Wolfgang Maus-Friedrichs

Technische Universität Clausthal | TUC · Department of Energy Research and Physical Technologies

The use of NaBH4 as a hydrogen storage material suffers to some extend from its deficient stability against chemicals and degradation at elevated temperatures. This disadvantage can be overcome by the use of polyelectrolytes as protective layers. Furthermore, the coating of NaBH4 with polyelectrolytes significantly enhances the release of hydrogen...

The fatigue corrosion cracking of the Al7075 alloy has been investigated by Scanning Electron Microscopy (SEM) and Auger Electron Spectroscopy (AES). Specimen exposed to cyclic load at room temperature until crack initiation show a significant increase of magnesium within a distance of about 1 μm around the crack, while almost no aluminum was left....

Dielectric Barrier Discharge plasma treatment of a titanium metal foil in oxygen, nitrogen and air under atmospheric conditions is investigated employing X-Ray Photoelectron Spectroscopy (XPS). We investigated three different reference samples and compare the results with a large number of studies on the XPS analysis of titanium compounds containin...

Wood and aluminum composites are becoming increasingly attractive due to their ability to combine the advantages of both materials: the lightweight nature of wood and the strength of aluminum. However, using conventional wood adhesives like polyvinyl acetate (PVAc) to bond these dissimilar materials is challenging and requires special surface treat...

Due to the high specific surface area of titanium aluminide powders, significant and unavoidable surface oxidation takes place during processing. The resulting oxides disrupt the conventional powder metallurgical process route (pressing and sintering) by reducing green strength and sintered properties. Oxide-free particle surfaces offer the potenti...

Plasma in hydrogen-containing atmospheres is an efficient method for the reduction of iron oxides. Although a vast number of approaches were performed for the reduction of bulk Fe oxides with thermal hydrogen plasmas, there is almost no information about the non-thermal plasma reduction efficiency in the atmospheric pressure range. In the current a...

The front cover artwork is provided by Prof. Maus-Friedrichs' group at the Clausthal University of Technology. The image shows the molecular interaction formed at the interface between the adhesive cyanoacrylate and a natively oxidized copper or aluminium surface. Read the full text of the Research Article at 10.1002/cphc.202300076.

As oxygen negatively affects most production processes in the metalworking industry, a truly oxygen‐free production environment appears attractive in terms of the resulting material and component properties. This overview summarizes research conducted within the Collaborative Research Centre (CRC) 1368. The objectives of this CRC are twofold. First...

The interaction of silane and water is discussed controversially in literature: some authors suggest monosilane and water react kinetically and sufficiently fast enough to remove water, while others state the reaction occurs only at elevated temperatures. This question is of technological interest for the removal of unavoidable water residues in Ar...

Cyanoacrylates are an extremely reactive class of adhesives. Despite their commercial use as instant adhesives, the adhesion mechanism, especially to technically relevant oxidized metal surfaces, has not yet been sufficiently investigated. In the present work, ultra‐thin ethyl cyanoacrylate films are deposited on copper oxide and aluminum oxide by...

Aluminium alloys, like AlMgSi1 and AlMg3, cannot be joined in industrial processes by laser beam brazing without the use of fluxes due to their resistant oxide layer. The aim of this study is to dispense with the use of flux. For the investigations, an oxygen-free atmosphere was created by using the highly reactive gas monosilane and thus achieving...

Nowadays, cold plasma techniques like dielectric barrier discharge (DBD) plasmas have attracted considerable interest in view of high deoxidation efficiencies as well as relative simplicity of setups. Although DBD plasma deoxidation of copper has been mainly studied in Ar/H2 mixtures, there is no information on reduction performance of such methods...

Oxide layers on metal surfaces adversely affect processability and material properties in many industrial applications. Although several plasma-based approaches for deoxidation were investigated in the past, oftentimes they either work under conditions expensive to create or require long processing times. In this study, the deoxidation effect of a...

We report on a new approach to transport samples for surface analysis safely from oxidation over long distances. The transport method is based on silane-doped inert gases, which are used as a transport medium. In this paper, we show that with the help of silane, highly purified inert gas atmospheres with oxygen contents of less than 10⁻¹⁵ mbar can...

