bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation der Partikelentwicklung entlang der Prozesskette geschmiedeter und einsatzgehärteter Bauteile aus mikrolegiertem 18CrNiMo7-6*
Authors: Konovalov S. , Clausen B. , Hoffmann F. , Zoch H.-W. , Prahl U. , Bleck W.
Published: December 2013

Kurzfassung

Die Steigerung der Aufkohlungstemperatur ist eine effiziente Vorgehensweise, um die Wirtschaftlichkeit von Einsatzhärteprozessen zu erhöhen. Allerdings muss hierzu neben einer Erweiterung des Legierungskonzeptes um Niob auch die gesamte Prozesskette betrachtet werden, um eine zielgerichtete Ausscheidungsentwicklung zur Sicherstellung der Feinkornbeständigkeit einzustellen. In der hier präsentierten Arbeit wird eine numerische thermodynamikbasierte Prozesskettensimulation von alternativen Prozessketten für Getriebebauteile vorgestellt mit dem Ziel, stabile Prozesse zur Einstellung von Feinkornstabilität auch bei erhöhten Einsatztemperaturen zu identifizieren.
Verbessertes Umformverhalten von höchstfesten 7xxx-Aluminiumblechen durch Halbwarmumformen*
Authors: Sotirov N. , Simon P. , Waltenberger T. , Uffelmann D. , Melzer C.
Published: December 2013

Kurzfassung

Die AlZnMgCu-Legierungen, die im Flugzeugbau bereits eine breite Anwendung finden, gehören zur Gruppe der aushärtbaren Aluminiumlegierungen und zeichnen sich als Blechwerkstoff durch hohe statische Festigkeiten (bis zu 700 MPa) aus. Das geringe spezifische Gewicht verbunden mit der hohen Festigkeit dieser Legierungsklasse ermöglicht deutliche Gewichtsreduktion bei gleicher Bauteilsteifigkeit im Vergleich zum Konkurrenzwerkstoff Stahl. Zur Verbesserung des bei Raumtemperatur geringen Umformvermögens der AlZnMgCu-Legierungen ist der Einsatz von Umformverfahren bei erhöhten Temperaturen erforderlich. Ein aussichtsreicher Ansatz zur Verbesserung der Umformbarkeit der höchstfesten Aluminiumlegierungen ist die Erhöhung der Temperatur in den Bereich des Halbwarmumformens unterhalb der Rekristallisationstemperatur des Werkstoffs. Im vorliegenden Beitrag werden anhand von Finite-Elemente-Prozesssimulationen und Umformversuchen die Potenziale zur Realisierung komplexer Tiefziehbauteile aus der höchstfesten AlZnMgCu-Legierung AMAG TopForm® UHS durch Halbwarmumformen gezeigt.
Low temperature gaseous surface hardening of stainless steel
Authors: Christiansen T. L. , Somers M. A. J.
Published: December 2013

The present contribution gives an overview of some of the technological aspects of low temperature thermochemical treatment of stainless steel. Examples of low temperature gaseous nitriding, carburising and nitrocarburising of stainless steel are presented and discussed. In particular, the morphology, microstructure and characteristics of so-called expanded austenite “layers” on stainless steel are addressed.
Evolution of residual stress in the diffusion zone of a model Fe-Cr-C alloy during nitriding*
Authors: Jegou S. , Barrallier L. , Kubler R. , Somers M. A. J.
Published: December 2013

Development and evolution of compressive residual stress during nitriding treatment are studied. A model carbon iron-based alloy Fe-3wt.%Cr-0.35wt.%C was nitrided in gas at 550 °C for different times. Microstructural investigation indicated an influence of the transformation and the associated carbon diffusion on the in-situ relaxation of residual stress induced by nitride precipitation. The transformation of initially present carbides into nitrides and the associated carbon accumulation ahead of the nitriding front is particularly taken into account. The distribution of residual stress in the nitrided case was predicted with a self-consistent mechanical model, using the volume changes associated with the phase transformations. To this end the nitrogen and carbon concentration distributions were converted into the equilibrium phase fractions of carbides and nitrides. An excellent correlation was obtained between experimental (X-ray diffraction analysis) and, thus, calculated independent residual stress distributions in the ferrite matrix.
Experimentelle Untersuchung und Modellierung des Niederdruck-Carbonitrierens*
Authors: Hagymási L. , Waldenmaier T. , Schwarzer J. , Schulze V. , Reimert R.
Published: December 2013

Kurzfassung

Das Gas-Carbonitrieren ist ein seit Jahrzehnten etabliertes Wärmebehandlungsverfahren. Im Vergleich zum reinen Aufkohlen, ermöglicht die zusätzliche Zugabe von Stickstoff eine höhere Härtbarkeit sowie eine bessere Anlass- und Verschleißbeständigkeit. Beim klassischen Verfahren besteht die Gefahr der Randoxidation der Bauteiloberflächen. In Abhängigkeit von der Bauteilbeanspruchung muss die Oxidschicht durch eine kostenintensive Nachbearbeitung entfernt werden. Bei komplexen Bauteilgeometrien, wie beispielsweise Tieflochbohrungen, ist eine Nachbearbeitung meist nicht möglich. Die Randoxidation kann durch das Niederdruck-Carbonitrieren vermieden werden. Ohne ein grundlegendes Verständnis über die Wechselwirkungen der Kohlenstoff- und Stickstoffdonatoren bei den Oberflächenvorgängen und des Kohlenstoffs und Stickstoffs beim Stofftransport in der Eisenmatrix ist jedoch eine Prozessauslegung bei diesem neuartigen Verfahren nur mit hohem zeitlichem und experimentellem Aufwand möglich. Daher soll der Stofftransport modelliert werden, um eine schnelle, simulationsgestützte Auslegung zu ermöglichen. In diesem Beitrag wird ein Modell zur vollständigen Beschreibung der Stofftransportvorgänge beim Niederdruck-Carbonitrieren vorgestellt. Ein Vergleich der mathematischen Ansätze mit den experimentellen Ergebnissen erfolgt nur bei der Beschreibung der Diffusion. Es werden die Ergebnisse zur Löslichkeit und zur Diffusion des Stickstoffs in den Einsatzstählen 20MnCr5 und 18CrNi8 präsentiert. Die Wärmebehandlung erfolgte in einem industriellen Vakuumofen. Im ersten Schritt wurde die Stickstofflöslichkeit in Abhängigkeit der Legierungszusammensetzung, des Drucks und der Temperatur untersucht. Im zweiten Schritt folgte die Modellierung der Diffusionsvorgänge. In erster Näherung zeigen die berechneten Verläufe der Kohlenstoff- und der Stickstoffkonzentrationen im Stahl eine gute Übereinstimmung mit den experimentellen Ergebnissen.
Systematische Untersuchung verschiedener Einflussgrößen auf die Maß- und Formänderungen von einsatzgehärteten Stirnrädern*
Authors: Steinbacher Matthias , Surm Holger , Clausen Brigitte , Lübben Th. , Hoffmann Franz
Published: December 2013

