MODIFIED GLASS BATCH CAN HAVE INCREASED ALUMINA CONTENT BY USING FELDSPAR TO IMPROVE GLASS PROPERTIES
Keywords:
Batch modification, alumina, glass melting ability, glass propertiesAbstract
The original glass composition of 72SiO2-15Na2O-7CaO-4.5MgO-1.5Al2O3 (in weight percent), made of sand (SiO2), soda ash (Na2CO3), dolomite (CaMg(CO3)2, sodium sulfate (Na2SO4), and feldspar (KNaAlSi3O8), was modified by adding more feldspar to increase the alumina content in glass compositions from 1.5 to 2.5 wt%. In glass, alumina (Al2O3) is a network modifier that can improve the mechanical strength and the water resistance of the glass. The results of the experiments of increasing the alumina from 1.5 to 2.5 wt%, the result indicated that the mechanical properties, tested by Vickers micro hardness, increased from 5000 MPa to 5300 MPa and the water solubility decreased from 0.80 to 0.40 mg Na2O per 50 ml H2O. The melting ability of the modified batches was investigated by using the batch-free time method. The thermal property was examined by a viscometer (fiber elongation method). The results showed that the melting ability of new batch did not significantly change and the thermal property remained moderately similar to the original. In summary, glass properties can be improved by adding feldspar to increase the alumina content up to 2.5%
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