Abstract
Plasma nitriding is an established process for increasing the corrosion and wear resistance of steel. However, the possibilities of modern developments in the field of high‐voltage plasma ...power supplies have been hardly investigated. For example, modern plasma generators allow improved arc management, which enable plasma nitriding at higher voltages.
In the present work, the influence of increased voltage (up to 800 V) on the nitriding of a ferritic steel X38CrMoV5‐1 was investigated. It was found that the thickness of the compound layer increases with increasing voltage. Especially at short process times the increased voltage leads to increased growth. An increase in the nitriding depth was also observed.
Furthermore, the increased voltage has an effect on the composition of the compound layer too. A moderate increase in ϵ‐nitride in the compound layer was observed.
One explanation for the observed behavior is the over proportional increase in power with increasing voltage, indicating an increased ionization rate of the plasma. Due to this, more diffusible species would be available for nitriding.
The presented results could be used to reduce process times, particularly where the formation of a compound layer is the aim of the process. An example of such a process is oxy‐nitriding.
Translation abstract
Das Plasmanitrieren ist ein etabliertes thermochemisches Verfahren zur Verbesserung der Korrosions‐ und Verschleißbeständigkeit von Stählen. Moderne technologische Entwicklungen auf dem Gebiet der Hochspannungsplasmastrom‐Versorgung und die Erforschung ihres Potenzials sind kaum untersucht worden. So ermöglichen moderne Plasmageneratoren ein deutlich verbessertes Arc‐Management, das Plasmanitrierprozesse bei höheren Spannungen ermöglicht. In der vorliegenden Arbeit wurde der Einfluss einer erhöhten Spannung (bis zu 800 V) auf das Nitrieren eines ferritischen Stahls (X38CrMoV5‐1) untersucht. Es wurde festgestellt, dass die Dicke der Verbindungsschicht mit steigender Spannung zunimmt. Insbesondere bei kurzen Prozesszeiten führt die erhöhte Spannung zu einem deutlich erhöhten Wachstum. Darüber hinaus wurde auch eine Zunahme der Gesamtnitriertiefe beobachtet. Darüber hinaus scheint die erhöhte Spannung einen Einfluss auf die Zusammensetzung der Verbindungsschicht zu haben. Mit zunehmender Spannung wurde eine moderate Zunahme von ϵ‐Nitrid in der Verbindungsschicht beobachtet. Eine Erklärung für das beobachtete Verhalten ist der überproportionale Anstieg der Leistung mit steigender Spannung, was auf eine erhöhte Ionisierungsrate des Plasmas hinweist. Dadurch stehen mehr diffusionsfähige Spezies für die Nitrierung zur Verfügung. Die vorgestellten Ergebnisse können genutzt werden, um die Nitrierprozesszeiten zu verkürzen, insbesondere wenn die Bildung einer Verbindungsschicht das Ziel des Prozesses ist. Ein Beispiel für solche Prozesse ist das Oxy‐Nitrieren.
Niobium-containing diamond-like carbon (Nb-DLC) films were deposited in a reactive high power impulse magnetron sputtering (HIPIMS) process, using a niobium target in an argon/acetylene atmosphere. ...Investigations of the electrical properties revealed their good suitability to serve as sensor material in strain gauges, with an elevated gauge factor of 35.5 and the possibility to adapt the temperature coefficient of the electrical resistance (TCR) to values near zero. Structure analysis of the crystallinity, chemical composition, and morphology of this material give insights of the correlations between structure and piezoresistive properties. A structure zone model in relation to the Nb content was developed, combining the results of the different measurements.
•Preparation of Nb-DLC by a combined HIPIMS/PECVD process•High gauge factor combined with a low TCR•TCR can be adapted, temperature compensation is possible.•Deeper perception on material structure•Structure zone model of Nb-DLC
The presented paper describes the role of surface technologies in the automotive industry. Various hard coatings like nitrides, diamond and cBN are used on tools for the manufacturing process. Due to ...their high hardness and low coefficient of friction, diamond-like carbon films will be indispensable for engine and power train components. The improvement of automotive glazings by optimization of optical and thermal properties of the glass is an ongoing development task. Coatings with switchable transmission, thin film solar cells as self-cleaning and self-healing surfaces will be features in the car of the future. Various atmospheric pressure and low pressure deposition processes are available. In this paper low pressure plasma and electrochemical deposition are in focus.
