Borosilicate glass is typically used for its heat and / or chemical resistance. There are many examples of applications where heat resistance is very important, including Pyrex® cookware, laboratory glassware, lighting, and domestic appliances (microwave plates, washing machine doors, and coffee pots).
A new and rapidly-growing application of heat-resistant borosilicate glass is in domestic or industrial solar thermal heating. In these applications, borosilicate glass tubes are the key component. In domestic systems, the glass tube contains a solar collector which captures energy from the sun. The industrial version (known as concentrated solar power) uses large diameter glass tubes carrying a heat transfer fluid onto which mirrors focus the sun.
Pharmaceutical packaging is an example of borosilicate glass being used for its chemical (and also optical) properties. Pharmaceutical (or neutral) glass can be engineered so that, in contact with aqueous solutions, it creates the same pH as is found in the human body.
Another important application of (alkali-free) borosilicate glass is thin film transistor liquid crystal display (TFT LCD) substrate glass, which is used in most flat panel displays such as cell phones, tablets and televisions. The glass is used to sandwich the liquid crystal part of the display. More recently, borosilicate cover glasses have appeared which are used as the scratch-resistant protective outer layer for touch screens.
In the glass manufacturing process, borates significantly lower melting temperature and inhibit crystallization of the glass, both of which greatly facilitate processing. In the final product, borates impart many valuable properties such as low thermal expansion coefficient, good thermal shock and temperature resistance, increased mechanical strength, and improved chemical durability.