Electrodeposited tungsten and molybdenum amorphous/nanocrystalline alloys. Deposition and properties.
|Mikolaj Donten , Zbigniew J. Stojek|
Uniwersytet Warszawski, Wydział Chemii, Warszawa, Poland
Amorphous and nanocrystalline materials are frequently used in contemporary engineering. Glassy metals offer unique properties such as high hardness, small abrasive wear, and increased corrosion resistance. Amorphous / nanocrystalline alloys containing tungsten and molybdenum are especially interesting, because in addition to the mentioned properties they exhibit useful magnetic properties. Finally they are extensively investigated.
The physical and chemical properties of amorphous alloys of either tungsten or molybdenum and one or more iron-group metals [1-3] make those alloys an alternative for the chromium plating. If the protective coatings are obtained by the electroplating processes, and contain a relatively high percentage of tungsten or molybdenum they will outperform hard chrome deposits. Those deposits also exhibit a good resistance to strong oxidizing acids such as nitric and hydrochloric acids, unlike the hard chrome which corrodes rapidly when it is in contact with these corrodents.
The obtained X-ray diffractograms and STM micrographs indicate that the tungsten amorphous alloys consist of closely packed nanofibers oriented perpendicularly to the substrate surface. For the molybdenum alloys, the amorphous character (grain size in the range of tens of nanometers) is obtained for its content higher than circa 20 at %. The amorphous Ni-Mo alloys never formed nanofibers, what was detected for the Ni-W alloys.
For a complete evaluation of this kind of alloys a reliable corrosion study were added to its characterization.
1. M. Donten, Z. Stojek, H. Cesiulis, J. Electrochem.Soc., 150 (2003) C95
2. Donten M., Cesiulis H., Stojek Z., Electrochim. Acta, 45 (2000) 3389-3396.
3. Donten M, Cesiulis H., Stojek Z., Electrochimica Acta, 50 (2005) 1405–1412.
Presentation: Oral at E-MRS Fall Meeting 2007, Symposium D, by Mikolaj Donten
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-22 17:20 Revised: 2009-06-07 00:44