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4703 |
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Wednesday, May 11, 2016, Room 3E 9:00 AM Cold Gas Spraying II |
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Microstructure and mechanical properties of cold sprayed Ni-Al2O3 coatings |
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Wojciech Zórawski* / Kielce University of Technology, Poland Anna Góral/ Institute of Metallurgy and Materials Science PAS, Poland Medard Makrenek/ Kielce University of Technology, Poland Szymon Kowalski/ Kielce University of Technology, Poland |
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The work concerns a study of the properties of a cold sprayed composite Ni-Al2O3 coatings. The Ni-Al2O3 powder (mixture of Ni (Metallisation P836) and Al2O3 (SM 6051)) was applied in the cold spraying process. The coatings were sprayed by means of Impact Innovations 5/8 system with three different contents of Al2O3 (20, 40 and 60 %wt.). To evaluate an influence of substrate topography on adhesion of Ni-Al2O3 coatings, the surface of 7075 Al alloy was prepared in three different ways (without treatment, sand blasted with small and large grit). The microstructure and composition of powders and coatings were analyzed by SEM FEI Nova NanoSEM 200 and TEM (FEI TECNAI G2). Their phase composition was studied with the use of a Bruker D8 Advance diffractometer. Microhardness was measured with a Vickers indenter. The topography of the substrate and coatings were analyzed by means of a Talysurf CCI-Lite non-contact 3D profiler. Mechanical properties were performed with Nanovea tester. The investigations revealed that the increase in ceramic content in the blend leads to an increase in Al2O3 amount in the cold sprayed Ni-Al2O3 coatings. The ceramic particles were mainly distributed between plastically deformed elongated nickel grains. It is also visible areas with a fragmentation of ceramic particles due to the impact of one or more incoming Al2O3 particles onto an embedded ce-ramic particle. All coatings were characterized by a high surface roughness. The coating Ni+40%wt Al2O3 showed the best retained balance between an amount of embedded Al2O3 particles and coat-ing porosity. |