L-269 Review of EMQ Tests - Part 1 Friction Sensitivity

As with sensitivity to impact, sensitivity to friction is considered part of the basic required information about the small scale sensitivity of energetic materials. The friction test is intended to reproduce the possible fretting of an energetic material in a casing or the effects of a tool scraping against an energetic material during explosives processing. However, many friction test machines and assessment methods exist for this purpose. The aim of this report is thus to review the different existing friction tests and how the friction sensitivity test results are affected by the test environment and the material properties.

A total of 12 friction tests were analysed and their characteristics have been compared. The friction tests considered to be the most commonly used (the BAM friction, the rotary friction and the ABL sliding friction tests) are further described in dedicated sections in the report. The main parameters affecting the friction sensitivity of a given energetic material are the temperature, ingredient morphology, hardness, the presence of a coating, and the particle size. Different empirical correlations have been proposed to correlate the friction sensitivity with other parameters such as the molecular structure, detonation parameters, thermal decomposition parameters or impact sensitivity. However, none of these parameters seem to unambiguously drive the friction sensitivity of a compound.