Galinstan® is a eutectic alloy composed of gallium, indium and tin (hence its name, which is derived from the gallium, indium and stannum, the latin name for tin).
Although galinstan is a registered trademark of the German medical company Geratherm Medical AG, many other companies offer similar alloys, which are non-toxic and have a very low melt temperature.
These properties make galinstan an ideal substitute for mercury, particularly in clinical thermometers, but also in coolants and thermal grease.
Composition:
There is no specific formula for galinstan, but a standard form is composed as follows:
- Gallium (Ga): 68.5%
- Indium (In): 21.5%
- Tin (Sn): 10%
Indium Corporation produces a mercury substitute alloy that is composed of 61% gallium, 25% indium, 13% tin and 1% zinc, and has a melt temperature of roughly 45°F (7°C).
Properties:
- Appearance: Silvery metallic liquid
- Odor: Odorless
- Solubility: Insoluble in water and organic solvents
- Specific Gravity: 6.4g/cc (room temperature)
- Melting Point: 2.2°F (-19°C) Boiling Point: >2372°F (>1300°C)
- Vapor Pressure: <10-8 Torr (500°C)
- Viscosity: 0.0024 Pa-s (room temperature)
- Thermal conductivity: 16.5 (W-m-1-K-1)
- Electrical Conductivity: 3.46×106 S/m (room temperature)
- Surface Tension: s= 0.718 N/m (room temperature)
Benefits:
Galinstan medical thermometers are considered more accurate than traditional mercury thermometers and much safer, as galinstan alloy is non-toxic and can be safely cleaned in cases of breakage. Also, as opposed to mercury, disposal of galinstan and galinstan thermometers does not pose any serious environmental threat.
Other:
According to Geratherm Medical, galinstan was awarded the gold medal for best new invention at the 1993 "Eureka" Inventors' Fair in Brussels.
