Structural investigations on TiAlN coatings alloyed with C
Research output: Thesis › Master's Thesis
TiAlN based hard coatings are widely applied on surfaces for cutting and forming tools because of their outstanding mechanical properties and oxidation resistance. Due to the steadily increasing demands on these coatings, the development of new alloy concepts is the focus of numerous scientific studies. In this work, the improvement of TiAlN coatings by alloying with carbon was investigated. A series of TiAlNC coatings with various C contents was synthesized by magnetron co-sputtering of Ti/Al und C targets in a mixed Ar-N2 atmosphere using deposition temperatures of 25 and 500 °C, respectively. The elemental composition of the coatings was analyzed by energy-dispersive X-ray spectroscopy, the microstructure by X-ray diffraction and the chemical bonding states by X-ray photoelectron spectroscopy and Raman spectroscopy. Furthermore, nanoindentation was used to characterize hardness and Young´s modulus of the coatings, while the electrical resistivity was measured by the four-point probe method. It was found that the C content and the deposition temperature have a significant effect on the microstructure and the mechanical and electrical properties of TiAlNC coatings. A microstructure evolution from crystalline TiAlN to amorphous TiAlNC was observed with increasing C content. Furthermore, the hardness of TiAlN coatings can be increased by the addition of C. Another observation was that higher C contents in the coatings lead to an increase of the electrical resistivity. These insights, found within this diploma thesis, may serve as a valuable basis for the further development of TiAlNC coatings.