thermal resistance. Numerical modeling predicts that this increase of thermal conductivity should be accompanied by reduction of the battery’s operation time from 345 to 250 s at 400°C, respectively. This study provides us with predictive tools of the thermal conductivity of thermal blankets subjected to pressure during the device operation.

BIO

B.Sc. in material science and physics, graduated at 2015
Works at Rafael in the power sources department since 2013 as an R&D engineer
Published one paper at the Power Sources Conference 2018: “Full Scale Thermo Electric Model of Thermal Batteries”.

Host: Assoc. Prof. Yaron Amouyal