1. Unique liquid metal properties
Surface tension:
The surface tension of mercury is as high as 487 dyn/cm (20℃), which is one of the highest among common liquids, making it easy to form spherical droplets (used for mirror flatness detection).
Application: Mercury film was used as the reference plane for early telescope mirror polishing.
Extremely low viscosity:
The dynamic viscosity is only 1.53 mPa·s (25℃), close to the viscosity of water (0.89 mPa·s), and has excellent fluidity.
Phenomenon: Fractal flow patterns are formed on inclined surfaces (can be used for microfluidics research).
2. Thermoelectric properties
Thermal conductivity:
The thermal conductivity is 8.3 W/(m·K), which is about 1/5 of iron, but the liquid properties make it an ideal medium for heat dissipation.
Application: Liquid mercury coolant for nuclear reactors (Russian BN series fast reactors).
Conductivity:
Resistivity is 95.8 nΩ·m (20℃), which is better than stainless steel (720 nΩ·m) and has been used for high-current circuit breaker contacts.
3. Density and compressibility
Density anomaly:
The density of solid mercury (α-Hg) is 14.193 g/cm³, which is higher than that of liquid (13.534 g/cm³), which is opposite to most substances.
Mechanism: Solid mercury has a rhombohedral structure with shorter atomic spacing.