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2014
Conference Paper
Titel
Comparison of alumina-titania coatings deposited by plasma and HVOF spray techniques
Abstract
In order to evaluate the possibilities of the new 1-cathode-3-anodes plasma spray technique, to assess the usability of in-flight particle measurements and to investigate the influence of aluminum titanate, thermally sprayed coatings were produced from alumina-titania feedstock powders. Coatings deposited by a 1-cathode-3-anodes plasma spraying technique (DeltaGun) were compared to those produced by conventional atmospheric plasma spraying (F6) and high velocity oxy-fuel (HVOF) spraying by means of coating quality and economy. Commercial (Al2O3-13 ma.%TiO2 and Al2O3-40 ma.%TiO2) and experimental (Al2O3-44 ma.%TiO2, which corresponds to the composition of the compound aluminum titanate, Al2TiO5) powders were used in this study. The different spray techniques were compared regarding their particle velocities and temperature. Also, deposition rate and efficiency were measured. Microstructure, phase composition, mass loss by cavitation, hardness, Young's modulus and electrical resistivity of the coatings were investigated. It was shown that both mechanical and electrical coating properties sprayed by the 3-anodes technique are comparable to those deposited by the conventional plasma spray technique. However, higher deposition rates were achieved, which results in considerably lower production times and costs especially for larger components. HVOF-coatings showed finer microstructures, lower cavitation wear and higher resistivity but much lower deposition efficiency compared to both APS processes.