ICMCTF2012 Session B5-1: Hard and Multifunctional Nano-Structured Coatings

Wednesday, April 25, 2012 8:00 AM in Room Royal Palm 1-3

Wednesday Morning

Time Period WeM Sessions | Abstract Timeline | Topic B Sessions | Time Periods | Topics | ICMCTF2012 Schedule

Start Invited? Item
8:00 AM B5-1-1 A study of microstructures and mechanical properties of cathodic arc deposited CrCN/ZrCN multilayer coatings
Cheng-Yi Tong, Jyh-Wei Lee (Ming Chi University of Technology, Taiwan); Sung-Hsiu Huang (National Chiao Tung University, Taiwan); Yi-Bin Lin, Chil-Chyuan Kuo (Ming Chi University of Technology, Taiwan); Tsung-Eong Hsieh (Gigastorage Corporation, Taiwan); Yu-Chen Chan, Hsien-Wei Chen, Jenq-Gong Duh (National Tsing Hua University, Taiwan)
The nanostructured CrCN/ZrCN multilayer coatings were deposited periodically by the cathodic arc deposition system. The bilayer period of CrCN/ZrCN multilayer coating was kept at 16 nm. The C2H2 gas flow rate was adjusted to fabricate the CrCN/ZrCN multilayer coatings with different carbon contents. The crystalline structure of multilayer coatings was determined by a glancing angle X-ray diffractometer. Microstructures of thin films were examined by a scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. A nanoindenter, scratch tester and pin-on-disk wear tests were used to evaluate the hardness, adhesion and tribological properties of thin films, respectively. It was found that the hardness and tribological properties were strongly influenced by the carbon contents of the CrCN/ZrCN multilayer coatings. Optimal carbon content was proposed in this work.
8:40 AM B5-1-3 Self-Organized nano-Labyrinth Structure in Magnetron Sputtered Zr0.6Al0.4N(001) Thin Films on MgO(001 )
Naureen Ghafoor, Lars Johnson (Linköping University, Sweden); Dmitri Klenov (FEI Company); Björn Alling (Linköping University, Sweden); Ivan Petrov, Joseph Greene (University of Illinois at Urbana-Champaign, US); Lars Hultman, Magnus Odén (Linköping University, Sweden)

Self-Organized nano-Labyrinth Structure in Magnetron Sputtered Zr0.6Al0.4N(001) Thin Films on MgO(001)

N. Ghafoor1, L. J. S. Johnson1, D. O. Klenov2, B. Alling1, I. Petrov1, 3, J. E. Greene1, 3,

L. Hultman1, M. Odén1

1Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden

2FEI Company, Building AAE, Achtseweg Noord 5, Eindhoven, The Netherlands

3 [http://www.mrl.uiuc.edu/], [http://www.uiuc.edu/],104 S. Goodwin Avenue, [http://www.city.urbana.il.us/Urbana/], IL 61801, USA

A unique self-organized nanostructure is reported for (Zr0.64Al0.36)N thin films that forms during reactive magnetron sputter deposition from elemental targets on MgO(001) substrates. HRTEM and EDX/STEM imaging shows that it consists of a nanolabyrinth of alternating ZrN-rich and AlN-rich lamellae along the MgO<110> in plane directions, with typical width of a 4 nm and that extends throughout the film thickness. According to ab-initio calculations, a significantly higher solid solution mixing enthalpy of c-Zr0.6Al0.4N (∆H=0.392 eV/f.u), compared to c-Ti0.6Al0.4N (∆H 0.178 eV/f.u) results in a comparatively higher driving force for isostructural decomposition in ZrAlN during secondary phase transformation on post annealing. Growth kinetics and pseudomorphic epitaxial forces also effects the segregation to occur during growth.

