Three point bend tests using a flexural testing machine were used as a standard method of determining fracture toughness. Glass with the highest fracture toughness value was determined through this process. Thermal proof stress testing was used in order to discover the relationship between fracture toughness and temperature for those samples with the greatest fracture toughness values. The devitrification rate was measured using the sodium nitrite additive at intervals from 1 day up to 7 days after casting
When we hear the word “glass” our mind immediately conjures up an image of transparent materials such as window panes, drinking glasses and bottles with colored liquids inside them. However, there are many different types of glasses which vary in their chemical compositions and physical properties – some are hard as diamonds while others are as soft as clay; some are clear like water while others have colors like green or blue; some can withstand great pressure while others shatter into pieces at much lower stresses than other types of glass would do under similar conditions.
The additives used in this project were lithium borate, sodium fumarate and calcium chloride. Sodium nitrite was also added in order to reduce storage time of devitrified samples. All three of the additives are added to soda-lime glass compositions and are found in small quantities within the overall composition of glass. The additive modifier can be polymerized or precipitated into a glass matrix during processing or quenched into an existing crystal structure while still molten; they take part in the formation process and contribute to its mechanical properties by increasing strength, decreasing brittleness at high temperatures, improving thermal shock resistance and acting as nucleating agents for crystallization.
In conclusion, the results show that additives can be added to glass in order to make it less brittle. The fracture toughness values for these samples will be higher than those of normal soda lime glasses which have similar compositions but do not have any additives added.