A Microwave Resonance Plasma Source (MRPS) operating at atmospheric pressure  allows the modification of a microcrystalline surface structure, which becomes amorphous to X-rays . In particular, the X-ray amorphous nitrided layers were formed on the surfaces of Ti, 304 SS, 316 SS, and 5140 plain steel [1-3], using a nitrogen-based atmosphere for the MRIPS. Generally, it is possible to alloy the amorphous layers by boron, carbon, chromium, etc, employing appropriate precursors in both gaseous and solid state.
This ability of the novel MRPS to amorphise a surface microcrystalline layer up to ~10 mm in-depth combined with alloying was used in this research to transform an original microcrystalline surface layer into the nanocrystalline state. The novelty of this research is to nanocrystallise a microcrystalline surface by the MRPS. The subsequent heat treatment in order to transform the initial metastable amorphous phase to the nanocrystalline state is common processing .
In addition to nitriding [1-3], carburising and boriding were realized by incorporation of carbon and boron into amorphised surface layers by use of helium and argon-helium plasmas operating at atmospheric pressure. Initially beforehand, carbon and boron were adhered to a surface of Ti, 304 SS, 316 SS, and 5140 plain steel. The following heat treatment of the amorphised surface layers allows the transformation of the amorphous phase into a nanocrystalline layer with grain sizes of 20-50 nm.
The MRPS can be applied in a well-controlled way for the solid state amorphisation of a surface layer, which is a transitional stage for nanocrystallization under an appropriate thermal annealing . This research and development have demonstrated the commercial potential of the MRPS for designing nanocomposite surfaces with a desirable combination of properties that can be practical for a range of engineering surfaces and used in various industrial applications. Application of this surface engineering nanotechnology for surface hardening of cutting edges of saw teeth for commercialization in wood industry with low production costs is considered here as an example.
1. A.L. Taube and G.M. Demyashev "Microwave Resonance Plasma Source" – in: Wiley Encyclopedia of RF and Microwave Engineering, Editor-in-Chief: Kai Chang, John Wiley & Sons, New York, 2004, (in press).
2. G.M. Demyashev, A.L. Taube, and E. Siores "Superhard Nanocomposites" – in: Encyclopedia of Nanoscience and Nanotechnology edited by H.S. Nalwa, American Scientific Publisher, Los Angeles (CA), 2003, vol. 10, p. 1-46. (www.aspbs.com/enn)
3. A.L. Taube, and G.M. Demyashev "Chemical action of microwave resonance plasma source on metallic surfaces" – Proceedings of the 9th International Conference on Microwave and High Frequency Heating. September 2-5, 2003. Loughborough, UK, p. 373-376.
4. K. Lu "Thermodynamics and Kinetics of the Amorphous-to-Nanocrystalline Transformation" – in: Processing and Properties of Nanocrystalline Materials. Edited by C. Suryanarayana, J. Singh, and F.H. Froes. TMS, Warrendale (1996), p. 23-33.
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