The unfolding of a sheared mechanically mixed third-body (TB) in tungsten/tungsten carbide sliding systems is studied using a combination of experiments and simulations. Experimentally, the topographical evolution and the friction response, for both dry and lubricated sliding, are investigated using an online tribometer. Ex situ X-ray photoelectron spectroscopy, transmission electron microscopy, and cross-sectional focused ion beam analysis of the structural and chemical changes near the surfaces show that dry sliding of tungsten against tungsten carbide results in plastic deformation of the tungsten surface, leading to grain refinement, and the formation of a mechanically mixed layer on the WC counterface. Sliding with hexadecane as a lubricant results in a less pronounced third-body formation due to much lower dissipated frictional power. Molecular dynamics simulations of the sliding couples predict chemical changes near the surface in agreement with the interfacial processes observed experimentally. Finally, online topography measurements demonstrate an excellent correlation between the evolution of the roughness and the frictional resistance during sliding.

No abstract

A first inter‐laboratory comparison was conducted to demonstrate and document the capability of interested laboratories to measure the fraction of COH species on a plasma oxidised poly(propylene) sample by using a chemical derivatisation XPS approach. This report presents the results from that inter‐laboratory comparison and includes the data received for the measured values and their associated standard deviations of laboratory means, at a 95% confidence level. The measurements were guided by a protocol developed within the group before and summarised shortly in the paper. Standard deviations that may characterise the state‐of‐the‐art for the nominally simple and rather often practised case of TFAA chemical derivatisation XPS of COH species on a plasma oxidised polyolefin surface are calculated following ISO 5725‐2:1994. The main conclusion is that the associated degree of equivalence reached by the participating laboratories in this comparison is still low. Further research to improve chemical derivatisation XPS protocols is mandatory.

This article presents a modular model library describing various processes of thermal building behaviour. The library is implemented in the modelling language Modelica emulating thermal building dynamics in a comprehensive way. This includes the heating, ventilation and airconditioning system as well as solar radiation and user behaviour. The way in which the dynamic behaviour of many coupled subsystems can be investigated in only one universal modelling and simulation environment will be illustrated. At the same time, the object-oriented and acausal language Modelica ensures a high degree of reusability. The library is free and can be downloaded from the website of the Modelica Association: http://www.modelica. org/libraries.shtml

The ability of the cleaning agents such as cyclohexane, acetone, isopropanol and hydrogen peroxide to remove oil from technical steel and titanium samples was studied in systematic experiments. The composition of the organic residues and the layer thickness on the differently cleaned surfaces were determined via X-ray photoelectron spectroscopy analysis, and the corresponding water contact angles were measured. The ability of the cleaning agents to remove oil was found to increase in the following order: acetone, isopropanol, cyclohexane and hydrogen peroxide. The relationship between the chemical composition of the residues and the observed contact angles is investigated, and a quantitative correlation is developed.