Structure and corrosion resistance of composite materials Cu-Mo-Zr-Y obtained by electron-beam evaporation-condencation
Journal Title: Вісник Тернопільського національного технічного університету - Year 2015, Vol 78, Issue 2
Abstract
This research studied the structure of composite materials Cu-Mo-Zr-Y obtained by electron-beam method of evaporation-condensation. It was found that the structure is related to the chemical composition of condensate. When Molybdenum content in Cu-Mo-Zr-Y condensates is under 5% of the mass, the obtained structure is close to indiscrete, without the typical signs of layering. When Molybdenium content is over 5% of the mass, compositional materials show properties of layering hierarchy on macro-, micro- and submicrolevels. Levels with different morphological structure (created by polygonal, column and spherical particles) can be observed in layering structure of one sample. To establish the possibility of work of composite materials Cu-Mo-Zr-Y contact in the air humid environment in on-off mode, studies of their corrosion resistance obtained by gravimetric method were provided together with comparative evaluation of composite materials Cu-Mo. The obtained results showed that the corrosion resistance of composite materials Cu-Mo and Cu-Mo-Zr-Y depends on chemical composition. Thus, the introduction of up to 5% Molybdenum weight in a copper matrix has almost no effect on corrosion resistance of Cu-Mo compared to pure copper. At higher concentrations of Molybdenum (up to 12%) corrosion resistance decreases (approximately to 20%), limiting the use of these materials in an oxidizing environment. Corrosion processes in condensates proceed electrochemically accompanied by dissolution of a more active metal - Molybdenum, which having a high affinity for oxygen, in water medium forms MoO2 and MoO3 oxides on the surface of the condensates. Depth corrosion indicators were calculated basing on gravimetric studies. It is shown that corrosion processes to a significant extent are slowed down by additional alloying of composite materials Cu-Mo by Zirconium and Yttrium in an amount of 0.2% by weight of each of the components, allowing to improve corrosion resistance of composite materials to 15-20%. It is related to the screening effect of the particles of Yttrium and Zirconium, which are located on the border of crystallites.
Authors and Affiliations
Vira Grechanyuk, Victoria Chornovol, Oleksandra Starostina, Vadim Kulichenko
Keywords
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