bluuebunny/crossref_metadata_2025 huggingface dataset:
Einfluss einer Cryobehandlung auf die Verschleißbeständigkeit von Stempeln*
Authors: Wendl F. , Oppenkowski A. , Groll E. , Troost G. , Weber S. , Theisen W.
Published: December 2013

Kurzfassung

Mit dem Ziel, die Lebensdauer von Werkzeugen oder Bauteilen zu verlängern, gewann die Cryobehandlung von Werkzeugstählen in den letzten Jahrzehnten zunehmend an Bedeutung. Dabei handelt es sich um einen einmaligen Zusatzprozess zur konventionellen Wärmebehandlung, bei dem das Werkzeug bis weit unterhalb von Raumtemperatur (−150 °C bis −196 °C) gekühlt wird. In zahlreichen Untersuchungen wird berichtet, dass eine deutliche Steigerung der Werkzeugstandzeit bzw. der Bauteillebensdauer durch diese Art der Behandlung erzielt werden kann. Trotz vieler Veröffentlichungen zu diesem Thema sind gerade die metallkundlichen Vorgänge während dieser Behandlung und die mikrostrukturellen Veränderungen noch nicht vollständig verstanden.

In dieser Studie werden die Auswirkungen einer Cryobehandlung insbesondere auf die tribologischen Eigenschaften des Kaltarbeitsstahls 1.2379 untersucht. Neben Laborversuchen wurden zusätzlich Standzeitversuche unter praxisnahen Bedingungen durchgeführt.
Influence of casting conditions on the solution treated microstructure of Ni-base superalloy
Authors: El-Bagoury Nader
Published: December 2013

Ni-base superalloy specimens were cast under different superheat levels, low and high, and various cooling rates. Solution treatment was carried out for 2 h at 1120 °C or 1180 °C then air cooled. The solution treatment at 1120 °C represents the standard solution treatment (SST) while that at 1180 °C represents the modified solution treatment (MST). DSC measurements, SEM and EDS emphasized that the α nodular and interdendritic γ/γ' phases found in as cast structure were entirely removed after solution treatment either at 1120 °C or 1180 °C. The volume fraction of η phase in microstructure of all specimens decreased with MST in comparison with SST. After SST and MST, needle like η phase had disappeared except in alloy H1 that was produced under lower cooling rate and high superheat, with SST. In addition to needle like shape, platelet η phase was found in the microstructure of H1 alloy after SST. The microstructure of other alloys contains η phase only with platelet shape. Generated metastable nano-scale γ' particles precipitated in alternating layers with η phase at the expense of transformed η phase. At the platelet η phase circumference, new γ phase with high Cr content was formed at the expense of the dissolved η phase during solution treatment.
Simulation der Ausscheidungsentwicklung entlang der Prozesskette für das Hochtemperatur-Aufkohlen*
Authors: Konovalov S. , Prahl U. , Kohlmann R. , Kozeschnik E. , Bleck W.
Published: December 2013

Kurzfassung

Die gezielte Zugabe von Mikrolegierungselementen ermöglicht für Einsatzstähle eine Aufkohlung bei hohen Einsatztemperaturen. Diese Legierungszugaben werden zur Ausscheidungshärtung sowie für die Erhöhung der Feinkornbeständigkeit durch Partikel-Pinning während der Hochtemperatur-Aufkohlung ausgenutzt.

In dieser Arbeit wird die Ausscheidungsentwicklung für einen mikrolegierten Stahl 25MoCr4 entlang einer exemplarischen Prozesskette für Getriebebauteile mittels STEM und EFTEM analysiert und mithilfe der Software MatCalc modelliert. Diese Prozesskette besteht aus einer FP-Glühung, einer Kaltumformung, einer weiteren FP-Glühung und einem anschließenden Einsatzhärten bei 1050 °C. Durch einen Vergleich der experimentellen mit den numerischen Simulationsergebnissen kann die Simulationskette validiert sowie der Einfluss der verschiedenen Mikrolegierungsausscheidungen auf die Zener-Kraft quantifiziert werden. Mit diesem validierten Modell wurden verschiedene Variationen dieser Prozesskette simuliert und ihr Einfluss auf die Zener-Kraft und somit die Feinkornbeständigkeit berechnet. Auf diese Weise können konkrete Optimierungshinweise formuliert werden.
Tailored Tempering – adjustment of local mechanical properties in hot formed parts
Authors: Sikora S. , Banik J. , Lenze F.-J. , Struppek T.
Published: December 2013

Kurzfassung

In den vorgestellten Untersuchungen wird die Möglichkeit der gezielten Festigkeitseinstellung durch temperierte Segmente innerhalb eines Umformwerkzeuges für den Werkstoff 22MnB5 dargestellt. Hierdurch können funktionale, pressgehärtete Bauteile zum Beispiel für den Einsatz in der PKW-Karosserie hergestellt werden. Durch eine gezielte reduzierte Abkühlgeschwindigkeit werden die möglichen Festigkeiten durch die jeweils stattfindende Gefügeumwandlung eingestellt. Dabei wird in der Untersuchung ein Abgleich zwischen ermittelten Härtewerten und mechanisch-technologischen Kennwerten aufgezeigt. Dies ist ein wesentlicher Bestandteil zur Auslegung von belasteten Strukturbauteilen
Investigations on parameters influencing thermal and frictional properties within hot stamping
Authors: Merklein M. , Stoehr T. , Svec T. , Wieland M.
Published: December 2013

