Heat Resistant Glass
Heat resistant properties for heat resistant glass are achieved through post-forming heat treatments and/or by additive elements which increase the temperature resistance of the glass. Heat resistant glass also goes through the process of annealing which helps to achieve the even cooling of a product or piece. This is important as uneven cooling results in stress points and weaknesses in a product, reducing the overall quality, and making it impractical for use as heat resistant glass. Glass that is resistant to shattering and cracking as a result of rapid temperature change has a low thermal expansion coefficient. This is the number that indicates how much a material expands or contracts and changes in terms of volume due to temperature adjustment. The lower the thermal expansion of a material, the more suited it is to being used in processes which require heat resistance. Common uses of heat resistant glass include: fire resistant windows, cookware and stove-top surfaces, fireplace screens, laboratory equipment such as beakers, bottles, flasks, dishes and test tubes.
Tempering is one example of a popular post-production process used to affect the properties of glass and make it more suitable for some applications. It balances the inner and outer stress of the glass by causing the internal parts of the glass products or shapes to contract and the surface tension to increase, resulting in a better balance of stresses in the glass. This is achieved through the application of heat, making it stronger and more resistant to being affected by temperature change.
Tempered glass is an example of standard glass that has undergone treatment to improve its strength and make it useful for a number of strategic applications.
Borosilicate glass, which is standard glass with the element of boron oxide added, is naturally a heat resistant type of glass, as is
quartz glass, which is made from pure silicon, and these types do not need further processing in order to be used as heat resistant glass. Soda-lime glass however, is able to undergo heat treatment procedures to improve its thermal handling capacity, and is usually tempered to improve its heat resistant properties.
