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1923 |
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Monday, May 03, 2010, Sophia Room 2:20 PM Cold Spraying 2 |
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Wear behavior of titanium coatings on aluminum light alloys obtained by cold gas spraying |
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Sergi Dosta* / Thermal Spray Centre (CPT) - Universitat de Barcelona, SPAIN Nuria Cinca/ Thermal Spray Centre (CPT), Spain Maria Barbosa/ Thermal Spray Centre (CPT), Spain J.M. Guilemany/ Thermal Spray Centre (CPT), Spain |
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It is well known the good corrosion resistance of aluminium due to the formation of a passivating oxide layer. Such corrosion resistance characteristic of most aluminium alloys can be, however, seriously affected by the addition of alloying elements which are introduced to improve the mechanical properties; this is the case of the 7075-T6 alloy, extensively used in aircraft industry. A possible approach to increase the corrosion resistance of this alloy is the deposition of a pure titanium coated layer. For this purpose, the novel Cold Gas Spraying technique is becoming an excellent alternative to other depositing methods for materials sensitive to oxygen reaction. As far as it is concerned, a wide range of spraying parameters was first tested in order to obtain a dense coating which can accomplish the desired properties. The deposition process has been then discussed in terms of particle size and morphology, powder feeding rate, as well as pressure and temperature of accelerating gas; the modification of these factors influence directly on particle velocities, making them possible to be above or below the critical velocity value. Moreover, once the corrosion properties are ameliorated by the presence of titanium, since titanium and titanium alloys generally exhibit poor fretting and wear resistance, the second goal of the present work has been to evaluate and compare the sliding wear properties of a Cold Gas sprayed titanium coating onto aluminium substrate 7075-T6 alloy with the corresponding uncoated specimen. It has been observed that the as-sprayed pure titanium?s friction and wear performance is governed by the plastic deformation behavior of the surface and subsurface layers and no oxide layer has been formed on the fresh coating while frictioning. |