In this study, the application of a dielectric barrierer discharge plasma for metal deoxidation was shown on differently oxidized copper surfaces in an Ar/H2 atmosphere at 100 hPa and room temperature. Plasma treatments with a discharge voltage of 11 kV and a frequency of 8.8 kHz yielded an almost complete deoxidation of samples with native Cu2O la...

In this study, the application of a dielectric barrierer discharge plasma for metal deoxidation was shown on differently oxidized copper surfaces in an Ar/H2 atmosphere at 100 hPa and room temperature. Plasma treatments with a discharge voltage of 11 kV and a frequency of 8.8 kHz yielded an almost complete deoxidation of samples with native Cu2O la...

Metastable Induced Electron Spectroscopy, Ultraviolet Photoelectron Spectroscopy (He I and He II), X-ray Photoelectron Spectroscopy, and Atomic Force Microscopy were employed to study the interaction of silver with lignin as well as with two of its natural precursors, coniferyl alcohol and sinapyl alcohol. For all three of them, no chemical interac...

The supply and processing of materials for highly stressed components are usually cost-intensive. Efforts to achieve cost and resource efficiency lead to more complex structures and contours. Additive manufacturing steps for component repair and production offer significant economic advantages. Machining needs to be coordinated with additive manufa...

Syntheses of push‐pull substituted non‐symmetric bis(thienyl)ethenes (BTEs) possessing a central perfluorocyclopentene core are described. The substituent effects of anisole, phenole, and phenolate as well as pyridine, pyridinium, and N ‐methylpyridinium substituents, joined via their 3‐ or 4‐positions to the central BTE core, respectively, cover t...

Self-assembling films typically used for colloidal lithography have been applied to pine wood substrates to change the surface wettability. Therefore, monodisperse polystyrene (PS) spheres have been deposited onto a rough pine wood substrate via dip coating. The resulting PS sphere film resembled a polycrystalline face centered cubic (FCC)-like str...

For understanding the interactions between adhesives and different surfaces, the in-situ characterization of the interface is essential. Especially for highly reactive cyanoacrylates, better known as super glues, the adhesion mechanism is poorly understood because, among other things, the characterization of the interface is difficult. The aim of t...

Self-assembling films typically used for colloidal lithography have been applied to pine wood substrates to change the surface wettability. Therefore, monodisperse polystyrene (PS) spheres have been deposited onto a rough pine wood substrate via dip coating. The resulting PS sphere film resembled a polycrystalline FCC-like structure with typical do...

The tunicate species Ciona intestinalis is a fast-growing marine invertebrate animal that contains cellulose in its outer part—the tunic. The high crystallinity and microfibril aspect ratio of tunicate cellulose make it an excellent starting material for the isolation of nanocellulose. In the present work, tunic from C. intestinalis was subjected t...

In the current study, the potential of dry machining of the titanium alloy Ti-6Al-4V with uncoated tungsten carbide solid endmills was explored. It is demonstrated that tribo-oxidation is the dominant wear mechanism, which can be suppressed by milling in an extreme high vacuum adequate (XHV) environment. The latter was realized by using a silane-do...

A process of removal of surface oxides from stainless steels AISI 304 and 446 that involves reduction by residual carbon, followed by formation and desorption of carbon monoxide, is studied by investigation of thermal desorption (with QMS) and SIMS. Carbon monoxide desorption is studied as a function of time and temperature by QMS, carbon diffusion...

Ensuring a high adhesion of amorphous carbon films to steel substrates remains a challenging task, sustaining continuous research efforts to improve the adhesion strength. Besides the interlayer system and the substrate material, surface pretreatments have a significant impact on the adhesion behavior. Within this context, the influence of the High...

In the plastic-processing industry, the formation of unknown deposits at the interface between polymer melt and steel surfaces can pose major challenges, which occurs especially on screws, barrels, and tools. These deposits will detach during production and lead to quality restrictions mostly as spots in the products. We investigated the interactio...

The adsorption behavior of thin films of 4-alkoxybenzoic acids (with either hydroxy-, methoxy-, propoxy-, pentoxy- and decoxy-chains) and terephthalic acid, evaporated on a Highly Oriented Pyrolytic Graphite (HOPG) surface was studied. The orientation of the molecules was characterized by Metastable Induced Electron Spectroscopy (MIES) and Ultravio...

