Important Key Process Simulations in the Field of Steel Metallurgy

During the last decade, the chair for ‘Simulation and Modelling of Metallurgical Processes’ (SMMP) has worked on different metallurgical processes with the highlights of the following five industrial relevant topics: (i) modelling the as-cast structures of large steel castings; (ii) exploring the formation mechanisms of macrosegregation; (iii) describing magnetohydrodynamic and electrochemical phenomena in remelting processes, (iv) understanding how solidification and flow can be influenced by magnetohydrodynamics during steel continuous casting; and (v) describing nozzle clogging in steelmaking processes. In this contribution, the main achievements from the group on the above five topics are briefly described.

Numerical and Experimental Modeling of Paper-Based Actuators

Microfluidic paper-based analytical devices (μPADs) have witnessed a great extent of innovation over the past decade, developing new components and materials assisting the diagnosis of different diseases and sensing of a wide range of biological, chemical, optical, and electrochemical phenomena. The novel paper-based cantilever (PBC) actuator is one the major components that allows autonomous loading and control of multiple fluid reagents required for the accurate operation of paper-based microfluidic devices. This paper provides an extensive overview of numerical and experimental modeling of fluidically controlled PBC actuators for automation of the paper-based assay. The PBC model undergoing hygro-expansion utilizes quasi-static 2D fluid loaded structure governed by the Euler–Bernoulli beam theory for small and moderately large deflections. The solution for the model can avail the response of paper-based actuators for response deflection θ, within 0° to 10° under the assumption of insignificant cross-sectional deformation. The actuation of PBC obtained using a quasi-static theory shows that our results are consistent with quantitative experiments demonstrating the adequacy of models.

Modeling Electro-Chemo-Mechanical Behaviors within the Dense BaZr 0.8Y0.2O3-δ Protonic-Ceramic Membrane in a Long Tubular Electrochemical Cell

This paper reports an extended Nernst–Planck computational model that couples charged-defect transport and stress in tubular electrochemical cell with a ceramic proton-conducting membrane. The model is particularly concerned with coupled chemo-mechanical behaviors, including how electrochemical phenomena affect internal stresses and vice versa. The computational model predicts transient and steady-state defect concentrations, fluxes, stresses within a thin BaZr0.8Y0.2O3−δ (BZY20) membrane. Depending on the polarization (i.e., imposed current density), the model predicts performance as a fuel cell or an electrolyzer. A sensitivity analysis reveals the importance of thermodynamic and transport properties, which are often not readily available.

Electrochemistry in an Optical Fiber Microcavity - Optical Monitoring of Electrochemical Processes in Picoliter Volumes

In this work, we demonstrate a novel method for multi-domain analysis of properties of analytes in volumes as small as picoliter, combining electrochemistry and optical measurements. A microcavity in-line Mach-Zehnder interferometer (µIMZI) obtained in a standard single-mode optical fiber using femtosecond laser micromachining was able to accommodate a microelectrode and optically monitor electrochemical processes inside the fiber. The interferometer shows exceptional sensitivity to changes in optical properties of analytes in the microcavity. We show that the optical readout follows the electrochemical reactions. Here, the redox probe (ferrocenedimethanol) undergoing reactions of oxidation and reduction changes the optical properties of the analyte (refractive index and absorbance) that are monitored by the µIMZI. Measurements have been supported by numerical analysis of both optical and electrochemical phenomena. On top of a capability of the approach to perform analysis in microscale, the difference between oxidized and reduced forms in the near-infrared can be clearly measured using the µIMZI, which is hardly possible using other optical techniques. The proposed multi-domain concept is a promising approach for highly reliable and ultrasensitive chemo- and biosensing.

Electrochemistry in an Optical Fiber Microcavity - Optical Monitoring of Electrochemical Processes in Picoliter Volumes

In this work, we demonstrate a novel method for multi-domain analysis of properties of analytes in volumes as small as picoliter, combining electrochemistry and optical measurements. A microcavity in-line Mach-Zehnder interferometer (µIMZI) obtained in a standard single-mode optical fiber using femtosecond laser micromachining was able to accommodate a microelectrode and optically monitor electrochemical processes inside the fiber. The interferometer shows exceptional sensitivity to changes in optical properties of analytes in the microcavity. We show that the optical readout follows the electrochemical reactions. Here, the redox probe (ferrocenedimethanol) undergoing reactions of oxidation and reduction changes the optical properties of the analyte (refractive index and absorbance) that are monitored by the µIMZI. Measurements have been supported by numerical analysis of both optical and electrochemical phenomena. On top of a capability of the approach to perform analysis in microscale, the difference between oxidized and reduced forms in the near-infrared can be clearly measured using the µIMZI, which is hardly possible using other optical techniques. The proposed multi-domain concept is a promising approach for highly reliable and ultrasensitive chemo- and biosensing.

From bulk to interface: electrochemical phenomena and mechanism studies in batteries via electrochemical quartz crystal microbalance

This tutorial review presents the fundamentals of EQCM, and recent achievements in the bulk phenomena and interfacial mechanisms in batteries revealed by the EQCM technique.