In the automotive industry hot stamping of boron manganese steels represents one of the major technologies to manufacture crash relevant structures within body in white considering aspects of light weight construction. Hot stamping can be described as a non-isothermal hot sheet metal forming process. Temperature control in the forming process plays an important role. The process is quite complex as temperature dependent material and process properties such as flow curves, heat transfer and friction coefficients have to be considered. To improve the knowledge about the process the influence of different process parameters and tool coatings on the heat transfer between tool and specimen is investigated. Additionally, the impact of monolayer, multilayer and superlattice coatings on the wear behavior and on friction is characterized. Furthermore, the effect of different austenitization parameter settings is analyzed with regard to the tribological conditions and resulting adhesive wear.
Erhöhung der tribologischen Beanspruchbarkeit von Aluminiumwerkstoffen durch die Kombination von Randschichtumschmelzlegieren und Nitrieren
Authors: Dalke Anke , Buchwalder Anja , Spies Heinz-Joachim , Biermann Horst , Klemm Marco
Published: December 2013

Kurzfassung

Der Oberfläche von Bauteilen aus Aluminiumlegierungen werden durch ein Plasmanitrieren erheblich verbesserte tribologische Eigenschaften verliehen. Die dünnen, harten Aluminiumnitridschichten versagen jedoch bei hohen Flächenpressungen durch die plastische Verformung des weichen Al-Substrates. Um nitrierte Al-Legierungen auch für tribologisch hohe Beanspruchungen nutzbar zu machen, sind zusätzliche Maßnahmen zur Abstützung der Nitridschicht notwendig. Dafür eignen sich hervorragend thermische Elektronenstrahl(EB)-Flüssigphasenbehandlungen wie das EB-Umschmelzlegieren (EBUL). Dabei werden durch das lokale Einlegieren eines geeigneten Zusatzstoffes die chemische Zusammensetzung der Randschicht modifiziert und neuartige, beanspruchungsgerechte Randschichten erzeugt. Die Kombination des EBUL mit dem Plasmanitrieren verbindet eine tief reichende Randschichtverfestigung mit der Erzeugung einer dünnen, harten Schicht und ermöglicht so die Herstellung gradierter Randschichtverbunde.

Diese Verfahrenskombination, bestehend aus EB-Umschmelzlegieren mit Kupfer-, Nickel- und Eisen-Basis-Zusatzstoffen und Plasmanitrieren, wurde am Beispiel einer Al-Guss- (AlSi10Mg) bzw. Knetlegierung (AlMg4,5Mn0,7) untersucht. Der Fokus der Untersuchungen lag dabei auf der Bewertung der metallurgischen Kompatibilität beider Prozesse im Hinblick auf die thermische Stabilität der EBUL-Schichten bei Nitriertemperatur (470 °C) und deren Eignung für die Erzeugung einer Nitridschicht durch das nachfolgende Plasmanitrieren. Die durchgeführten Verschleißversuche verdeutlichen das Potenzial dieser Duplexbehandlung für Al-Legierungen.
“The Faster the Better” – heat treatment of hot work tool steels
Authors: Strobl V. , Dickinger N. , Siller I. , Schneider R.
Published: December 2013

This article intends to draw attention to the problems and some solutions manufacturers face when using tool steels. Remarkable improvements have been made in the performance of this important steel group within the last decade. Enhanced material properties have been achieved by increasing cleanliness, homogeneity and modification of chemistry as well as a better understanding of heat treatment and operating conditions. These advances have led to increased loading as well as larger dimensions of tools and dies. This increase in size in particular implicates significant challenges to steel making, tool making and heat treatment. The material properties of tool steels are discussed exemplary for hot work tools steels along with a description of typical heat treatment parameters. Attention is paid on the very narrow range of treatment parameters that give desirable material properties.
The influence of quenchant composition on the cooling rate
Authors: Matijević B. , Pedišić Lj. , Vlašić L.
Published: December 2013

Adequate selection of quenching media decreases the risk of tensile stresses, and also of cracking and workpiece distortion. High-performance quenching oils must have very high oxidation and thermal resistance and low sludge formation, must be non-staining and have a high flash point and acceptable heat-transfer characteristics. The quenching media contain a base oil and different types of additives according to application requirements. Mineral oils, synthetic and natural oils, used separately or in combination, may be used as base oils. Mineral base oils are widely used because of their advantages with respect to stability in comparison to natural oils, or lower prices in comparison to synthetic oils. There are numerous compounds available for use but, besides their functional properties, the environmental and safety requirements have to be considered in the selection of components. Based on that, barium additives must be replaced with less harmful compounds. Petroleum derivatives should be replaced with renewable base stocks that are biodegradable, which is a general trend in lubricant development. By changing the composition of quenching oils, base oils and additives, heat transfer characteristics are also changed. In this study, the results of investigation into physical and chemical properties and also cooling characteristics of new quenching oils with different compositions are presented. Cooling curves for different compositions have been evaluated according to the ISO 9950 Standard.
Analysis of the cooling conditions during heat treatment of die casting dies by use of FEM simulation
Authors: Zinner S. , Lenger H. , Jesner G. , Siller I.
Published: December 2013

To improve the quality of typical hot work tool steels the tool steel producers did a lot of optimization work on production technology and alloy design since the last years. Thereby the relevance of the heat treatment on the material properties was often neglected. Especially the effect of big dimensions of die casting dies on the quenching rates of hardening processes was discussed on a very small scale [1–4]. The most important material properties are affected by the heat treatment condition. Consequently, the heat treatment has a significant influence on the life time of die casting dies.

