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5517 |
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Post-spraying annealing of aluminum-nickel composite cold sprayed coatings by various methods |
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Marcin Winnicki* / Wroclaw University of Science and Technology, Poland Agnieszka Baszczuk/ WrocBaw University of Science and Technology, Poland Marek Jasiorski/ WrocBaw University of Science and Technology, Poland Aleksandra MaBachowska/ WrocBaw University of Science and Technology, Poland Marcin Korzeniowski/ WrocBaw University of Science and Technology, Poland |
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Intermetallic Al-Ni compounds are promising in various high temperature applications in aerospace, electrochemical and environmental industries. It is due to their properties such as high-temperature strength, low density, high creep and corrosion as well as oxidation resistance. The paper presents influence of two different heating methods: (i) static in furnace, and (ii) dynamic by resistivity, on microstructure and mechanical properties of Al-Ni-Al2O3 coating. Three types of powder composition with Al to Ni ratio of 25/75, 50/50 and 75/25 wt. % were used. What is more, 33 wt. % of Al2O3 ceramic powder was added to the powders to increase coatings density. Prepared in this way powders were mixed in ball mill. The Al-Ni-Al2O3 coatings were deposited by low-pressure cold spraying with the use of air as propellant gas. The microstructure of mixed powders as well as sprayed and annealed Al-Ni-Al2O3 coatings was analysed using scanning electron microscope and x-ray diffraction. Microhardness measurements were conducted to confirm uniformity of post-annealing material transition. The results showed that various intermetallic compounds of AlNi group were achieved after annealing of different coatings. High density of as-sprayed coating ensured dense intermetallic compound after annealing. Furnace heating in 500 °C for 4 h produced coating with uniform intermetallic phases and alumina distribution, while dynamic resistivity heating moved alumina particles to the coating border. Therefore, coatings after resistivity heating had in the centre regions free of alumina particles. |