Low-Cost Membranen für die Vanadium-Redox-Flow-Batterie

Reinforced proton exchange membranes (gPEM) are fabricated by coating a polymer suspension onto a polymer mesh. The polymer suspension contains solved poly(ether sulfone) (PES) and dispersed poly(styrene). The poly(styrene) is cross linked, sulfonylated and sulfonated. By using a poly(ether ether ketone) (PEEK) mesh with a thickness of 128 µm higher proton conductivities were measured compared to Selemion CMVN and Nafion N115 at 25 °C. An energy efficiency of 68.6 % was measured with Nafion N115, an energy efficiency of 53.1 % with CMVN and an energy efficiency of 69.4 % with a fabricated reinforced membrane at a current density of 100 mA cm⁻² in a vanadium redox flow cell.     

Influence of in-plane and out-of-plane machining on the surface topography,the removal mechanism and the flexural strength of 2D C/C-SiC composites

Ceramic Matrix Composites (CMCs) are increasingly demanded especially for the production of structural components for several industries such as aerospace because of their excellent thermo-mechanical and fatigue properties. As one of the last production steps final machining is necessary to meet the required tolerances. From the economic point of view final machining of CMCs is highly critical and special knowledge is assumed to avoid irreparable damage, because of their heterogeneous, anisotropic and brittle nature. In this work diamond grinding and diamond milling have been applied to a 2D C/C-SiC composite at various feed rates and cutting speeds and in both main laminate directions, in-plane and out-of-plane. The microstructures of in-plane and out-of-plane machining indicate different material removal mechanisms due to different composite architecture. Increasing feed rate leads generally to more surface defects and consequently to higher roughness. Little influence on the four-point-bending strength was observed when changing the machining speed.     

Zur Beanspruchung metallischer Werkstoffe im Bereich der Elastizitätsgrenze

Zusammenfassung Durch Modifikation wird das Prandtl-Reuss-Modell im elastisch-plastischen übergangsbereich zur Beanspruchungshypothese erweitert. Die Theorie wird versuchstechnisch verifiziert. Herrn Professor Dr.Ulrich Gonser zum 65. Geburtstag gewidmet Der Stiftung Volkswagenwerk danken die Autoren für die Bereitstellung von Sachmitteln.     

Poly(2,2-dimethyltrimethylene carbonate)-block-poly(dimethylsiloxane)-block-poly(2,2-dimethyltrimethylene carbonate). Synthesis and thermal properties

Lithium salts of hydroxytelechelic poly(dimethylsiloxane) [poly-(DMS)] were used as initiators for the anionic ring-opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC). Triblock copolymers were obtained in high yields. Complexation of the active site in DTC polymerization by the poly(DMS) chain leads to a decrease in polymerization rate. The thermal properties of the copolymers of different compositions were determined. Catalysed thermal degradation of the block copolymers leads to cyclic oligomers D_n and DTC upon ring-closing depolymerization.     

Analyse der verschiedenen Einflüsse auf die Kaltwalzbarkeit von FeSi-Legierungen

Bekanntlich steigt die Kaltsprödigkeit von FeSi-Legierungen mit dem Si-Gehalt, was die technische Nutzbarkeit auf Legierungen mit weniger als etwa 3,5% Si beschränkt. In dieser Arbeit werden die Einflüsse auf die Kaltsprödigkeit untersucht und im einzelnen die folgenden Gefügeparameter untersucht: Legierungszusammensetzung, Korngröße, Ordnungszustand.     

Decentralized control approach to complex planning processes

Macroeconomic planning is considered as a multicriterial decision problem with respect to the controlled distribution of resources and national product. By overlapping decomposition possibilities for decentralized control approach to multicriterial decision making and control are studied.A general method of interactive multicritical decision is proposed.     

Gepulste Hochleistungs‐Magnetron‐Plasmen (HPPMS)

Control of High Power Pulsed Magnetron Plasmas (HPPMS) by Monitoring Current‐Voltage Characteristics High Power Pulsed Magnetron Sputtering (HPPMS) plasmas are perfectly suited for the synthesis of ceramic coatings with superior properties. This excellent performance is induced by the very peculiar energetic particle flux reaching the substrate to be coated. The ion energy distribution originates from the formation of localized ionization zones which can be imaged by fast cameras. In commercial HPPMS reactors, however, only much simpler methods such as current voltage characteristics (VI curves) are accessible. By a proper interpretation of those VI curves, it is possible to identify the favorable operation mode of an HPPMS plasma. The VI curves vary with target material, but they are sensitive to the occurrence of localized ionization zones, which represent the optimum for the operation parameter window of HPPMS plasmas.