TY - THES

T1 - Alloying of TiAlN single- and multi-layer thin films

AU - Radanitsch, Jörg

N1 - embargoed until null

PY - 2009

Y1 - 2009

N2 - Cathodic arc evaporated TiAlN coating systems alloyed with B, Si, Ta and V have been investigated, grown at bias voltages of -40 and -80 V and in the form of single and multi-layer coatings. In case of multi-layer architecture, Ti0.5Al0.5N was used as a template layer. The alloying elements Si and B push the coating systems structure to higher hexagonal phase fractions, while Ta and V promote formation of the face-centered cubic (fcc) phase. It was found that the fcc phase can also be fostered through higher bias voltage or multi-layer architecture. For the later, fcc structured Ti0.5Al0.5N layers in between the alloyed TiAlN layers provide a template effect. There, the Ti0.5Al0.5Ns fcc structure promotes growth of the following TiAlN layers with higher fcc phase fractions. Mechanical properties mainly depend on the phase composition and the layer architecture. In general, higher fcc phase fractions are beneficial for higher hardness and Youngs modulus, which is also the case for smaller grain sizes. B-, Si- and Ta-alloyed coatings show improved oxidation behaviour compared to unalloyed TiAlN coatings. Multi-layering leads to structural changes which positively affect the oxidation resistance. However, highly fcc structured coating materials (e.g. stabilized by Ta) did not show this improvement of the multi-layer design. The oxidation resistance of V alloyed multi-layer coatings is enhanced by the Ti0.5Al0.5N template layer which here acts as a difusion barrier. The higher bias voltage induces stresses which can be harmful for oxidation resistance. At room temperature, wear is influenced by tribochemical reactions of Ti. Thus, the higher Ti contents within multi-layer coatings had a negative influence on the room temperature wear behaviour. At high temperatures, wear is found to be determined by the mechanical and oxidation properties. Here, the multi-layer architecture provides advantages compared to the single layer architecture.

AB - Cathodic arc evaporated TiAlN coating systems alloyed with B, Si, Ta and V have been investigated, grown at bias voltages of -40 and -80 V and in the form of single and multi-layer coatings. In case of multi-layer architecture, Ti0.5Al0.5N was used as a template layer. The alloying elements Si and B push the coating systems structure to higher hexagonal phase fractions, while Ta and V promote formation of the face-centered cubic (fcc) phase. It was found that the fcc phase can also be fostered through higher bias voltage or multi-layer architecture. For the later, fcc structured Ti0.5Al0.5N layers in between the alloyed TiAlN layers provide a template effect. There, the Ti0.5Al0.5Ns fcc structure promotes growth of the following TiAlN layers with higher fcc phase fractions. Mechanical properties mainly depend on the phase composition and the layer architecture. In general, higher fcc phase fractions are beneficial for higher hardness and Youngs modulus, which is also the case for smaller grain sizes. B-, Si- and Ta-alloyed coatings show improved oxidation behaviour compared to unalloyed TiAlN coatings. Multi-layering leads to structural changes which positively affect the oxidation resistance. However, highly fcc structured coating materials (e.g. stabilized by Ta) did not show this improvement of the multi-layer design. The oxidation resistance of V alloyed multi-layer coatings is enhanced by the Ti0.5Al0.5N template layer which here acts as a difusion barrier. The higher bias voltage induces stresses which can be harmful for oxidation resistance. At room temperature, wear is influenced by tribochemical reactions of Ti. Thus, the higher Ti contents within multi-layer coatings had a negative influence on the room temperature wear behaviour. At high temperatures, wear is found to be determined by the mechanical and oxidation properties. Here, the multi-layer architecture provides advantages compared to the single layer architecture.

KW - PVD Mehrlagenschichten TiAlN legieren Tantal Bor Silizium Vanadium Oxidationsverhalten Struktur

KW - PVD TiAlN multi-layer alloying tantalum boron silicon vanadium oxidation

M3 - Diploma Thesis

ER -