Kurzfassung

Hoch belastete Zahnräder werden üblicherweise wärmebehandelt, um den betriebsbedingten Belastungen zu widerstehen. Im Zusammenhang mit Bauteilen des Antriebstrangs, insbesondere Zahnrädern, wird häufig das Verfahren des Einsatzhärtens eingesetzt. Dabei werden verschiedene Verzüge beobachtet, deren Untersuchung im Folgenden dargestellt wird. Als Probekörper dienten schrägverzahnte kleinmodulige Stirnräder. Die Einsatzhärtung wurde in einer Zwei-Kammer-Vakuumanalage vom Typ IPSEN RVTC 224 mittels Niederdruckaufkohlen und Hochdruckgasabschreckung durchgeführt. Die Untersuchungen wurden durch die Anwendung von Design-of-Experiments (DoE)-Methoden unterstützend begleitet. Bezüglich ihres Einflusses auf den Verzug der Zahnräder standen die drei aufeinanderfolgenden Wärmebehandlungsschritte Erwärmen, Aufkohlen und Abschrecken im Fokus der Untersuchungen. Die in den Untersuchungen des Erwärmprozesses variierten Parameter sind der Chargenaufbau, der Wärmeübergangsmechanismus sowie die Temperatur der ersten Haltestufe für den Temperaturausgleich in der Charge. Die in der Aufkohlung variierten Größen sind die Aufkohlungstiefe und der Randkohlenstoffgehalt sowie die Atmosphäre während der Diffusions- und Haltephasen. Das Abschrecken wurde nicht variiert. Die Änderung der Maß- und Formabweichungen durch die Wärmebehandlung wurde durch 3-D-Koordinatenmessung des Grundkörpers und der Verzahnung vor und nach der Wärmebehandlung ermittelt. Die Einflüsse der untersuchten Parameter auf die Maß- und Formänderungen der Zahnräder wurden durch eine Varianzanalyse der Versuchsergebnisse statistisch bewertet und die Signifikanz verifiziert.
Microstructure, hardness, corrosion and dry wear of 17wt%Cr-3wt%C-7wt%Mo cast iron
Authors: Wiengmoon A. , Pearce J.T.H. , Imurai S. , Chairuangsri T.
Published: December 2013

The microstructure of a 17wt%Cr-3wt%C white cast iron with relatively high Mo addition (7 wt.-% Mo) has been investigated by X-ray diffraction, light microscopy, scanning electron microscopy and transmission electron microscopy together with energy dispersive X-ray spectroscopy. Mo dissolves partly in the matrix and partly in the typical Cr-rich M7C3 eutectic carbide and also leads to microstructural modification by forming a fine Mo-rich lamellar structure at interdendritic regions with a volume fraction of 11 %. The Mo-rich phase in this lamellar structure may also be a carbide of the M6C type and is believed to form at the later stage of solidification by a subsequent eutectic reaction. Destabilization heat treatment at 1000°C for 4 hours followed by air hardening results in precipitation of M7C3 and M23C6 secondary carbides, transformation of dendritic and eutectic austenite to martensite with some austenite being retained, and modification of local chemical composition, importantly an increase in the Mo and C content in the matrix. This causes a significant improvement in hardness, corrosion and dry wear properties. Tempering at 450°C for 4 hours leads to more temper-carbide precipitation and formation of ferrite, possibly by decomposition of retained austenite. However, an improvement in properties was not observed.
Niederdruckaufkohlung von chromhaltigen Sinterstählen für Zahnräder
Authors: Dlapka M. , Danninger H. , Gierl C. , Altena H. , Stetina G. , Orth P.
Published: December 2013

Kurzfassung

In den letzten Jahren haben chromhaltige pulvermetallurgische Stähle auf der Basis vorlegierter Pulver wie Astaloy CrL (Eisen + 1,5% Chrom + 0,2% Molybdän) und Astaloy CrM (Eisen + 3% Chrom + 0,5% Molybdän) zunehmend Interesse gefunden. Die Gründe hierfür sind einerseits die niedrigeren Kosten für Chrom verglichen mit traditionellen Legierungselementen in der Pulvermetallurgie, wie Molybdän, Nickel und Kupfer, andererseits die mittlerweile in der Industrie verfügbaren deutlich verbesserten Sinteröfen, die eine sauerstofffreie Atmosphäre und hohe Temperaturen ermöglichen. Bei der Verwendung entsprechender Sinter- und Wärmebehandlungsbedingungen erzielen diese chromhaltigen Stähle hervorragende mechanische Eigenschaften bei relativ niedrigen Materialkosten.

