Non-reactively sputtered ultra-high temperature Hf-C and Ta-C coatings

Lasfargues, H.TU Wien, Inst Mat Sci & Technol, A-1060 Vienna, Austria. (författare)

Transition metal carbides are known for their exceptional thermal stability and mechanical properties, notably governed by the carbon content and the prevalent vacancies on the non-metallic sublattice. However, when using reactive deposition techniques, the formation of amorphous C-containing phases is often observed. Here, we show that non-reactive magnetron sputtering of HfC0.89 or TaC0.92 targets lead to fully crystalline coatings. Their C content depends on the target-to-substrate alignment and globally increases from HfC0.66 to HfC0.76 and from TaC0.69 to TaC0.75 with increasing bias potential from floating to - 100 V, respectively, when using a substrate temperature T-sub of 500 degrees C. Increasing T-sub to 700 degrees C leads to variations from TaC0.71 to TaC0.81. All HfCy films are single-phase face-centered cubic, whereas the TaCy films also contain small fractions of the hexagonal Ta2C phase. The highest hardness and indentation modulus among all coatings studied is obtained for TaC0.75 with H = 41.9 +/- 03 GPa and E = 466.8 +/- 15 GPa. Ab initio calculations predict an easy formation of vacancies on the C-sublattice, especially in the Ta-C system, and a temperature driven stabilization of defected structures at high temperatures, with fewer vacancies on the C sublattice for Hf-C than for Ta-C The predicted phase stability is proven up to 2400 C for both systems by annealing experiments in vacuum.

Glechner, T.TU Wien, Inst Mat Sci & Technol, A-1060 Vienna, Austria. (författare)
Koller, C. M.TU Wien, Inst Mat Sci & Technol, A-1060 Vienna, Austria. (författare)
Paneta, ValentinaUppsala universitet,Tillämpad kärnfysik(Swepub:uu)valpa412 (författare)
Primetzhofer, DanielUppsala universitet,Tillämpad kärnfysik(Swepub:uu)danpr521 (författare)
Kolozsvari, S.Plansee Composite Mat GmbH, D-86983 Lechbruck, Germany. (författare)
Holec, D.Univ Leoben, Dept Phys Met & Mat Testing, A-8700 Leoben, Austria. (författare)
Riedl, H.TU Wien, Inst Mat Sci & Technol, A-1060 Vienna, Austria. (författare)
Mayrhofer, P. H.TU Wien, Inst Mat Sci & Technol, A-1060 Vienna, Austria. (författare)
TU Wien, Inst Mat Sci & Technol, A-1060 Vienna, Austria.Tillämpad kärnfysik (creator_code:org_t)

Ingår i:Surface & Coatings Technology: ELSEVIER SCIENCE SA309, s. 436-4440257-89721879-3347

Av författaren/redakt...: Lasfargues, H.; Glechner, T.; Koller, C. M.; Paneta, Valentin ...; Primetzhofer, Da ...; Kolozsvari, S.; visa fler...; Holec, D.; Riedl, H.; Mayrhofer, P. H.; visa färre...

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