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In water based solutions, electrodeposition of Pd and Pd alloys is complicated due to hydrogen embrittlement. This can be avoided by using non-aqueous solutions like deep eutectic solvents ...

Quenching and partitioning (Q&P) treatments result in promising mechanical properties of advanced high-strength steels. However, recent studies indicate that Q&P steels are very susceptible to hydrogen embrittlement (HE). Using slow strain-rate tests, the effects of hydrogen charging in different media without and with recombination poison were investigated for Fe-0.38C-1.92Si-0.66Mn-1.39Cr in quenched and tempered as well as Q&P conditions. In addition, corrosion tests and Zn electroplating of tensile specimens were performed. In both heat-treatment states, it was found that the intensified hydrogen-charging conditions using a recombination poison strongly impact the result of HE investigations: HE only occurs when a recombination poison is present. In addition, the negative influence of hydrogen formed during Zn electroplating can be limited by using proper electrolytes and electrical parameters. This allows keeping the HE susceptibility of the Q&P steel low in practical applications when recombination poisons are absent.

In der Automobilindustrie ist die Anwendung von monolithischen Profilstrukturen etabliert. Jedoch bietet der Einsatz von Hybridprofilen, die aus einem faserverstarkten Polymer (FVK) und einer duktilen Metalllegierung bestehen, eine im Vergleich vorteilhafte Kombination aus mechanischen Eigenschaften und resultierendem Bauteilgewicht. Um eine effiziente Fertigung und damit den industriellen Einsatz von Metall-FVK-Hybridprofilen anzustreben, werden in diesem Kapitel zwei intrinsische Fertigungsprozesse vorgestellt. Dabei ermoglichen die Prozesse einerseits die Verarbeitung einer thermoplastischen und andererseits einer duroplastischen Kunststoffmatrix. Neben der Entwicklung und Validierung dieser Produktionsprozesse werden, mit dem Ziel einen bestmoglichen Korrosionsschutz bei einer zugleich hohen Haftfestigkeit zu realisieren, Konzepte zur Gestaltung der Grenzschicht der artverschiedenen Werkstoffe betrachtet. Des Weiteren werden Methoden zur Simulation und zur mechanischen Prufung der gefertigten Hybridprofile aufgezeigt. Zusatzlich soll dabei auch auf die Messung und die gezielte Modifikation von Eigenspannungen, die sich infolge der Verarbeitung der verschiedenen Materialien einstellen, eingegangen werden.

According to the concept of an intrinsic hybrid composite, adhesive bonding is designed for generating the connection between the applied fiber reinforced polymer and a metallic insert. To induce adhesive bonding, a metallic insert, made of aluminum, is coated. This contribution focusses on the development of a suitable coating system. To this end, the coating system must meet certain requirements. On one hand, demands on the coating like ductility can be deduced from analyzing the manufacturing process. On the other hand, requirements like corrosion protection as well as high static and dynamic strength arise from specific applications under considerations. The utilized coating system is based on organically modified silicate layers (Ormosil) applied using a sol–gel process. To prove that this coating system fulfils the requirements, the corrosion protection is analysed by impedance spectroscopy. Furthermore, different mechanical experimental investigations are performed to verify the ductility of the coating as well as the strength of the resulting interface. Hence, it is shown that the considered coating system can be applied for the analysed intrinsic hybrid composite manufactured in series.

The cypress bark beetle,Phloeosinus armatus, is a common element of the dying cypress tree system in East-Mediterranean countries. Adult beetles congregate for breeding on this ephemeral resource. We studied three traits that characterize this beetle's sexual behavior and linked them to its reproductive success: mating system, mate choice, and parental care. We found that the females are the ‘pioneering sex’, excavating the mating chamber. The average female is slightly larger than the male, and female and male body size is correlated, demonstrating size-assortative mating. The time it takes for a male to enter the mating chamber is positively correlated with female size and negatively correlated with its own size, which is perhaps responsible for this assortative mating. Males remain in the gallery during the period of oviposition, gradually leaving soon after the eggs hatch. The number of eggs laid and tunnel length are positively correlated with male body size. Finally, in the presence of both parents, more eggs are laid than when the female alone is present, demonstrating the important contribution of biparental care for reproductive success. We suggest that the interaction between a monogamous mating system, assortative mating, and biparental care contributes to reproductive success.