For this reason a FEM model was adapted to simulate the heat treatment processes especially for tool steel dies for die casting processes. The main target of heat treatment simulation is to determine at least the temperature evolution in every point of the material as a function of cooling characteristics. Additional results of this simulation are the microstructure, residual stresses and distortion of the dies after the heat treatment procedure. The model includes physical properties, phase transformation and transformation plasticity. Cooling curves can be determined depending on the quenching situation and the quantity of phases like martensite, bainite and retained austenite. A correlation between cooling condition and toughness of the material was developed and compared with measured results.
Qualitätssicherung in der Wärmebehandlung∗
Authors: Sommer P.
Published: December 2013

Kurzfassung

Seit mehr als 25 Jahren werden in Wärmebehandlungsbetrieben standardisierte Qualitätssicherungsnormen angewendet. Die Bedeutung dieser Maßnahmen wird von den Wärmebehandlungsbetrieben und deren internen und externen Auftraggebern gleichermaßen als sehr wichtig eingestuft. Dennoch existieren noch immer sehr unterschiedliche Auffassungen darüber, welche Voraussetzungen für eine sachgerechte Wärmebehandlung erforderlich sind und wer dafür die Verantwortung trägt. Es werden konkrete Beispiele angeführt, die diesen Konflikt deutlich machen. Schließlich wird eine Empfehlung ausgesprochen, die AWT möge Kriterien für einen Fachauditor Wärmebehandlung erarbeiten.
Geregeltes Carbonitrieren∗
Authors: Bischoff S. , Klümper-Westkamp H. , Hoffmann F. , Zoch H.-W.
Published: December 2013

Kurzfassung

In der Vergangenheit wurde das Carbonitrieren vornehm­lich zur Verbesserung der Härtbarkeit der Randschicht und zum Minimieren des Verzugs bei niedriglegierten Stählen eingesetzt. In den letzten Jahren hat es sich jedoch Anwendungen erobert, in denen mit definiert eingestelltem Gehalt an stabilem Restaustenit die Lebensdauer tribologisch beanspruchter Bauteile deutlich verlängert werden kann. Um die Vorteile des Carbonitrierens für das Bauteil voll ausschöpfen zu können, ist es notwendig, die bisherige Prozessführung zu verbessern. Mit dem entwickelten Carbonitriersensorsystem ist es möglich, den Prozess des Carbonitrierens sicher und reproduzierbar zu gestalten, sodass definierte Kohlenstoff- und Stickstofftiefenprofile anlagenunabhängig und reproduzierbar eingestellt werden können. Der Kohlenstoffpegel wird hierbei unter Berücksichtigung des aktuellen Kohlenmonoxidgehalts über eine Sauerstoffsonde geregelt und die Regelung des Stickstoffgehaltes erfolgt über den Restammoniakgehalt, gemessen im Abgas.
Analyse der Grenzschicht zwischen Aluminium und Titan nach dem Verbundstrangpressen∗
Authors: Striewe B. , Grittner N. , von Hehl A. , Hunkel M. , Stelling O. , Schaper M. , Zoch H.-W. , Bach Fr.-W.
Published: December 2013

The combination of different metallic materials enables the design of lightweight structures with tailor-made properties. In contrast to conventional joining methods, for example fusion welding, by co-extrusion no degradation occurs in the materials structure in the form of heat affected zones or pore formation. Therefore, co-extrusion exhibits an attractive alternative for joining aluminium and titanium based alloys. The performed extrusion experiments were focused on the co-extrusion of aluminium (EN AW-6082) and titanium (TiAl6V4), where titanium is the reinforcing element that is inserted in aluminium profiles. During co-extruding an intermetallic layer with a thickness of 1 to 3 µm arises in the bonding zone between aluminium and titanium. In this layer an enrichment of elements of the aluminium alloy, such as silicon, was observed. The formation of the intermetallic layer and the strength of the compounds were examined at various positions after the co-extrusion and after subsequent heat treatment. The investigation of the intermetallic layer was performed with light optical microscope, scanning electron microscope and electro probe micro analysis. The mechanical properties were determined by tensile tests. The heat treatment led to the intended hardening of the aluminium alloy. However, the layer thickness did not change. The tensile tests specimen showed different failure locations. The heat treatment led to increased tensile strength values, but also to a decreased yield strength level.
Kostenoptimierung durch Änderung der Legierungszuschläge für wärmebehandelbare Baustähle
Authors: Schifferl H. , Zamberger S. , Jöller A.
Published: December 2013

The substitution of expensive alloying elements like Mo and Ni by cheaper ones, e. g. Mn or B-Ti, was studied on the Q&T steel 42CrMo4 and the case-hardening steel 18CrNiMo7-6 based on equal hardenability. The alternative alloying concepts met the requirements for hardenability and mechanical properties in both steel types. The total substitution of Mo by Mn in the Q&T steel caused a loss in low temperature impact toughness. Residual elements (P, As, etc.) seem to promote this kind of temper embrittlement, so for temperature-critical cases the Mo content must be adapted. In the case-hardening steel the substitution of a part of Mo and Ni by Mn or B-Ti resp. lead to a tolerably reduced impact toughness and tooth impact bending force. Nb addition improved the impact toughness. The presented concepts of substitution offer a considerable potential for saving costs for alloy additions.
Einführung in die Grundlagen des Distortion Engineering
Authors: Lübben Th. , Zoch H.-W.
Published: December 2013

Kurzfassung

Auf dem HärtereiKongress 2012 wurde im Rahmen einer vollständigen Session ein Überblick über wesentliche Erkenntnisse des Sonderforschungsbereichs „Distortion Engineering“ präsentiert. Im vorliegenden Beitrag werden zunächst die Grundlagen der Verzugsentstehung vermittelt. Dabei werden die grundlegenden Mechanismen vorgestellt, die Systematik der unvermeidbaren Maß- und Formänderungen besprochen und für die vermeidbaren Verzäge das Konzept des Verzugspotenzials und der zugehörigen Träger erläutert. Darauf aubauend werden die Methode „Distortion Engineering“ und die Ansätze der erweiterten Verzugsbeschreibung für Welle, Scheibe und Ring besprochen. Auf dieser Basis werden in den folgenden vier Beiträgen dieses Hets diese hemen präsentiert:

