Braun R.,German Aerospace Center |
Lange A.,German Aerospace Center |
Hovsepian P.Eh.,Sheffield Hallam University |
Ehiasarian A.P.,Sheffield Hallam University |
And 3 more authors.
Materials at High Temperatures | Year: 2011
TiAlYN/CrN and CrAlYN/CrN nanoscale multilayer coatings were deposited on γ-TiAl specimens using magnetron sputtering techniques. The nitride layers were manufactured by unbalanced magnetron sputtering (UBM) and high power impulse magnetron sputtering (HIPIMS). The CrAlYN/CrN coatings had an oxy-nitride overcoat. On some of the coated samples an additional alumina topcoat was deposited. The oxidation behaviour of the different coatings was investigated at 750 and 850°C performing quasi-isothermal oxidation tests in laboratory air. Mass change data were measured during exposure up to failure or the maximum exposure length of 2500 h. When exposed to air at 750°C, the Ti-based nitride films exhibited higher oxidation resistance than the Ti-45Al-8Nb substrate material. The alumina topcoat enhanced the oxidation protection of this coating system, acting as diffusion barrier to oxygen penetration. At 850°C, the TiAlYN/CrN films exhibited poor stability and rapidly oxidised, and therefore were not applicable for long-term protective coatings on γ-TiAl alloys. The beneficial effect of the additional Al 2O 3 layer was less pronounced at this exposure temperature. The Cr-based nitride films exhibited high oxidation resistance during exposure at 850°C. HIPIMS deposition improved the oxidation behaviour of the CrAlYN/CrN nanoscale multilayer coatings in comparison to UBM coatings. For these coatings, the decomposed and partially oxidised nitride films were an effective barrier to oxygen inward diffusion. The alumina topcoat did not significantly increase the oxidation resistance of the γ-TiAl alloy coated with Cr-based nitride films.
Harkonen E.,University of Helsinki |
Kolev I.,Hauzer Techno Coating BV |
Diaz B.,Chimie Paristech |
Swiatowska J.,Chimie Paristech |
And 8 more authors.
ACS Applied Materials and Interfaces | Year: 2014
Atomic layer deposition (ALD) is a thin film deposition technique that is based on alternating and saturating surface reactions of two or more gaseous precursors. The excellent conformality of ALD thin films can be exploited for sealing defects in coatings made by other techniques. Here the corrosion protection properties of hard CrN and diamond-like carbon (DLC) coatings on low alloy steel were improved by ALD sealing with 50 nm thick layers consisting of Al2O3 and Ta2O5 nanolaminates or mixtures. In cross sectional images the ALD layers were found to follow the surface morphology of the CrN coatings uniformly. Furthermore, ALD growth into the pinholes of the CrN coating was verified. In electrochemical measurements the ALD sealing was found to decrease the current density of the CrN coated steel by over 2 orders of magnitude. The neutral salt spray (NSS) durability was also improved: on the best samples the appearance of corrosion spots was delayed from 2 to 168 h. On DLC coatings the adhesion of the ALD sealing layers was weaker, but still clear improvement in NSS durability was achieved indicating sealing of the pinholes. © 2014 American Chemical Society.
Hauzer Techno Coating Bv | Date: 2012-10-30
An apparatus for the manufacture of at least substantially hydrogen-free ta-C layers on substrates, which includes a vacuum chamber, which is connectable to an inert gas source and a vacuum pump, a support device in the vacuum chamber, at least one graphite cathode having an associated magnet arrangement forming a magnetron that serves as a source of carbon material, a bias power supply for applying a negative bias voltage to the substrates on the support device, at least one cathode power supply for the cathode, which is connectable to the at least one graphite cathode and to an associated anode and which is designed to transmit high power pulse sequences spaced at intervals of time, with each high power pulse sequence comprising a series of high frequency DC pulses adapted to be supplied, optionally after a build-up phase, to the at least one graphite cathode.
Hauzer Techno Coating BV | Date: 2012-08-30
A vacuum coating apparatus and method comprising a vacuum chamber, at least one pair of opposing cathodes, a power supply adapted to supply an AC voltage to said opposing cathodes to operate them in a dual magnetron sputtering mode, wherein at least one further cathode for PVD coating is provided in said vacuum chamber, characterized in that the at least one further cathode is a magnetron cathode and a further power supply is provided in the form of a pulsed power supply or a DC power supply is provided which is connectable to the magnetron cathode or arc cathode.
Hauzer Techno Coating BV | Date: 2011-01-27
A coating apparatus having a vacuum chamber, a plurality of cathodes arranged therein and also a HIPIMS power source, characterized in that in addition to at least one coating cathode which can be operated with the HIPIMS power source a plurality of etching cathodes is provided which are smaller in area in comparison to the coating cathode, with the etching cathodes being connectable in a predetermined or predeterminable sequence to the HIPIMS power source.