Accession Number:

AD0686952

Title:

SPONTANEOUS EXPLOSION DURING CRYSTAL GROWTH OF LEAD AZIDE,

Descriptive Note:

Corporate Author:

EXPLOSIVES RESEARCH AND DEVELOPMENT ESTABLISHMENT WALTHAM ABBEY (ENGLAND)

Personal Author(s):

Report Date:

1969-03-01

Pagination or Media Count:

7.0

Abstract:

Spontaneous explosion of lead azide during crystallisation is well known but little understood. Results of many experiments are analysed covering crystallisation by metathesis, including hydrazoic acid gas reacting with lead salt solutions, and by recrystallisation of lead azide from aqueous ammonium acetate. Vigorous agitation and hydrophilic colloids as additives suppress spontaneous explosions. There is no evidence connecting their occurrence with three polymorphic modifications. They can be predicted with reasonable accuracy by the authors ammonium acetate method which has proved also that the explosions originate in the very early stages of crystal growth and are not related to larger crystals. A finely divided form of lead azide has been prepared which is especially sensitive to ignition by electric spark. From these results a possible mechanism is proposed which assumes that a thin layer of nuclei forms as the surface of the supersaturated solution from which electrical energy is channelled toward a point of critical potential difference with respect to a successive layer. Author

Subject Categories:

  • Physical Chemistry
  • Ammunition and Explosives

Distribution Statement:

APPROVED FOR PUBLIC RELEASE