ICMCTF2003 Session B8-1: Hard and Multifunctional Nano-structured Coatings

Monday, April 28, 2003 10:30 AM in Room Golden West

Monday Morning

Start	Invited?	Item
10:30 AM	Invited	B8-1-1 Constitution- and Nanostructure Modelling in Thin Films H. Holleck (Forschungszentrum and University Karlsruhe, Germany); H. Leiste, M. Stueber, S. Ulrich (Forschungszentrum Karlsruhe, IMF I, Germany) Nanoscale thin films for tribological applications can be subdivided into nanostructured multilayer films, nanocomposite films, nanocrystalline metastable films, nanostabilized single and multilayer films and nanograded films. Aside from the leading role of materials selection and deposition characteristics, nanostructure, interface areas, grain size and distribution, layer thickness, surface and interface energy, texture as well as stress and strain conditions are principal factors determining constitution, properties and performance of these coatings. The functional and structural design of the films together with new tools of modelling constitution and nanostructure can result in tailored multifunctional films to be applied as protective coatings under severe and complex loadings for tools and components. In particular new metastable nanocrystalline films can be deposited by vapor quenching. A thermodynamic and kinetic modelling results in new film materials, tailored with respect to constitution, properties and performance. Various new concepts for tailoring thin films as protective coatings, elaborated in the last years, are described, compared and critically discussed.
11:10 AM		B8-1-3 Growth, Structure, and Mechanical Properties of Single-crystal MAX Phase Ti₂AlN Thin Films Prepared by Reactive Magnetron Sputtering T. Joelsson, A. Hörling (Linköping University, Sweden); J. Sjölen, L. Karlsson (SECO Tools AB, Sweden); P.O. Persson, J. Birch, L. Hultman (Linköping University, Sweden) Single crystal Ti₂AlN thin films has been prepared using UHV reactive magnetron sputtering from a Ti-Al target in a discharge of Ar/N₂ gas on MgO(111) substrates. This ternary nitride is a member of the so-called MAX-phases, which is a large family of nano-laminar carbides and nitrides. The general formula for these compounds is M_n+1AX_n (n= 1,2,3), where M is an early transition metal, A is an A-group (mostly IIIA and IVA) element, and X is C and/or N. The properties attributed to this class of materials is a combination of typical ceramic properties, such as high melting point, thermal shock resistance and high temperature oxidation resistance with typical metallic properties such as good electrical and thermal conductivity. We present the first report of MAX phase nitrides synthesized with thin film techniques. The films were grown in an ultra high vacuum (UHV) deposition chamber equipped with a DC current regulated 3" magnetron. All depositions were carried out at 830°C.The films were grown to a thickness of 800 nm. The films have been analyzed using XRD and TEM. The c- and the a-lattice parameters of the as-deposited Ti₂AlN(0002) films structure were found to be 13.7 and 3.07 Å respectively, in agreement with reports from bulk measurements. Initial results from nanoindentation experiments for the Ti₂AlN film shows hardness, 14 GPa and Youngs modulus E, 260 GPa.
11:30 AM		B8-1-4 The Deposition and Properties of Nanoscale Mutilayer MoCrTiAlN Hard Coatings using Unbalanced Magnetron Sputtering Technique S. Yang, H. Sun, D.G. Teer (Teer Coatings Ltd, United Kingdom) Nanoscale MoCrTiAlN multilayer hard coatings have been produced using magnetron sputter ion plating with Ti, Al, Cr and Mo metal targets. M42 tool steel and stainless steel substrates were used for this study. Grazing angle and conventional XRD were used to analyse structures of the coating. Initially a CrMo metal alloy adhesion layer was deposited, followed by a CrMoN layer and finally a constant nano-scale CrMOTiAlN multilayer. A series of coatings was deposited while varying the rotation speed of substrate turntable to produce multilayers with different period value, λ. Nitrogen was controlled using an optical emission monitor with feed back control to produce stoichiometric coatings. The hardness of the coatings as a function of λ was studied. The composition and microstructure were studied using GDOES, XRD and TEM. The coated samples were heated in air for three hours at temperature up to 900°C and the wear properties of the coatings were investigated using a pin-on-disc tester. It has been shown that this MoCrTiAl nanoscale multilayer coating has high hardness, high toughness, exceptional wear resistance, and these properties were retained after heat-treatment. The practical performance of the coating was accessed by testing coated carbide drills under accelerated dry conditions.