WTC2005-64372 ADSORPTION OF A FATTY ACID ONTO A DEFORMED ELECTROGALVANIZED STEEL SHEET

ABSTRACT During forming operation of electrogalvanized steel sheets, the crystallographic orientation of the zinc coating may evolve from a pyramidal texture to a basal one. As a consequence, the adsorption of lubricant additives onto the zinc surface may be altered. Plane-strain compression tests and XRD analysis are carried out to study the texture evolution. After deformation, the samples are cleaned and their reactivity versus fatty acids are measured by ToF-SIMS analysis. It is shown that fatty acids adsorb much more strongly on a pyramidal oriented zinc surface than on a basal one

Tribology of plane strain compression tests on aluminium strip using ToF-SIMS analysis of transfer films

International audienceAn experimental investigation of the tribology during plane strain compression of aluminium strip using steel tools is described. A formulated lubricant containing ester, and hexadecane containing 0, 0.05 and 0.5% stearic acid, are used as lubricants. The friction factor is measured for a wide variety of process conditions and correlated with surface analysis techniques including ToF-SIMS (time-of-flight secondary ion mass spectroscopy). The roughness of the tool is clearly seen imprinted on the strip, indicating that any hydrodynamic or hydrostatic film separating the tool and strip is very small. With clean tools and longitudinal strip roughness, the friction stress equals the shear yield stress of the metal. For transverse strip roughness, hydrodynamic or hydrostatic effects lead to a reduced friction factor. With these cleaned tools there is no effect of additive concentration. After a small number of indents a transfer film builds up on the tool, leading to a fall in friction factor. The strip takes on a smeared appearance with black lines running in the direction of relative slip between strip and tool. This transfer layer is of a 'low friction slurry' type, which is easily wiped-off using tissue paper. The effectiveness of this transfer layer in reducing friction increases with increasing indentation speed and additive concentration. ToF-SIMS analysis shows that this transfer layer contains aluminium and aluminium stearate-the latter being formed specifically by reaction of stearic acid with fresh metal surface formed during deformation

Experimental approaches to better understand the retention of aroma compounds in oro-naso-pharyngeal cavities

Better understanding the persistence of aroma compounds during food consumption has constituted a challenging issue in food science for a long time. Due to the complexity and the diversity of the phenomena involved, it has often been studied through in vitro approaches. The main objective of the present study was to propose a global approach to address this topic in in vivo conditions. Four simple experimental protocols were developed to differently expose the compartments of naso-oro-pharyngeal cavities to flavored gaseous samples. Assumptions on possible mechanisms (mass transfer, dilution, interactions with mucosa and/or saliva, etc.) were proposed to explain the shapes of release kinetics that were observed. Release differences appeared to be dependent on the physicochemical properties of volatile molecules, on the physiological characteristics of individuals (notably saliva properties) and on the compartment of the naso-oro-pharyngeal cavities that was considered. These achievements constitute a first step to progress in the understanding of relationships that exist between aroma release and perception