An important and growing field of lubrication lies in the use of solid films, although they are in general more expensive than oils or greases, and require specialist attention both in mechanical design and in coating application techniques. In this paper, the general classification of solid lubricant types is reviewed, along with the reasons for choosing, and methods of depositing, solid lubricants, in particular MoS2. The best‐performing and most flexible technique for making MoS2 films is by physical vapour deposition (PVD), and the variants of that technology are considered. The intrinsically lubricating, lamellar structure of pure MoS2 is described, along with a brief summary of its wear and failure modes. Present applications for lubrication by MoS2 in spacecraft and dry machining are outlined, as are anti‐adhesive uses in extruding and moulding. The current state of the art of modification of MoS2 films consists in the addition of dopants (co‐sputtering), in multilayering as a series of films, each fulfilling a specific task, or in stacking repeating nano‐metre‐scale films. Composite films of MoS2 islands in a hard film matrix are also being developed.
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Two-step laser mass spectrometry (LZMS) was applied to study the chemical nature of adsorbates on aerosol particles which were collected from different sites, e.g. in the countryside, in an industrial zone, by a downtown road, and in a tunnel. The method combines infrared laser desorption from the particle surfaces followed by ultraviolet laser post-ionization of the desorbed neutral molecules. Because of the high sensitivity and optical selectivity of LZMS, virtually no sample preparation is needed, and mass spectra can be recorded in a very short time. Qualitative and quantitative comparisons of plycyclic aromatic hydrocarbons in different sampling areas were carried out. By scanning the ionization laser wavelength, two-dimensional UV/MS spectra can be generated for better identification of the adsorbed species.
A complete study on the energy partitioning upon laser-induced thermal desorption of aniline from silica surfaces was undertaken. The measurements include characterization of the aniline–quartz adsorption system using temperature-programmed desorption, the extrapolation of quasiequilibrium desorption temperatures to the regime of laser heating rates on the order of 109–1010 K/s by computational means, measurement of the kinetic energy distributions of desorbing aniline using a pump–probe method, and the determination of internal energies with resonance-enhanced multiphoton ionization spectroscopy. The measurements are compared to calculations of the surface temperature rise and the resulting desorption rates, based on a finite-difference mathematical description of pulsed laser heating. While the surface temperature of laser-heated silica reaches about 600–700 K at the time of desorption, the translational temperature of laser-desorbed aniline was measured to be Tkin=420±60 K, Tvib was 360±60 K, and Trot was 350±100 K. These results are discussed using different models for laser-induced thermal desorption from surfaces.
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