Due to a combination of different classes of materials, intrinsic hybrid composites are characterised by high strength and low weight. The mechanical properties of hybrid parts are mainly determined by the interface between the different materials. Consequently, this interface has to be considered in detail within the development of an intrinsic hybrid composite. The general approach of the considered composite is the combination of a mechanical form fit with adhesive bonding. This contribution focuses on the development, production and characterisation of the interface between aluminium and a fibre reinforced polymer as well as of the hybrid composite.

Organo-functional silane coupling agents are widely used to promote adhesion in between inorganic and organic materials. Amino-functional silanes can improve bonding with polyamide. Aiming on a mechanically performant aluminum-polyamide joints, the effect of six amino silanes of different chemical structure, namely number and type of amine groups and alkyl spacers lengths, on the joint strength is investigated by means of lap-shear testing. Higher shear strengths are found along with a more pronounced capability of the amine group to form hydrogen bonds with polyamide. The results show that an additional amine group within the organo-functional group can increase joint strength, whereas long alkyl spacers reduce the observed joint strength. It is shown that high lap-shear strengths, in maximum about 15 MPa for N-(2-aminoethyl)-3-aminopropyltrimethoxysilane are achieved and that the high reproducibility can be assured when using right processing routines.

In this study, the electrodeposition of palladium alloys was investigated in a choline chloride/urea based deep eutectic solvent containing sulfosalicylic acid dihydrate as organic additive and Pd(II) + Ag(I), Pd(II) + Pt (II), or Pd(II) + Pt (II) + Ag(I) as metal components. The electrochemical behavior of the electrolytes was characterised by cyclic voltammetry. The electrodeposition processes require nucleation overpotential. Energy-dispersive X-ray data indicated that the layer thickness and composition of the produced Pd–Ag, Pd–Pt, and Pd–Pt–Ag films could be varied by changing the deposition mode. Additions of Ag(I) to the Pd and Pd–Pt electrolytes enhanced the overall metal deposition rate. Scanning electron micrographs of the electrodeposits showed that in general, the Pd alloys deposited by pulse current were nodular and relatively compact, whereas the films deposited by potentiostatic deposition were less dense and covered with dendrite-like and sharp-edged crystallites. Data collected from X-ray diffraction (XRD) experiments proved the existence of metallic alloys.

Plasma electrolytic oxidation (PEO) is a common means for the surface modification of light metals. However, PEO of magnesium substrates in dilute electrolytes generally leads to the formation of coatings consisting of unfavorable MgO magnesium oxide. By incorporation of electrolyte components, the phase constitution of the oxide coatings can be modified. Coatings consisting exclusively of MgAl2O4 magnesium-aluminum spinel are produced by PEO in an electrolyte containing hydroxide, aluminate, and phosphate anions. The hardness of the coatings is 3.5 GPa on Martens scale on average. Compared to the bare substrate, the coatings reduce the corrosion current density in dilute sodium chloride solution by approx. one order of magnitude and slightly shift the corrosion potential toward more noble values.

In recent years, the growing environmental awareness has led to the development of energy-efficient products, for example by the replacement of steel as construction material by aluminium to save weight and thus increase the energy-efficiency of mobile systems. However, to address the energy-efficiency of a product holistically, the energy consumption of the production process also has to be considered. For the anodic oxidation process of the AlMgSi1 aluminium alloy, the influence of the sulphuric acid concentration, the glycolic acid concentration, the electrolyte temperature and current density on coating thickness, hardness, ductility and wear resistance (scratch test), as well as on the consumption of electrical energy and process costs for the oxide coating formation are investigated using a design of experiments (DOE). An analysis of variance (ANOVA) is conducted to assess the significance of the parameters for the coating and process properties. For the considered range of the process parameters a significant enhancement of thickness, hardness and wear resistance of the coatings alters also energy consumption during anodic oxidation and process costs, which are assessed by material flow cost accounting (MFCA). Keywords: Anodic oxidation, Aluminium, Energy efficiency, Hardness, Ductility

