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2134 |
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Wednesday, May 05, 2010, Sophia Room 1:40 PM Wear Protection 3 |
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Comparison of two structure scales
of plasma sprayed alumina/titania coatings
on the mechanical and tribological properties
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Vargas Fabio / University of Antioquia, Colombia Hélène Ageorges* / University of Limoges, France Weidong Xin/ University of Limoges, France Fabio Vargas/ University of Limoges, France Pierre Fauchais/ University of Limoges, France María López/ University of Antioquia, Colombia |
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Alumina coatings doped with 13 % wt TiO2 exhibit better wear resistance under tribological conditions, thanks to their improved toughness. Two different types of alumina/titania coatings, with the same titania content, have been elaborated by atmospheric plasma spraying (APS). The aim was to compare the effect of both different structures on the mechanical and tribological properties and especially on toughness and wear resistance. The raw materials used were Al2O3-13 wt % TiO2 powders with two different structures: micrometer sized ones, with two distributions (5 ? 30 μm and 15 ? 45 μm), and agglomerated nano-meter sized particles (grain diameters between 200 to 500 nm) with a size distribution between 45 and 60 µm. Coatings have been sprayed onto low carbon steel (XC38) substrates with several spray parameters, the plasma forming gas being a mixture of Ar and H2 (45/15 L/min). The wear resistance of coatings was determined by using the ball on disk test. The linear speed between the coated disc and the alumina ball of 6 mm in diameter was 0.1 m/s and the normal load was set in 5 N. Tests were carried out during 20,000 cycles in dry condition with and without a N2 jet. Coating toughness was determined by indentation tests, using Lawns?Evans?Marshall equation. The effect of toughness on the wear resistance of both types of alumina ? titania coatings was studied. Results have shown that coatings obtained with nanostructured particles have a lower hardness than those obtained with the microstructured ones, but their friction coefficient is half that of coatings obtained with microstructured particles. |