Mechanismen der Verzugsentstehung bei Wälzlagerringen aus 100Cr6 [1]

Verzugskompensation an Wälzlagerringen aus 100Cr6 [2]

Analyse von Seigerungen und seigerungsbedingtem Verzug am Beispiel des Einsatzstahls 20MnCr5 [3]

Verzugsentstehung bei geschmiedeten Scheiben aus 20MnCr5 – Einluss von Umformung und Gefügestruktur [4]
Experimentelle und numerische Untersuchung zum induktiven Vorschubhärten von Profil führungsschienen
Authors: Hahn M. , Autenrieth H. , Meyer O. , Schulz A. , Zoch H.-W.
Published: December 2013

Kurzfassung

Mithilfe numerischer Methoden lassen sich reale Produktionsprozesse virtuell abbilden und ermöglichen so rechnergestützte Parameterstudien zur Prozessauslegung und -optimierung. Insbesondere bei sehr großen und teuren Bauteilen, hohem experimentellen Aufwand oder schwer zugänglichen Messgrößen kann die Modellierung eines Herstellungsprozesses gegenüber der üblicherweise sehr aufwändigen experimentellen Prozessauslegung einen effizienten Beitrag zu einer optimalen Prozessführung leisten. Die vorliegende Arbeit beschäftigt sich zu diesem Zweck mit der Modellierung des induktiven Randschichthärtens im Vorschubverfahren am Beispiel einer Profilführungsschiene. Es wird ein Simulationsmodell vorgestellt, mit dem sich die Temperaturverteilung im Bauteil sowie die zu erwartenden Härtezonen und Mikrostrukturen infolge der induzierten Wirbelströme in Abhängigkeit verschiedener Eingabeparameter berechnen lassen. Das Modell wird anhand von experimentellen Daten unter Parametervariation abschließend validiert. Es konnte eine gute Übereinstimmung zwischen Simulation und Experiment erreicht werden.
Kurzzeit-Rekristallisationsglühen von Mikrobauteilen aus X5CrNi18-10 im Fallrohrofen∗∗
Authors: von Bargen R. , von Hehl A. , Zoch H.-W.
Published: December 2013

Kurzfassung

Um den gestiegenen Anforderungen an die Prozesse zur Fertigung von Kleinstbauteilen hinsichtlich Baugröße, Stückzahl, Kosten und Qualität gerecht zu werden, wurde der Sonderforschungsbereich 747 „Mikrokaltumformen“ der Deutschen Forschungsgemeinschaft an der Universität Bremen initiiert. Ein elementarer Prozessschritt in der Fertigung ist die Wärmebehandlung. Sie dient einerseits dazu, die Umformeigenschaften durch Glühbehandlungen einzustellen und andererseits, die Gebrauchseigenschaften z. B. hinsichtlich Festigkeit zu optimieren. Für Kurzzeitwärmebehandlungen von Kleinstbauteilen zum Beispiel aus Stahl wurde eine Anlage zur Wärmebehandlung im Fall entwickelt. In einem 5,5 m langen vertikalen Rohrofen wurden rundgeknetete Bauteile aus dem austenitischen Stahl X5CrNi18-10 bei verschiedenen Temperaturen sehr feinkörnig und homogen rekristallisiert.
Plasmanitrieren von Warmarbeitsstählen für die Massivumformung∗
Authors: Hoja S. , Klümper-Westkamp H. , Hoffmann F. , Zoch H.-W.
Published: December 2013

Kurzfassung

Um den hohen Beanspruchungen bei der Warmmassivumformung zu begegnen, werden die Oberflächen und Randbereiche der eingesetzten Werkzeuge nitriert. Neben dem Gasnitrieren werden die Werkzeuge alternativ durch Salzbadnitrocarburieren behandelt. Das Plasmanitrieren wird nur zum geringeren Teil angewendet. Dabei bietet die Behandlung im Plasma einige verfahrensspezifische Vorteile gegenüber dem Gasnitrieren, die auch für die Behandlung von Schmiedegesenken interessant sind. Beispielsweise lassen sich partielle Behandlungen im Plasma einfacher und sauberer durchführen und höher legierte Stähle können problemlos im Plasma nitriert werden, da immer wieder auftretende passivierende Oxidschichten durch ein Reinigungssputtern vor dem Nitrieren entfernt werden. Die Untersuchungen beschäftigen sich mit der Nitrierung der in der Warmmassivumformung häufig eingesetzten Stähle X38CrMoV5-3 und X40CrMoV5-1. Für die Nitrierbehandlung standen eine geregelte Gasnitrieranlage sowie zwei Plasmanitrieranlagen zur Verfügung, sodass nicht nur ein Vergleich der Nitriermedien Gas und Plasma, sondern auch der Plasmanitrierung in unterschiedlichen Anlagen gezogen werden konnte. Eine der Anlagen verfügt außerdem über ein aktives Gitter, daher konnte neben dem konventionellen Plasmanitrieren auch die ASPN-Technik (Active Screen Plasma Nitriding) angewendet werden. Es werden die Vor- und Nachteile der einzelnen Behandlungsmethoden im Hinblick auf die Nitrierung von Schmiedegesenken diskutiert.
Gas quenching process optimization to minimize distortion of a thin-wall ring gear by simulation∗
Authors: Li Z. , Ferguson B. L.
Published: December 2013

