GLASS WORKABILITY STUDY AND CORRELATION OF MELTING HISTORY, MICROSTRUCTURE, APPARENT LIQUIDUS TEMPERATURE, AND MECHANICAL STRENGTH

The glass workability during the forming process has been discussed from the aspects of rheology, heat transfer, and microstructure. The rheological behaviour and heat-transfer characteristic of glass determine the workability of glass. However, the accidentally caused changes of glass structure during melting, fining and forming can affect the workability; therefore, the apparent liquidus temperature and crystal structure of bad workability glass have been studied and compared with the good workability glass. It is found that the apparent liquidus temperature study seems to be an effective method for determining the good and bad workability glasses. The results from the mechanical strengths study of the good workability glass shows evidence of microvoids of the order of 400 Å existing in the glass structure. However, there is no such evidence in the bad workability glass; therefore, it is believed that a large flaw size, or stress concentration around the inclusions existed in the bad workability glass. © 1979 Chapman and Hall Ltd.