Sulfur hexafluoride is a colorless, odorless, non-toxic and non-flammable inert gas. SF6 is a strongly electronegative gas, whose molecules are easy to adsorb free electrons to form large negative ions, which weaken the collision ionization process in the gas. Therefore, its electrical insulation strength is very high, about 2.5 times that of air insulation strength in uniform electric field. SF6 gas has a thermal decomposition peak at T ≈2000K, so when the AC arc current crosses zero, SF6 has a much stronger cooling effect on arc path than air, and its arcing capability is about 100 times that of air. SF6 gas has been used as arc extinguishing medium for hV circuit breakers since the late 1950s due to its excellent arc extinguishing performance, insulation performance and good chemical stability. In uHV and UHV circuit breakers, SF6, as an arc extinguishing medium, has replaced oil and has largely replaced compressed air.

Sulfur hexafluoride also has great medical applications.

Contrast-enhanced ultrasound is a technology similar to CT enhancement, which is the third revolutionary change in the history of ultrasound development. The contrast agent used in ceUS is sulfur hexafluoride microbubble, which is a microvascular tracer. It is injected by intravenous group in elbow and reaches the target. It can display the microcirculation perfusion of the target in real time. Therefore, the allergy rate is extremely low and no allergy test is needed. And can achieve real-time, dynamic, repeatable high, low cost, no radiation.

Although sulfur hexafluoride has many advantages as a contrast agent, not all of them are applicable. Contraindications include severe chronic bronchitis, emphysema, pulmonary heart disease and severe coronary heart disease. They are used in the differentiation of benign and malignant parenchymal lesions such as liver, kidney and thyroid, cardiac chamber and myocardial contrast echocardiography, angiography of blood vessels, and trauma to parenchymal organs.