Papers

ICMCTF2008 Session B6-4: Hard and Multifunctional Nano-Structured Coatings

Tuesday, April 29, 2008 1:30 PM in Room Golden West

Tuesday Afternoon

Start	Invited?	Item
1:30 PM		B6-4-1 A Comparative Study of Nitride and Oxide Based Coatings for High Performance Machining F. Papa, R. Tietema, T. Krug (Hauzer Techno Coating BV, Netherlands) Cathodic arc deposited AlTiN and TiSiN coatings have been proven to improve abrasion and oxidation resistance of cutting tools in high performance machining applications, which are mostly done under dry/MQL circumstances. Such applications demand that the coating acts as a thermal barrier in order to prevent heat transfer to the tool. By combining these coatings with a sputtered γ-Al2O3 topcoat, the oxidation resistance of the coating can be further increased while also reducing the chemical reactivity. Alumina has proven itself in applications where thermal fatigue is playing an important role. It has been shown that thermal cracking and crater wear are highly reduced in these cutting applications. Machining tests in various alloys have been performed in order to compare the effects of coating material and layer thickness. The material properties of the coatings have also been analyzed and will be shown. All coatings were deposited with hybrid arc/sputter technology in an industrial Hauzer Flexicoat tool coating system.
2:10 PM		B6-4-3 Addition of Oxygen in Structural and Mechanical Properties of Nitride Based Nanocomposite Coatings A. Karimi (Swiss Federal Institute of Technology Lausanne (EPFL), Switzerland); M. Morstein, P. Karvankova, A. Lümkemann, T. Cselle (Platit AG, Switzerland) A new generation of multifunctional coatings has been developed combining nanocomposite and non-nanocomposite materials in a single, triple-zone layer structures. These structures offer a much wider variety of property combinations and provide a new degree of control of nanomechanical and thermo-physical coating properties. One new building block within this concept is the addition of oxygen into nitride-based nanocomposite coatings, which opens new options in microstructural design, but also challenges processing and characterisation. In this paper, we present recent results on the formation, microstructure, and mechanical properties of AlTiCrNO and AlSiCrNO coatings deposited using cylindrical rotating arc cathodes. The role of the N:O ratio and deposition temperature will be emphasised. Addition of oxygen also strongly affects morphology and crystallographic orientation of coatings, due to structural transitions and activation of new growth mechanisms. Using XRD techniques including Bragg Brentano and pole figure measurements we have observed a particular growth phenomenon which appears by the crystallographic tilting and inclination of preferred orientations. These results will be discussed with respect to the performance of oxygen-modified triple coatings in high-performance dry cutting, and compared to nitride representatives such as nACRo3.
2:30 PM		B6-4-4 Chromium Oxide and Oxynitride Coatings Deposited by Reactive Pulsed dc Magnetron Sputtering P. Eklund (University of Aarhus, Denmark); N.-J. Mikkelsen (CemeCon Scandinavia A/S, Denmark); M. Sridharan (University of Aarhus, Denmark); E. Bienk (CemeCon Scandinavia A/S, Denmark); J. Bøttiger (University of Aarhus, Denmark) Chromium oxide and oxynitride coatings are of interest in such diverse areas as hard coatings, anti-sticking films for plastic moulding and wear protection on digital recording devices. Here, we investigate CrO_x and CrO_xN_y coatings deposited at substrate temperatures below 300 °C using reactive pulsed dc magnetron sputtering in an industrial coating facility (CemeCon CC800/9MLT). X-ray diffraction and electron microscopy showed that the as-deposited CrO_x coatings crystallized in an α-Cr₂O₃ structure in an amorphous matrix for low substrate temperatures (180 °C), at which the as-deposited coatings exhibited a globular morphology. Nanoindentation yielded hardness and elastic-modulus values of 20 GPa and 200 GPa, respectively. Higher deposition temperature resulted in increased crystallinity. Furthermore, multilayer structures comprising Cr and nanocrystalline CrO_x were synthesized by deposition at reduced oxygen flow employing one-axis substrate rotation. A subsequent increase to nominal oxygen flow resulted in renucleation of α-Cr₂O₃.
2:50 PM		B6-4-5 Interfacial Fracture Toughness of Transition Metal Nitrides C.K.Y. Chen, M. Bielawski (National Research Council Canada) Interfacial fracture toughness is one of the key parameters in assessing and controlling the quality and performance of multiple-layer coatings. This paper reports on a systematic study of interfacial toughness of transition metal nitrides using ab initio density functional theory (DFT) calculations. The transition metal nitrides TiN, CrN and VN were selected for this study. The interfaces in these nitrides were constructed and the interfacial energy, work of adhesion, interface structures and electronic structures were calculated and discussed. On the basis of calculated debonding energy of the interface and elastic moduli of the contact materials, the interfacial fracture toughness was evaluated. In addition, the trends in interfacial fracture toughness were analyzed for two specific orientations, (001) and (111). The electronic density of states at interfaces was used to explain fracture toughness values obtained from the DFT calculations. It is proposed to use the interfacial fracture toughness as guidance for the development of multi-layer coatings for either wear or erosion protection.
