A range of soda-lime-silica glasses based on the composition 16% Na2O, 10% CaO and 74% SiO2 have been prepared with hydroxyl ion contents which varied from 59 to 780 ppm. The hydroxyl ion contents were determined using transmission Infra-red spectroscopy. The mechanical strength properties were investigated using the constant moment, double cantilever beam arrangement for fracture mechanics studies, and under atmospheres of 1% and 60% relative humidity. Four point bend studies under liquid nitrogen, and at room temperature were carried out using a number of different loading rates. In addition extensive Hertzian fracture and Vickers hardness testing has been carried out. The results of these experiments were analysed in terms of a continuum model of mechanical strength based on fracture mechanics concepts. The fracture mechanics experiments indicated that fracture toughness increased slightly with increasing hydroxyl ion content. Under Stage I subcritical slow crack growth at 60% relative humidity, crack velocities were greater in high hydroxyl ion content glasses than in low hydroxyl ion content glasses. In addition the effects of hydroxyl ion content on the low temperature viscosity, D.C. conductivity and elastic moduli, have been investigated. The viscosity was observed to decrease with increasing hydroxyl ion content, as did the activation energy for viscous flow. The D.C. conductivity decreased with increasing hydroxyl ion content. The mechanical strength results were interpreted in terms of stress-corrosion behaviour, influenced by alkali ion diffusion to the crack tip.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:349451 |
| Date | January 1983 |
| Creators | Chlebik, Adam |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/111969/ |
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