Allerdings ist für diese Materialien eine konventionelle Gasaukohlung mit anschließender Ölabschreckung nicht möglich, da die Kohlungsgase immer signiikante Mengen an sauerstohaltigen Verbindungen enthalten, welche in die ofenen Poren der Sinterteile eindringen können und Oxidation der Teile, nicht nur der Oberläche, sondern auch des Inneren, bewirken, was zu einer deutlichen Versprödung führen würde. Auch kann das Härteöl die Poren kontaminieren, was die Notwendigkeit für teure Waschoperationen der Teile bedingt und damit zu erhöhten Kosten führt.

In der hier vorliegenden Arbeit wurde als Alternative für diese oxidationsempindlichen, chromhaltigen Materialien die Niederdruckaukohlung kombiniert mit einer Hochdruckgasabschreckung untersucht. Es konnte gezeigt werden, dass diese Wärmebehandlung eine sehr gute Methode für die Randschichthärtung chromhaltiger Sinterstähle ist.
Analyse von Seigerungen und seigerungsbedingtem Verzug am Beispiel des Einsatzstahls 20MnCr5
Authors: Hunkel M.
Published: December 2013

Kurzfassung

Seigerungen sind chemische Inhomogenitäten, die sich beim Strangguss nicht vermeiden lassen. Die Orts- und Richtungsabhängigkeit von Mikro- und Makroseigerungen im Halbzeug wurden eingehend charakterisiert. Schwerpunkte der Charakterisierung waren die hochaufgelöste chemische Analyse mittels Elektronenstrahl-Mikrosonde und metallographische Untersuchungen. Über Dilatometerversuche wurde das orts- und richtungsabhängige Umwandlungs- und Dehnungsverhalten bestimmt. Der seigerungsbedingte Verzug nach der Wärmebehandlung wurde an einfachen zylindrischen Wellen untersucht, um eine Überlagerung mit geometriebedingtem Verzug zu vermeiden. Die Wellen wurden langsam im Ofen abgekühlt, blindgehärtet oder einsatzgehärtet. Ein wärmebehandlungsbedingter Verzug wurde dabei möglichst klein gehalten. Analysiert wurden die Längenänderung und die Krümmung der Wellen. Alle Experimente zum seigerungsbedingten Verzug erfolgten an einer Charge aus dem Werkstoff 20MnCr5. Zum Vergleich wurde zusätzlich seigerungsfreier sprühkompaktierter 20MnCr5 eingesetzt.
Verzugskompensation an Wälzlagerringen aus 100Cr6
Authors: Lütjens J. , Surm H. , Hunkel M.
Published: December 2013

Kurzfassung

Beim Härten von Wälzlagerringen kommt es ot zu Maßund Formabweichungen, die während der abschließenden Hartbearbeitung kostenintensiv korrigiert werden müssen. Diese Verzüge treten aufgrund von prozess-, material- oder konstruktionsbedingten Einlüssen auf. Der im Rahmen des Sonderforschungsbereichs 570 „Distortion Engineering“ verfolgte Ansatz betrachtet diese Einlüsse prozessübergreifend, d. h. frühere Prozessschritte künnen in späteren Schritten auftretenden Verzug durch Einbringen eines Verzugspotentials hervorrufen. Basierend auf einem detaillierten Wissen um die einzelnen Verzugspotentiale kann so eine Verzugskompensation während einzelner Prozessschritte erreicht werden. Im vorliegenden Beitrag wird die Anwendung der Methode „Distortion Engineering“ und die Ansätze der erweiterten Verzugsbeschreibung auf die Verzugskompensation beim Härten von Wälzlagerringen aus 100Cr6 besprochen. Dazu wurden die Ringe in einer speziell aufgebauten Einzelteil-Wärmebehandlungsanlage mit der Möglichkeit zur gezielt inhomogenen Erwärmung wie auch Abschreckung gehärtet. Rundheitsmessungen vor und während des Prozesses dienten als Grundlage für eine individuell abgestimmte Wärmebehandlung. Mit dieser Maßnahme konnte die Rundheitsabweichungen signiikant reduziert werden.
Analysis of surface layer characteristics for sequential cutting operations
Authors: Schulze V. , Osterried J. , Strauß T. , Zanger F.
Published: December 2013

For manufacturing processes like milling, broaching and skiving tools with multiple cutting edges are used. The geometry and the characteristics of the machined components are the result of sequential cuts. A finite element model is built up including the sequential cutting by transferring component states between work piece models. The model is validated by comparing residual stresses between numerical and experimental results. Small element sizes allow for a detailed resolution of quantities describing the component state. Characteristics of the specific depth profiles are used for the analysis of residual stresses. The influence of process parameters and the number of simulated sequential cuts are examined. Sequential cuts show an influence on surface residual stresses. Residual stresses decrease for low cutting velocities and slightly increase for high cutting velocities. Tensile stresses also reach to deeper areas of the surface layer with increasing number of cuts. Compressive stresses pass through a significant maximum before decreasing to a constant value. A steady stress state is identified after ten sequential cuts.
Microstructure evolution of the air-hardening steel LH800® due to heat treatment
Authors: Schaper M. , Grydin O. , Nürnberger F.
Published: December 2013

To characterize microstructural and properties changes of the air-hardening steel LH800® due to heat treatment various experimental investigations were carried out. Amongst others, the TTA-austenite grain size diagram, the martensite transformation curve and the tempering diagram were determined. Based on the experimental data the coefficients of the Koistinen-Marburger model were calculated. This allows for a mathematical description of the martensite formation during hardening. The obtained data can be used not only to improve the experimental process design but also to provide information to improve existing numerical models.
Non-destructive determination of local damage and material condition in high-performance components
Authors: Reimche W. , Bruchwald O. , Frackowiak W. , Bach Fr.-W. , Maier H. J.
Published: December 2013

