“A research group led by NI Guohua from the Institute of Plasma Physics, Hefei Institutes of Physical Science realized the rapid nitriding of stainless steel surface and moreover they revealed the mechanism of non-thermal arc plasma nitriding at atmospheric pressure.
Nitriding of stainless steel surface produces Fe-N solid solution and nitride diffusion layer, which can significantly improve the wear-resistance and corrosion resistance of stainless steel materials, which enables its wide application in related industries.
However, it also faces limits set by Ion nitriding technology itself which is time-consuming and complicated as well as put the environment at risk by Ammonia. In this regard, how to realize atmospheric plasma nitriding with simple and rapid process flow has always been under the spot light when it comes to stainless steel surface nitriding.
In this study, NI’s team used non-thermal transfer arc plasma to realize the rapid nitriding of stainless steel surface, and revealed the mechanism of non-thermal arc plasma nitriding at atmospheric pressure.
They developed an alternating current-driven non-thermal transferred arc plasma torch to generate arc plasma which was used for steel nitriding. In the nitriding process, the arc root was attached on the surface of stainless-steel sample to achieve the purpose of high efficient nitridation.
Moreover, they found that, at hydrogen concentration 0%, the N atom concentration was small, and the nitriding effect was not obviously. When the hydrogen was added into the nitrogen plasma, the NH radical concentration increased rapidly. The NH radical could be absorbed on the sample surface and dissociated into N atom and H atom, and the N atom would penetrate to the sample then lead to the obvious nitriding effect, which suggested that the N atom permeated the stainless steel mainly came from NH radical.”