Dependence of Hardness of Silicate Glasses on Composition and Thermal History

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The prediction of hardness is possible for crystalline materials, but so far not possible for glasses. In this work, several important factors that should be used for predicting the hardness of glasses are discussed. To do so, we have studied the influences of thermal history and chemical composition on hardness of silicate glasses. E-glasses of different compositions are subjected to various degrees of annealing to obtain various fictive temperatures in the glasses. It is found that hardness decreases with the fictive temperature. Addition of Na2O to a SiO2-Al2O3-Na2O glass system causes a decrease in hardness. However, hardness cannot solely be determined from the degree of polymerisation of the glass network. It is also determined by the effect of ionic radius on hardness. However, this effect has opposite trend for alkali and alkaline earth ions. The hardness increases with ionic radius for the alkali series, whereas it decreases for the alkaline earth series. Hence, the field strength of modifiers, the packing density of modifiers, and other factors must be taken into account when predicting hardness from chemical composition. The principles used in the calculation of hardness of crystalline materials only partly apply to glasses.
Original languageEnglish
Publication date2 Jun 2010
Publication statusPublished - 2 Jun 2010
Event10th ESG Glass Conference - Magdeburg, Germany
Duration: 31 May 20102 Jun 2010


Conference10th ESG Glass Conference

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