Of the differences between gas quenching and immersion quenching processes, the major difference is the presence of boiling during the early stages of quenching in oil or water. The formation of a vapor phase has a dramatic effect on both the overall and local rates of heat removal from the parts being quenched, and on part distortion. With the absence of a quenchant phase change, gas quenching is touted to result in uniform heat extraction, thus lessening part distortion. Gas quenching is not without inherent problems. Nonuniform gas flow around a part contributes to distortion, and nonuniform cooling at different locations contributes to the variance of distortion. This paper discusses difficulties associated with gas quenching a thin walled ring gear that is prone to distortion. Heat treat process simulation was used to model the low pressure carburization and high pressure gas quenching of a carburized 5130 steel ring gear. Process variables investigated include fan speed and cooling durations of different quenching stages. The intent is to reduce distortion by controlling the overall gas velocity through adjustment of the fan speed, whereby the local cooling rates can be controlled to better accommodate the dimensional change associated with steel phase transformations during quenching.
Influence of cutting parameters, tool coatings and friction on the process heat in cutting processes and phase transformations in workpiece surface layers∗
Authors: Schulze V. , Michna J. , Zanger F. , Faltin C. , Maas U. , Schneider J.
Published: December 2013

The surface states and thus the functionality of machined workpieces are influenced by parameters of the process and the cutting tool. Depending on these variables different mechanical and thermal loads lead to changing characteristics of components. This paper presents a 2D-FE-cutting simulation model predicting machining induced phase transformations of workpiece surface layers for the steel 42CrMo4 (AISI 4140) considering detailed friction modeling between tool and workpiece, based on tribological experiments. The cutting simulation model was developed using the commercial software ABAQUS. Friction and phase transformations are implemented using specific user subroutines. The model calculates the process of austenization and the transformed volume fraction of the phases ferrite/perlite, bainite and martensite. Additional thermo dynamical simulations of the heat transfer using the code INSFLA are performed. The simulated temperatures, cutting forces and phase transformations are compared to orthogonal cutting experiments.
Beitrag zur Verbesserung der Prozesssicherheit von Carbonitrierprozessen∗
Authors: Clausen B. , Hoffmann F. , Zoch H.-W.
Published: December 2013

Kurzfassung

Bisherige Forschungsergebnisse weisen darauf hin, dass durch Stickstoff stabilisierter Restaustenit eine positive Wirkung auf die Dauerfestigkeit hat, insbesondere bei Anteilen von Hertz'scher Pressung im Belastungskollektiv. Das Carbonitrieren wird deshalb in der industriellen Praxis heute wieder häufiger angewandt bzw. gefordert. Die meisten Betriebe werden bei Interesse für dieses Verfahren anstreben, die Behandlungen in vorhandenen Aufkohlungsanlagen durchzuführen. Erfahrungen aus der Praxis zeigen jedoch, dass es mit dem derzeit vorliegenden Kenntnisstand sehr schwer ist, reproduzierbare Ergebnisse einzustellen. Die Erfahrungen deuten darauf hin, dass sich für Carbonitrierbehandlungen in Aufkohlungsanlagen starke Ofenkonditionierungs- und Memory-Effekte ergeben, wobei erhebliche Einflüsse der Ofenbaumaterialien festgestellt werden. In dieser Veröffentlichung werden die Ergebnisse von mit umfassender Analysetechnik begleiteten Langzeitcarbonitrierprozessen zusammengefasst und so die Änderungen in der Atmosphäre in einem ausgemauerten Ofen dargestellt. Aus der ermittelten Gaszusammensetzung werden Kohlenstoff- und Stickstoffpegel berechnet und mit den experimentellen Ergebnissen verglichen. Kurzzeit- und Langzeitkonditioniereffekte werden dadurch sichtbar. Die Versuche zeigen, wie Carbonitrierprozesse hinreichend beschrieben werden können und wie eine Regelung von Carbonitrierprozessen aufgebaut werden kann.
The Potential of Alkyl Polyglucosides and Polyethylene Glycol Glucosides Coatings for Improving the Storage and Shelf-Life of Pineapples
Authors: Jin Xin , Zhang Shufen , Yang Jinzong , Li Yanke
Published: December 2013

Alkyl polyglucosides (APGs) and polyethylene glycol glycosides (PEGG) were applied as coatings on fresh pineapple to extend their postharvest shelf-life and to prevent Black Heart (BH). The pineapples were coated with solutions of APGs and PEGG, and the tissue firmness, total soluble solids (TSS), grade of freshness, incidence and grade of BH were measured. The APGs and PEGG were obviously able to reduce the decay incidence, firmness and flavor loss as well as retard color change and ripening rate of pineapples during storage. C12/14-APGs could not only improve quality and shelf-life characteristics, but also markedly reduce incidence of BH. The combination of APGs with PEGG showed the obvious synergism for preventing BH.
Characterization of Langmuir-Monolayers of Molecular Tweezers and Clips by Means of Brewster-Angle-Microscopy
Authors: Rehage H. , Achenbach B. , Klärner F.-G. , Kamieth M. , Panitzky J.
Published: December 2013

Molecular clips and tweezers tend to bind selectively electron deficient aromatic and aliphatic substrates. These interesting processes of molecular recognition are usually investigated in dilute solutions of organic or aqueous solvents. Due to discrepancy between polar and hydrophobic groups, molecular clips and tweezers are surface-active chemical compounds which can form monomolecular films at the surface of water. In this publication, we have systematically investigated the self-association and phase-behavior of these artificial receptors by means of pressure-area-isotherms and Brewster-Angle-Microscopy (BAM). We observed spherical and rod-shaped two-dimensional aggregates in the liquid condensed phase. The size and shape of these domains are similar to corresponding structures of classical surfactants.
Environmental Care and Consumer Protection – Example for the Official Survey of Laundry Detergents and Cleansing Agents
Authors: Rohrdanz A. , Kratz E.
Published: December 2013

The official survey of detergents and cleansing agents includes both: the environmental care by overlooking the regulations of the Washing and Cleaning Act and the consumer protection, which is established in the Food and Consumer Goods Act and the Chemical Law.

