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2615 |
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High thickness A-357 aluminum alloy coatings deposited by coldspray for the repair of aeronautic components |
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Simone Vezzù* / Veneto Nanotech , ITALY Silvano Rech / associazione CIVEN, ITALY Andrea Trentin/ associazione CIVEN, ITALY Giovanni Paolo Zanon/ AVIO spa, ITALY |
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In view of the high cost of manufacture of high performance aeroengine components, the importance of maintenance and repair is crucial. In particular the use of thermal techniques such as welding or thermal spray deposition to repair aluminium and magnesium aircraft components could affect noticeably the substrate coating interface as well the residual stress state and the microstructure of the whole zone subjected to the thermal input. In this field, Coldspray deposition is gaining more and more interest in the aeronautic industry for the deposition of thick coatings of temperature sensitive materials such as aluminium and magnesium alloys thanks to the low deposition temperature and thermal input to the substrate, low residual stress, porosity and oxygen content of deposited coatings. This study investigates the effectiveness of coldspray deposition for the repair of aeronautic gearbox and components. A-357 (low Be) aluminium alloy coatings has been deposited by using CGT Kinetic3000 deposition system with nitrogen as carrier gas. The coatings has been deposited on A-357 substrates in view of repair applications with coating thicknesses ranging from 0.5 up to 10 mm. The as-deposited coatings have been extensively characterised in terms of morphology, microstructure and porosity as well in mechanical properties. Coating adhesion and cohesion has been evaluated by standard ASTM C-633 and TCT test respectively. Yield Strength and Ultimate Tensile Strength have been also evaluated by tensile tests performed on properly designed specimens. Finally, some industrial parts have been repaired by coldspray, machined and tested following the aeronautic procedures. |