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2929 |
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Tribological performance by elastic and plastic contacts of AT-13 and AT-45 coatings elaborated by plasma and flame spray |
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Hélène Ageorges* / University of Limoges,SPCTS , FRANCE Fabio Vargas / University of Limoges/ University of Antioquia, France/Colombia Pierre Fauchais/ University of Limoges, France Esperanza Lopez/ University of Antioquia, Colombia |
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Alumina titania coatings with 13 wt% and 45 wt.% of TiO2 (AT-13 and AT-45 respectively) were sprayed by atmospheric plasma spray and oxy-acetylene flame using microstructured powders. Additionally, nanostructured powders (AT-13) were sprayed by plasma spraying. The particles from powders were sprayed using oxyacetylene flame and plasma jets with different enthalpies in order to vary the physical and chemical properties of coatings. The effect of the structural characteristics of the coatings was studied, as well as the influence of their chemical composition and phases, on mechanical properties and tribological behavior. The wear resistance was determined by dry elastic contact between an alumina ball 6 mm in diameter and the coated discs, applying a load of 5 N on the alumina ball during 20,000 cycles. The ball was moved on the polished coating surface using a linear speed of 0.1 m/s. Also drilling tests between a HSS steel drill bit of 12,5 mm and the surface of coating were carried out in order to determine the wear resistance to plastic contact. The wear test results show that AT-13 coatings are more resistant than the AT-45 ones, due to the presence of ± and ³ alumina, which are phases of high mechanical resistance. On the contrary AT-45 coatings consist of Al2TiO5 and Al6Ti2O13 phases that are brittle and of low hardness. In elastic contact a reduction of the wear resistance of coatings was not evident but in plastic contact the plasma sprayed coatings were more resistant than those deposited by oxy-acetylene flame because of their more homogeneous structure and their better inter-lamellar cohesion. |