Spontaneous combustion and pyrophoric properties of some powder materials

Conclusions

• 1. The effect of spontaneous ignition was observed and the flash points were determined for metallic powders of titanium, zirconium, and hafnium in a nitrogen medium.

• 2. It has been established that, although the amount of the diluent in mechanical mixtures with metallic titanium, zirconium, and hafnium powders does not influence the flash point of the latter, it still reduces the pyroeffect in spontaneous ignition.

• 3. The moisture and granularity of powdered zirconium considerably affect its flash point in a nitrogen medium. Zirconium powder must be dried befor it is subjected to heat treatment.

• 4. The pyrophoric properties of titanium, zirconium, molybdenum, and tungsten powders in pure form as well as in mixtures with carbon black or boron were investigated, and the temperatures at which the pyroeffect arises in these powders in inert media or in vacuum were determined.