Ion-conductivity of thin film Li-Borate glasses

In dieser Arbeit wurde die spezifische Leitfähigkeit von dünnen Lithium-Borat Schichten untersucht. Dazu wurden mit Hilfe der Ionenstrahlzerstäubung Li-Borat Glasschichten mit Dicken zwischen 7 und 700 nm hergestellt. Die spezifische Leitfähigkeit der Schichten wurde mit Hilfe der Impedanz-Spektroskopie untersucht. Wir haben gefunden, dass im Falle der extrem dünnen Schichten (< 100 nm) die spezifische Gleichstromleitfähigkeit der Schichten nicht mehr materialspezifisch, sondern stark dickenabhängig ist. Zusätzlich wurde in dieser Arbeit eine physikalische Interpretation für das sogenannte ‚Constant Phase Element’ (CPE) gefunden. Dieses empirische Element beschreibt die Deformation der Halbkreise im Nyquist Diagramm. In dieser Arbeit wurde ein Ersatzschaltbild gemäß dem CMR Model entwickelt, und dadurch eine physikalische Interpretation für das CPE beruhend auf der Ionendynamik vorgestellt

Passive Filter Design Algorithm for Transient Stabilization of Automotive Power Systems

The automotive power system is being increasingly expanded by adding high-dynamic power electronics. These components can potentially cause malfunction or failure of safety-relevant low-voltage components. The susceptibility to disturbances is often reduced by usage of oversized passive input electronics. This paper introduces an alternative means of disturbance suppression by the introduction of system integrated adaptive passive filters. A proposed methodology is presented for examining the suitability of potential access points within complex networks. An algorithmic procedure for the parametrization of several switchable bandpass filter stages is explained. The in-vehicle measurement demonstrates the effectiveness of the dimensioned filter being able to reduce disturbances at 70 kHz by more than 75 %.Passive Filter Design Algorithm for Transient Stabilization of Automotive Power SystemsacceptedVersio

EIS of carburised CoCrMo: Evolution of parameters characterising the metal-electrolyte interface

Corrosion-wear is of major concern for Cobalt-Chromium-Molybdenum (CoCrMo) hip implants as it leads to premature failure of the prosthesis and treating the CoCrMo surface using low temperature carburising treatment is a plausible investigation to mitigate such problem. This diffusion treatment introduces a supersaturated carbon solid solution, termed S-phase, which hardens the CoCrMo without detriment to the corrosion resistance. There are only basic studies on the electrochemical characteristics of S-phase surface and therefore, from a scientific and industrial point of view, there is a lot of scope to investigate it further. This research uses electrochemical imped ance spectroscopy (EIS) to study the metal/electrolyte interface and how it changes after carburising and over a time span of 24 h. The technique reveals that the CoCrMo/Ringer's solution interface contains a highly resistant passive film and an electrical double layer when under equilibrium conditions. Comparison of the impedance results attained when testing untreated and carburised CoCrMo reveals that the treated metal has a passive film which has higher polarisation resistance compared to that of the untreated alloy. This may have been a consequence of the fact that the treated metal's passive film has lower time constant dispersion and faster film growth kinetics compared to the untreated alloy's passive film. In addition, both untreated and carburised interfaces suffer a considerable loss in their polarisation resistance after 20 h of testing which indicates a non-monotonic relationship between passive film impedance and electrochemical potential.peer-reviewe