ÚMVI-odbor kovových materiálů

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    Elastic moduli and elastic anisotropy of cold sprayed metallic coatings
    (Elsevier, 2016-04-15) Seiner, Hanuš; Čížek, Jan; Sedlák, Petr; Huang, Renzhong; Čupera, Jan; Dlouhý, Ivo; Landa, Michal
    Resonant ultrasound spectroscopy is applied to analyze the elastic anisotropy of thick copper, aluminum, titanium, and nickel coatings prepared by cold spraying and to determine the respective elastic moduli. The results show that the coatings exhibit only weak deviations from perfect isotropy, and the obtained elastic moduli are comparable with those of the corresponding polycrystalline bulks. The increased internal friction observed in some of the studied coatings may indicate grain refinement and consequent grain boundary sliding.
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    Higher in-flight particle velocities enhance in vitro tribological behavior of plasma sprayed hydroxyapatite coatings
    (Elsevier, 2016-11-01) Khun, Nay Win; Li, Zhong Alan; Khor, Khiam Aik; Čížek, Jan
    Hydroxyapatite (HA) coatings were deposited onto Ti6Al4V substrates via atmospheric plasma spraying under systematically varying spray parameters, leading to different in-flight particle velocities. Morphology, composition, and tribological properties of the coatings were then studied. The coatings deposited at higher in-flight particle velocities exhibited smoother surface topography, better inter-particle bonding and higher Young’s modulus and hardness. Ball-on-disc tribological results showed that the friction and wear of the HA coatings significantly decreased with increased in-flight particle velocity under both dry and wet (Hanks’ solution) conditions. All HA coatings exhibited lower friction and wear during the wet sliding due to the lubricating effect of the solution.