With the progress in materials science and production technology and the establishment of light-weight design in many fields of the industry, the application of light metals no longer requires only mechanical strength, but also a significant protection of the material against wear and corrosion. Hard and wear-resistant oxide coatings on aluminium are produced by plasma electrolytic oxidation (PEO). During PEO, a conversion of the aluminium substrate to a ceramic oxide takes place. While the role of strength-giving alloying elements like Cu, Mg/Si, Zn, and Zn/Cu on the PEO process has selectively been subject of investigation in the past, the significance of the alloy composition for the service properties of the coatings is still unknown. Therefore, the performance of PEO coatings produced on the widely used commercial high-strength alloys AlCu4Mg1 (EN AW-2024), AlMgSi1 (EN AW-6082), and AlZn5.5MgCu (EN AW-7075) is examined with regard to their behaviour in the rubber-wheel test according to ASTM G65 and the current density-potential behaviour of the substrates with undamaged and worn coatings in dilute NaCl solution. To give a reference to the unalloyed material the testings were carried out also on Al 99.5 (EN AW-1050) which was treated in an adjusted PEO process. Although differences in the conversion of intermetallic phases during PEO and the phase composition of the coatings on the various substrates are determined, the service properties are hardly depending on the alloying elements of the investigated aluminium materials. The wear rates in the rubber-wheel test are low for all the alloyed samples. The current density-potential curves show a decrease of the corrosion current density by approximately one order of magnitude compared to the bare substrate. Eventually, previous wear of the coatings does not deteriorate the corrosion behaviour. PEO layers on technically pure aluminum can resist the testing regimes if they are prepared in an electrolyte with an elevated silicate content and without additional hydroxide ions, during a longer process time.

The anodic oxidation process is an established means for the improvement of the wear and corrosion resistance of high-strength aluminum alloys. For high-strength aluminum-copper alloys of the 2000 series, both the current efficiency of the anodic oxidation process and the hardness of the oxide coatings are significantly reduced in comparison to unalloyed substrates. With regard to this challenge, recent investigations have indicated a beneficial effect of nitric acid addition to the commonly used sulphuric acid electrolytes both in terms of coating properties and process efficiency. The present work investigates the anodic oxidation of the AlCu4Mg1 alloy in a sulphuric acid electrolyte with additions of nitric acid as well as oxalic acid as a reference in a full-factorial design of experiments (DOE). The effect of the electrolyte composition on process efficiency, coating thickness and hardness is established by using response functions. A mechanism for the participation of the nitric acid additive during the oxide formation is proposed. The statistical significance of the results is assessed by an analysis of variance (ANOVA). Eventually, scratch testing is applied in order to evaluate the failure mechanisms and the abrasion resistance of the obtained conversion coatings.

Aluminium matrix composites (AMCs) consisting of high-strength, age-hardenable aluminium alloys and homogeneously dispersed hard particles open up new possibilities in designing light-weight material based security related structures. The susceptibility of the matrix alloy to selective corrosion can be reduced significantly by anodic oxidation. A powder-metallurgical processed alloy AlCu4MgMn with hard particles and a commercial wrought alloy for reference were used for the investigations.In order to control the microstructure of anodic aluminium oxide (AAO) formed on AMCs, it is necessary to understand the formation mechanism and the influencing parameters. Therefore in a first run, the anodizing behaviour of matrix alloy was separated from the behaviour of hard particles. The AAO coatings show small growth rates on the matrix and the reference alloy accompanied by a complex pore structure which differs from the ordered vertical pore structure on pure aluminium. Depending on the type and the size as well as the anodizing parameters, the particles are either incorporated into the AAO coating unchanged or partly resp. completely oxidized. The AAO microstructure changes significantly in dependence of the anodizing parameters. It is shown that a technically relevant coating thickness can be achieved on AMCs by choosing appropriate process parameters.

Self-tapping aluminium screws are an innovative joining technology for the assembly of lightweight components in industrial scale. It has been established in the past that porous anodic oxide coatings in many cases reduce the fatigue strength of specimens without notches. In the present work, the fatigue behaviour of notched specimens, i.e. self-tapping screws made from aluminium alloys EN AW-6056, 6082 (both in a conventional state and in a fine-grained state produced by equal channel angular pressing – ECAP) and 7068 with and without oxide coatings is examined. The coatings are produced by hard anodising and are necessary for the thread-forming process during assembly. While the coatings do not affect the static tensile strength, they reduce the fatigue strength for the specimens of the 6056 and the 6082 alloy. For the 7068 alloy a slight increase in fatigue strength is discovered on a low load horizon. The scatter of endured fatigue cycles until fracture of specimens is generally reduced by the anodic oxide coatings.

The influence of adding alfa-Al2O3 nanoparticles with different concentrations into Watt's bath under the application of ultrasound during electrodeposition was investigated by means of electrochemical impedance spectroscopy (EIS) in the galvanostatic mode. The characteristics of the double layer during nickel deposition were affected by the existence of Al2O3 nanoparticles in the electrolyte. In this study, the results of the impedance were correlated with the layer properties, e.g. the mean grain size, the incorporation of particles in the deposit and the strengthening performance. It became obvious that there is a good relationship between the EIS data and layer properties, which makes the impedance spectroscopy a reliable tool for predicting the properties in dispersion coatings. Copyright © 2015 John Wiley & Sons, Ltd.

