Borosilicate Glass: Properties and Diverse Applications
Borosilicate Glass: Properties and Applications
Laboratory Equipment
Virtually all modern laboratory glassware is made from borosilicate glass due to its exceptional chemical and thermal resistance, as well as its good optical clarity. While borosilicate glass can react with sodium hydride to produce sodium borohydride, a common laboratory reducing agent, its overall inertness makes it ideal for a wide range of laboratory applications. Fused quartz, with its higher melting point and UV transmission, is used in specific equipment like tube furnace liners and UV cuvettes. However, the cost and difficulty of working with quartz make borosilicate glass the preferred choice for most laboratory equipment.
Electronics Cooling
During the mid-twentieth century, borosilicate glass tubing was used to circulate coolants, often distilled water, through high-power vacuum tube-based electronic equipment, such as commercial broadcast transmitters.
Cookware and Kitchenware
Borosilicate glass is widely used in cookware, particularly in measuring cups with screen-printed graduated measurements commonly found in American kitchens. Its thermal resistance makes it suitable for oven use and its non-reactive nature ensures that it doesn’t affect the taste or quality of food.
Aquarium Heaters
Aquarium heaters often utilize borosilicate glass due to its high heat resistance, allowing it to withstand the significant temperature difference between the water and the nichrome heating element.
Other Applications
- High-Quality Flashlights: Many high-quality flashlights use borosilicate glass lenses for their superior light transmittance compared to plastics or lower-quality glass.
- High-Intensity Discharge (HID) Lamps: Several types of HID lamps, including mercury vapor and metal halide lamps, use borosilicate glass as the outer envelope material due to its heat resistance and ability to withstand high temperatures.
- Specialty Pipes: Borosilicate glass is used to make specialty marijuana and tobacco pipes because its high heat resistance enhances durability.
- Glass Guitar Slides: Most premanufactured glass guitar slides are made from borosilicate glass.
- Art and Lampworking: New lampworking techniques have led to artistic applications of borosilicate glass, including contemporary glass marbles, jewelry, kitchenware, sculptures, and artistic glass tobacco pipes. The introduction of vibrant colors has further expanded the creative possibilities of borosilicate glass in the art world.
- Beverage Glassware: High-quality beverage glassware sometimes utilizes borosilicate glass for its durability, microwave compatibility, and dishwasher safe properties.
- Telescope Mirrors: Most astronomical reflecting telescope mirrors are made from borosilicate glass because its low coefficient of thermal expansion ensures minimal distortion with temperature changes, resulting in precise optical surfaces.
- Optical Lenses: Schott BK-7, a finely made borosilicate crown glass, is commonly used for making instrument lenses due to its high optical quality. Less expensive borosilicate glasses, like Schott B270, are used in”crown glas” eyeglass lenses. However, ordinary borosilicate glass used in kitchenware or telescope mirrors is unsuitable for high-quality lenses due to striations and inclusions.
- Solar Thermal Technology: Borosilicate glass is a preferred material for evacuated tube solar thermal technology due to its strength and heat resistance.
- Microelectromechanical Systems (MEMS): In the semiconductor industry, borosilicate glass is used in the development of MEMS as part of etched silica wafer stacks bonded to etched borosilicate glass.
- Space Shuttle Tiles: The thermal insulation tiles on the Space Shuttle were coated with borosilicate glass for protection against extreme temperatures during re-entry.
- Lighting Refractors: Lighting manufacturers utilize borosilicate glass in their refractors.
- Organic Light Emitting Diode (OLED) Displays: Borosilicate glass, particularly BK7, is a common substrate in OLED fabrication due to its optical and mechanical properties and cost-effectiveness. The thickness of BK7 glass substrates for OLEDs is typically less than 1 millimeter.
- Pharmaceutical Packaging: Borosilicate tubing is used to produce parenteral drug packaging, including vials, pre-filled syringes, ampoules, and dental cartridges. Its chemical resistance minimizes sodium ion migration, making it suitable for injectable drug applications. This type of glass is typically referred to as USP/EP JP Type I.
- Radioactive Waste Disposal: Borosilicate glasses are used for the immobilization and disposal of radioactive waste. High-level radioactive waste is incorporated into alkali borosilicate or phosphate vitreous waste forms through a process called vitrification. The high chemical durability of vitrified glass ensures the safe containment of radioactive waste for thousands or even millions of years.