In modern aircraft engines, a high number of complex high-performance components are employed, which are partly subjected to extreme loading. For instance, the high-pressure turbine blades of the first stage after the combustor are both thermally-mechanically loaded and experience severe corrosive attack. Therefore they are furnished with several protective systems in order to improve the fatigue life and reliability of the high-temperature material blades employed. A ceramic thermal barrier coating insulates the internally and film-cooled blades against the hot gas stream whilst the underlying layer (PtAl, Al, MCrAlY) protects the substrate material against corrosive attack and oxidation. Owing to the low electrical conductivity of the materials employed in the multilayered system of the high-pressure turbine blades with layer thicknesses of 20–150 μm, conventional eddy-current and thermographic technologies are only suitable to a limited extent to non-destructively detect the condition of the individual layers separately from the substrate material. In contrast to this, with the aid of multi-parameter, high-frequency eddy-current technologies and high-frequency induction thermography using pulsed excitation, the eddy-currents with test frequencies in the mega-Hertz range (up to 100 MHz) can be limited to the near subsurface and produce standard penetration depths of <50 μm; which enables the layer and substrate materials to be differentially studied. The objective of the present study was to non-destructively detect the condition of the coatings, to characterise and determine the thickness of the coating as well as to detect the condition of the substrate material and sensitively analyse local damage and defects.
Sensor für die Regelung der Kohlenstoffübertragung bei der Niederdruckaufkohlung∗
Authors: Gräfen W. , Berg H. J. , Seehafer K. , Zosel J.
Published: December 2013

Kurzfassung

Für die zeitnahe Regelung von Anlagen zur Niederdruckaufkohlung werden robuste Sensoren und Messsysteme benötigt, die ein Signal zu dem momentan in den Werkstof übergehenden Kohlenstof liefern. Für diese Applikation wurde ein coulometrischer Festelektrolytsensor auf der Basis von stabilisiertem Zirconiumdioxid eingesetzt, der die kontinuierliche Umsetzung eines Teilstroms des Ofenabgases mit Sauerstof ermöglicht. Untersuchungen mit diesem Sensor im Labor und an einer Einkammer-Anlage im Vergleich mit einem H2-Wärmeleitfähigkeitssensor (WLD) zeigen, dass der Titrationsstrom deutlich schneller reagiert als das Signal des WLD und nach einer Kalibrierung als direktes Maß für den Kohlenstofübergang herangezogen werden kann. Der Vergleich der mit dem coulometrischen Sensor online gemessenen integralen Kohlenstofübertragung mit dem oline bestimmten Kohlenstofproil der behandelten Werkstücke zeigt im Rahmen der erreichbaren Genauigkeit eine zufriedenstellende Übereinstimmung.
Neues kennzahlbasiertes Regelungskonzept für das kontrollierte Plasmanitrieren und -nitrocarburieren
Authors: Klümper-Westkamp H. , Gaus J.-H. , Bischoff S. , Rohde J. , Winter K.-M.
Published: December 2013

Kurzfassung

Das Plasmanitrieren und -nitrocarburieren ist ein seit Langem in der industriellen Produktion etabliertes Verfahren. Dieses plasmaunterstützte thermochemische Randschichtverfahren wird auf verschiedenste Stahl-Bauteile angewandt, um den Verschleißwiderstand, die Korrosionsbeständigkeit sowie die Schwingfestigkeit zu steigern. Nach dem Stand der Technik wird der Prozess heute im Bereich der anomalen Glimmentladung als gepulstes Plasma in einem elektrisch beheizten Warmwandofen durchgeführt. Durch die Einstellung der Begasungszusammensetzung sowie der Plasmaparameter ist es möglich, verschieden dicke Verbindungsschichten mit unterschiedlicher Phasenzusammensetzung, Härte und Morphologie einzustellen. Die hierfür notwendigen konstanten Gas- und Plasmaparameter werden in der Regel vorab experimentell ermittelt. Das Einstellen der optimalen Parameter, um die angestrebte Randschichtspezifikation reproduzierbar und prozesssicher zu erreichen, erfordert eine Menge Expertenwissen und Experimente. Weitere Einflussfaktoren auf die Verbindungsschichtausbildung, wie die Chargengröße, die Chargenzusammensetzung, der Reinigungszustand der Charge, der Chargenaufbau, die Temperaturverteilung in der Charge, die Sauberkeit des Ofens sowie die Leckrate der Vakuumanlage sind schwierig zu berücksichtigen und können große Abweichungen im Randschichtaufbau verursachen. Um diesen Missstand zu überwinden, wurde ein neues Regelungskonzept entwickelt. Untersuchungen zur Gaszusammensetzung des Plasmanitrier- und -nitrocarburierprozesses zeigen unter anderem einen signifikanten Ammoniakanteil, obwohl kein Ammoniak zum Prozess zugegeben wird. Die neue Regelung des Plasmaprozesses zur definierten Einstellung definierter Verbindungsschichten und Randschichten basiert auf der Gasanalyse des Prozessgases, zusammen mit den Plasmaparametern und daraus abgeleiteten Kenngrößen.
Study on Surface Activity and Critical Aggregation Concentration of Sucrose Esters Containing Different Isomers of Mono-, Di- and Polyesters
Authors: Yanke Li , Shufen Zhang , Qinghui Wang , Jinzong Yang
Published: December 2013

We have studied the surface properties of a series of synthesized sucrose esters with different hydrophobic chain lengths (C12–C18). The critical aggregation concentration (CAC) values for sucrose stearates and palmitates primarily decrease and then increase, but the surface tension (γCAC) values all increase with decreasing the proportion of monoesters. However, in the case of sucrose laurates, the CAC values decrease with the decrease in the proportion of monoesters. Except for sucrose stearate, the CAC values for other sucrose esters decrease but the the γCAC values increase with the increase of the tail length when the proportion of monoesters is remained unchangeable. In order to further interpret the observation, the lowest-energy conformations generated by MM2 for sucrose mono-, di- and triester are given. In comparison with monoester, the molecular dimensions of diester and triester are more bulky and the structures are more three-dimensional. The sucrose esters containing lower proportion of monoesters can produce higher cross-sectional area per molecule than the monoester, and therefore have higher surface tension.
Synthesis of Novel Arylalkyl Sulfonate Surfactants
Authors: Zhigang Xu , Yu Zhao , Bing Yuan , Weihong Qiao , Zongshi Li , Lubo Cheng
Published: December 2013