The application of Al/Mg compound materials for lightweight structures is limited by their corrosion susceptibility. The primary corrosion attack takes place at the Mg component. This may partly be caused by galvanic corrosion and partly by the insufficient formation of a natural passive layer on magnesium. Therefore, oxide coatings were produced on the co-extruded Al/Mg compounds by simultaneous plasma electrolytic oxidation (PEO). A silicate-alkaline and a silicate-phosphate-alkaline electrolyte were used for the coincident production of coatings with a thickness of several 10 microns on both the aluminum and the magnesium component. The inherent flaws of the coating (pores, cavities) allow for the infiltration with an epoxy-based sealant. The electrochemical behavior of the magnesium component covered with the oxide coatings with and without sealing was compared with reference to the unmodified surface. The surface modification (PEO w/wo sealing) significantly decreases the corrosion susceptibility of the Mg component, and thus of the compound.

This paper introduces a phenomenological calculation approach for the electrolytic pulse deposition of nickel under high polarisation based on an equivalent electrical circuit. In a quasistationary state of the deposition, the electrolyte resistance and double layer parameters are identified by electrochemical impedance spectroscopy and galvanostatic polarisation. The charge–transfer resistance of both the anodic and cathodic electrode double layer is inversely proportional to the current density. This means the overpotentials over the electrode double layers are independent of the current density. For short pulse on-times and off-times (up to 10 ms), the behaviour of the electrolytic cell is mainly determined by the double layer characteristics and the calculation approach therefore allows the prediction of the current–potential behaviour during pulse deposition under high polarisation. For larger pulse widths, the time-dependent evolution of the overpotentials occurring at the electrode/electrol...

Effizienter Leichtbau erfordert intelligente Werkstoffe, die vielseitige Funktionen erfullen. Ein Losungsansatz besteht darin, Kohlenstofffasergewebe galvanisch zu metallisieren, um funktionelle kohlenstofffaserverstarkte Kunststoffe (CFK) herzustellen. Es resultiert eine rissfreie, homogene Nickelschicht auf der Gewebeoberflache. Durch eine geeignete Wahl der Beschichtungsparameter wird daruber hinaus jede einzelne Faser des gesamten Gewebes gleichmasig metallisiert und eine Anwendung in funktionellen kohlenstofffaserverstarkten Kunststoffen fur Leichtbauwasserstoffspeicher ermoglicht. Schlusselworter: Metallisierte Kohlenstofffasern / funktionelle CFK / galvanische Abscheidung Efficient lightweight construction requires intelligent materials that meet versatile functions. One approach to produce functional carbon fiber-reinforced plastics (CFRPs) is the metallization of carbon fiber fabrics. This results in a crack-free, homogeneous nickel layer on the fabrics’surfaces. By selecting suitable layer parameters, every single fiber of the entire fabrics will be evenly metallized and allow the application of functional CFRPs as lightweight hydrogen storage.

In the recent decades, various process windows have been found for plasma anodising of aluminium surfaces to produce wear-resistant alumina coatings. The coatings offer a high hardness and provide an excellent bonding to the substrate material, thus preventing spallation under mechanical or tribological load. In the present study, coatings with a high abrasive wear resistance and a hardness of up to 12 GPa were produced in an electrolyte of 5 g/l sodium metasilicate and 5 g/l potassium hydroxide at a current density of 30 A/dm2. To understand the reasons for the high wear resistance, the morphology as well as the phase composition and distribution within the coating were examined globally and locally using X-ray diffraction with conventional and grazing incidence and electron backscatter diffraction. The analyses show that the coating globally is comprised of approximately one third of α-alumina, one third of γ-alumina and one third of amorphous alumina with locally varying phase content.

