Physical and Chemical Properties

• Boiling point: 160°C (760 mmHg)
• Density: 0.96
• Vapor pressure: 1.33 hPa at 20°C
• Flash point: 38°C
• Form: Liquid
• Water solubility: 16.662 mg/L at 25°C
• Dielectric constant: 4.1 (20°C)
• LogP: 0.04

Tetraethyl Orthosilicate (TEOS) Basic Properties

• Molecular formula: Si(OC₂H₅)₄
• Appearance: Colorless transparent liquid with special odor
• Relative density: 0.933
• Melting point: -77°C
• Boiling point: 166.5°C
• Viscosity: 0.00179 Pa·s (20°C)
• Refractive index: 1.3837 (20°C)
• Stability: Stable under anhydrous conditions; hydrolyzes in water to ethanol and silicic acid; soluble in alcohol, ether and other organic solvents

Main Applications

• Used as insulating material and coating for electronics industry, zinc powder coating binder, optical glass treatment agent, coagulant, organic silicon solvent, precision casting binder.
• Used for making molds for metal investment casting.
• After complete hydrolysis, produces ultra-fine silica powder for phosphors.
• Used in organic synthesis, soluble silicon preparation, catalyst preparation and regeneration.
• Used as crosslinking agent and intermediate for silicone production.
• Raw material for heat-resistant and chemical-resistant coatings.
• Basic raw material for high-grade crystals and optical glass treatment.
• Used as solvent for mural pigments, providing excellent durability and color brightness.

Product Characteristics

• Produced by reacting silicon tetrachloride with anhydrous ethanol: SiCl₄ + 4C₂H₅OH → Si(OC₂H₅)₄ + 4HCl
• Industrial grade is a mixture of ethyl silicate and polyethyl silicate.
• No gelation by itself; requires hydrolysis under acidic or alkaline conditions to form complex silicate and then gel.
• Advantages: no harmful impurities, no low-melting substances formed during use; controllable processing performance; high refractoriness, good thermal shock stability, high dimensional accuracy and smooth surface; air-hardening with high strength after curing; forms high-strength ceramic bonding at high temperatures.
• Suitable for prefabricated monolithic refractories, especially multi-layer composite preforms.

Hazards

• Low toxicity but strong irritation to eyes and respiratory tract.
• High concentration inhalation causes irritation and may damage lungs, liver and kidneys; anemia observed in animal tests.
• Symptoms: eye and respiratory irritation; high concentration may cause anesthesia; prolonged exposure may lead to death.
• Flammable, moderate fire risk.
• US permissible exposure limit: 10 ppm (85 mg/m³).

Safety Information

• UN Dangerous Goods Code: 1292
• Hazard Class: 3.2
• Packing Group: III