Borosilicate Glasses

Silica (SiO2) 65-80%

Boric Oxide (B2O3) 8-25%

Sodium Oxide (Na2O) ~4%

Aluminum Oxide (Al2O3) 2-5%

Borosilicate glasses are known for their resistance to thermal shock and low coefficients of thermal expansion. Borosilicate glasses come in a variety of compositions, and therefore offer a wide range of application uses. Borosilicate glasses can be found in laboratory glassware, medical syringes and ampoules, implantable medical devices, electronic components, lighting components and refractors, solar thermal technology, and more. Due to its superior durability, borosilicate glass is often used for harsh or demanding applications where thermal, mechanical, or chemical resistance is needed. This glass can withstand exposure from harsh chemicals like jet fuel, hydraulic fluid, acids, saline solutions, and petroleum products.

Borosilicate glasses are categorized into three subtypes, depending on their boric oxide content. Non-alkaline-earth borosilicate glasses typically have over 80% silica content and 12-13% boric oxide, and offer high chemical durability and low thermal expansion. Alkaline-earth-containing borosilicate glasses typically contain 75% silica, 8-12% boric oxide, and up to 5% alumina. This composition creates a slightly softer glass with high chemical resistance. High-borate borosilicate glasses contain 65-75% silica and 12-25% boric oxide, with smaller amounts of alkalis and alumina. This composition offers lower softening points, low thermal expansion, and high electrical insulation. This particular composition also places it in the coefficient of thermal expansion range to be sealed with Molybdenum or Tungsten.

Our Borosilicate Glass Materials

Elan 15

Density: 2.22

Coefficient of Expansion: 33

Corning Pyrex Substitute

Common Uses:
Applications requiring heat resistance


Elan 28

Density: 2.03/2.12

Coefficient of Expansion: 30.5

Dielectric Constant: 4.1

Designation for Corning 7070

Common Uses:
Compression seal with Nickel Alloys No. 42, No. 52 or No. 4, or with Kovar


Borosilicate Properties

  • Low coefficient of thermal expansion
  • Excellent thermal resistance
  • Superior chemical resistance
  • Good mechanical strength
  • Variety of compositions depending on specific application

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