[Back]


Publications in Scientific Journals:

H. Asanuma, F. Klimashin, P. Polcik, S. Kolozsvári, H. Riedl, P.H. Mayrhofer:
"Hard Ti-Al-N endowed with high heat-resistance through alloying with Ta and Ce";
Surface & Coatings Technology, 372 (2019), 0257-8972; 26 - 33.



English abstract:
Recently we showed that Ta as well as Ce significantly increase the thermomechanical properties and oxidation resistance of Ti-Al-N coatings. Here we investigate their synergistic effect by comparing single-phase face centered cubic (fcc) structured Ti0.39Al0.61N, Ti0.40Al0.58Ce0.02N, Ti0.43Al0.51Ta0.06N, Ti0.44Al0.44Ta0.12N, Ti0.43Al0.42Ta0.14Ce0.01N, and Ti0.43Al0.35Ta0.21Ce0.01N coatings, which were prepared by reactive magnetron sputtering of corresponding powder metallurgically prepared composite targets. Especially the Ti0.43Al0.42Ta0.14Ce0.01N coating outperforms the others in hardness, thermal stability and oxidation resistance. This coating is prepared with a Ti0.44Al0.44Ta0.10Ce0.02 target, which allows for a 2.8 times higher deposition rate than the Ti0.50Al0.50 target (for the preparation of a fcc-Ti0.39Al0.61N) under the same deposition parameters (temperature, gas flow, sputtering current, bias potential). The hardness of Ti0.43Al0.42Ta0.14Ce0.01N is 35 GPa in its as-deposited single-phase fcc state, and still 34 GPa after vacuum-annealing at 1200 °C, where only a very small fraction of hexagonal phase-formation can be detected. Ti0.39Al0.61N shows 30 GPa in as-deposited state and 27 GPa after vacuum-annealing at 900 °C (peak-hardness of 32 GPa with Ta = 800 °C), where already hexagonal phases form. But even more striking is the improved oxidation resistance, which outperforms those of the individual Ta or Ce alloyed Ti-Al-N, due to the cumulative effect of Ta and Ce. With a Ta/Ti ratio of ~1/3, Ti0.43Al0.42Ta0.14Ce0.01N provides the optimum Ta content for the formation of a stable and dense TiO2-containing scale, and the additional 1 at.% Ce-metal-fraction enables the growth of a dense and well-adherent protective oxide scale. Based on our results we can conclude, that the combined alloying of Ta and Ce to Ti-Al-N improves the deposition characteristics, thermomechanical properties, as well as thermal stabilities (incl. oxidation resistance), which should provide a better performance of thereby protective machining tools.

Keywords:
Ti-Al-N; Cerium; Tantalum; Thermal stability; Oxidation resistance;


"Official" electronic version of the publication (accessed through its Digital Object Identifier - DOI)
http://dx.doi.org/10.1016/j.surfcoat.2019.05.018


Created from the Publication Database of the Vienna University of Technology.