The work of the official survey was illustrated by example of the analytics and assessment of fragrances in laundry detergents and cleansing agents and the use of limonene as solvent was shown. The results of the examinations were presented.
Microemulsions Formed by a Catanionic Surfactant or by an Ionic Surfactant with an Organic Counterion
Authors: Friman R. , Backlund S. , Høgnesen E. , Austad T.
Published: December 2013

The phase diagrams at 298.2 K for the systems heptylammonium heptanoate-heptane-water, butylammonium decanoate-butanol-decane-water and butylammonium decanoate-butanol-decane-sodium chloride (aq) have been determined. A large three-phase region and an extensive microemulsion phase were obtained for the heptylammonium heptanoate system. Addition of both cosurfactant and electrolyte brings about a separation into three phases in the butylammonium decanoate-water system. All three-phase systems were characterized by low inter-facial tensions. Sound velocity, conductivity, and viscosity measurements were used successfully for qualitative studies of microstructural transitions in the isotropic microemulsion phase.
Structure-Activity Relationships for Sorption of Alkyl Trimethyl Ammonium Compounds on Activated Sludge
Authors: García M. T. , Campos E. , Sánchez-Leal J. , Comelles F.
Published: December 2013

Association of quaternary ammonium based surfactants with activated sludge from wastewater treatment plants has been studied. Adsorption isotherms on activated sludge particles and surface properties of a series of alkyl trimethyl ammonium compounds have been investigated. The effect of alkyl chain length and the water hardness in those physical-chemical properties have been evaluated. Adsorption on sludge increased with increasing the alkyl chain length in the cationic surfactant molecule. Linear relationships between critical micelle concentration (-log CMC) and efficiency of adsorption at the liquid/gas interface (pC20), and the number of carbon atoms in the alkyl chain length were found for the alkyl trimethyl ammonium compounds. Water hardness decreased the CMC values of the tested alkyl trimethyl ammonium homologues and the extent of their sorption to activated sludge. Langmuir and Freundlich adsorption isotherms described satisfactorily the equilibrium adsorption of the cationic surfactants on activated sludge.
Design Criteria, Mechanical Features, Advantages and Performances of Multitube Falling Film Sulphonation Reactor
Authors: Adami Icilio
Published: December 2013

Anionic Surfactants, and Sulphonates in particular, will continue to keep their important rule in Detergents formulation for generations to come.

The sulphonation Reactor is the key-tool to generate Sulphonated Molecules for Detergent application, therefore the efforts in improving the specific technology are focused on the best possible design and search for optimum operation of the same.

The limits of the present technology are discussed and the peculiarity and advantages of the latest generation of Multi Tube Falling Film Reactor are valued by highlighting:

Design basis

Construction accuracy

Operating conditions and savings

Achievable products quality
30th Anniversary of the Expert Group Detergent Chemistry: From an Isolated Problem Solving to Sustainable Responsibility
Authors: Hauthal Hermann G.
Published: December 2013

The 30th anniversary of the GDCh-Fachgruppe Waschmittelchemie (Expert Group Detergent Chemistry) was celebrated at this year's Conference in Königswinter. Unfortunately, only some 80 people attended this fine meeting that was focused on Ecology/Toxicology but also encompassed stimulating papers in Basics/Mechanisms, Raw Materials/Syntheses, and Applications. 19 lectures and 13 posters were given. The anniversary marked the end of the conference in this form because the annual meeting of the Expert Group will be developed to a European Detergents Conference (EDC) that will be embedded in the next SEPAWA Kongress 2005 for the first time.

At the anniversary's celebratory convention D. Schermer, Chairman of the Expert Group, reviewed the activities of the Expert Group, which was founded in 1974 in Bamberg to meet the need of scientifically based open discussions on ecological issues of detergent chemistry. In the meantime, the Group has been developed into an active forum for scientific exchange in all fields of detergent chemistry. Furthermore, it has contributed to the practicable solution of many environmental problems and to a more serious public discussion about surfactants and detergents. Many problems remain to be solved, and therefore an active cooperation also with other expert groups of the German Chemical Society (GDCh) is crucial.

In his celebrating address W. Koch, General Manager of the GDCh, stressed that in its early days the Group had implemented consumer and environmental protection in its catalogue of topics. In so far, the today's motto “From an isolated problem solving to a sustainable responsibility” is just a consequent extension of its activities. He also asked all members to strive for new members of the GDCh to strengthen this scientific society as one of the largest in Europe.

In his celebratory lecture D. Ruchay, Monheim, Germany, summarized “30 Years of Water Protection in Germany – Through Societal Cooperation to Success”.

After World War Two there were no municipal and industrial sewage plants in Germany able to work. The infrastructure of waste water management was built up very slowly in the first 20 years after the war. Correspondingly the quality of the inshore waters impaired dramatically.

Since 1970 the water quality improved significantly. At that time the water management act had been tightened considerably and the waste water fee depending on the quality and pollution of the waste water was established.

Today the water quality in the German inshore waters is fair up to good, but the ecological situation has still to be improved. For some years the water regulations are laid down decisively by the European Union (The Water Framework Directive, The Urban Waste-water Treatment Directive, The Integrated Pollution Prevention Control Directive).
Commercial Surfactants for Use in CO2 – a Survey
Authors: Hebach A. , Oberhof A. , Dahmen N. , Beeh M.
Published: December 2013

This paper reappraises the dry cleaning process using compressed Carbon Dioxide as washing fluid, specifically in view to cleaning enhancement options. At first, the cleaning cycle of the process is presented. Thereafter, suitable surfactant classes are discussed against the background of prolific as well as an environmentally benign process. Among the most promising structures are the alcohol ethoxylates. Their physical properties such as solubility, phase behaviour, and interfacial activity were intensely studied. The performance of test-formulations in cleaning tests is promising and already suitable for outer garment cleaning. A new way of enhanced mechanical action was already demonstrated in a lab-scale apparatus.
Synthesis, Separation and Adsorption of Naphthalene Sulphonate Formaldehyde Condensates
Authors: Yan Li , Liangjun Dong , Zongshi Li , Weihong Qiao
Published: December 2013

