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2522 |
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Thursday, September 29, 2011, Saal B2.1 4:00 PM Plasma Spraying 3 |
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Titanium dioxide coatings sprayed by a water stabilized plasma gun (WSP) with argon and nitrogen as the powder feeding gas: differences in structural, mechanical and photocatalytic behavior |
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Pavel Ctibor / Instritute of Plasma Physics ASCR, Czech Republic Zdenk Pala / Institute of Plasma Physics v.v.i., Academy of Sciences of the Czech Republic, Czech Republic Karel Neufuss/ Institute of Plasma Physics v.v.i., Academy of Sciences of the Czech Republic, Czech Republic Vaclav Stengl/ Institute of Inorganic Chemistry v.v.i., Academy of Sciences of the Czech Republic, Czech Republic Igor Pis/ Department of Surface and Plasma Science, Faculty of Mathematics and Physics, CharlesUniversity, Czech Republic Tatiana Zahoranova/ Department of Surface and Plasma Science, Faculty of Mathematics and Physics, CharlesUniversity, Czech Republic Vaclav Nehasil/ Department of Surface and Plasma Science, Faculty of Mathematics and Physics, CharlesUniversity, Czech Republic M. Vilemova*/ , |
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Titanium dioxide coatings were sprayed by a water stabilized plasma gun (WSP) to form robust self-supporting bodies with a photocatalytically active surface. Agglomerated nanometric powder was used as a feedstock. In one case argon was used as a powder-feeding as well as coating-cooling gas whereas in the other case nitrogen was used for both purposes. Stainless steel was used as a substrate and the coatings were released after cooling due to the thermal expansion differences. Over 1 millimeter thick self-supporting bodies were studied by XRD, chemical analyses, XPS, UV-VIS spectrophotometry and photocatalytic tests. Majority of the tests was done at the surface as well as at the bottom side representing the contact surface with the substrate during the spray process. Porosity was studied by image analysis on polished cross sections where also microhardness was measured. Dominant phase present in the sprayed samples is rutile whereas anatase was the main minor component identified. Hydrogen content in the nitrogen-sample was higher whereas the character of the optical absorption edge was very similar for both samples. Photoelectron spectroscopy revealed higher amount of hydroxyl groups chemisorbed on the surface of the nitrogen-sample. The photocatalytic activity was tested by decomposition of acetone at UV illumination, whereas also the end products - CO and CO2 - were monitored. The nitrogen-sample was revealed as the more efficient photocatalyst. |