The high degree of ionization of the sputtered material during the coating process is one of the main features of HIPIMS (high power impulse magnetron sputtering). The use of HIPIMS leads to better ...film quality for hard coatings based on metal nitrides and to more conformal coatings during via fillings with high aspect ratios used in microelectronics. HIPIMS metal oxides are used in many applications, including optical coatings for filters or transparent conducting oxides in photovoltaics, low emissivity coatings, heat mirrors or panel heaters, as well as touch panels and displays.
Several coatings based on HIPIMS were developed to reveal the benefits of this technology for applications. An overview of applications in industry and research is presented.
This work investigates the influence of substrate temperature and applied bias voltage on the resulting microstructure and crystallographic properties of gas flow sputtered (GFS) partially yttria ...stabilized zirconia coatings (PSZ).
On a FeCrAlY-alloy substrate PSZ coatings were deposited at substrate temperatures of 500°C, 650°C and 800°C with bias voltages up to −100V and were subsequently analyzed utilizing SEM, FIB and XRD.
Without bias voltage, all coatings were columnar and composed of small stacked platelets, but they varied in their porosity and morphology. Higher substrate temperatures lead to higher adatom mobility decreasing the porosity and the deposition rate. For all microstructures a distinct growth direction of the columns is observed changing from 〈111〉 (500°C and 650°C) to 〈100〉 (800°C). For the 〈111〉 morphology, three ridges at intervals of 120° are observed throughout the whole column. In addition to the tetragonal/cubic phase, monoclinic fractions are found at the two lower substrate temperatures.
The application of a negative bias voltage enhances the surface mobility of the film-forming adatoms and can cause densification due to atom displacements, resputtering or channeling phenomena. Moderate bias voltages up to −40V result in more regular columns and a lower porosity. For high bias voltages (−100V), the densification effects seem to dominate leading to fully dense coatings with residual stresses up to −2.5GPa and no preferential grain orientation, rendering this bias value unsuitable for thermal barrier coatings.
•Various different microstructures can be produced utilizing the GFS process.•Without negative bias voltage, all coatings were columnar.•Low bias voltages enhance the adatom mobility.•For higher bias voltages densification effects dominate.•For TBCs, bias voltages higher than −40V should be avoided.
The aim of this work is to gain an understanding of the influence of substrate temperature during deposition on the resulting microstructure and crystallographic properties of gas flow sputtered ...(GFS) partially yttria stabilized zirconia coatings (PSZ).
PSZ coatings were deposited on a FeCrAl-Alloy substrate, varying the substrate temperature between 500°C and 800°C. Regardless of the substrate temperature, all coatings were columnar, but varied in their morphology. Four different groups of sub-microstructures, each defined by a substrate temperature range, were identified based on morphology and X-ray diffraction (XRD) pattern.
The two low-temperature groups exhibit a novel microstructure characterized by three dense ridges at intervals of 120° converging at the column center. Supported by these ridges small stacked plates lead to a featherlike porosity. The XRD pattern revealed a monoclinic fraction, besides the tetragonal and/or cubic one, and a 〈111〉 growth direction. Higher temperatures diminish the monoclinic fraction until it vanishes at 800°C accompanied by a change in growth direction to 〈100〉.
Thermal cycling experiments were conducted between 1050°C and 100°C. Macroscopic spallation occurred for one group while the other samples were intact after the end of the experiment at 1300cycles. Microscopic delaminations were found between a pure alumina scale and a mixed oxide zone, consisting of zirconia particles embedded into an alumina matrix. A hypothesis was proposed explaining the observed failure mode.
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•Depending on the substrate temperature 4 groups of microstructures are identified.•Higher substrate temperatures decrease the deposition rate and the porosity.•The growth direction of the columns changes from ⟨111⟩ to ⟨100⟩ at 800°C.•Highly porous coatings fail due to the formation of a mixed oxide and buckling.•Denser coatings fail due the coalescence of segmentation and delamination cracks.
Koi herpesvirus (KHV) causes KHV disease (KHVD). The virus is highly contagious in carp or koi and can induce a high mortality. Latency and, in some cases, a lack of signs presents a challenge for ...virus detection. Appropriate immunological detection methods for anti‐KHV antibodies have not yet been fully validated for KHV. Therefore, it was developed and validated an enzyme‐linked immunosorbent assay (ELISA) to detect KHV antibodies. The assay was optimized with respect to plates, buffers, antigens and assay conditions. It demonstrated high diagnostic and analytical sensitivity and specificity and was particularly useful at the pond or farm levels. Considering the scale of the carp and koi industry worldwide, this assay represents an important practical tool for the indirect detection of KHV, also in the absence of clinical signs.
