| AVS 62nd International Symposium & Exhibition | |
| Advanced Surface Engineering | Tuesday Sessions |
| Session SE+PS-TuA |
| Session: | Pulsed Plasmas in Surface Engineering |
| Presenter: | Robert Franz, Montanuniversität Leoben, Austria |
| Authors: | R. Franz, Montanuniversität Leoben, Austria F. Mendez Martin, Montanuniversität Leoben, Austria G. Hawranek, Montanuniversität Leoben, Austria P. Polcik, PLANSEE Composite Materials GmbH, Germany |
| Correspondent: | Click to Email |
Hard and wear-resistant coatings based on the system aluminium and chromium represent the state of the art in the protection of tools used in metal cutting operations. Using cathodic arc deposition techniques in nitrogen and/or oxygen atmospheres, nitrides, oxides or oxynitrides can be synthesised. The growth conditions encountered in processes employing cathodic arc plasmas are typically characterised by a high degree of ionisation and high deposition rates. For the supply of the non-gaseous elements during the deposition, it is common to use multi-element cathodes containing the desired Al/Cr ratio. These cathodes are usually composite cathodes and are widely used in industrial-scale deposition systems since they facilitate an easier process control and reproducibility. However, the plasma conditions in the cathodic arc plasma using such multi-element cathodes and their erosion behaviour in reactive atmospheres are only scarcely studied.
In the present investigation, AlCr composite cathodes with compositions of 75/25, 50/50 and 25/75 at.-% were exposed to cathodic arc plasmas in N2 and O2 atmospheres. Due to periodic melting and solidification of the cathodes’ near-surface region in the cathode spots, an intermixing of the elements Al and Cr and the formation of intermetallic phases occurred which was analysed by recording elemental distribution maps in the cross-sections using scanning electron microscopy. By comparing regions of strong erosion with areas less affected by the cathodic arc plasma, poisoning effects due to reactions of the metals in the cathodes and the background gas could be identified and were analysed in detail. The conductivity of the formed nitrides and oxides on the surface of the AlCr composite cathodes was decisive for the characteristics of the cathodes’ erosion behaviour. All results regarding the cathode erosion and the phase changes are compared to similar studies on TiAl [1] and Al0.7Cr0.3 [2, 3] cathodes and are put in context with recently reported arc plasma properties obtained with the same AlCr cathodes and gas atmospheres [4, 5].
References:
[1] D. Rafaja, C. Polzer, G. Schreiber, P. Polcik, M. Kathrein, Surf. Coat. Technol. 205 (2011) 5116–5123.
[2] J. Ramm, A. Neels, B. Widrig, M. Döbeli, L.D.A. Vieira, A. Dommann, H. Rudigier, Surf. Coat. Technol. 205 (2010) 1356–1361.
[3] M. Pohler, R. Franz, J. Ramm, P. Polcik, C. Mitterer, Surf. Coat. Technol. 206 (2011) 1454–1460.
[4] R. Franz, P. Polcik, A. Anders; IEEE Trans. Plasma Sci. 41 (2013) 1929–1937
[5] R. Franz, P. Polcik, A. Anders; Surf. Coat. Technol. 272 (2015) 309–321