Borosilicate Glass
Borosilicate glass is a heat and shatter resistant material that is composed of silica and at least 5% boron oxide. Also referred to as Pyrex, this glass is mostly designed for products that handle strong acids, alkalis and are used in high-temperature autoclaves, hot plates and open flames. It is mostly used to produce laboratory equipment like beakers, test tubes and telescope mirrors because of its high chemical resistance. Aquarium heaters, flashlight lenses, microwave-safe glass and kitchen ware and precision optical lenses are also often made of borosilicate glass because it exhibits a high temperature range and when dropped, it cracks into big pieces rather than shatters into hundreds of small splinters, making clean up safer and easier.
Because it requires higher heat and more labor during production than standard glass, borosilicate glass tends to be more expensive. However, no other glass is able to handle harsh and volatile chemicals like nuclear waste. Its coefficient of expansion is one third that of standard glass, which reduces the material stresses caused by temperature gradients. This makes borosilicate glass more resistant to breaking, although it will do so if dropped on a hard surface or exposed to sudden and radical temperature change. During formation, the glass must be heated to 1200 degrees F, which is higher than other types of glass. Borosilicate glass is manufactured by adding boron to the traditional glass ingredients-silicate sand, soda and ground lime.