Initial Stages in the Metal-dusting Process on Alloy 800

The initial stages of the metal-dusting process on Alloy 800 at 620 °C were investigated by light optical microscopy, RAMAN spectroscopy, atomic-force microscopy, Auger electron spectroscopy, transmission-electron microscopy and electron back-scatter diffraction. As it turned out the incubation period for metal-dusting is characterized by simultaneous formation of a heterogeneously growing oxide scale and deposition of carbon. The material surface shows different tarnish colors depending on the substrate-grain orientation with different susceptibility to the beginning of metal-dusting attack. “Low-index” grains were not attacked within the times investigated while the other grain orientations showed pitting. Carbon is evidently incorporated into the oxide scale from the very beginning of exposure with different intensities depending on the underlying substrate-grain orientation leading to differences in the tarnish colors. As a consequence carbides are formed even underneath “dense” oxide layers. Evidently metal-dusting attack starts at positions of the oxide scale where “higher carbon concentrations” are present.     

Comparing orthogonal force and unidirectional strain component processing for tool condition monitoring

Signal processing using orthogonal cutting force components for tool condition monitoring has established itself in literature. In the application of single axis strain sensors however a linear combination of cutting force components has to be processed in order to monitor tool wear. This situation may arise when a single axis piezoelectric actuator is simultaneously used as an actuator and a sensor, e.g. its vibration control feedback signal exploited for monitoring purposes. The current paper therefore compares processing of a linear combination of cutting force components to the reference case of processing orthogonal components. Reconstruction of the dynamic force acting at the tool tip from signals obtained during measurements using a strain gauge instrumented tool holder in a turning process is described. An application of this dynamic force signal was simulated on a filter-model of that tool holder that would carry a self-sensing actuator. For comparison of the orthogonal and unidirectional force component tool wear monitoring strategies the same time-delay neural network structure has been applied. Wear-sensitive features are determined by wavelet packet analysis to provide information for tool wear estimation. The probability of a difference less than 5 percentage points between the flank wear estimation errors of above mentioned two processing strategies is at least 95 %. This suggests the viability of simultaneous monitoring and control by using a self-sensing actuator.     

Computer optimization of trailer suspensionsOptimisation par ordinateur des suspensions de remorque

This paper presents an optimization procedure which has been developed to select appropriate suspension design parameters for a simple two wheel trailer. A modern approach to the optimization problem has been used applying non-linear programming to the constrained search for the minimum of an objective function. The acceleration response to roadway input of selected points on the load of the trailer has been designated for minimization. This acceleration has an important significance to the trailer design because of its effect on the stable and smooth ride of the trailer. Two computational procedures have been used and the results compared. The first approach involves the linear superposition of responses to a series of discrete sinusoidal inputs while the second applies more contemporary random vibration theory using power spectral density curves to simulate the actual road surfaces. The results of the optimization procedure are then compared with the response characteristics of the original trailer design and demonstrate that a substantial improvement has been made.     

Magnetron-sputtered cobalt-based protective coatings on ferritic steels for solid oxide fuel cell interconnect applications

Co, Co–Mn (67:33 at.%) and Co–Cu (67:33 at.%) coatings were fabricated using magnetron sputtering on two kinds of ferritic stainless steels (Crofer22APU and F17TNb) in order to form spinel protective coatings on metallic interconnects for solid oxide fuel cells. Despite the thickness unevenness at different regions, dense metallic coatings were successfully applied onto all necessary surfaces of the channelled interconnect substrates. Upon oxidation, spinel oxide coatings with very low Cr content were formed, reducing effectively the Cr release. Among the three protective coatings, Co–Cu coating showed the lowest area specific resistance (<15 mΩ cm² at 800 °C).     

The Effects of Embedded Dipoles in Aromatic Self‐Assembled Monolayers

Using a representative model system, here electronic and structural properties of aromatic self‐assembled monolayers (SAMs) are described that contain an embedded, dipolar group. As polar unit, pyrimidine is used, with its orientation in the molecular backbone and, consequently, the direction of the embedded dipole moment being varied. The electronic and structural properties of these embedded‐dipole SAMs are thoroughly analyzed using a number of complementary characterization techniques combined with quantum‐mechanical modeling. It is shown that such mid‐chain‐substituted monolayers are highly interesting from both fundamental and application viewpoints, as the dipolar groups are found to induce a potential discontinuity inside the monolayer, electrostatically shifting the core‐level energies in the regions above and below the dipoles relative to one another. These SAMs also allow for tuning the substrate work function in a controlled manner independent of the docking chemistry and, most importantly, without modifying the SAM‐ambient interface.     

Tuning the Electronic Structure of Graphene through Collective Electrostatic Effects

Electrostatically designing materials opens a new avenue for realizing systems with user‐defined electronic properties. Here, an approach is presented for efficiently patterning the electronic structure of layered systems such as graphene by means of collective electrostatic effects. Using density‐functional theory simulations, it is found that lines of polar elements can strongly modify the energy landscape of this prototypical 2D material. This results in a confinement of electronic states in specific regions of the sample and, consequently, in a local energetic shift of the density of states. The latter is also directly reflected in the details of the band structure of the electrostatically patterned sample. Finally, it is shown that the approach can also be successfully applied to other 2D materials such as hexagonal boron nitride, where the effects are predicted to be even more pronounced than in graphene.     

Pyrazolonderivate. III. [2] Ein Beitrag zur Stereochemie von N,N-disubstituierten 4-Aminomethylen-3-methyl-1-phenyl-Δ2-pyrazolinonen-(5)

Pyrazolone Derivatives. III. A Contribution to Stereochemistry of N, N-Disubstituted 4-Aminomethylene-3-methyl-1-phenyl-Δ²-pyrazolinones-(5) The N,N-disubstituted 4-aminomethylene-Δ²-pyrazolinones-(5) 1 and 2 show a hindered internal rotation around the bond indicating a considerable polarisation of the system. This assumption is supported by i.r.-spectroscopic measurements which show that the CO-bond order decreases with increasing solvent polarity. Compounds 1 and 2 exist in the Z-configuration relative to the exocyclic CC-double bond. That can be attributed to a steric hindrance in the E-configuration of the aminomethylene-substituents with the methyl-group at the pyrazolone-ring.     

Pyrazolonderivate. IV [9]. Zur Tautomerie und Stereochemie von 4-Aminomethylen-Δ2-pyrazolinonen-(5)

Pyrazolone Derivatives. IV. Tautomerism and Stereochemistry of 4-Aminomethylene-Δ²-pyrazolinones-(5) Tautomerism and stereochemistry of compounds of type 1 were investigated by ¹H-n.m.r.- and i.r.-spectroscopy. Dynamic ¹H-n.m.r. study with ¹⁵N-labelled compounds shows, that 1 exist in solution as 4-aminomethylene-Δ²-pyrazolinones-(5) with strong intramolecular hydrogen bonds. Compared to 4-unsubstituted Δ²-pyrazolinones-(5) polar solvents do not change the tautomeric equilibrium of 1 . The N-aryl-substituted compounds have a higher NH-acidity than N-alkyl-substituted derivatives. In crystalline state the N-alkyl-substituted compounds 1g, h exist in the E-configuration as 4-aminomethylene-Δ²-pyrazolinones-(5) with intermolecular hydrogen bond. At higher temperatures or in solution the Z-isomer is formed spontaneously.