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Bruchköbel, Germany

Skalecki M.G.,IWT - Foundation Institute of Materials Engineering | Klumper-Westkamp H.,IWT - Foundation Institute of Materials Engineering | Hoffmann F.,IWT - Foundation Institute of Materials Engineering | Zoch H.-W.,IWT - Foundation Institute of Materials Engineering | And 2 more authors.
ASM International - 28th Heat Treating Society Conference, HEAT TREATING 2015 | Year: 2015

Plasmanitriding is a thermochemical surface heat treatment of steel components to produce nitride layers which increase wear-, corrosion- and fatigue resistance. Research into plasmanitriding lately showed that there is a significant and characteristic amount of ammonia formed off the process gases nitrogen and hydrogen. This research paper is aimed to analyze the influence of plasma treatment parameters, such as pressure, voltage, temperature and nitrogen to hydrogen ratio on the atmosphere and the formation of ammonia during plasmanitriding. The ammonia content is measured in the exhaust gas. By correlating the measured ammonia with the treatment parameters and modeling the nitriding process, the ammonia content can then be predicted. Further a plasma nitriding potential, comparable to the gas nitriding potential, based on ammonia content is calculated and its practicability as process control parameter is shown by correlating the potential with the nitriding results, e.g. the formation of ϵ and γ' nitride phases. © 2015 ASM International®.

Klumper-Westkamp H.,Stitung Institute For Werkstotechnik | Gaus J.-H.,Nabertherm GmbH | Bischof S.,ROHDE Schutzgasofen GmbH | Rohde J.,ROHDE Schutzgasofen GmbH | Winter K.-M.,Process Electronic GmbH
HTM - Journal of Heat Treatment and Materials | Year: 2013

Plasma nitriding and nitrocarburizing has been established in industrial production since many years. his thermochemical surface treatment is applied to various steel components in order to enhance wear resistance, corrosion resistance and fatigue resistance. he process is done at the state of art in a pulsed discharge technique in the region of anomalous glow discharge in a conventional heated furnace. By adjusting the gas composition and plasma parameters diferent compound layers with diferent thickness, composition, hardness and morphology can be produced. Up to now applications run under constant gas and plasma parameters, which have to be investigated and evaluated before. A lot of expert knowledge and experience is necessary to get the right parameters for the production of the intended compound layer speciication and to secure the reproducibility. Further inluencing aspects on the compound layer formation as batch size, batch surface, batch cleanliness, jigging, temperature distribution, cleanliness and leak rate of the plant are diicult to take into account and can cause large deviations. To overcome these disadvantages a new concept for controlled processing is developed. Investigations in analyzing the exhaust gas of the plasma nitriding process gas showed a signiicant amount of ammonia, although no ammonia is added to the process. Based on process gas analysis together with plasma process parameters and thereof derived speciic characteristic numbers a closed loop control for deined nitriding and nitrocarburizing of well deined layer characteristics is invented.

Bischof S.,ROHDE Schutzgasofen GmbH | Klumper-Westkamp H.,IWT - Foundation Institute of Materials Engineering | Hofmann F.,IWT - Foundation Institute of Materials Engineering | Zoch H.-W.,IWT - Foundation Institute of Materials Engineering | Rohde J.,ROHDE Schutzgasofen GmbH
HTM - Journal of Heat Treatment and Materials | Year: 2013

The well-established gas carburizing procedure has the disadvantage that for control reasons an oxygen containing carburizing atmospheres must be used. his inevitably leads to a damage of the component surface in the form of surface oxidation. In order to suppress damage by oxidation and efusion of manganese and to keep investment costs low, research has been conducted by foundation IWT Bremen and Rohde Schutzgasöfen GmbH speciically at atmospheric pressure. Recent heat treatment results in an industrial plant ofer a promising perspective. With pulsed atmospheric nitrogen-acetylene- processes 1 mm CHDs were reproducible accomplished with 18CrNiMo7-6 (1.6587) avoiding manganese efusion and surface oxidation almost completely.

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