Specimens of austenitic AISI 304 and ferritic 446 (contains 1.7 wt.% Al) underwent heat treatments up to 1200 °C in ultrahigh vacuum (UHV) in an analysis chamber with a base pressure of 10⁻¹⁰ mbar and high vacuum (HV) in an industrial vacuum brazing furnace with a base pressure of 10⁻⁶ mbar. The effect of the two oxygen partial pressure ranges on s...

Nanoparticles are coated in-flight with a plasma-enhanced chemical vapor deposition (PECVD) process at ambient or elevated temperatures (up to 300 �C). Two silicon precursors, tetraethyl orthosilicate (TEOS) and hexamethyldisiloxane (HMDSO), are used to produce inorganic silica or silica-organic shells on Pt, Au and TiO2 particles. The morphology o...

TiO2 nanoparticles show a high photocatalytic activity and are used in the semiconductor industry or medicine for example. During the manufacturing process problems like agglomeration or phase transition at higher temperatures occure. Therefore the idea of this project is to cover the TiO2 nanoparticles with a silicon oxide coating in order to incr...

Silicon dioxide coatings are applied via a two step process using a dielectric barrier discharge (DBD) plasma treatment. In the first processing step a mixture of silane and nitrogen is employed for the DBD plasma treatment to deposit the primer Si:N:H coating. In the second step the primer coating is exposed to oxygen plasma treatment for a conver...

We present the use of a dielectric barrier discharge (DBD) for the removal of irritant gases. To study the detailed plasma mechanisms, an experimental set-up was constructed that provides a significant concentration of the irritant gas. The gas stream is analyzed with and without plasma treatment using a commercial system based on a quadrupole mass...

The use of CaCO3, FeCl3, and FeOOH as powder sorbents for a plasma-based hydrogen sulfide removal from biogas mixtures was investigated. No plasma-enhanced surface reactions were observed during the processing. However, the high surface area provided by the powders led to an increased deposition of atomic sulfur. The dissociation of H2S in dielectr...

The polymerization of methyl methacrylate via plasma discharges is well known today. Usually, plasma-enhanced chemical va- por deposition (PECVD) is used to deposit polymer coatings. Solid coatings are formed out of the liquid phase from methyl methacrylate via dielectric barrier discharge. The formation of the coating proceeds in the gas and the l...

Abstract: The deposition of silicon-containing films is possible in a very simple manner via plasma-enhanced chemical vapor deposition (PECVD). A dielectric barrier discharge (DBD) plasma was used to prepare SixHyNz films from 1.5% monosilane (SiH4) diluted in nitrogen. These films were easily transformed into stoichiometric silicon dioxide (SiO2)...

Emissions of sulphur dioxide (SO2) are highly problematic for climate, health and buildings. The amount of SO2 emitted each year, however, is currently increasing. One main origin of SO2 emissions is the transportation sector. Further, a significantly increasing source is the use of biomass for energy production. Dielectric barrier discharge plasma...

Der positive Effekt kalter Plasmen in Form von dielektrisch behinderten Entladungen bei der Unterstützung von Verbrennungsvorgängen ist bereits vielfach demonstriert. Anhand der Behandlung magerer Propan-Luft-Gemische mit Brennstoffkonzentrationen von 125 – 1000 ppm, d.h. weit unterhalb der Zündschwelle, konnte der Nutzen von dielektrisch behindert...

Manganese(II) biphenyl-4,4'-dicarboxylate, prepared by crystallization of a mixture of biphenyl-4,4'dicarboxylic acid, manganese(II) chloride, and di(4-pyridyl) acetylene as base in a mixture of dimethylformamide, ethanol and water in a closed vessel at elevated temperatures forms a 3D network of {[Mn(bpdc)(H2O)(2)][Mn(bpdc)(H2O)]} containing one f...

A novel approach for the purification of inert gases by means of a dielectric barrier discharge (DBD) plasma has been demonstrated for argon and nitrogen. A rotating sacrificial electrode has been employed together with an electrode cleaning system to remove passivating product films during the plasma processing and thus enhance capacity and reacti...

The adsorption of thiophene from the gas phase onto clean and oxidized titanium foils as well as onto perchloric acid or bromine pretreated titanium foils did not yield any chemical interaction or even stable adsorption. Especially the oxidative polymerization as classical approach for the synthesis and deposition of polythiophene cannot be employe...