3:10 PM		B6-4-6 Hard Amorphous Si-B-C-N Films with Ultra-High Thermal Stability J. Vlcek, J. Houska, S. Hreben, J. Capek, P. Zeman, R. Cerstvy (University of West Bohemia, Czech Republic) Novel quaternary Si-B-C-N materials attract great attention due to their possible high-temperature and harsh-environment applications (protective coatings, microelectronics and optoelectronics). The Si-B-C-N films were deposited on Si and SiC substrates by dc magnetron co-sputtering using a single C-Si-B or B₄C-Si target in nitrogen-argon gas mixtures. Elemental compositions of the films, their bonding structure, and mechanical and optical properties, together with their oxidation resistance in air, were controlled by compositions of the targets and the gas mixture, by an rf induced negative substrate bias voltage and by a substrate temperature. Extensive molecular-dynamics simulations of these materials were carried out to explain their structure and unique properties. The films (typically 1-7 µm thick) were found to be amorphous in nanostructure with a density of 2.4 - 3.3 gcm^-3, very smooth surface (R_a less then 1 nm) and good adhesion to various substrates (Si, SiC, glass and steel) at a low compressive stress (1.0 - 1.6 GPa). They exhibited high hardness (up to 45 GPa), elastic recovery (up to 88 %), optical transparency and wear resistance at extremely highoxidation resistance in air (even above 1500°C) and stability of the amorphous state (up to a 1700 °C limit imposed by thermogravimetric analysis). [1] J. Vlcek, S. Potocky, J. Cizek, J. Houska, M. Kormunda, P. Zeman, V. Perina, J. Zemek, Y. Setsuhara, S. Konuma, J. Vac. Sci. Technol. A 23, 1513 (2005). [2] J. Houska, J. Vlcek, S.Hreben, M.M.M. Bilek, D.R. McKenzie, Europhys. Lett. 76, 512 (2006). [3] J. Houska, J. Vlcek, S. Potocky, V. Perina, Diamond Relat. Mater. 16, 29 (2007).
3:30 PM		B6-4-7 Dense Nanostructured Coatings Deposited By The Solution Precursor Plasma Spray Process M. Gell, E.H. Jordan, M. Teicholz, D. Chen (University of Connecticut); X. Ma, J. Roth (Inframat Corporation) The Solution Precursor Plasma Spray Process (SPPS) can used to make nanostructured coatings that are thin and thick and that are porous and dense. The process can also be used to preforms for structural and functional applications. This presentation will focus on dense, nanostructured coatings with a thickness from 50 to 150 microns. The SPPS process has been used to make a variety of dense coatings, including partially stabilized zirconia (YSZ), alumina-YSZ and titania. The basic principles for making dense coatings will be described. These include precursor processing, atomization and injection methodology,and substrate surface and temperature control. The microstructure and properties of these coatings will be described.
3:50 PM		B6-4-8 Biomimetic Polymer-Ceramic Multi-Functional Nanocomposites A.R. Waite (Air Force Research Laboratory (AFRL/RXBT)/University of Dayton/UTC, Inc.); J.G. Jones (Air Force Research Laboratory (AFRL/RXBT)); C. Muratore (Air Force Research Laboratory (AFRL/RXBT)/UTC, Inc.); H. Jiang (Air Force Research Laboratory (AFRL/RXPJE)/Materials Sci. & Tech. Applications, LLC); J. Enlow (Air Force Research Laboratory (AFRL/RXPJE)/UES, Inc.); T.J. Bunning (Air Force Research Laboratory (AFRL/RXPJE)); A.A. Voevodin (Air Force Research Laboratory (AFRL/RXBT)) A novel polymer-ceramic nanocomposite was synthesized following an inspiration found in nature with a sea urchin tooth, where a combination of bio-process produced polymers and ceramics in one material was responsible for a high toughness and stability. Room temperature Plasma Enhanced Chemical Vapor Deposition (PECVD) was used to synthesize a highly cross-linked fluoropolymer film while low temperature Reactive Magnetron Sputtering (RMS) was utilized to deposit layers of TiO₂. Layers within 100-130 nm thickness were produced with multiple polymer/TiO₂ stacks. Adhesion between the fluoropolymer and TiO₂ layers as well as the adhesion between the polymer and substrates was studied. The substrates included both rigid (Si wafers and quartz disks) and flexible (low density polyethylene) materials. Additionally, tribological testing of the nanocomposite was performed with a pin-on-disk tribometer. In addition to the mechanical and tribological characterization, the combination of polymers and high dielectric constant oxides were studied for opto-electronic properties. The low refractive index PECVD fluoropolymer was optimized to a refractive index of 1.40 while the high refractive index RMS amorphous TiO₂ was optimized to a refractive index of 2.35.
4:10 PM		B2-11 Studies on Al-Cr-Si-W-N Hard Coatings M. Lechthaler, S. Eggenberger (OC Oerlikon Balzers AG, Liechtenstein) Within last years, AlCrN coatings figured out to be promising modern coatings with a continuously growing application field due to their beneficial chemical, mechanical and tribological properties. This study aims to present the structure and the properties of arc evaporated AlCrSiWN-coatings prepared from targets which contain beside Al and Cr also Si and W. The combined addition of the Si and W was investigated at Si contents of 5 %at and 10 %at and W contents of 2 %at and 5 %at. In further tests, the Si and W concentration was kept constant at 10 %at and %at respectively, and the Al/Cr ratio was varied towards higher and lower Al-contents. To ensure an equal substrate adhesion, all coatings were prepared with a TiAlN interlayer. The microstructure and layer constitution was analyzed by Scanning Electron Microscopy (SEM). The incorporation of Si and W into the AlCrN coating and the crystalline structure was investigated in detail by High Resolution Transmission Electron Microscopy (HR-TEM). X-Ray Diffraction (XRD) and Selected Area Electron Diffraction (SAED) served to determine the influence of the composition on the crystal structure and the coating texture. Hardness and Young’s modulus were investigated by nanointendations. Finally, the correlation between analytical findings and the cutting performance was evaluated by milling tests in hardened tool steel.