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[en] The vapor cloud produced by a magnetron sputtering gun in the vacuum chamber is not uniform. In order to coat substrates within a desired tolerance of thickness uniformity, a 'flattening' of the vapor flux distribution is required. This is achieved by means of mechanical masks which intercept the vapor cloud, by a carefully designed motion of the substrate through the vapor cloud, or by a combination of both. The present work describes a design method for masks, to be used with planar substrates, and its application in the case of a Varian S-GUN magnetron sputtering gun. By using the mask the coating thickness uniformity on large ring shaped flat substrates, 200 mm wide, has been improved from ±35% to ±9% around the mean value of the thickness. (author)

[en] Short communication

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[en] Titanium is a stabilizer of the high temperature γ phase in dilute U-Ti alloys. A variety of structures may be obtained when samples are cooled from the γ-phase region to room temperature at different rates and under different conditions. We have studied the decomposition modes of the γ phase of U-3.7 at.% Ti alloy, at several isothermal heat treatments followed by quenching to room temperature. SEM and XRD techniques were employed. (orig./TW)

[en] Selected soil samples collected in Kuwait locations where residues of DU ammunition existed as a legacy of the 1991 Gulf War, have been investigated by scanning electron microscopy equipped with an energy dispersive X-ray fluorescence detector (SEM- EDXRF) with the objective to identify the presence of DU particles and characterize their shape and size. The isotopic and total bulk concentrations of uranium in the samples were measured by inductively coupled plasma mass spectrometry (ICP-MS) and alpha spectrometry. The samples studied by SEM-EDXRF were prepared by gently tapping an aluminum stab covered with a doubled-sided adhesive carbon disk, thereby ensuring that the physical integrity of the samples was maintained. The results have indicted that soil collected just below (∼ 5 cm) corroded DU penetrators contained several DU oxide particles (isotopic ratio ²³⁵U/²³⁸U = 0.0021) ranging in size from 1 to 10 microns (approximate geometrical diameter) having an irregular shape. The particles are most likely corrosion products from the DU penetrators. Some particles are imbedded in a larger matrix containing aluminum oxide (corrosion product of the penetrator jacket) and silica (sand). Swipes collected inside holes in tanks hit by DU ammunition, using ultra-pure cotton cloths, have indicated the presence of many small DU particles in the range 1 to 10 microns. In this case the particles were found to contain also small quantities of Fe, probably the results on alloying process occurring when the DU penetrators impact with the tank armor. (author)