Thermal shock resistance test on ZnS domes

Yarden B. Weber; Tal Azoulay; Elaad Mograbi; Evyatar Kassis; Shay Joseph; Doron Yadlovker

doi:10.1117/12.2581326

12 April 2021 Thermal shock resistance test on ZnS domes

Yarden B. Weber, Tal Azoulay, Elaad Mograbi, Evyatar Kassis, Shay Joseph, Doron Yadlovker

Proceedings Volume 11740, Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXXII; 1174010 (2021) https://doi.org/10.1117/12.2581326
Event: SPIE Defense + Commercial Sensing, 2021, Online Only

Abstract

With the advances in the field of high speed and low altitude missiles, thermal shock resistance of IR material domes becomes more critical than ever. In such applications the friction between the dome and the air gives rise to severe aerothermal heating, that can elevate the temperature of the dome well above 250°C in a matter of seconds. Designing the ZnS dome's thickness is a result of a tradeoff between several constraints. Rain Shock and hail impact resistance requirements pull us towards higher thickness. On the other hand, thermal shock resistance favors thinners thicknesses. We present here a recent research of the thermal shock resistance of Rafael made CVD ZnS domes. The method of heating chosen was quenching in hot oil. Ten domes of each type were immersed in mildly stirred oil, heated to consecutively elevated temperatures between 100°C-300°C, and let to cool to room temperature after each step. According to the literature, mildly stirred oil has a heat transfer coefficient in the range of h = 250 ~ 1000 W/m²K, hence for a 4 mm thick ZnS dome, we reach a Biot number between β = 0.06 ~ 0.24 . This is well in the range that is representative of missile dome aerothermal heating, i.e. β = 0.01 ~ 5 . All twenty domes survived the immersions without shattering. This implies that the material properties and process parameters of the Rafael dome production line, exhibits high resistance to thermal shock. Further tests are under way.

Conference Presentation

Citation Download Citation

Yarden B. Weber, Tal Azoulay, Elaad Mograbi, Evyatar Kassis, Shay Joseph, and Doron Yadlovker "Thermal shock resistance test on ZnS domes", Proc. SPIE 11740, Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXXII, 1174010 (12 April 2021); https://doi.org/10.1117/12.2581326

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