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...
moreThe 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.
Gas nitriding is known as a convenient process to improve the wear resistance of steel components. A precipitation-free hardening by low-temperature processes is established to retain the good corrosion resistance of stainless steel. In...
moreGas nitriding is known as a convenient process to improve the wear resistance of steel components. A precipitation-free hardening by low-temperature processes is established to retain the good corrosion resistance of stainless steel. In cases of thermal spray coatings, the interstitial solvation is achieved without an additional surface activation step. The open porosity permits the penetration of the donator media and leads to a structural diffusion. An inhomogeneous diffusion enrichment occurs at the single spray particle edges within the coating’s microstructure. A decreasing diffusion depth is found with increasing surface distance. The present study investigates an adjusted process management for low-temperature gas nitriding of high velocity oxy-fuel-sprayed AISI 316L coatings. To maintain a homogeneous diffusion depth within the coating, a pressure modulation during the process is studied. Additionally, the use of cracked gas as donator is examined. The process management is ...
Austenitic stainless steel exhibits an excellent corrosion behavior. The relatively poor wear resistance can be improved by surface hardening, whereby thermochemical processes offer an economic option. The successful diffusion enrichment...
moreAustenitic stainless steel exhibits an excellent corrosion behavior. The relatively poor wear resistance can be improved by surface hardening, whereby thermochemical processes offer an economic option. The successful diffusion enrichment of bulk material requires a decomposition of the passive layer. A gas nitriding of high velocity oxygen fuel spraying (HVOF)-sprayed AISI 316L coatings without an additional activation step was studied with a variation of the process temperature depending on the heat-treatment state of the coating. A successful nitrogen enrichment was found in as-sprayed condition, whereas passivation prevents diffusion after solution heat treatment. The phase composition and microstructure formation were examined. The crystal structure and lattice parameters were determined using X-ray diffraction analysis. The identified phases were assigned to the different microstructural elements using the color etchant Beraha II. In as-sprayed condition, the phase formation in...
A process for the simultaneous plasma-electrolytic anodic oxidation (PAO) of a compound consisting of an Al (AlMgSi1) and Mg (AZ31) alloy is introduced. Using this process, an almost uniformly thick, compact oxide coating on both compound...
moreA process for the simultaneous plasma-electrolytic anodic oxidation (PAO) of a compound consisting of an Al (AlMgSi1) and Mg (AZ31) alloy is introduced. Using this process, an almost uniformly thick, compact oxide coating on both compound partners can be produced provided that the narrow window of this process is determined and kept. The most important parameters for the simultaneous plasma
Thermal spraying is one of the most variable and diverse surface coating techniques concerning materials to be processed as well as possible geometries to be coated. The group of thermal spray processes covers a large parameter field to...
moreThermal spraying is one of the most variable and diverse surface coating techniques concerning materials to be processed as well as possible geometries to be coated. The group of thermal spray processes covers a large parameter field to combine nearly each coating with each base material. Thermally sprayed coatings can be applied very evenly and therefore allow to be applied on final-shaped components. Otherwise, if further treatment or finishing is necessary, thermal spray coatings can be processed by grinding or even milling. Masking during the coating process permits the selective coating of specific surface parts or the application of required geometrically structures, e. q. conductor structures. The main application field of thermal spray coatings is the (combined) wear and corrosion protection of selected component parts.
To produce silver-based contact materials such as silver/tin oxide different ways are possible. All usual technologies have their typical advantages and disadvantages. Expensive techniques are characterised by a very fine reinforcement...
moreTo produce silver-based contact materials such as silver/tin oxide different ways are possible. All usual technologies have their typical advantages and disadvantages. Expensive techniques are characterised by a very fine reinforcement distribution. Techniques with a high output quantity display a very limited particle distribution within the matrix material. By means of the economical mechanical alloying process, particle-reinforced metal-matrix composite powders
ABSTRACT Magnesiumlegierungen sind sehr korrosionsanfllig, was ihre Anwendung unter korrosiven Bedingungen einschrnkt. Eine Möglichkeit, um Magnesium vor aggressiven Umweltbedingungen zu schützen, ist das Beschichten. Es werden Ergebnisse...
