Substitution halogenierter Kohlenwasserstoffe in der Metallreinigung Teilvorhaben 4. Abschlussbericht

SIGLEAvailable from TIB Hannover: F93B1174+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

New corrosion inhibitors for evaporative cooling systems

Corrosion of heat exchangers and installations in evaporative cooling systems is a serious problem of industry, as it may lead to increased maintenance effort, damages, up to plant shut-down causing high cost. Furthermore, there may be a high environmental impact due to the discharge of blow-down water containing heavy metals or hazardous compounds, which may enter the water system via leakages. State of the art corrosion inhibitor programs are based on phosphate, phosphonates, zinc and combinations thereof. Although generally satisfying control of corrosion can be achieved, all programs suffer more or less severe drawbacks, such as lack of biodegradability, content of heavy metals or necessity of pH control combined with acid dosage. Consequently, there is a need of corrosion inhibitors having an improved environmental profile and/or an improved performance. This paper shows the first results of two newly developed corrosion inhibitors. Both molecules are based on modified organic acids, free of heavy metals, one additionally doesn’t contain phosphorous. Corrosion tests have been carried out with carbon steel specimen in dependence of inhibitor concentration, water composition and water temperature. Electrochemical methods, e.g. voltammetrie and polarization resistance, were applied as well as beaker tests and long term tests in cooling circuit simulating devices. Furthermore, the anti-scaling efficiency of the new inhibitors was studied. The results of the corrosion tests clearly show an excellent efficiency of both substances, that meets the performance of commercially available corrosion inhibitors. In addition to this the phosphorous containing molecule shows a very good inhibition of calcium carbonate scaling, similar or even better compared to the performance of modern polycarboxylates. Thus, it could be the backbone of a complete treatment program for cooling systems. The second corrosion inhibitor could be applied in phosphorous and heavy metal free corrosion inhibition programs

New corrosion inhibitors for evaporative cooling systems

Corrosion of heat exchangers and installations in evaporative cooling systems is a serious problem of industry, as it may lead to increased maintenance effort, damages, up to plant shut-down causing high cost. Furthermore, there may be a high environmental impact due to the discharge of blow-down water containing heavy metals or hazardous compounds, which may enter the water system via leakages. State of the art corrosion inhibitor programs are based on phosphate, phosphonates, zinc and combinations thereof. Although generally satisfying control of corrosion can be achieved, all programs suffer more or less severe drawbacks, such as lack of biodegradability, content of heavy metals or necessity of pH control combined with acid dosage. Consequently, there is a need of corrosion inhibitors having an improved environmental profile and/or an improved performance. This paper shows the first results of two newly developed corrosion inhibitors. Both molecules are based on modified organic acids, free of heavy metals, one additionally doesn’t contain phosphorous. Corrosion tests have been carried out with carbon steel specimen in dependence of inhibitor concentration, water composition and water temperature. Electrochemical methods, e.g. voltammetrie and polarization resistance, were applied as well as beaker tests and long term tests in cooling circuit simulating devices. Furthermore, the anti-scaling efficiency of the new inhibitors was studied. The results of the corrosion tests clearly show an excellent efficiency of both substances, that meets the performance of commercially available corrosion inhibitors. In addition to this the phosphorous containing molecule shows a very good inhibition of calcium carbonate scaling, similar or even better compared to the performance of modern polycarboxylates. Thus, it could be the backbone of a complete treatment program for cooling systems. The second corrosion inhibitor could be applied in phosphorous and heavy metal free corrosion inhibition programs

Verringerung der Umweltbelastung durch Reduzierung der Halogenkohlenwasserstoffemission bei Reinigungsverfahren in der Elektroindustrie Abschlussbericht. T. A

At the start of the project halogenated hydrocarbons (HHC) were used on a large scale for cleaning parts in the electrical industry to meet the high requirements of manufacturing. However, the use of these chemicals causes a serious danger to the environment. The aim of the project was the development of non polluting cleaning processes to reduce the consumption of HHC and also the environmental pollution without a deterioration of the surface state quality and production safety. As an alternative mainly processes with aqueous media come into consideration. Therefore tests samples have been cleaned with several media under practical conditions and the properties of the cleaned surfaces determined by visual inspection and surface analytics. Starting from products already introduced in the market several aqueous based cleaners have been developed fulfilling the high requirements of the electrical industry with respect to material compatibility and cleaning efficiency. Optimization based upon the results of fundamental physico-chemical investigations. To avoid a shifting of environmental problems from the air into the water, concepts for prolongation of life-time of the cleaning baths have been worked out by means of membrane techniques, especially ultrafiltration. To get a longer term corrosion protection anticorrosive agents free from HHC were tested achieving a good corrosion protection with small weight of layer. (orig.)Zu Beginn des Projektes wurden fuer die Reinigung von Bauteilen in der Elektroindustrie in grossem Umfang Halogenkohlenwasserstoffe (HKW) eingesetzt, um die hohen Reinheitsanforderungen in der Fertigung zu erfuellen. Der Einsatz dieser Stoffe bedingt jedoch eine erhebliche Gefaehrdung der Umwelt. Ziel des Vorhabens war es, umweltfreundliche Reinigungsverfahren ohne Einbussen in der Qualitaet des Oberflaechenzustandes und der Fertigungssicherheit zu entwickeln, um den Verbrauch von HKW und damit die Umweltbelastung zu reduzieren. Als alternative Reinigungsverfahren boten sich in erster Linie Prozesse mit waessrigen Medien an. Deshalb wurden verschiedene Probekoerper mit verschiedenen Reinigungsmethoden unter praxisnahen Bedingungen behandelt und die Beschaffenheit der gereinigten Oberflaechen durch visuelle und oberflaechenanalytische Verfahren bestimmt. Ausgehend von markteingefuehrten Produkten wurde ein Anzahl von waessrigen Reinigern entwickelt, die den hohen Anforderungen der Elektroindustrie hinsichtlich der Materialvertraeglichkeit und der Reinigungswirkung entsprechen. Dabei basierten die Optimierungsarbeiten auf den Ergebnissen grundlegender physikalisch-chemischer Untersuchungsmethoden. Um eine Verlagerung der Umweltproblematik von der Luft auf das Wasser zu vermeiden, wurden Konzepte zur Standzeitverlaengerung der Waschflotten unter Einsatz von Membranverfahren, insbesondere der Ultrafiltration ausgearbeitet. Zur Erzielung eines laengerfristigen Korrosionsschutzes wurden HWK-freie Korrosionsschutzmittel geprueft, wobei ein guter Korrosionsschutz bei geringem Schichtgewicht erzielt wurde. (orig.)SIGLEAvailable from TIB Hannover: FR 7003 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman