KIT scientists for the first time use methylamine for low-pressure carbonitration
Combustion engines still have much potential to save energy and reduce emissions. The present trend is to use smaller engines of the same or even increased power. Engines with a reduced cylinder capacity consume less fuel due to their smaller weight, smaller friction, and smaller amount of exhaust heat.
This so-called downsizing, however, is associated with even higher mechanical and thermal loads acting on the already highly loaded components of diesel injection systems, for instance. Diesel injection systems have to reach higher injection pressures and improved injection accuracies in order to meet the requirements of downsizing. Hence, injection nozzles have to be made of highly stable materials.
An attractive and inexpensive option is the use of low-alloy steels, i.e. types of steel containing not more than five mass percent of metals other than iron. Such steels can be machined well in the soft state and are then hardened for use.
A hard surface with a tough core is obtained. Scientists of KIT's Engler-Bunte Institute are now working on a new process for the case-hardening of steel, namely, low-pressure carbonitration: At temperatures between 800 and 1050°C and total pressures below 50 millibars, the surface of the components to be hardened is specifically enriched with carbon and nitrogen and subsequently hardened by quenching. The project headed by David Koch is aimed at studying the fundamentals of low-pressure carbonitration and developing this process to maturity in cooperation with research and industry partners.
"Low-pressure carbonitration combines the advantages of low-pressure processes with those of atmospheric carbonitration," David Koch explains. Atmospheric carbonitration damages the surface of the components treated by oxidation. This can be prevented by low-pressure processes. In addition, a more homogeneous hardness profile is generated in the component, in particular in case of complex component geometries.
So far, low-pressure carbonitration has been carried out nearly exclusively using ammonia as a nitrogen donor together with a carbon donor, i.e. ethyne or propane. The KIT scientists have now studied other gases and gas mixtures for suitability for low-pressure carbonitration. Their efficiency in enriching the surface layer with carbon and nitrogen was tested using a thermobalance.
Together with researchers of Robert Bosch GmbH, Stuttgart, they found that methylamine (CH3NH2) and dimethylamine ((CH3)2NH) process gases cause a good enrichment of the surface layer with carbon and nitrogen. The results obtained for low-pressure carbonitration with methylamine are now presented in the HTM -- Journal of Heat Treatment and Materials.
When using methylamine for low-pressure carbonitration, only one gas instead of two is required and the usually applied two process steps can be reduced to a single one. Compared to the use of ammonia as nitrogen donor together with a carbon donor, methylamine alone reaches a higher nitrogen enrichment in the surface layer.
As carbon enters the surface layer in parallel, the process duration is shortened considerably. Methylamine also allows for carbonitration at much higher temperatures, which additionally shortens the process duration. Moreover, the degree of utilization of methylamine as a process gas is better, as a result of which the amount of gas used can be reduced.
The KIT scientists are now working on further optimizing low-pressure carbonitration with amines. Work focuses in particular on improving the homogeneity and free adjustment of carbon and nitrogen input. The next goal is to transfer the process from the laboratory to the pilot scale.
D. Koch, L. Hagymási, T. Waldenmaier, S. Bajohr, R. Reimert: Niederdruck-Carbonitrieren mit Aminen. HTM -- Journal of Heat Treatment and Materials. 70 (2015) 4; pages 171 - 182. DOI: 10.3139/105.110263
Karlsruhe Institute of Technology (KIT) is a public corporation pursuing the tasks of a Baden-Wuerttemberg state university and of a national research center of the Helmholtz Association. The KIT mission combines the three core tasks of research, higher education, and innovation. With about 9,400 employees and 24,500 students, KIT is one of the big institutions of research and higher education in natural sciences and engineering in Europe.
Since 2010, the KIT has been certified as a family-friendly university.
Monika Landgraf | EurekAlert!
PRESTO – Highly Dynamic Powerhouses
15.05.2017 | JULABO GmbH
Making lightweight construction suitable for series production
24.04.2017 | Laser Zentrum Hannover e.V.
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...
Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...
Scientists from the MPI for Chemical Energy Conversion report in the first issue of the new journal JOULE.
Cell Press has just released the first issue of Joule, a new journal dedicated to sustainable energy research. In this issue James Birrell, Olaf Rüdiger,...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
19.09.2017 | Event News
19.09.2017 | Physics and Astronomy
19.09.2017 | Power and Electrical Engineering