Thermoplastic hybrid laminates are a novel class of material compounds that offer the possibility for large-scale production routes. The laminates consist of an assembly of fiber-reinforced semi-finished layers and metallic sheets in an alternating arrangement. Through the targeted combination of the individual sub-components, a high performing lightweight material with tailor-made properties is achieved. The paper focuses on an advanced thermoplastic hybrid laminate of the CAPAAL type, which is made up of continuous carbon fiber-reinforced polyamide sheets, aluminum top sheets and with continuous glass fiber-reinforced polyamide interlayers in between. The mechanical performance under quasi-static and 3-point bending fatigue, the corresponding damage as well as failure mechanisms are investigated. Under quasi-static bending, a comparatively high stiffness (52 GPa) and strength (645 MPa) in comparison to the commercially established thermosetting hybrid laminates were achieved while even at high strains no interfacial delamination was observed. The bending fatigue tests show that pure elastic loading of the laminate is below the fatigue limit and the laminate withstands one million load cycles without any measurable damages in the individual sub-components. Higher loads are leading to crack propagation inside the aluminum top sheet, whereas only the highest loads applied induced additional damage occurrence inside the thermoplastic matrix. For the first time, investigations on the mechanical performance of a CAPAAL type hybrid laminate under fatigue bending loads are presented. Hereby, in combination with the fast manufacturability of the laminate as a semi-finished product and its subsequent high formability, the suitability for e.g. automotive applications is demonstrated.

Anodizing with closed electrolytic free jet enables the resource-efficient, local conversion and surface structuring of the high-strength alloy EN AW-7075 T6 aiming at the local improvement of the tribological behavior of functional surface areas. The objective of the present work was to confine the current distribution on the specimen's surface and to achieve a stronger localization of the coating oxide layer. For this purpose, the processing parameters working distance, voltage and process duration were varied systematically. Based on the refractive index of the porous oxide and laser scanning microscope imaging of the interference lines, the maximum thicknesses of the anodized spots were calculated. Moreover, the coating microstructure was investigated by scanning electron microscopy and the surface topography was measured with a stylus profiler. The results show that the reduction of the working distance to 100 μm enables a significantly improved localization of the coating growth at substantially lowered process voltages. Thus, the energy-efficient production of localized, wear-resistant oxide spots for tribological applications with local functionalization of surfaces through anodization by closed electrolytic free jet is proven.

Multi-material design is a key technology for lightweight design and calls for combining different materials such as steels, light metals and composites like carbon fiber reinforced plastics (CFRP) into load-bearing structures. Due to the minor chemical affinity of such materials and contact corrosion aspects, the design of an appropriate interface is a current challenge. Aiming on highly performant single-stage manufacturing processes, the paper presents investigations on several surface treatment techniques like a laser pretreatment, the use of primers and a sol-gel coating. Beside investigations on the achievable joint strengths, the corresponding joining concepts to facilitate the in-mould assembly of hybrid structures are validated. In this case the intrinsic manufacturing methods of the Resin Transfer Moulding (RTM) and the Automated Fiber Placement (AFP) technology are presented. Furthermore corrosion protection measures for CFRP and aluminum are analyzed via immersion and salt spray tests.

The properties of Ni-P composite coatings are related to the microstructure evolution by co-deposition of phosphorus, particle incorporation and subsequent annealing. This study focuses primarily on the effect of phosphorus content in the electrolyte on the incorporation of sub-micron diamond particles in order to understand the complex influence of Ni/Ni3P crystallization and particle embedment on Martens hardness.

Electrodeposition of palladium from a non-aqueous electrolyte solution [choline chloride/urea/palladium(II)chloride] has been carried out by direct and pulse current electroplating. In this study, the influence of an organic additive (nicotinic acid amide), current mode (direct current or pulse current deposition) and hydrodynamic on the surface morphology of electroplated palladium films was investigated. In order to determine the surface morphology and thickness of the electrodeposited palladium layers, a scanning electron microscope and an energy dispersive X-ray fluorescence spectroscope were used. In addition, the cell voltage during the different electrodeposition experiments was recorded and analysed. The experimental results showed that the surface morphology of the palladium deposits could be remarkably affected either by addition of the additive or by applying pulse current. Pulse plating and the selected inhibitor mutually interfere with each other, causing changes in the microstructure of the palladium deposits (e.g. smoothening or forming of micro-cracks). It was possible to optimise the palladium deposit quality by applying pulse current or by addition of the appropriate inhibitor.

The physical and electrochemical characteristics such as density, viscosity, electrical conductivity and cyclic voltammetry of three different non-aqueous palladium electrolytes were analysed. The cyclic voltammetry behaviour showed typical reduction and oxidation peaks corresponding to the deposition and stripping of palladium in the electrolytes employed. The electrodeposition of palladium films from choline chloride/ethylene glycol (ChCl-EG), choline chloride/urea (ChCl-urea) and 1-butyl-3-methylimidazolium chloride-tetrafluoroborate (BMIM-Cl-BF4) solutions was demonstrated. Compact deposits were obtained with galvanostatic electrolysis. The scanning electron micrographs of the deposits revealed predominantly nodular Pd particles.

