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AlSi7Mg/SiCp aluminium matrix composites (AMCs) with a high ceramic content (35 vol.%) that were produced by using the field-assisted sintering technique (FAST) were subjected to tribological preconditioning and evaluated as a potential lightweight material to substitute grey cast iron brake discs. However, since an uncontrolled running-in process of the AMC surface can lead to severe wear and thus to failure of the friction system, AMC surfaces cannot be used directly after finishing and have to be preconditioned. A defined generation of a tribologically conditioned surface (tribosurface) is necessary, as was the aim in this study. To simulate tribological conditions in automotive brake systems, the prepared AMC samples were tested in a pin-on-disc configuration against conventional brake lining material under dry sliding conditions. The influence of the surface topography generated by face turning using different indexable inserts and feeds or an additional plasma electrolytic treatment was investigated at varied test pressures and sliding distances. The results showed that the coefficient of friction remained nearly constant when the set pressure was reached, whereas the initial topography of the samples studied by SEM varied substantially. A novel approach based on analysing the material ratio determined by 3D surface measurement was developed in order to obtain quantitative findings for industrial application. [ABSTRACT FROM AUTHOR]

Abstract: This work systematically investigates and models the retention behavior in organic solvent nanofiltration in solvent mixtures using a dense PDMS-based composite membrane. Experiments with n-alkanes as solutes with different chain lengths (142–339kgkmol−1) were performed. The transport of these solutes is comprehensively quantified not only in pure solvents such as toluene, isopropanol or methanol but also in binary mixtures of isopropanol/toluene and methanol/toluene. Depending on the solvent and on the ratio of these solvents in case of binary mixtures, considerable differences in the retention behavior of these solutes were discovered. Even negative retention could be observed. Using model parameters from single solvent/solute mixtures, a Maxwell–Stefan model based on the assumption of a solution–diffusion transport mechanism was used to predict the solvent as well as the solute fluxes in multi-component mixtures. A good agreement between experimental data and model could be achieved with pure solvent fluxes and solvent fluxes in binary mixtures. However, predictions of solute retentions in solvent mixtures based on solutes/single solvent systems were insufficient and indicate a richer transport complexity in the binary solute/solvent/membrane system. [Copyright &y& Elsevier]