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An investigation on thermodynamic properties of quartz and borosilicate glass in hydrofluoric acid (HF) medium
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Author : Sarath Menon, Arpita Shukla, S. Noyel Victoria and R. Manivannan*
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ABSTRACT
Glass has become a key ingredient in microsystem technology. Etching of quartz and borosilicate glass in hydrofluoric acid is conducted to investigate the material removal for various applications. This is ascribable to their inherent unique properties. In this present study, effect of time, etchant composition and temperature on static etch rates of two different glass coupons were investigated. The results divulge that etch rates tend to increase with time, HF concentration and solution temperature. Further thermodynamic analysis of dissolution process was performed to evaluate the Arrhenius energy, enthalpy and entropy of activation of the glass coupons in HF medium. Borosilicate showed higher activation energy in comparison with quartz. Endothermic nature of dissolution process is confirmed by the positive value of enthalpy. Negative sign of entropy reflects that activation complex is controlling the process of dissolution.
KEYWORD
Glass, hydrofluoric acid, etching, thermodynamic analysis