AVS 53rd International Symposium
    Advanced Surface Engineering Friday Sessions
       Session SE1-FrM

Paper SE1-FrM8
Reactive dc Magnetron Sputtering of Ti-A-CN (A=Si, and Ge) MAX-Phase Thin Films

Friday, November 17, 2006, 10:20 am, Room 2007

Session: Coatings with Enhanced Thermal Stability & MAX Phases
Presenter: H. Högberg, Linköping University, Sweden
Authors: H. Högberg, Linköping University, Sweden
P. Eklund, Linköping University, Sweden
J. Emmerlich, Linköping University, Sweden
J. Frodelius, Linköping University, Sweden
O. Wilhelmsson, Uppsala University, Sweden
U. Jansson, Uppsala University, Sweden
L. Hultman, Linköping University, Sweden
Correspondent: Click to Email
The M@subn+1@AX@subn@(n=1 to 3) phases exhibit a unique set of properties, described as being a combination of metallic and ceramic, reflected by the values reported for Ti@sub3@SiC@sub2@ on good oxidation and thermal shock resistance as well as high electrical conductivity. These attributes that stem from an anisotropic hexagonal crystal structure formed by early transition metals (M), group 14-16 elements (A) and carbon or nitrogen (X) are shared by the ~60 MAX phases. However, the extent is dependent on choice of material system and stoichiometry. The structure allows for freedom in substitution of elements of all the three constituents, opening possibilities to further tailor the properties of these materials by synthesis of quaternary and higher-order phases. In this study, we present results from thin film growth of the quaternary Ti-Si-C-N and Ti-Ge-C-N systems on Al@sub2@O@sub3@(0001) substrates at temperatures in the range 500 to 1000 @supero@C, using d.c. magnetron sputtering from elemental sources and growth in Ar/N@sub2@ plasmas. XRD shows a temperature-dependent growth behavior for epitaxial ternary Ti@sub3@SiC@sub2@ and Ti@sub2@GeC as seen by the possibility to synthesize single-phase films at 850 @supero@C, while lower temperatures result in growth of cubic phases. Higher temperatures promote surface segregation of the A-element as particularly pronounced in the Ti-Ge-C system resulting in growth of less Ge-rich stoichiometries. The addition of N@sub2@ to single-phase films in the Ti-Ge-C system results in growth of films of lower crystalline quality and thickness, and with nucleation of cubic phases as the flow of N@sub2@ is increased.