Borosilikat

Borosilikat, or borosilicate glass, is a family of glassy materials based on silica (SiO2) with a significant content of boron oxide (B2O3). The boron oxide modifies the glass network, lowering its thermal expansion and increasing resistance to heat and chemical attack. Typical formulations contain around 80% SiO2 and 10–15% B2O3, with small amounts of alkali and aluminum oxides to tailor workability and durability.

Properties of borosilicate glass include a low coefficient of thermal expansion, roughly in the 3–4 × 10^-6 per degree Celsius range, which gives high resistance to thermal shock compared with ordinary soda-lime glass. It remains optically clear and demonstrates good chemical durability against many acids and bases. While inherently brittle, it performs well at elevated temperatures and is widely used where thermal stability and chemical resistance are important.

Production and variants: Borosilicate glass is formed by melting silica with boron oxide and other modifiers, then shaping by blowing, pressing, or casting. The common general-purpose form is designated by a relatively low thermal expansion coefficient (often referred to as Type 3.3 in some standards). The family also includes specialty borosilicate glasses with adjusted compositions for improved optical, mechanical, or thermal properties, as well as glass-ceramics derived from borosilicate networks for particular applications.

Applications: It is widely used for laboratory glassware such as flasks, beakers, condensers, and reaction vessels due to thermal resistance and chemical durability. In consumer products, borosilicate glass is used for cookware and bakeware in many regions. It also serves in certain industrial components, optics, and high-temperature instrumentation where stable performance under heat is required.

History: Development of borosilicate glass began in the late 19th to early 20th century, with notable commercial adoption by Corning Glass Works (notably under the Pyrex brand) and continued production by other manufacturers, including Schott. It remains a standard material for high-temperature laboratory work and specialized engineering uses.