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- Zeitschriftenartikel (6) (entfernen)
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- Friction (2)
- 2, 4, 6-trinitrophenol (1)
- 2,4,6-trinitrophenol (TNP) (1)
- Adhesion (1)
- Angle-resolved scattering (1)
- Atomic force microscopy (1)
- Contact mechanics (1)
- DLC (1)
- Dynamic ploughing lithography (1)
- Elastic contact (1)
Observation of nanoscale hot-spot generation on a 2, 4, 6-trinitrophenol (TNP) single crystal
(2011)
An energetic material (EM) creates a local thermal point when it accepts energy and the EM will explode due to thermal decomposition when the hot-spot temperature reaches the explosive temperature. The initial stage of the hot-spot formation on 2, 4, 6-trinitrophenol (TNP) single crystal has been observed at the nanometer scale using atomic force microscopy (AFM). The hot-spot generation has been directly initiated by means of an AFM tip. The phenomenon is accompanied by producing agglomerated spherical-like nanoparticles due to a low-temperature decomposition of TNP. It has been observed that the agglomerated particles are produced outside of the stimulated region. The observed decomposition process at the nanoscale doesn't lead to a self-sustaining shock as detonation or explosion. The results are of interest in relation to explore the origin of deformation-induced chemical decomposition or detonation of EM.
Zero wear (Null Verschleiß)
(2013)
For the first time, we report the direct observation of the nanoscale adsorption and desorption of 2,4,6-trinitrophenol (TNP) molecules on the crystal surface during atomic force microscopy scanning. Our results reveal the position instability of TNP molecules at the border of molecular layers under normal ambient conditions. The observed phenomena are of great interest for exploring the origin of hot-spot generation on the surface of energetic materials. On the basis of the explored properties of TNP crystal, a plausible mechanism of hot-spot formation upon weak initiation at the nanoscale is proposed.
We review contact mechanics with emphasis on the rheological (time dependent) properties of polymers and their relations to surface roughness, material properties, and friction as well as wear behavior of rubbing polymer surfaces. The main concept of polymer mechanics related to tribology consists of three basic elements involved in friction: deformation resulting in the real area of contact of rough surfaces, contact adhesion, and shear and rupture of materials in the contact during the sliding friction. The results of classical work are included, which addresses the real contact area calculation and the description of adhesion interaction between rough surfaces. A brief review of experimental investigations concerning the surface characterization by means of bearing curves, the intermolecular force interaction using the adhesion parameter, the effect of temperature on the real contact area, the formation of transferred polymer film during friction, and tribological behavior of ultrathin polymer layers are presented and their implications discussed.
Recent developments in micromechanics and nanotribology have made adhesion effects very important in the study of actual contact formation and sliding friction. The present work considers the experimental and simulation data on the formation of the adhesion contact and sliding friction for rough surfaces. The simulation of discrete contact was carried out using the AFM images of topography as a source of real surface geometry at micro/nanoscale. The proposed approach of contact modelling is not using the statistical parameters of roughness, but it provides the estimation of the additional adhesion induced contact areas and their influence on sliding friction. The friction law of Bowden and Tabor was used for validation of simulation and experimental data. Furthermore, the workhardening effect was taken into account in simulation of sliding friction, and this enabled to reach a more successful fit of experimental data. The obtained results of the computer simulations will provide a way of studying the movable contact or at least transition from static to dynamic friction at the micro/nanoscale level.
This paper shows how Angle-Resolved Scattering can reveal wear on engineered surfaces. The samples studied, three discs made of steel 100Cr6H used in gear wheels in the automotive industry, were assessed after they had undergone ball-on-disc tests. Scattering maps recorded for spatial frequencies from 0.1 µm-1 to 2.7 µm-1 show a contrast inversion around 0.36 µm-1 revealing the wear trace. Besides measurements of rms roughness, where mean values are 20 nm and 24 nm depending on the locations considered, stationarity and isotropy, we demonstrate the ability of the technique to reveal localized wear on this type of surface in a rapid, robust and convenient way. We show that the tool trace is influenced by the load magnitude rather than by the number of oscillation cycles and highlight the key role played by surface roughness in how the sample responds to wear tests.