Advanced Graded Protective Coatings, Deposited by EB-PVD
Authors: Movchan Boris A. , Yakovchuk Kostyantyn Yu. 
Published: March 2009

Electron beam technology (EB-PVD) and equipment for one-stage deposition of advanced
graded protective coatings using a composite ceramic ingot for evaporation are described. This
technology allows replacing the flat interface between coating layers by a graded transition zones and
achieve of a high degree of reproducibility of the composition, structure and lifetime of the
functionally graded coating in compare with traditional multi-stages technologies of protective
coating deposition.A design of the composite ceramic ingot is considered, as well as the ability to
regulate in a broad range the composition, structure and properties of all levels of the graded
protective coating including transition zones and coating layers. Examples and variants of advanced
graded protective coatings with their structures and properties are given (thermal barrier, hard
erosion-resistant and damping coatings) for aerospace and gas-turbine industry application deposited
by one-stage EB-PVD process. Total cost of one-stage EB-PVD deposition process at least 2 times
less in compare with traditional technological processes of protective coating deposition due to using
only one EB-PVD unit and elimination of multistage nature of process cycle.Laboratory and
productive electron-beam units designed and manufactured at ICEBT are considered.
Development of modern protective coatings, technologies and equipment for their application is
focused, primarily, on improvement of the durability and main service properties of the
coating/protected item system, ensuring a reliable reproducibility of the coating structure and
properties, shortening the cost and time of the entire technological cycle of their deposition. The
existing traditional technologies of deposition of multilayer protective coatings, for instance, thermal
barrier coatings (TBC), containing a oxidation-resistant metal bond coat and outer low
thermal-conducting ceramic layer, are multi-stage, with combination of such processes as diffusion
saturation, galvanic coating, plasma spraying and electron beam deposition [1-3]. Use of diverse
expensive equipment, availability of intermediate mechanical and thermal treatments, as well as the
operations of surface cleaning, apply considerable limitations both on widening of the sphere of such
coating application, and their further development in terms of improvement of the structure and
properties.
The one-stage electron beam technology developed at ICEBT for deposition of advanced
protective coatings based on evaporation of a composite ingot and allowing deposition of functionally
graded coatings in one process cycle, meets the above goals to a considerable extent [4,5]. The
technology is based on the use of the known phenomenon of fractionating at evaporation of
multicomponent systems, containing elements with different melting temperature and vapour
pressure, and their subsequent condensation under vacuum, allowing the flat interface, for instance
between the metal and ceramic layers, to be replaced by a transition zone of the graded composition
and structure.
Fig.1 gives the schematic and appearance of a composite ingot used for one-stage deposition of
advanced graded protective coatings in vacuum by its electron beam evaporation from one crucible.
The ingot base material determines the purpose of the graded coating. For instance, Al2O3, TiC,
TiB2, B4C, MgO, etc. can be used as the base of the ingot for deposition of hard wear-resistant,
erosion-resistant and damping coatings. For the case of TBC, this is zirconium dioxide with additives