A method of synthesizing novel arylalkyl sulfonates is introduced. Reaction conditions were assessed by the measurement of iodine value. Catalysts with little pollution were used in the study.
Comparison of Composition and Properties of Ethoxylated Dodecanoic acid obtained in the Presence of Various Catalysts
Authors: Trathnigg B. , Hreczuch W. , Szymanowski J. , Rappel C. , Hödl R.
Published: December 2013

Oxyethylation of dodecanoic acid was performed in the presence of a conventional alkaline catalyst, a homogeneous alkaline earth metal catalyst and a heterogeneous rare earth metal catalyst, respectively. As the result, three series of products were obtained in a range of average polyaddition degrees from N = 3 up to N = 9. The content of the obtained products was determined analytically by different chromatographic techniques: Size Exclusion Chromatography (SEC) with dual detection, gradient Liquid Adsorption Chromatography (LAC) with evaporative light scattering detection (ELSD), and Liquid Exclusion Adsorption Chromatography (LEAC), a new technique, which allows quantitatively accurate determination of the oligomer distribution of ethoxylates.

It was found that the applied catalysts significantly influenced the obtained homologue distributions and the content of di-esters and polyethylene glycols as byproducts. Much more selective ethoxylation is observed in the presence of the multivalent metal catalysts. As the result, the equivalent product series exhibit significant differences of physicochemical properties and surface activity. The new capabilities in analytical determination of the complex mixture of ethoxylated acids and the detected substantial differences in their chemical content can give a new input for more detailed investigation of these products.
Determination of Alcohol Ethoxylate Components in Sewage Sludge
Authors: Matthijs E. , Burford M. D. , Cassani G. , Comber M. H. I. , Eadsforth C. V. , Haas P. , Klotz H. , Spilker R. , Waldhoff H. , Wingen H.-P.
Published: December 2013

An analytical method has been developed for the determination of alcohol ethoxylate (AE) components in sewage sludge. The method has been extensively ring tested in several industrial laboratories and concentrations in sludge samples from a number of EU countries have been obtained. The method is based on a methanol soxhlet extraction of centrifuged sludge, which is then cleaned up using an alumina column, followed by derivatisation with naphthoyl chloride and a further alumina column clean-up. The extract is analysed using high performance liquid chromatography (HPLC) with fluorescence detection. The method is capable of determining alcohol ethoxylate components in the range of C12–C18 alkyl chain lengths with an ethoxylate chain of EO4 up to approximately EO20 in sludge samples. The detection limit is approximately 20–30 mg kg−1 of total AEs in dry weight of sludge. Using the method, sludges from several European Sewage Treatment Plants (STP) were analysed. The concentration of the AEs, which are primarily linear, in digestor inlet averaged 1164 mg kg−1 (550–2947 mg kg−1) and in outlet sludges the mean value obtained was 167 mg kg−1 (<22–468 mg kg−1). At those plants in which concentrations were monitored in both inlet and outlet sludges, removal of the AEs by anaerobic digestion at the STP averaged 82% (range 61–93%). The interlaboratory relative standard deviation of the procedure was around 40% for the digester sludges analysed. The method developed provides a more accurate estimate of the environmental level of AE components compared to existing colorimetric approaches, but the method will over-estimate the concentration of alcohol ethoxylates in sludges due to the non-specific nature of the detection. However, it is sufficiently robust and accurate to estimate alcohol ethoxylates in sludges and hence concentrations that could be applied to soil.
Surface Tension and Micellization of Aqueous Alkyl Polyglucosides Solutions: Influence of the Molecular Structure and the Addition of Electrolyte
Authors: Jin Xin , Zhang Shufen , Yang Jinzong
Published: December 2013

Sugar-based surfactants have recently attracted considerable interest. In this work, the surface tension and critical micelle concentration (CMC) of alkyl polyglucosides (APGs) with differences in both alkyl chain lengths and average degree of polymerization (DP) were measured, and the effects of sodium chloride and sodium hydroxide on the surface tension and CMC of aqueous solutions of APGs were investigated. The alkyl chain length has a far stronger influence on the CMC than the degree of headgroup polymerization. The addition of sodium chloride to solutions of APGs has a relatively small effect compared with ionic surfactants. The observed effects of sodium hydroxide were explained in terms of the salting out of the hydrocarbon chains of APGs and the hydrotropic effect due to a negative charge on APGs micelles resulting in the deprotonation of the glucose fraction in strong alkaline system.
A Protocol to Examine the Colour Damage Profile of Bleach Containing Detergents
Authors: Luijkx G. C. A. , Hild R. , Krijnen E. S. , Lodewick R. , Rechenbach T. , Reinhardt G. , Phillips D. A. S.
Published: December 2013

In the development of new and improved bleach systems for detergents there is a need for a reliable and generally accepted protocol to test colour and fibre damage. We here describe a protocol to screen detergents on colour damage/fading under European wash conditions, using a recently developed set of dyed fabrics.

The test protocol has been evaluated in an inter-laboratory test and was found to be robust in the sense that it gave similar results in different laboratories. Hence the protocol described is recommended for testing the colour damage/fading properties of oxidative bleach containing detergents for the European market.
Process Management Based on Analysis of Surfactant Properties
Authors: König V. , Schulze L. , Haberland R.
Published: December 2013

One goal of optimising cleaning processes is the economic use of surfactant. To find the optimum concentration of active surfactants for a stable and high cleaning quality, a measurement technique to determine this concentration is required, in order to establish a correlation to the cleaning result.

The article introduces a modified surface tension measurement method to determine the concentration of active surfactants in process conditions. Based on this method, a new generation of inline tensiometers had been developed. These Instruments allow continuously monitoring the active surfactant concentration in a cleaning bath.

