Overview
Hydrofluoric acid (HF) is a solution of hydrogen fluoride in water, known for its ability to dissolve silica-based materials including glass. Unlike most acids, HF penetrates tissue deeply, making it exceptionally dangerous to handle. Industrial-grade HF typically ranges from 40-70% concentration, while reagent-grade solutions are commonly 48-49%. The acid's unique properties make it indispensable in high-tech industries, though its toxicity demands rigorous safety protocols.
Physical and Chemical Properties
HF exhibits unusual characteristics compared to other mineral acids. It forms hydrogen bonds in both liquid and gaseous states, creating polymerized chains. The acid weakly dissociates in water, with dilute solutions being more corrosive than concentrated ones due to increased ionization. Notably, HF reacts with silicon dioxide (SiO₂) to form hexafluorosilicic acid, enabling glass etching. This reaction underpins its use in semiconductor manufacturing for cleaning silicon wafers. The acid also forms stable complexes with metal ions, particularly aluminum and iron.
Main Applications
In electronics manufacturing, HF cleans and etches silicon wafers during chip production. The petroleum industry uses it as a catalyst in alkylation processes to produce high-octane gasoline. Other applications include stainless steel pickling, rare earth element extraction, and fluorochemical synthesis. Dental technicians employ dilute HF for porcelain restorations, while artisans use it for decorative glass etching. The acid's ability to dissolve oxides makes it valuable for cleaning metal surfaces before plating or welding.
Safety and Storage
HF requires polypropylene or PTFE containers as it corrodes glass and metals. Storage areas must have calcium gluconate gel (antidote) and emergency showers. Even small skin exposures can cause systemic toxicity leading to hypocalcemia. Facilities handling HF should implement rigorous engineering controls including fume hoods and gas detectors. Personnel need acid-resistant suits, face shields, and respiratory protection. Spill kits must contain specialized neutralizers like calcium carbonate or magnesium oxide.
B2B Procurement Guide
Buyers should verify suppliers' compliance with transportation regulations (e.g., UN1790 for >60% solutions). Technical specifications should include metallic impurity levels for electronics-grade HF. Consider on-site generation systems for large-scale users to minimize transport risks. Contracts should address delivery methods (dedicated tankers vs. drums) and emergency response support. Many regions require permits for quantities exceeding threshold limits (typically 1,000 lbs).