Director of Chalmers Production Area of Advance, Researcher at the Division of Materials and Manufacture, Department of Industrial and Materials Science, Chalmers University of Technology, Göteborg, Sweden
Prof. Lars Nyborg
Director of Chalmers Production Area of Advance, Researcher at the Division of Materials and Manufacture, Department of Industrial and Materials Science, Chalmers University of Technology, Göteborg, Sweden
Graphene oxide (GO) can be used as an electron acceptor for polymeric solar cells but still band gap matching for electron donor and acceptor demands more study. The generation of the exciton in such materials is intimately related to the optical band gap. However, exciton dissociation is related to transport band gap that controls the device performance, particularly the open circuit voltage and short circuit current. Therefore, the modulation of the optical gap is useful because it results into tuning of the transport gap. The interest of the present work is to study the reduction of graphene oxide (GO) at room temperature, using environmental friendly reagents like glucose, fructose and ascorbic acid for the modulation of a band gap. It has been found that glucose and fructose function effectively only in presence of NH4OH. Although ascorbic acid can reduce GO alone, NH4OH speeds up the reaction. The optical band gap of GO can be reduced and tuned effectively from 2.7eV to 1.15eV
The effect of temperature on the NaCl-induced atmospheric corrosion of the Mg–Al alloy AM50 has been investigated in the laboratory. The corroded samples were analyzed gravimetrically and by SEM, EDX, XRD, and FTIR. The atmospheric corrosion of 99.97% Mg was also studied for reference. While the NaCl-induced atmospheric corrosion of AM50 is strongly reduced with decreasing temperature, 99.97% Mg does not exhibit such a trend. The temperature dependence of the atmospheric corrosion of alloy AM50 is attributed to the aluminum content in the alloy. Several crystalline magnesium hydroxy carbonates formed at 4 and 22°C but were absent at −4°C
The use of cryogenic coolants has emerged as a way to improve productivity in machining Ti-alloys. In this study, liquid carbon dioxide is used as coolant in face milling of Ti-6Al-4V with PVD coated inserts. The influence of coolant flow rate on tool life is studied by means of controlled experiments. Tool life is shown to improve with higher flow rates of coolant, the effect being stronger in cryogenic compared to wet milling due to the fact that the cryogenic coolant delays the wear development. The tool life is determined by notch wear irrespective of coolant nature in titanium milling. Different analyses were used to understand the mechanism behind the delay of notch wear development when using carbon dioxide coolant