فهرست مطالب مجتبی معین افشاری

In this article which is the outcome of a joint project between Science and Industry University of Iran and Shishe Va Gas co, an assessment on the laboratory scale production of four different groups of Non – fluoride opals is carried out.In this project ten samples of calcium- phosphate opals with different chemical compositions, five samples of calcium – zinc - phosphate opals, twelve samples of spontaneous calcium – magnesium opals and fourteen samples of spontaneous calcium opals were produced in laboratory.In all tests, the completely mixed batch was heated at 1450 °c in a high alumina refractory crucible for 2 hours. The molten glass produced was then poured into a small preheated steel mould (at 400 °c) with the dimensions 150×20×20 mm.Finally all the glass samples were annealed at Tg + 5 °c for 30 minutes.The problems facing the melting and fining of opal batches, and also the effect of chemical composition (specially with respect to alakali and alkali earth oxides) on the opacity of glass samples are considerered and discussed thoroughly. Physical and chemical properties of opal glass samples including dilatometric curves, opacity, bending strength, resistance to alkaline and acidic solutions were tested according to standard procedures, and the results are presented in the article, Based on these results, the optimum chemical composition for each group of opal glasses is advised.