Zirconium is capable of exothermic reactions with many other elements and compounds. Zirconium powder is easy to catch fire and explode in air. Therefore, the safety protection in the production and use of zirconium powder must be considered. When the average particle size of zirconium powder is less than 10 μm, spontaneous combustion and explosion often occur when it is dispersed in the air. Zirconium chips catch fire easily and burn at extremely high temperatures.
The limiting conditions for spontaneous combustion and explosion have not been determined, which may depend on the average size, quantity distribution, temperature, humidity and surface state of the zirconium powder particles. Studies have shown that the minimum energy required to ignite the zirconium dust mist is within the range of 5-40mJ. When the minimum energy varies from 0. 4 to 240 μJ, the zirconium thin layer can ignite. There is no obvious relationship between the minimum energy required to ignite the zirconium dust mist and the energy required to ignite the zirconium powder thin layer. The maximum explosive pressure of zirconium powder depends on the concentration of the powder and the individual properties of the particles, i.e. particle size and surface state.