moreABSTRACT Magnesiumlegierungen sind sehr korrosionsanfllig, was ihre Anwendung unter korrosiven Bedingungen einschrnkt. Eine Möglichkeit, um Magnesium vor aggressiven Umweltbedingungen zu schützen, ist das Beschichten. Es werden Ergebnisse über das Korrosionsverhalten der aus verschiedenen Elektrolyten galvanisch verzinkten Magnesiumknetlegierung AZ31 gezeigt. Die Bewertung der Korrosionsprozesse in chloridhaltigen Lösungen erfolgte durch elektrochemische Messungen.Durch einstündige Auslagerung der beschichteten Proben wurde festgestellt, dass dicke und dichte galvanische Zinkschichten auf AZ31 die Korrosionseigenschaften verbessern. Eine Erhöhung der Immersionszeit führt jedoch zu einer Verschlechterung der Korrosionseigenschaften. Elektrolytische Zinkschichten, die durch einen konsekutiven alkalisch / sauren Prozess erzeugt werden, stabilisieren die Schicht und verbessern somit die Korrosionsbestndigkeit des beschichteten AZ31.Zinc-Plating of Magnesium AlloysMagnesium alloys are highly susceptible to corrosion that limits their application when exposure to corrosive service conditions is needed. One of the ways to prevent corrosion is to coat the magnesium-based substrate to avoid a contact with an aggressive environment. Results concerning corrosion behaviour of wrought AZ31 magnesium alloy with electrolytic zinc coatings deposited from different electrolyte solutions are described. Evaluation of corrosion processes in chlorides containing solutions was performed by electrochemical measurements.It was found that thick and dense electrolytic zinc coatings formed on AZ31 significantly improve the corrosion behaviour of magnesium alloy after one hour immersion of zinc coated magnesium alloys in corrosive media. Further increase of immersion time leads to relatively fast decrease of corrosion properties. Electrolytic zinc coatings obtained in consecutive alkaline / acidic process demonstrate an improvement of corrosion resistance of coated AZ31. The time to coating degradation strongly increases.
... 4.3.3 Nachbehandlung, Einlagerung von Farbstoffen Mehrere Versuchsreihen wurden durchgeführt, um Mög-lichkeiten zu finden, über bestimmte Nachbehandlungen wei-tere Steigerungen der Durchschlagsspannung zu erzielen. ... 8. R. Dizon,...
more... 4.3.3 Nachbehandlung, Einlagerung von Farbstoffen Mehrere Versuchsreihen wurden durchgeführt, um Mög-lichkeiten zu finden, über bestimmte Nachbehandlungen wei-tere Steigerungen der Durchschlagsspannung zu erzielen. ... 8. R. Dizon, Aluminium 1973, 5, 357. ...
By means of dynamic–mechanical analysis (DMA), selected application-specific properties of flax- and hemp-fibre reinforced polypropylenes (PPs) have been determined for material characterisation. The compound samples were manufactured...
moreBy means of dynamic–mechanical analysis (DMA), selected application-specific properties of flax- and hemp-fibre reinforced polypropylenes (PPs) have been determined for material characterisation. The compound samples were manufactured both by consolidation of hybrid non-wovens and compounding and injection moulding with the addition of natural fibres. The conditioning (long and short fibres), the manufacturing process and the processing parameters are the most
ABSTRACT 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...
moreABSTRACT 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.
One of the major causes of deterioration of reinforced concrete structures is chloride-induced corrosion of the reinforcing steel. This phenomenon is significantly influenced by the presence of cracks. This paper presents the experimental...
moreOne of the major causes of deterioration of reinforced concrete structures is chloride-induced corrosion of the reinforcing steel. This phenomenon is significantly influenced by the presence of cracks. This paper presents the experimental and numerical results on the influence of cracks on chloride penetration in concrete structures. The experimental results were obtained with the non-steady state migration test, described in
... Insights into the potential interaction between the components of a composite can be obtained by a more detailed knowledge of ... It is outside the scope of this review to comment on these different models, and the reader is therefore...
more... Insights into the potential interaction between the components of a composite can be obtained by a more detailed knowledge of ... It is outside the scope of this review to comment on these different models, and the reader is therefore directed ... Workers Fiber γd S (mN/m) γ + S γ − S ...
1Chemnitz University of Technology, Institute for Composite Materials and Surface Technology, D-09107 Chemnitz, Germany. 2Chemnitz University of Technology, Department for Materials and Impact Engineering, Erfenschlager Str. 73, D-09125...
more1Chemnitz University of Technology, Institute for Composite Materials and Surface Technology, D-09107 Chemnitz, Germany. 2Chemnitz University of Technology, Department for Materials and Impact Engineering, Erfenschlager Str. 73, D-09125 Chemnitz, ...
The work focuses on the potential of structural and chemical examinations by scanning electron microscopy based methods for archaeometric studies on ceramics. Achieved by a single preparation technique (polished block sections), the...
moreThe work focuses on the potential of structural and chemical examinations by scanning electron microscopy based methods for archaeometric studies on ceramics. Achieved by a single preparation technique (polished block sections), the feasibility and benefits of electron backscatter diffraction are demonstrated as case studies using polychrome examples of pre-Columbian pottery (Wari, Moche and Cajamarca). Elemental and phase maps allow for separate consideration of clay and temper. Identification of mineral phases and intergrowths of temper particles provide information for clarifying clay procurement and firing techniques with respect to local versus non-local pottery to enlighten trade relations, technological transfer and shared heritage of pre-Columbian cultures.