Enhanced use of lightweight materials, namely aluminium and magnesium, requires the application of appropriate production techniques. Self-tapping screws represent an innovative joining technology. High-strength aluminium alloys can be used as screw material. Stringent requirements regarding the wear resistance of screw surfaces result from the thread-forming process. These requirements are met by oxide ceramic conversion layers produced by hard anodizing. Based on application-oriented testing methods, the influence of hard anodized layers on the screwing behaviour and susceptibility to stress corrosion cracking of high-strength aluminium screws is examined.

Thermally sprayed alumina coatings are widely used in a range of industrial applications to improve wear and erosion resistance, corrosion protection and thermal insulation of metallic surfaces. These properties are required for many components to be used for production processes in the paper and printing industry. Another appropriate method to produce ceramic coatings is the plasma electrolytic oxidation (PEO). However PEO can only be applied on self-passivating metals like aluminium, titanium, magnesium and their alloys. The present paper concerns a combination of cost-efficient arc spraying and flame spraying of Al coatings (Al99.5, AlCu4Mg1) on steel substrates and post-treatment by plasma-electrolytic oxidation (PEO). The microstructure and phase composition of generated oxide coatings are examined and discussed. The created Al 2 O 3 layers show outstanding hardness up to 1600 HV0.1, good bonding strength and excellent abrasion resistance compared to atmospheric plasma-sprayed Al 2 O 3 -coatings. The results show the superior performance of PEO-coatings and demonstrate their applicability for technical components in extreme operating conditions.

1,4-Diazidobuta-1,3-dienes (Z,Z)-10, 17, and 21 were photolyzed and thermolyzed to yield the pyrid-azines 13, 20, and 23, respectively. To explain these aromatic final products, the generation of highly strained bi-2H-azirin-2-yls 12, 19, and 22 and their valence isomerization were postulated. In the case of meso- and rac-22, nearly quantitative formation from diazide 21, isolation as stable solids, and complete characterization were possible. On the thermolysis of 22, aromatization to 23 was only a side reaction, whereas equilibration of meso- and rac-22 and fragmentation, which led to alkyne 24 and acetonitrile, dominated. Prolonged irradiation of 22 gave mainly the pyrimidine 25. The change of the configuration at C-2 of the 2H-azirine unit was observed not only in the case of bi-2H-azirin-2-yls 22 but also for simple spiro-cyclic 2H-azirines 29 at a relatively low temperature (75 degrees C). The fragmentation of rac-22 to give alkyne 24 and two molecules of acetonitrile was also studied by high-level quantum chemical calculations. For a related model system 30 (methyl instead of phenyl groups), two transition states TS-30-31 of comparable energy with multiconfigurational electronic states could be localized on the energy hypersurface for this one-step conversion. The symmetrical transition state complies with the definition of a coarctate mechanism.

Die Umsetzung der Mischbauweise in der Automobilindustrie und in der Luft- und Raumfahrt stellt das Fugen mittels Schraube vor neue Problemstellungen. Anodisierte hochfeste Aluminiumschrauben sollen gewindefurchende Stahlschrauben ersetzen und die Schadigung der Werkstoffverbunde durch elektrochemische Korrosion verhindern. Untersucht wurden die Korrosions- und Verschleisbestandigkeit sowie das Einschraubverhalten anodisierter Aluminiumschrauben bezuglich der gewahlten Verfahrensvarianten Direkt- bzw. Flussigkontaktierung. Die hartanodisieren Schrauben sind korrosions- und verschleisbestandig und eignen sich fur die Direktverschraubung. Die Ergebnisse zeigen, dass durch eine gezielte Oberflachenveredelung der Anwendungsbereich von anodisierten Aluminiumschrauben deutlich erweitert werden kann.

Three different methods to prepare 1,4-diazidobuta-1,3-dienes are presented: nucleophilic substitution of electron-poor dichlorinated substrates, nucleophilic addition of hydrazoic acid at an electron-deficient diallene, and a sequence of prototropic isomerizations of propargyl sulfones followed by nucleophilic additions. In all cases, isolation and assignment of the diastereomeric products was possible, and some sequential reactions, such as reduction or 1,3-dipolar cycloaddition of the azido groups, were performed.