Ten components of NaNSF were separated by thin layer chromatography (TLC) by using F254 silica gel plates as fixed phase and acidic alcohol solution as mobile phase. Adsorption of naphthalene sulphonate formaldehyde (NaNSF) on titania surface was studied through fundamental principles of surface physical chemistry, and the saturation adsorption of NaNSF was found to be much lower than that of dispersant in disperse dyes. This study is of reference significance to the investigation of mechanism of adsorption of dispersant on dyes, cement, and so on.
The Self-Assembly of an Amphiphilic Block Copolymer: A Dissipative Particle Dynamics Study
Authors: Schulz S. G. , Frieske U. , Kuhn H. , Schmid G. , Müller F. , Mund C. , Venzmer J.
Published: December 2013

The self-assembly of a poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) blockcopolymer (EO13PO30EO13) in the presence of water was investigated. The phases have been studied with the mesoscopic simulation technique Dissipative Particle Dynamics (DPD). The micellar, hexagonal, lamellar, bicontinuous and inverse micellar phase have been identified with this method and showed remarkable agreement with the experimental phase behavior. This work showed that the Dissipative Particle Dynamics simulations are also suitable for complicated polymer systems such as the EO13PO30EO13 triblock copolymer.
Rapeseed Methyl Ester Ethoxylates: A New Class of Surfactants of Environmental and Commercial Interest
Authors: Renkin M. , Fleurackers S. , Szwach I. , Hreczuch W.
Published: December 2013

The two last decades have been marked by an increasing environmental awareness. In relationship to detergents, renew-ability, biodegradability, and ecotoxicity have become important issues in the study, development and application of surfactants. In this respect, rapeseed methyl ester ethoxylates are an interesting new class of nonionic surfactants that gain more and more interest on the market. They are easily to formulate into attractive liquid detergents with high cleaning performance and show a more favorable ecotoxicological profile compared to fatty alcohol ethoxylates.
Study of the Cloud Point of C12 E6 Nonionic Surfactant: Effect of Additives
Authors: Alibrahim M.
Published: December 2013

Addition of electrolytes to surfactant solutions does change the temperature at which the clouding phenomena occur. Electrolytes have a large effect on the cloud point (CP) of hexa ethyleneglycol mono-n-dodecyl ether (C12 E6)/water system, because of their effect on water structure and their hydrophilicity. In this work we report the effect of electrolytes (KCl, NaCl and Na2CO3) on the (CP) of C12 E6/water system. It has been observed that the cloud point as a function of electrolyte's concentration, depends mostly on the electrolyte's charge. Furthermore it has been observed that the two factors, temperature and salt concentration mainly affect equivalently the phase separation of C12 E6/water system. Moreover, ionic surfactants such as sodium dodecyl sulfate (SDS) and carboxylate ethoxyle (TDC) have been used to investigate their effect on CP of C12 E6.
Surfactant Enhanced Washing of Drilling Fluids, a Promising Remediation Technique
Authors: Torres L. G. , Lemus X. , Urquiza G. , Verdejo A. , Iturbe R.
Published: December 2013

In this work, drilling fluids with 135 400 mg kg−1 of total petroleum hydrocarbons (TPH) were washed with six different surfactants (the non-ionic Emulgin 600, Emulgin 1000, Brij 35 and Tween 80, ionic SDS, and zwitterionic Polafix CAPB) and their mixtures. Due to the high Ca content in the samples, three different approaches were employed when washing with SDS, because of its ionic character: a) using mixtures of surfactants, b) addition of NaCl, and c) addition of a Ca sequestrant, i. e., sodium metasilicate. Drilling fluids were washed; TPH, electric conductivity (EC, as an indirect measurement of salinity), and pH values were measured before and after the washing process. Surface tension of the clean and spent washing solutions (surfactant or surfactants mixture, with or without salts) was measured.

TPH removals as high as 75% were achieved using SDS + sodium metasilicate. EC values diminished 75% with the washing process, but for the experiments in which salts were added, increments in electric conductivity of up to 367% were observed. Regarding the pH changes, initial sample pH value was 7.77, and in most cases this value was reduced, except for some of the cases where salt was added. Surfactant solution's surface tension changes (before and after the washing process) correlated fairly with TPH removals.
Testing Robustness and Compatibility of Colour Damaging Washing Tests
Authors: Reinhardt G. , Ulshöfer H.
Published: December 2013

Uncertainty concerning the colour damaging effect of new bleach systems often is a major hurdle for their market introduction. In this study we have therefore examined the colour damaging effect of various bleach activators, peracids and catalysts using a newly developed Reactive Dye Set. The trials were carried out according to ISO 105-C09 (diagnostic single wash test) and a similar test as well as the recently developed colour damage profile test (20 wash cycles). The results show that new bleach systems can differ significantly from conventional activators in their reactivity and selectivity towards the individual dyeings. Each system produces a characteristic damage profile. ISO 105-C09 appears not to be suitable for prediction of the effect of new bleach systems such as perimidic acids as well as all bleach catalysts.
Effect of Aromatic Ring in the Alkyl Chain on Surface Properties of Aryl Alkyl Sulfonate Surfactants
Authors: Zhigang Xu , Chenguang Bi , Yuehong Tian , Weihong Qiao , Zongshi Li , Lubo Cheng
Published: December 2013

