Aluminum-rich TiAlCN coatings by Low Pressure CVD

作者：Endler I^*; Hoehn M; Herrmann M; Holzschuh H; Pitonak R; Ruppi S; van den Berg H; Westphal H; Wilde L

来源：Surface and Coatings Technology, 2010, 205(5): 1307-1312.

DOI：10.1016/j.surfcoat.2010.09.002

• TiAlCN
• Hard coating
• CVD
• Wear

Ti(1-x)Al(x)N is a well established material for cutting tool applications exhibiting a high hardness and an excellent oxidation resistance. A main route for increasing the performance of Ti(1-x)Al(x)N is the incorporation of further elements. Therefore the main objective of this work is to improve the properties and wear resistance of aluminum-rich CVD-TiAIN coatings by incorporating carbon. A new Low Pressure CVD process was employed for the deposition of a very aluminum-rich TiAlCN layers. The process works with a gas mixture of TiCl(4), AlCl(3), NH(3), H(2), N(2), Ar and ethylene as carbon source. In this work microstructure, composition, properties and cutting performance of CVD-TiAlCN coatings were investigated.
Hard aluminum-rich TiAlCN coatings were obtained at 800 degrees C and 850 degrees C consisting of a composite of fcc-Ti(1-x)Al(x)N and minor phases of TiN, h-AlN and amorphous carbon. WDX analysis indicates only a low carbon content <2 at%. Lattice constant calculations suggest that carbon atoms should not be incorporated in the Ti(1-x)Al(x)N lattice. From TEM analysis and Raman spectroscopy it is evident that carbon is mainly located at the grain boundaries as a-C phase. Therefore these fcc-Ti(1-x)Al(x)N(C) coatings with low carbon content are rather a composite of fcc-Ti(1-x)Al(x)N and an amorphous carbon phase (a-C). At 900 degrees C the metastable fcc-Ti(1-x)Al(x)N nearly disappears and co-deposition of TiN and h-AlN occurs. The layers deposited at 800 degrees C and 850 degrees C possess a high hardness around 3000 HV and compressive stress. CVD-TiAlCN coatings prepared at 850 degrees C shows also an amazing thermal stability under high vacuum conditions up to 1200 degrees C. Aluminum-rich composites fcc-Ti(1-x)Al(x)N/a-C with x > 0.8 exhibit a superior cutting performance in different milling tests.

• 出版日期2010-11-25