Diamond layer makes steel rock hard
Dutch chemist Ivan Buijnsters from the University of Nijmegen has successfully produced a diamond layer on a steel substrate. This opens up the possibility of wear-resistant tools. The secret to this technique is an adhesive layer between the steel and the diamond layer.
Buijnsters made diamond layers by allowing methane gas diluted in hydrogen gas to dissociate on a hot wire just above the substrate. The carbon atoms present in the methane dropped onto the substrate and formed a thin layer of diamond there. However, this technique did not work on a steel substrate. Graphite mostly formed on this.
The researcher discovered why a diamond layer could not be created on some types of steel. During the deposition process the carbon penetrated several micrometres into the metal, where it formed iron carbides. Subsequently, graphite formed instead of diamond. This effect was found to be less strong in stainless steel, although it was still strong enough to prevent the formation of a well-sealed diamond coating.
To solve this problem Buijnsters looked for a material that could be placed between the steel and diamond layers. The material had to adhere well to the steel and be a suitable substrate for diamond growth. Silicon was an obvious choice. However, the carbon atoms diffused through the intermediate silicon layer into the iron causing the steel to weaken.
An intermediate layer of chromium nitride was found to work well. It was relatively easy to apply a good-adhering intermediate layer using a deposition apparatus. Good diamond layers were formed on certain types of tool steel in particular. However, the diamond layers on stainless steel were of a lower quality.
A surface treatment of steel with boron was also found to result in a good intermediate layer, even on stainless steel. An advantage of this treatment is that the difference in expansion between diamond and steel is gradually dissipated. After the production of diamond at about 600 oC, the steel contracts much more than the diamond coating and the coating can become detached as a result of this. A treatment with boron gives the external surface of the steel an expansion coefficient more or less comparable to that of diamond. This effect gradually decreases from the surface of the steel inwards.
Nalinie Moerlie | alfa
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
X-ray study throws light on key process for production
A Swedish-German team of researchers has cleared up a key process for the artificial production of silk. With the help of the intense X-rays from DESY's...
For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.
According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...
New success for Konstanz physicists in studying the quantum vacuum
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...