Surface properties of a series of aryl alkyl sulfonate surfactants were investigated. A strong structure-activity relationship was observed, depending on the variation of aromatic ring size in the hydrophobic chain. The results show that the size of aromatic ring, introduced to the carbon chain, affects their surface and thermodynamic properties. The values of critical micelle concentration (cmc), surface excess concentration (Γmax), effectiveness (Πcmc), to reduce surface tension of water, are decreased with increasing the aromatic ring size from phenyl to methylnaphthyl. While, the values of surface tension (γcmc) at cmc, Gibbs energy of micellization (ΔGmic°), and minimum area per molecule (Amin) are increased. Hence, the dominant factor of influencing on the area per molecule of aryl alkyl sulfonate surfactants would be the size of aryl alkyl chains.
Synthesis of New Family of Dialkylaryl Disulfonate Gemini Anionic Surfactant
Authors: Li Z. , Yuan R. , Yin F.
Published: December 2013

A new family of dialkylaryl disulfonate Gemini-type anionic surfactant were synthesized based on the reaction of olefin sulfonic acid (C14AOS acid) with different aromatics. New synthesis route do not require the conventional alkylation unit and strong acid catalysts, and the resulting Gemini-type anionic surfactant differ from existing products by having the sulfonyl group attached to the alkyl chain rather than the aromatic ring. To optimizing reaction condition, a reliable double-wavelength spectrophotometric method and iodine value method were employed for measurement the conversion of the aromatics. The experimental has confirmed that the reaction time and temperature are mainly the factors of the effect of conversion. Under 150°C, C14AOS acid reacts with different aromatics for 4 or 5 hours to form dialkyaryl disulfonic acid, and dialkyaryl disulfonic acid was then neutralized to dialkyaryl disulfonate Gemini-type anionic surfactant. Some surface active property has been investigated too. The critical micelle concentration of ditetradecylbenzene disulfonate, ditetradecylnaphthalene disulfonate, ditetradecylmethylnaphthalene disulfonate, ditetradecylphenanthrene disulfonate, ditetradecyldiphenylether sulfonate, ditetradecyldiphenylmethane sulfonate and ditetradecylbenzophenone sulfonate were 1.7 × 10−4, 8.082 × 10−6, 2 × 10−5, 2.158 × 10−3, 5.0 × 10−6, 1.0 × 10−5 and 1.33 × 10−5 mol l−1. Above datum showed the aromatics of the surfactant may effect on surface active property obviously. Among these, some dialkylaryl disulfonate gemini anionic surfactant have very higher surface active than conventional dodecylbenzene sulfonate and may be widely used in industry and household.
Role of Heat Treatment on the Performance of Polymers as Iron Oxide Dispersants
Authors: Amjad Z.
Published: December 2013

The influence of heat treatment on the performance of various polymers as iron oxide dispersants in an aqueous system has been investigated. The polymers evaluated include: homo-polymers of acrylic acid, methacrylic acid, maleic acid; co-polymer of, acrylic acid:2-acrylamido-2-methylpropane sulfonic acid; ter-polymers of acrylic acid:2-acrylamido-2-methyl propane sulfonic acid:sulfonated styrene, and acrylic acid:2-acrylamido-2-methylpropane sulfonic acid:t-butylacrylamide. It has been found that all polymers lose performance to a varying degree when exposed to thermal treatment (150°C, 200°C, 20hr). The performance data also suggest that sulfonated styrene containing ter-polymer is a better iron oxide dispersant than the ter-polymer containing 2-acrylamido-2-methylpropane sulfonic acid and tertiary butylacrylamide. In the case of co-polymer of acrylic acid:2-acrylamido-2-methylpropane sulfonic acid, the thermal treatment exhibits strong negative influence on the dispersancy power of the polymer. The results have been explained in terms of loss of 2-acrylamido-2-methylpropane sulfonic acid and t-butylacrylamide in the co- and ter-polymers, as determined by FT-IR and NMR methods, leading to the formation of poly(acrylic acid).
Spectrometric Determination of Detergency of Laundry Detergents Using Sudan Red IV as Label
Authors: Li H. , Wang Y. , Hu Y.
Published: December 2013

A new spectroscopic method was proposed for evaluating detergency of laundry detergents. In the determination process, salad oil labeled by Sudan Red IV was the simulated lipidic dirt, which was distributed on textile by a centrifugal way adding ultrasonic to simulate the washing mechanical force. The residual oil left after washing was determined according to the maximum absorbance of Sudan Red IV at 502nm. The method precision was satisfactory with a relative standard deviation of RSD = 2%. The relative deviation between the spectrometric and the gravimetric method was less than 2%.
Removal of Acid Yellow 34 from Aqueous Solution by Activated Charcoal of Animal Bones
Authors: Bangash F. K. , Alam S.
Published: December 2013

Activated charcoal prepared from the animal bones at different temperatures (600–1000°C) was characterized for surface area, pore volume and by FTIR, EDS, SEM and XRD techniques. The surfaces contained functional groups like carboxyl's and ketones which disappeared at above 800°C, favoring exposure of porous structural surfaces; resulting in enhancement of the adsorption capacity. At the high temperatures the carbon content in the charcoal increased while oxygen got decreased. Adsorption kinetics of acid yellow 34 on the prepared activated charcoal was studied at 10°C and 45°C. Bangham and Parabolic diffusion kinetic models fitted the adsorption data. The two components of the intraparticle diffusion plots suggested that the adsorption process proceeded by surface adsorption and intraparticle diffusion. The thermodynamic parameters of adsorption, such as rate constant (kad), activation energy (DE¿), enthalpy (DH¿) and entropy (DS¿) were evaluated from the first order rate kinetics. The enthalpy of activation (DH¿) indicated that the process was endothermic in nature and its values decreased with the increase in activation temperature. The negative entropy of activation DS¿ reflect the affinity of charcoal toward dye and it decreased with the increase in activation temperature indicating that the dye molecules take more oriented position on the surface of charcoal.