Papers by Keyword: CrTiAlN Coatings

Abstract: CrTiAlN hard coatings have been deposited on H13 steel for improving the oxidation resistance by Closed Field Unbalanced Magnetron Sputter Ion Plating (CFUMSIP). The phase components, surface and section morphology of H13 steel before and after oxidation were analyzed by XRD and SEM. The results showed that the columnar crystal film possesses three major parts, i.e., the internal Cr bonding layer, the intermediate CrN transition layer, the external CrTiAlN gradient coating. The selective oxidation of Cr element was found on the surface of uncoated H13 steel while oxidation, but a continuous protective layer was not formed because of low Cr content, finally a lot of alpha Fe₂O₃ particles took place on the surface of H13 steel owing to the oxidation of the matrix element. O element can diffuse much more easily through the coating and oxide scales at 800 °C, and spallation and cracks were not found during the oxidation. These results indicated that the CrTiAlN coating have excellent high-temperature oxidation resistance at 800 °C.

Abstract: Quaternary CrTiAlN hard coatings were deposited by closed field unbalanced magnetron sputtering ion plating technique onto steel substrates, and their structural, mechanical, and tribological properties after heat treatment in air at different temperatures (500-900 oC) were studied and compared by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-indentation, and pin-on-disc (POD) tribometer, etc. The onset temperature of oxidation was determined by thermogravimetric analyser (TGA). The compositional depth profiles before and after the heat treatments were examined by X-ray photoelectron spectroscopy (XPS) in order to study the oxidation mechanism. The experimental results indicate that the CrTiAlN coatings have excellent oxidation resistance and thermal stability, and outperform the traditional hard coatings like TiN and TiAlN in terms of higher oxidation temperature, hardness, adhesion, and wear resistance. It is expected that the CrTiAlN coatings with superior properties should have better performance in dry high speed machining.