The article shows how to interpret the measurement results for the process control. Exemplarily at the use of online measurement in metal cleaning processes, the potential to provide a higher level of process quality control will be illustrated.
Are Oxygen Demands Relevant for Today's Environmental Assessment of Detergents?
Authors: Boeije G. , Klein H. J.
Published: December 2013

Though oxygen demands are critical measurements for waste water treatment plant operation and water quality management, they are of little relevance to assess or rank the environmental quality of detergents. It is argued that: (1) No accurate measurements of the oxygen demand of bleach detergents can be made, because these products release oxygen during the measurement. (2) When waste water is adequately treated, under normal operating conditions the oxygen demand (organic loading) of the raw sewage has no influence on river quality. (3) Oxygen demand values are narrowly focused on environmental exposure, while they do not take into account the potential for ecotoxicological effects. (4) Short-term biological oxygen demand measurements are useful for the monitoring of ‘average sewage', but they are unreliable to assess the biodegradability of more specific substances or products. Instead of oxygen demands, more holistic evaluations based on risk assessment or on life cycle analysis are scientifically preferred.
Spreading Characteristics of Aqueous Surfactant Solutions on Polymer Surfaces
Authors: Dutschk V. , Breitzke B.
Published: December 2013

The objective of this work was the analysis of dynamic wetting behaviour of aqueous surfactant solutions on polymer surfaces in respect of spreading characteristics evaluation. Surfactants with different ionogeneity (ionics and non-ionics) in a wide concentration range were used in this study. The sessile drop method was used to measure the contact angle, base radius and height of a drop containing surfactant as functions of time. Five polymer surfaces of different surface free energy were well prepared and characterised for this study.

The analysis of the time dependency of the drop base radius reveals that the long-term spreading behaviour for all surfactant solutions follows power law with exponent values much lower than 0.1 which agrees neither with the diffusion-controlled spreading nor with Tanner's law. On the basis of experimental results, we conclude that a transfer of surfactant molecules on the bare polymeric surface in front of the moving liquid takes place as described by Starov et al. The transfer time can be used as a spreading characteristic which decreases with increasing concentration as predicted by Starov et al.
Studies on Flocculation of Egyptian Kaolin Suspensions by Anionic Polyacrylamide in the Presence of Surfactants
Authors: El-Rahiem Fatma H. Abd
Published: December 2013

This papers reports the results of studies on flocculation of kaolin suspension by anionic polyacrylamide (PAM-A) flocculants in the presence of surfactant. They were namely anionic Sodium Dodecyl Sulphate (SDS), cationic Cetyl Trimethyl Ammonium Bromide (CTAB) and a non-ionic surfactant of polyoxyethylenic ether with trade name Triton (TX 100). The adsorption of PAM-A for fresh kaolin as well as surfactant pretreatment kaolin corresponding to about 50% coverage on the surface. Pretreatment of kaolin with all three surfactants form bigger flocs with PAM-A. The highest settling rate is obtained by flocculation the SDS-pretreatment kaolin. The influence of simultaneous addition of PAM-A and surfactants from their mixtures on flocculation is dependent on the nature of mutual interaction of PAM-A and surfactant. Simultaneous addition of PAM-A with either SDS or TX 100 increases settling rate, whereas it decreases when added from its mixture with CTAB.

On the other hand, the optimum dose of PAM-A and 0.2 g/kg SDS-pretreatment preconcentrate El-Tih Egyptian kaolin is applied. The flocculation product a kaolin concentrate of minimum TiO2 content (0.27%) and the degree of whiteness (93.5) is obtained from TiO2 content (1.52%) and the degree of whiteness (63) of the original.
The Influence of Hydrophobic Counterion on the Phase Behavior of Ionic Surfactants
Authors: Abdel-Rahem Rami
Published: December 2013

This paper investigates the effects of counterion microenvironments on the phase properties of ionic surfactants. The results of different isomers of hydroxy naphthoic acids (x, y HNC) and the cationic surfactant hexadecyltrimethylammonium hydroxide (HTAOH) are included. Mixing 3,2 HNC, 2,1 HNC or 6,2 HNC with micellar solutions of HTAOH transforms the micellar microstructure into different morphologies depending on the counterion microenvironments. The vesicles at equal concentration ratio of 3,2 HNC/HTAOH and 2,1 HNC/HTAOH have been characterized by freeze fracture electron microscopy (FF-TEM) and small angle neutron scattering (SANS). 6,2 HNC/HTAOH system does not form a liquid crystalline phase (Lα-phase) at and above the equal concentration ratio. With these systems the effects that the hydrophobic counterion microenvironments have on the aggregate microstructure, rheological behavior, Krafft temperature and other physiochemical properties are discussed.
Influence of some Chromium Complexes on the Conversion Rate of Glycidol – Fatty Acid Reaction
Authors: Janiš R. , Klásek A. , Krejčí J. , Bobálová J.
Published: December 2013

Monoacylglycerols – thanks to their amphipathic properties – belong among non-ionogenic surfactants. Their additional unique properties, such as antistatic, microbicidal, and lubricating, are also well known. One possibility for preparing pure individual monoacylglycerols is the reaction of fatty acid with glycidol. In this paper, the catalysis of this reaction with some chromium(III) complexes is described. Compounds prepared in high yields were 1-monoacylglycerols of caprylic, capric, lauric, oleic, and palmitic acids, the purity of which was verified by high performance liquid chromatography.
Pulmonary Surfactant and its in vitro Assessment Using Axisymmetric Drop Shape Analysis (ADSA): A Review
Authors: Zuo Y. Y. , Neumann A. W.
Published: December 2013