This publication describes a new quick and economical method for the simulation of tool wear in the deep drawing and stretch forming of steel sheets in the area of the drawn edge. This method also ...allows a comparative evaluation of the properties of different tool materials versus reference materials. In order to reduce the amount of required test cycles, a controlled amount of wear–inducing particles is added to the contact zone between tool and sheet metal.
Initially, investigations with a high–load tribometer were carried out for the selection of suitable wear–inducing particles. In order to cause a degree of wear similar to normal circumstances within a shorter amount of time, wear–inducing particles were added. Signs of wear were analysed by scanning microscopy and EDX analysis. The wear particles were also used for wear initiation for a strip drawing test.
Subsequently, a wear testing stand was modified for the new concept allowing for a controlled amount of wear particles to be applied. After optimization of the test parameters, it was found that after 50 strokes with a test time of 2.5min a result similar to 94,000 strokes without wear particles was obtained.
•A new quick and economical method for the simulation of tool wear in deep drawing.•Modified wear test device, with transfer possibility to other wear test systems.•Representation of test limits by the juxtaposition of different tool materials.
Plasmanitrieren bietet großes Potenzial, die Verschleißeigenschaften von austenitischen Stählen zu verbessern. Es werden neben den Werkstoffen 1.4307 und 1.4404 die Titan‐stabilisierten Güten 1.4541 ...und 1.4571 betrachtet, um insbesondere den Einfluss der Titanstabilisierung auf das Nitrierergebnis und das Korrosionsverhalten zu untersuchen. Außerdem wurde untersucht, inwieweit der Herabsetzung der Korrosionseigenschaften durch kaltumformungs‐induzierte Defektstrukturen durch die Titanstabilisierung begegnet werden kann. Im Vergleich zu den Werkstoffen 1.4307 und 1.4404 wird bei beiden titanstabilisierten austenitischen Stählen weniger Stickstoff in Bereichen mit Umformmartensit und niedrigen Nitriertemperaturen eingebaut, während an Gleitbändern eine erhöhte Eindiffusion von Stickstoff zu beobachten ist. Die Korrosionsbeständigkeit verbessert sich generell durch die hier verwendeten Plasmanitrierparameter. Generell bewirkt eine höhere Dicke der beim Plasmanitrieren erzeugten S‐Phase eine bessere Korrosionsbeständigkeit sowie eine höhere Oberflächenhärte. Die Titanstabilisierung hemmt die Stickstoffdiffusion bei hohen Umformmartensitgehalten und niedrigen Nitriertemperaturen und fördert die Diffusion an Gleitlinien.
Translation
Plasma nitriding offers great potenzial for improving the wear properties of austenitic steels. Here, the austenitic standard grades 1.4307 and 1.4404, as well as the titanium‐stabilized grades 1.4541 and 1.4571 were investigated regarding the influence of the material condition on the nitriding result and corrosion behavior. Special focus was put on the influence of the Ti‐stabilisation. In addition, it was investigated to what extent corrosion properties are influenced by cold‐forming induced defect structures. In comparison to 1.4307 and 1.4404, less nitrogen is incorporated in areas with forming martensite in titanium‐stabilized austenitic steels and lower nitriding temperatures, while an increased diffusion of nitrogen is observed, when only slip bands are present. The corrosion resistance is generally improved by the plasma nitriding parameters used for this study. In general, a higher thickness of the S‐phase, which forms during the plasma nitriding, results in better corrosion resistance and higher surface hardness. The titanium stabilization inhibits nitrogen diffusion in the presence of deformation induced martensite at lower nitriding temperatures and promotes diffusion in the presence of deformation induced slip bands.
Der Einfluss einer Titanstabilisierung austenitischer Stähle mit verschiedenen Kaltumformgraden auf das Nitrierergebnis wurde untersucht. Die Wirkung der Titanstabilisierung auf die Korrosionsbeständigkeit, die Härte und die Dicke der sich ausbildenden, stickstoffreichen S‐Phase ist von der Art der sich bei der Kaltumformung bildenden Defekte abhängig.
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