In the development of dry self-lubricating composites, not only solid lubricant particle size and distribution are important, but also the correct selection of the solid lubricant characteristics, which should be stable, i.e. not reactive, during the whole processing. In this work, Fe+9 vol% h-BN composites were produced by uniaxial cold compaction and sintering, for which a reaction between h-BN and iron was detected after sintering at 1,150°C. The reaction phase was characterized by optical and scanning electron microscopy and identified by X-ray diffraction and energy-dispersive X-ray spectroscopy. The newly formed phase had high hardness when compared with the iron matrix. The resulting composites presented a high friction coefficient and high wear.

Une meilleure connaissance du débit de dose absorbée à l’échelle de la molécule d’ADN passe par l’étude de l’évolution spatio-temporelle de la distribution de radicaux libres créés 10-12 secondes après irradiation d’un fragment d’ADN linéaire. Le présent travail consiste en l’étude des processus de diffusion et de réaction de ces radicaux avec les bases principales de l’ADN : la cytosine, la thymine, l’adénine et la guanine. Dans cet objectif, nous appliquons l’équation de diffusion (∂Ci/∂t = Di∇2Ci + F) pour simuler les processus chimiques menant à la détermination des concentrations et des rendements radiochimiques des espèces e-aq, H, OH, des cassures simple et double brin de l’ADN, et nous tenons compte de l’effet radio protecteur des molécules telles que : DMSO (diméthyle sulfoxyde -CH3SOCH3-), Tris ((HOCH2)3CNH2), Formiate de sodium (HCOO-).

The use of Pt to mark the initial location of heterophase boundaries in solid-state reactions was extended to investigate the motion of interfaces during a thin-film solid-state reaction between In2O3 and MgO in the presence of an electric field. The Pt markers were prepared by sputtering a thin Pt film onto a single-crystal substrate. The resulting multilayer was then heated prior to thin-film deposition to de-wet the Pt film and thus form an array of small, isolated particles. These particles serve as fine-scale markers for tracking the motion of interfaces. However, there are certain situations in which the markers can move with the interface.

The kinetics of a thin-film, solid-state reaction were investigated in the spinel-forming oxide system Fe2O3/MgO. In this study, epitactic thin films of Fe2O3 (α, or corundum, structure) were deposited on (001)-oriented MgO using pulsed-laser deposition (PLD). The resulting diffusion couples were then reacted at elevated temperatures in air to induce the reaction between the thin-film and bulk substrate to form the spinel, MgFe2O4. Both the as-deposited and reacted diffusion couples were characterized using low-voltage scanning and transmission electron microscopy. These techniques allow the kinetics of the reaction and the structural properties of the spinel to be investigated.

Analysed compositions of coexisting phases from cordierite-amphibole-bearing rocks (cordierite-orthoamphibole-cummingtonite-garnet-staurolite-spinel-opaque ores) and mica schists (garnet-staurolite-biotite-muscovite-plagioclase-andalusite-quartz) have been used in conjunction with experimentally determined equilibria to estimate pressures and temperatures of metamorphism for the rocks of the Outokumpu district. The data do not determine a single point in P-T space, but bracket an area such that T ≈ 600 ± 50°C and P ≈ 3·5 ± 1 kb. These conditions represent the maximum temperature attained by the rocks, and the associated sulphide ore bodies, during the Svecokarelian orogeny and are consistent with a regional palaeogeotherm of c. 50°C/km.

Assessment of the composition of the coexisting phases in the cordierite-amphibole-bearing rocks, particularly the Fe-Mg-bearing phases, indicates that it is unlikely that either iron or magnesium was mobile during metamorphism and that the equilibrium assemblage represents essentially isochemical metamorphism of a rock composition that predates the metamorphism. A similar genesis is considered likely for the cordierite-anthophyllite rocks of Orijärvi in southern Finland which forms the basis of the classic statement of the magnesium-metasomatism hypothesis.