In high temperature arc,high purity sulfur hexafluoride will decompose and ionize with energy consumption,which has a great influence on thermal conductivity.Thus,the thermal conductivity at this time can be considered to be composed of two parts,namely,the standard thermal conductivity and the components related to decomposition and ionization reactions.

　　However,for gas medium,the heat transfer ability of high purity sulfur hexafluoride is often not a simple conduction effect,but largely depends on convection heat transfer.Convective heat transfer is due to the existence of local pressure difference,so that the gas medium produces macroscopic movement to diffuse the heat out.The convective heat transfer ability of gas medium is related to the specific heat capacity and viscosity of gas.

　　Secondly,the diameter of sulfur hexafluoride molecules is larger than that of oxygen and nitrogen molecules in air,so that the average free travel of free electrons in sulfur hexafluoride gas is greatly shortened,which makes it difficult to accumulate energy in the electric field,thus reducing the collision free ability of free electrons.

　　In sulfur hexafluoride,the insulation strength of sulfur hexafluoride gas is very high precisely because the net collision free coefficient of electricity is very small and the negative ions with low mobility are easy to combine with positive ions to form neutral molecules.

　　The insulation strength of sulfur hexafluoride gas remains basically unchanged in the range of the frequency of external AC voltage from the industrial frequency to the communication frequency.Therefore,sulfur hexafluoride gas is also widely used in many off-frequency electrical and electronic equipment,such as coaxial cables,waveguides,radar devices,etc.