Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 59: Poster Session III (Nanotribology; Polymeric biomolecular films; Organic electronics and photovoltaics, Covalent networks on surfaces; Phase transitions; Particles and clusters; Transparent conductive oxides)

O 59.1: Poster

Wednesday, March 16, 2011, 17:30–21:00, P3

Nanoscale hotspot formation in an energetic material during friction — Alexander Kovalev and •Heinz Sturm — BAM - Federal Inst. Mat. Res. Testing, FG "Scanning Probe Microscopy, Tribology and Wear Protection", 12200 Berlin

The chemical-mechanical decomposition of energetic materials is not fully understood, and the initial decomposition steps are not firmly established yet. The nanoscale formation of the hot-spot on 2,4,6-trinitrophenol (TNP) single crystal has been studied using atomic force microscopy (AFM). Indentation and plowing AFM techniques were used for destructive modification of TNP crystal surface. Microcrystals of TNP were grown on a gold substrate by fast evaporation from aqueous saturated solution. During friction we observed features of TNP crystal at the nanoscale which are difficult to explain from the macroscopic point of view of explosion. Occasionally, the hotspot has occurred spontaneously during the scanning process. According to the accepted knowledge of chemical reaction/decomposition of energetic materials the main decomposed substances are gases CO2 and NO2. But, in our experiments, agglomerated solid particles have been occurred on a surface of TNP crystal. It is known that TNP has two polymorph structures. Additionally, partially decomposed TNP may have still a phenyl ring, so pi- pi-complexes may be formed. However, we observed that friction at the nanoscale does not stimulate spontaneous decomposition. The observed behaviours of energetic materials at the nanoscale need further elucidation.