NiCo–Al2O3 composite coatings were prepared by electrodeposition in a sulfamate plating bath containing Al2O3 particles to be co-deposited under sonication. For reliable determination of the microstructure, detailed studies on composite cross-sections were carried out by energy-dispersive spectrometer (matrix composition, particle content) and FE-SEM/electron backscattered diffraction data (particle distribution, grain size), accompanied by XRD analyses concerning texture, lattice parameter, grain size, and residual stress. The NiCo matrix with a Co/Co + Ni ratio up to 0.4 is a face-centered cubic solid solution with and fiber textures. The distribution of the particles (size 250 nm) was well-dispersed and enhanced up to 15 wt.% by ultrasound application during plating. Vickers hardness increased up to 50% by dispersion hardening. First-order residual stress in the matrix increased with rising Co content, thus decreasing wear resistance and revealing the complex of composite properties with partially opposite effects.

After aluminum alloys undergo severe plastic deformation there is an interest in what grain refining is obtained and is determined from the orientation data detected from backscatter electron diffraction in lateral resolution. The quality of backscatter diffraction depends on the fraction of successful indexings, which presupposes an appropriate preparation of the surface. Vibration polishing results in a matrix nearly free of deformation and excellent levelling of the precipitates whereas relief formation (often occurring in oxide polishing) and dissolution (often occurring in electro-polishing) of those phases will reduce the band contrast and indexing quality. The results thus obtained from backscatter electron diffraction are backed by scanning electron microscopy images in transmission.

Im Sinne des Leichtbaus und damit einhergehender okonomischer und okologischer Aspekte ist die Verwendung hochfester Al-Schrauben besonders interessant. Gegenstand des Projektes T1 ist der Transfer unterschiedlicher, in Grundlagenversuchen als erfolgversprechend eingestufter Oberflachenbehandlungsverfahren in die industrielle Bewertung und Nutzung. Das Augenmerk richtet sich auf Schutzschichten, die als Konversionsschichten aus dem Substrat entstehen (Anodisieren). Diese Verfahrensgruppe hat das Potenzial, eine anforderungsgerechte Oberflachenveredelung auf Al-Schrauben zu erzielen. The use of high-strength Al screws is of particular interest with regard to lightweight construction and its respective economic and ecological aspects. The subject of the project T1 is the transfer of different surface treatments that have been classified promising in fundamental experiments into industrial assessment and application. The focus is on protective coatings which develop from the substrate (anodizing). This process group offers the potential to obtain the required surface refinement of the Al screws.

In the areas of automotive, aeronautics and civil structures, lightweight construction is a current and a future need. Thus, multi material design has rapidly grown in importance, especially hybrid materials based on fiber reinforced plastics and aluminum offer great potential. Therefore, mechanical interlocking is a convenient way of designing the interface. Laser structuring is already used to generate a variety of surface topographies leading to high bond strengths. This paper investigates different laser structures aiming on highest joint strengths for aluminum and glass fiber reinforced polyamide 6 interfaces. Self-organizing pin structures comprised by additional micro/nano features as well as drilled hole structures, both ranging on the micrometer range, are compared to corundum blasting as a standard method for surface conditioning. For the presented surface structures, thermal joining and ultrasonic assisted joining are regarded towards their potential for an optimum joint design.

Ni-Al2O3 composite coatings electrodeposited from Watt’s electrolyte include Al2O3 nano-and submicron particles. The effect of particle size and concentration of the particles in the electrolyte were investigated on the morphology and incorporation value of particles into the deposits. The influence of alumina particles on the electrodeposition behavior of Ni was also studied by means of electrochemical impedance spectroscopy. The results achieved from the impedance measurements and the correlation with the layer characterization could help to better understand the codeposition mechanism derived from the impact of different particle characteristics including size and concentration on the nature of the double-layer. The increase in the concentration of particles from 1 to 20 g/l resulted in an increase of the double-layer capacity and decrease of the charge transfer resistance, while the addition of submicron particles had a higher influence on the characteristics of the double-layer compared to the nano particles. Although the alumina particles with submicron size could stimulate the incorporation of particles faster than those with nano size, the strengthening performance of the layers not only depended on the incorporation value of the particles, but also on the microstructure of the deposits.

There are various opportunities to improve the adhesion between polymer and metal in metal-plastic composites. The addition of a bonding agent which reacts with both joining components at the interfaces of the composite can enhance the bonding strength. An alternative method for the adjustment of interfaces in metal-plastic composites is the specific surface structuring of the joining partners in order to exploit the mechanical interlock effect. In this study the potential of using an adhesion promoter based on twin polymerization for metal-plastic composites in combination with different methods of mechanical surface treatment is evaluated by using the tensile shear test. It is shown that the new adhesion promoter has a major effect when applied on smooth metal surfaces. A combination of both mechanical and chemical surface treatment of the metal part is mostly just as effective as the application of only one of these surface treatment methods.