Die Anwendung von Plasmen zur Beschichtung von Oberflächen bietet großes Potential, bestehende Prozesse zu vereinfachen und neuartige Funktionsoberflächen zu erzeugen. Durch die Verwendung von Plasmen können einfachere, kostensparende und besser handhabbare Arbeitsgase als in der klassischen chemischen Gasphasenabscheidung verwendet werden. Gleichz...

The adsorption behavior of thin films of terephthalic acid (TPA) evaporated on a gold surface as well as on an aluminum foil was studied. The orientation of the molecules was characterized by metastable induced electron spectroscopy (MIES) and ultraviolet photoelectron spectroscopy (UPS). To make sure that the evaporation of TPA is nondestructive,...

Mithilfe einer dielektrischen Barriereentladung (Dielectric Barrier Discharge, DBD) sollen verschiedene nanoskalige Materialien mit einer Siliziumoxid-Schicht umgeben werden. Im Rahmen dieses Projektes sollen zum einen Untersuchungen mit Partikeln auf Substraten durchgeführt werden, um Informationen über Mechanismen und ideale Versuchsbedingungen z...

One aim of this work was the chemical modification of surfaces of Scots pine (Pinus sylvestris L.) sapwood veneer chips by covalently bonded substances for improved hydrophobicity. The durable attachment of organosilyl moieties to the surface was in focus. Several benzotriazolyl-Activated p-silylated benzoic acid derivatives were applied to the est...

The deposition behavior of bisphenol A polycarbonate (BPA-PC) on a Au(111) single crystal has been studied. Thin films of PC were prepared by in situ evaporation of PC pellets under UHV conditions. The resulting PC/Au(111) interfaces were characterized by means of Ultraviolet Photoelectron Spectroscopy (UPS), X-ray Photoelectron Spectroscopy (XPS)...

We have employed Metastable Induced Electron Spectroscopy, Ultraviolet Photoelectron Spectroscopy, X-ray Photoelectron Spectroscopy and Atomic Force Microscopy to investigate the adsorption behavior of silver on Ar plasma treated pine wood chips. The plasma treatment of wood surfaces in argon leads to a hydrophobization of the surfaces by the detac...

Metal hydrides are promising compounds for the storage of hydrogen especially in the transport sector. Their high reactivity with moisture and difficult handling in ambient atmosphere prevents their easy application in tanks and thus the market penetration of this very promising and clean technology. In the present work we investigated the way to p...

Self-assembling systems of colloidal spheres are widely used as templates for the structured deposition of metals and semiconductors. Multilayer samples of ordered polystyrene spheres are prepared by a flow induced process. The subsequent surface activation by a dielectric barrier discharge in oxygen is followed by the fabrication of protecting pol...

In the present paper, the decomposition and the crystallization behaviour of amorphous Si2C films, which were deposited by r.f. magnetron co-sputtering on Si wafer substrates, are investigated. For analysis, the following methods were used: x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), grazing incidence x-ray diffr...

The adsorption behavior of silver atoms on a glucose film and their interaction was investigated by metastable induced electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy as well as atomic force microscopy. Glucose is found to form micro droplets on gold substrates with typical diameters/d...

Metastable induced electron spectroscopy, ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy as well as atomic force microscopy were employed to study the adsorption of silver on cellulose as well as its precursor cellobiose. The formation of silver nanoparticles encapsulated by the organic film previously found for the mon...

The coating of titanium dioxide nanoparticles with silicon dioxide has been carried out by dielectric barrier discharge (DBD) plasma treatments to enhance the ther-mostability of Titania for applications at high temperature processes. During the first coating processing step, a closed film of silicon nitride was produced via plasma treatment in a g...

The coating of different substrates with silicon dioxide films is of great interest for a variety of applications ranging from gate oxide layers and anti-reflective glasses to protective coatings against influences as reactive gases, sintering during high temperature processes and many more. The use of plasma-based processes for the film deposition...

Residuals of lubricants adhere as very thin layers of hydrocarbons to the surfaces of cold rolled aluminium foil. Subsequent processing of the foil requires a cleaning process. In this study, a new approach to degrease the aluminium is examined that employs an atmospheric pressure plasma treatment of the surface. X-ray photoelectron spectroscopy is...

