Efficient Production of Novel Fe-based Coatings for Large-area Applications by Means of AC-HVAF Spraying

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The recently developed AC-HVAF spray process provides higher particle velocities and lower particle temperatures compared to conventional HVOF spraying due to very high flow rates of compressed air. This process is suitable for spraying finer spray powders. This process is advantageous in terms of efficient production of large-area coatings because of its high spray rates. AC-HVAF spraying of novel Fe-based feedstock materials for large-area applications is not documented in literature. The purpose of this proposal is the fundamental investigation of AC-HVAF spraying of novel Fe-based feedstock materials for efficient production of wear and corrosion protective coatings in terms of large-area applications such as cylinder dryers of paper machines. The special process characteristics of the AC-HVAF will be combined with the high wear and corrosion resistance of novel Fe-based materials to achieve economic and ecologic advantages compared to established arc-sprayed Fe-based coatings as used in paper machines today. These advantages are attributed to reduced coating thickness, shorter spray time, less consumption of feedstock materials, reduced finishing work and improved thermal conductive behavior. A suitable process must be developed in order to achieve this purpose. Therefore, particle velocities and temperatures depending on process parameters and powder fractions will be investigated in the process development. Their influences on coating formation, oxidation of feedstock materials and coating microstructure will be studied. The expected advantages will be demonstrated by determination of mechanical and thermos-physical properties of the coatings and their wear and corrosion behavior in comparison with established arc-sprayed coating.