Recent progress in the study of pulmonary surfactant is reviewed. The first half of this paper provides general background in both physiological and clinical perspectives. The second half focuses on the in vitro assessment of pulmonary surfactant using methods based on a drop shape technique, Axisymmetric Drop Shape Analysis (ADSA). Theories, experiments, and techniques of image analysis used in these ADSA methods are briefly described. Typical applications of these methods are discussed in detail. It is concluded that the accuracy, versatility, and simplicity of these ADSA methods render them suitable to the study of pulmonary surfactant.
Soiling Tendency of Worn, Plastic Flooring Materials Related to their Surface Topography
Authors: Kuisma R. , Pesonen-Leinonen E. , Redsven I. , Reunanen E. , Kymäläinen H.-R. , Sjöberg A.-M. , Hautala M.
Published: December 2013

The soiling and cleanability of eleven worn commercial plastic floor coverings were examined. The new and worn floor coverings appeared very similar in both visual and stereo microscopic inspection. However, wear had caused changes to both topography and cleanability parameters. Profilometer measurements provided information on the topography of new and worn floor coverings. According to the results new surfaces did not always clean better or become soiled more easily than worn coverings. Therefore, we cannot derive a general rule of relationship between wear, soiling and cleanability. The general premise that a rough surface will yield poor cleanability was not confirmed here for all materials.
Effect of Alcohols on the cmc and Micelle Ionization Degree of Alkanediyl-α,ω-bis(Dimethyldodecylammonium Bromide) Surfactants
Authors: Benrraou M. , Zana R.
Published: December 2013

The critical micelle concentration (cmc) of three dimeric surfactants of the alkanediyl-α,ω-bis(dimethyldodecylammonium bromide) type, one trimeric surfactant and two conventional monomeric surfactants has been measured in the presence of increasing amounts of linear 1-alcohols (methanol to hexanol), using the electrical conductivity method. The results show little difference in the variations of cmcA/cmcW (cmcA and cmcW = cmc values in a water/alcohol mixture and in water) for the monomeric, dimeric and trimeric surfactant with the alcohol concentration for alcohols that are very soluble in water (methanol and ethanol) or hardly soluble in water (pentanol and hexanol). Significant differences are observed only for alcohols that are partitioned between water and micelles (mainly propanol and butanol). Large differences in the solubility of butanol in micellar solutions of the three dimeric surfactants observed at high surfactant concentration appear to be associated to differences in micelle shape. The ionization of dimeric surfactant micelles in ethanol/water mixtures increases nearly linearly with the ethanol content.
Conductivity of Strontium Soaps in Water
Authors: Varma R. P. , Goel H.
Published: December 2013

The conductance of the solutions of strontium octanoate, hexanoate and pentanoate have been measured in water at 35–50 °C in order to determine the micellar behavior of strontium soaps in water. The result shows that these soaps behave as weak electrolyte in water and the Debye Hückel Onsager equation fails for solution of these soaps.
Dynamic Surface Tension: Industrial Applications and Characterisation of Commercial Surfactants*
Authors: Miller Dennis , GmbH Clariant
Published: December 2013

In recent years dynamic surface tension has become increasingly used in industrial laboratories. For a wide range of applications it can be used to improve surfactant selection.

Dynamic surface tension is a non-linear function of surface age and concentration. This must be taken into account when comparing surfactants. The concepts of effectiveness (magnitude of effect) and efficiency (concentration required for desired effect) are discussed. Efficiency parameters are more time-consuming to measure, but may give more relevant and reliable information.

A ring test with an anionic surfactant using the maximum bubble pressure method showed good agreement between six laboratories. The results indicated that c20(concentration for reducing surface tension by 20 mN m−1) at 0.1 s lifetime is a robust parameter for surfactant characterisation.
Surface and Foaming Properties of Alkylamine Oxide: Protonation and Counterion Effects
Authors: Song Shi-Li , Hu Zhi-Guo , Dong Jin-Feng , Zhang Gao-Yong
Published: December 2013

The influence of protonated species or nonionic forms of N, N-bis(2-hydroxyethyl) dodecylamine oxide (C12DHEAO) on interfacial properties is studied by measuring foamability, foam stability, equilibrium surface tension and surface viscosity. Surface tensions of the protonated species with various counterions, Cl−, NO3
−, ClO4
− and BF4
− show a decrease in the following order: C12DHEAO Cl− > C12DHEAO NO3
− > C12DHEAO ClO4
− > C12DHEAO BF4
−. Foamability done using shaking method shows a reverse order for Cl−, NO3
−, ClO4
−. But the foamability of C12DHEAO BF4
− is lower than that of C12DHEAO ClO4
−. This has been explained in terms of the differences in the lipophilicity the micellar stability. This is further confirmed by our dynamic surface tension results. The equilibrium surface tension values for 20mM C12DHEAO solution shows a vague minimum in the range 4.20 < pH < 5.81. The foamability of C12DHEAO solution shows decrease with the values of pH. This can be elucidated by the differences in the interactions between cationic and nonionic species, nonionic and nonionic forms. The foam of protonated C12DHEAO having counterions Cl−, NO3
− and ClO4
− are very unstable. The foam stability of C12DHEAO BF4
− is much greater than other protonated C12DHEAO. The foam stability of C12DHEAO solution at different values of pH shows similar order as surface tension. Foam are more stable in the range 4.20 < pH < 5.81 than that at other values of pH.
Performance of some Surfactants as Wetting Agents
Authors: Shalaby M. N. , El-Shamy O. A. A.
Published: December 2013

The wetting power of anionic surfactant: sodium dodecyl sulfate (SDS), and nonionic surfactants: polyoxyethelene(14)monolaurate [La(EO)14] and polyoxyethelene(14)monooleate [Ol(EO)14] has been studied to determine their performance as wetting agents. The study reveals that the nonionic compound with a long hydrophobic chain exhibits higher wettability than the shorter one when used at very low concentrations (below CMC), and the reverse is shown with high concentrations (above CMC). The wetting power of the investigated surfactants increases as the CMC values increases. In case of the nonionic compounds and at surfactant concentrations equal their CMC values, Ol(EO)14 shows a higher wetting power than La(EO)14 while it possesses a lower HLB value. The anionic surfactant shows an optimum wetting in comparison with the tested nonionic ones. The wettability of all the investigated samples increases as the surface tension of their solutions increases to the allowed limit that can be reached in the presence of surfactant.
Polymeric Surfactants: Novel Agents with Exceptional Properties
Authors: Garnier S. , Laschewsky A. , Storsberg J.
Published: December 2013

