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1213 |
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Tuesday, June 03, 2008, Room 08 11:10 AM Nanomaterials 1 Most coating materials gain superior coating performance when applied as nanostructured coating, new designed materials and optimized processes show promising results for this |
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Microstructural, tribological and corrosion aspects of thermally sprayed Ti-Cr-Si-O coatings showing icosahedral phases |
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Stephan Siegmann / EMPA - Materials Science and Technology, CH P. P. Bandyopadhyay* / Department of Mechanical Engineering, IIT Kharagpur, INDIA Mousab Hadad/ EMPA Thun, Materials Technology, Switzerland Christian Jaeggi/ EMPA Thun, Materials Technology, Switzerland |
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This paper is a first report of thermally sprayed Ti 60 Cr 32 Si 8 (atoms %) alloy coatings. It has been reported previously that such an alloy assumes quasicrystallinity in presence of oxygen, when made to undergo rapid quenching. In these cases, either Titanium or Silicon is used as an alloying element, so that either of them can act as an oxygen attractor. This paper describes the production of a quasicrystal coating by thermal spraying the alloy in air, i.e. in presence of oxygen, either by flame or atmospheric plasma spraying. The spray parameters for both processes have been varied in the experiment in a wide range. A vacuum plasma sprayed coating served as an oxygen-free reference. This investigation includes a detailed study of the microstructure and phases by optical microscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-Ray Diffractomerty (XRD), microhardness and image analysis. An estimate of the composition of the coating has been done using Glow Discharge Optical Emission Spectroscopy (GDOES).The parametric variations have been correlated with the coating microstructure. We found in the study a certain likelihood of obtaining quasicrystals by atmospheric plasma spraying of this alloy under favorable parametric conditions. The tribological properties of these coatings were studied using a ball on disc reciprocating tribometer. The corrosion properties of one representative coating have been studied using potentio-dynamic method and the corrosion response has been correlated with the coating?s microstructure. |