Beside lithium batteries, PEM fuel cells are the most promising strategy as a power source to achieve the targets for introducing and increasing the usage of electric vehicles. Due to limited space and weight problems, water cooled, metallic bipolar plates in a fuel cell metal stack are preferred in motor vehicles. These plates are stamped metal sheets with a complex structure, interconnected media-tight. To meet the multiple tasks and requirements in use, complex and expensive combinations of materials are currently in use (carbon fiber composites, graphite, gold-plated nickel, stainless and acid resistant steel). The production of such plates is expensive as it is connected with considerable effort or the usage of precious metals. As an alternative, metalloid nitrides (CrN, VN, W2N, etc.) show a high chemical resistance, hardness and a good conductivity. So this material category meets the basic requirements of a top layer. However, the standard methods for their production (PVD, CVD) are expensive and have a slow deposition rate and a lower layer thicknesses. Because of these limitations, a full functionality over the life cycle of a bipolar plate is not guaranteed. The contribution shows the development and quantification of an alternative production process for bipolar plates. The expectation is to get significant advantages from the combination of chromium electrodeposition and thermochemical treatment to form chromium nitrides. Both processes are well researched and suitable for series production. The thermochemical treatment of the chromium layer also enables a process-integrated brazing.

Hybrid parts, which combine low weight with high strength, are moving into the focus of the automotive industry, due to their high potential for usage in the field of crash-relevant structures. In this contribution, the development of an intrinsic hybrid composite is presented, with a focus on the manufacturing process, complex simulations of the material behaviour and material testing. The hybrid composite is made up of a continuous fibre- reinforced plastic (FRP), in which a metallic insert is integrated. The mechanical behaviour of the individual components is characterised. For material modelling, an approach is pointed out that enables modelling at large strains by directly connected rheological elements. The connection between the FRP and the metallic insert is realised by a combination of form fit and adhesive bonds. On the one hand, adhesive bonds are generated within a sol gel process. On the other hand, local form elements of the metallic insert are pressed into the FRP. We show how these form elements are generated during the macroscopic forming process. In addition, the applied sol gel process is explained. Finally, we consider design concepts for a specimen type for high strain testing of the resulting interfaces.

We performed a transplant experiment to compare the life histories and morphologies of five geographically representative antlion Myrmeleon hyalinus populations along a sharp climatic gradient, from a Mediterranean climate in Israel's north to a desert climate in the south. Larvae were raised in two environmental chambers simulating Mediterranean and desert climates to investigate the extent to which the different populations exhibit phenotypic plasticity. Along the north-to-south climatic gradient, we observed a gradient in body mass prior to pupation and in pupation rate. Mediterranean populations suffered higher mortality rate when exposed to desert conditions, whereas the mortality rate of desert populations was consistent between Mediterranean and desert conditions. Our results regarding body mass, pupation rate and mortality rate suggest that Mediterranean populations had a more flexible response compared with desert populations. An analysis of digital photographs was used to measure population morphological differences, which were usually indicative of a decrease in trait size along the north-to-south gradient. We show how climatic gradients translate into phenotypic differences in an antlion population and provide a morphometric tool to distinguish between instar stages.

The title compound crystallizes in the triclinic space group P1 with a = 6.323(7), b = 6.964(8), c = 11.740(13)A, α = 104.602(19), β = 98.867(19), γ = 98.726(19)°, V = 484.4(9)A3, and Z = 1. The X-ray structure analysis of this compound leads to revision of the previously published isomeric constitution.

The sonographic diagnosis of a fetal goiter, confirmed at delivery, is described in a fetus exposed to large doses of propylthiouracil, which was administered to the mother. The pregnancy was also complicated by recalcitrant premature labor secondary to polyhydramnios. The intraamniotic instillation of thyroxine decreased the size of the fetal goiter, and numerous therapeutic amniocenteses permitted continuation of the pregnancy, so a mature infant with a goiter but no airway obstruction was delivered. Amniotic fluid reverse-T3 assays confirmed fetal utilization of the thyroxine. Fetal thyroid physiology is discussed briefly along with the benefits of the antenatal sonographic diagnosis of fetal goiter.