The adsorption of silver on lignin is of great interest for the modification of wood surfaces with antibacterial coatings. The natural precursors during the biosynthesis of lignin are mainly the monolignols sinapyl alcohol and coniferyl alcohol. These have been used as model systems to get a better understanding of the interaction of silver with li...

Titanium dioxide nanoparticles are used commonly in various applications due to their high catalytic activity. Many of these applications require subsequent treatments after the deposition of the TiO2 particles. Some of these include thermal processing at high temperatures, e.g. roof tiles. For all of these applications, the crystal structures as w...

Multilayer polystyrene (PS) colloid crystals are exposed to a dielectric barrier discharge (DBD) in a mixture of nitrogen and silane as processing gas. This yields a closed layer of silicon nitride on the PS spheres. In a second step silicon nitride is oxidised to SiO 2 in an oxygen-DBD. Finally PS is pyrolytic decomposed leaving a colloid crystal...

The coating of the model substrate titanium dioxide with silicon dioxide has been investigated by means of X-ray Photoelectron Spectroscopy, Metastable Induced Electron Spectroscopy, Ultraviolet Photoelectron Spectroscopy and Atomic Force Microscopy. The silicon was deposited using the gaseous precursor silane, which was diluted in 97% nitrogen for...

Titanium dioxide nano particles are used commonly in various applications due to their high catalytic activity. Many of these applications require subsequent treatments after the deposition of the TiO2 particles. Some of these include thermal processing at high temperatures, e.g. roof tiles. During such procedures the nano particles transform from...

The hydrophobation of wood surfaces is of great technological interest and a variety of approaches is being followed to earn contact angles as large as possible. The high contact angles for both, polar and non-polar liquids that are found for Lotus leaves may thus be advantageous over current methods and may also bring in many new applications. Res...

Deformable sandwich sheet materials have the advantage to be produced as raw materials and to be formed afterwards to even complex geometries. Moreover they are cost effective and predestinated for mass production. For such systems the necessity is given for a good bonding to guarantee a good shear transfer between the single layers. Because of def...

The lipids of the stratum corneum comprise the most important components of the skin barrier. In patients with ichthyoses or atopic dermatitis, the composition of the skin barrier lipids is disturbed resulting in dry, scaly, itching erythematous skin. Using the latest X-Ray Photoelectron Spectroscopy (XPS) technology, we investigated the physiologi...

Titanium dioxide nano particles are used commonly in various applications due to their high catalytic activity. Many of these applications require subsequent treatments after the deposition of the TiO2 particles. Some of these include thermal processing at high temperatures, e.g. roof tiles. During such procedures the nano particles transform from...

The adsorption of silver on different organic substrates is of great technological interest for various applications. Over the past 20 years, especially silver nano particle coatings drastically increased in importance, due to their outstanding functionality. One of the most common applications of silver particles is the functionalization of surfac...

X-Ray Photoelectron Spectroscopy (XPS), Metastable Induced Electron Spectroscopy (MIES) and Ultraviolet Photoelectron Spectroscopy (UPS) were applied to study the interaction of H2O molecules with iron films. During the interaction with H2O molecules under ultrahigh vacuum conditions, an oxide film is formed on the iron surface. UPS and XPS still s...

The thermal stability of amorphous Si2C films was studied by means of X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES), Grazing Incidence X-ray Diffractometry (GIXRD), Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). The films were deposited by magnetron sputtering onto silicon single crystals. The as-d...

Polystyrene nanospheres are currently under investigation as litography masks and templates for the production of hollow inorganic spheres which have promising applications in catalysis and energy storage. In this regard the chemical functionalization and stabilization of the polystyrene framework is crucial. Thin films of ordered polystyrene nano...

Metastable Induced Electron Spectroscopy, Ultraviolet Photoelectron Spectroscopy, X-ray Photoelectron Spectroscopy, and Atomic Force Microscopy have been employed to study the adsorption of silver and cinnamyl alcohol on Au(111) and Si(100) substrates. Initially, these investigations were carried out preceding the investigation of the adsorbtion be...

The influence of an atmospheric pressure plasma treatment on wood extractives has been investigated by means of surface energy determination and XPS. Polar and disperse component of the surface energy show only marginal influence of plasma treatment, whereas XPS indicates plasma induced oxidation and degradation of the extractives.