This article presents recent progress in the field of polymeric surfactants made of permanently amphiphilic block copolymers or of stimulus-sensitive ones. We highlight key points in the design of amphiphilic macromolecules, to yield polymer surfactants with tailor-made properties, as well as recently developed and still challenging application fields for this new class of surfactants. The efficiency boosting of amphiphilic block copolymers as co-surfactants in microemulsions is discussed, as are surface modification by polymer surfactants, and stabilization of dispersions. Moreover, the use of block copolymers in nanosciences is presented, for instance as a tool for nanomaterial fabrication, or for biomedical and cosmetic applications in bio-nanotechnology. Finally, self-assembly and applications of some newly developed “exotic” amphiphilic block copolymer structures as new surface-active materials will be highlighted.
Hydrolysis of δ-Layered Sodium Disilicate in Ions Binding Process
Authors: Dong J.-X. , Xu H. , Zhang G.-Y. , Liu L. , Li J.-P.
Published: December 2013

In different type water, the hydrolysis of δ-modification layered sodium disilicate (δ-Na2Si2O5) was investigated by employing XRD, FT-IR, SEM chemical analysis and residual solid yield. δ-Na2Si2O5was transported to another layered sodium silicate-kanemite (NaHSi2O5·3H2O with cation exchange ability) in distilled water near the concentration in a magnitude, which is used by washing clothing. At the same concentration, δ-Na2Si2O5changed to a mixture of kanemite, Ca(OH)2and insoluble amorphous solid in water with Ca2+cations; a mixture of kanemite and insoluble amorphous solid in water with Mg2+cations. The evidence which δ-Na2Si2O5partly transport to another ion exchangeable single layer silicate (kanemite) indicated the existence of cation exchange on δ-Na2Si2O5. Another evidence which δ-Na2Si2O5partly dissolve and react with Ca2+and Mg2+cations indicated the existence to form precipitation. The experimental data suggested that the divalent cation binding process of δ-Na2Si2O5belongs to a mixture process with divalent cations exchange with Na+cation and precipitation in form of insoluble amorphous solid.
Synthesis and Properties of Sugar-Based Gemini Surfactants
Authors: Shi J. , Li Q.-D. , Xia X.-C.
Published: December 2013

A series of new gemini surfactants having hydrophilic glucosides were synthesized from glucose via two different synthesis roads, including N,N′-didodecyl-N,N′-bis-(1-glucosyl-2-hydroxyl-propyl)-p-phthaloyl amide [B(DG)PA], N,N′-didodecyl-N,N′-bis(1-glucosyl-2-hydroxyl-propyl)-2,5-dicarboxylate p-phthaloyl amide [B(DGC)PA], N,N′-didodecanoyl-N,N′-bis-(1-glucosyl-2-hydroxyl-propyl) ethylenediamine [B(DG)EA], and N,N′-didodecanoyl-N,N′-bis-(1-glucosyl-2-hydroxyl-propyl) hexanediamine [B(DG)HA]. The final products were characterized by IR and NMR spectral measurements and by interfacial tension measurements. The critical micellar concentrations (cmc) of these gemini surfactants were determined to be 2.49 × 10−6, 1.93 × 10−6, 2.47 × 10−6 and 1.66 × 10−6 mol L−1, respectively, which are about one order of magnitude lower than the corresponding monomeric surfactants (GHPDA). The results showed that these synthesized sugar-based gemini surfactants had high abilities to reduce the surface or oil-water interface tension. The high surface activity of these synthesized molecules was attributed to their unique structure where two optimally spaced hydrophobic chains and hydrophilic groups were present.
New Vesicle Gels in Household Applications
Authors: Müller F. , Peggau J. , Meyer J. , Scheuermann R.
Published: December 2013

Stable dispersions of either gas bubbles or solid particles like abrasives become increasingly attractive for the home care market. The property to yield a stable dispersion is not necessarily linked to a high viscosity in general but requires a highly viscous, solid-like behaviour under rest as well as a liquid-like flow behaviour under shear. A gel comprising such a yield zone can be obtained by creating multi-lamellar vesicles with a rather stiff shell. Due to the repulsion forces of opposite electric charges the combination of suitable anionic and cationic surfactants yields vesicles that are inflexible enough to comprise a yield zone. Surfactants which are appropriate to yield suitable vesicle gels can be chosen according to their spatial dimensions since the geometry of the molecules determines their aggregation behaviour. With this, new formulation possibilities for bathroom cleaners or scouring liquids are available.
Sensitive Potentiometric Method for Determination of Micromolar Level of Polyethoxylated Nonionic Surfactants in Effluents
Authors: Sak-Bosnar M. , Madunic-Cacic D. , Matesic-Puac R. , Grabaric Z.
Published: December 2013

The Metrohm NIO surfactant electrode has been used as end-point indicator for potentiometric titration of low concentration level of polyethoxylated nonionic surfactants. This can be achieved by using of a diluted titrant concentration, thus reducing the amount of precipitate formed during titration and preventing the electrode deterioration. The solutions of low levels (down to 10−6 mol/L) of selected nonionic surfactants containing 5 to 23 EO groups were successfully titrated with diluted (as low as 10−4 mol/L) sodium tetraphenylborate as standard anionic titrant, increasing up to 20 times the sensitivity of the method. The low surfactant concentration has been determined in synthetic formulations of widely used detergent products and industrial waste waters. The titration end-point has been determined by applying extended Savitzky-Golay least-squares regression. The accuracy and precision has been evaluated by using the standard addition method. Relative standard deviation within results was between 3.4 and 12.8 % depending on the sample complexity and the surfactant concentration level.