Helium

Helium is widely used in military industry, scientific research, petrochemicals, refrigeration, medical care, semiconductors, pipeline leak detection, superconducting experiments, metal manufacturing, deep-sea diving, high-precision welding, optoelectronic product production, etc.

1. Low-temperature cold source: Taking advantage of the low boiling point of liquid helium of -268.9°C, liquid helium can be used for ultra-low temperature cooling. Ultra-low temperature cooling technology is widely used in fields such as superconducting technology. Superconducting materials need to be at low temperatures (around 100K) to exhibit superconducting properties. In most cases, only liquid helium can easily achieve such extremely low temperatures. . Superconducting technology has major applications in maglev trains in the transportation industry and MRI equipment in the medical field.

2. Balloon inflation: Since the density of helium is much smaller than that of air (the density of air is 1.29kg/m3 and the density of helium is 0.1786kg/m3), and its chemical properties are extremely inactive, it is safer than hydrogen (hydrogen can burn in the air, may cause explosion), helium is often used as the filling gas in spacecraft or advertising balloons.

3. Inspection and analysis: The superconducting magnet of the nuclear magnetic resonance analyzer commonly used in instrument analysis needs to be cooled by liquid helium. In gas chromatography analysis, helium is often used as a carrier gas. Taking advantage of its good permeability and non-flammability, helium also Used in vacuum leak detection, such as helium mass spectrometer leak detector, etc.

4. Shielding gas: Taking advantage of the inactive chemical properties of helium, helium is often used as a shielding gas for welding of magnesium, zirconium, aluminum, titanium and other metals.

5. Other aspects: Helium can be used as a pressurized gas in high vacuum devices, nuclear reactors, and in rockets and spacecrafts to transport liquid propellants such as liquid hydrogen and liquid oxygen. Helium is also used as a cleaning agent for atomic reactors, as a breathing gas mixture in the field of ocean development, as a filling gas for gas thermometers, etc.

Melting point -272.2°C (25 atmospheres);

Boiling point -268.9℃;

Density 0.1785g/L

Critical temperature-267.8℃

Critical pressure 2.26 atmospheres

Thermal conductivity 151.3W/(m·K)

The crystal structure unit cell is a hexagonal unit cell