Glass-to-metal seal absorb the stresses from thermal expansion mismatches. Due to its very low vapor pressure, indium finds use in glass-metal seals used in vacuum technology. Gallium is a soft metal with melting point at 30 °C. It readily wets glasses and most metals and can be used for seals that can be assembled/disassembled by just slight heating. It can be used as a liquid seal up to high temperatures or even at lower temperatures when alloyed with other metals (e.g. as galinstan). Mercury is a metal liquid at normal temperature. It was used as the earliest glass-to-metal seal and is still
Ionic liquid piston compressor Ionic liquid piston compressor An ionic liquid piston compressor, ionic compressor or ionic liquid piston pump is a hydrogen compressor based on an ionic liquid piston instead of a metal piston as in a piston-metal diaphragm compressor. An ionic liquid compressor takes advantage of two properties of ionic liquids—their virtually non-measurable vapor pressures and large temperature window for the liquid phase—in combination with the low solubility of some gasses ("e.g." hydrogen) in them. This insolubility is exploited by using the body of an ionic liquid to compress hydrogen up to 1000 bar (14,500 psi) in hydrogen filling stations. Linde's ionic