The phase segregation is studied in 1.5 µm thick (Zr0.64Al0.36)N films grown at different temperatures between 500-900 °C. It is shown that a maximum hardness of ~38 GPa is associated with a nano-labyrinthine nanostructure that forms at higher temperatures. The ZrN/AlN phase separation is complete at 900°C. The ZrN rich platelets retain the original B1 NaCl structure with cube on cube epitaxy with the MgO substrate, whereas the AlN-rich regions transform to wurtzite. The geometrical arrangement and the mutual relationships of the two phases on decomposition will be presented with respect to the growth temperatur
9:20 AM B5-1-5 Erosion Mechanisms of Hard Nanocomposite Coatings
Etienne Bousser, Ludvik Martinu, Jolanta Klemberg-Sapieha (École Polytechnique de Montréal, Canada)

Economic and technological progress as well as environmental concerns requires that modern equipment be designed with ever more stringent performance criteria, frequently pushing components to the very limits of their capabilities. Consequently, tribological deficiencies, such as lubrication breakdown, excessive wear and tribo-corrosion, are amplified leading to unnecessary operational costs, decreased efficiency and premature failure. Therefore, appropriate material’s selection for a given application must be guided by an accurate understanding of the intervening tribological processes.

Solid Particle Erosion (SPE) occurs in situations where hard solid particles present in the environment are entrained in a fluid stream, and impact component surfaces. It is well known that ductile materials erode predominantly by plastic cutting or ploughing of the surface, while brittle materials do so by dissipating the particle kinetic energy through crack nucleation and propagation. Although the most widely accepted brittle erosion models were developed more than 30 years ago, little has been published on how the material removal process differs for hard brittle coatings when compared to bulk materials. In this presentation, we outline the work performed at École Polytechnique on understanding the material loss mechanisms occurring during the SPE of hard coatings.

In the first part, we will discuss the validity of existing brittle SPE models when applied to the erosion of hard coatings. We examine the mechanisms by which surfaces dissipate the kinetic energy of impacting particles, and compare the erosive response of brittle bulk materials to that of hard coatings. Also, we investigate the means by which surface engineering can enhance erosion resistance, and correlate surface mechanical properties to the erosion behaviour of brittle bulk materials and coatings. We will show that the experimental results are also well supported by the finite element modelling of single particle impacts of coated surfaces.

The second part of the talk will focus more closely on TiN-based hard nanocomposite coatings and on the role microstructure has on the surface mechanical properties and on the enhanced erosion performance. Finally, erosion tests being notoriously inaccurate, we discuss the methodology of coating erosion testing, and present a novel in-situ erosion characterization technique used for time-resolved erosion testing.
10:00 AM B5-1-7 Effects of structure and phase transformation on fracture toughness and mechanical properties of CrN/AlN multilayers
Manfred Schlögl, Jörg Paulitsch, Jozef Keckes, Christoph Kirchlechner, Paul Mayrhofer (Montanuniversität Leoben, Austria)

Transition metal nitrides, such as CrN are highly attractive materials for a wide range of applications due to their outstanding properties like high hardness, excellent corrosion and oxidation resistance. Consequently, many research activities deal with their synthesis-structure-properties-relations. However, also because the fracture toughness of thin films is a difficult-to-obtain material property, only limited information is available on this topic. Therefore, this work is devoted to the study of the fracture mechanisms of CrN based thin films with the aid of in-situ scanning electron microscopy microbending, microcompression and microtension tests. The small test-specimens are prepared by focused ion beam milling of individual free-standing thin films. As generally monolithic coatings with their columnar structure provide low resistance against crack formation and propagation we perform our studies for CrN thin films and CrN/AlN multilayers. The latter offer additional interfaces perpendicular to the major crack-propagation-direction having different elastic constants and shear modulus and binding characteristics. Adjusting the AlN layer-thicknesses to ~3 and ~10 nm allows studying the impact of a cubic stabilized AlN layer and an AlN layer composed of cubic, amorphous and hexagonal fractions being extremely sensitive to stress fields.

The microtests clearly demonstrate that the monolithic CrN as well as the CrN/AlN multilayer coating with the ~10 nm thin AlN layers (and hence a mixture of cubic, amorphous and hexagonal AlN phases) fail as soon as small cracks are initiated. Contrary, the CrN/AlN multilayer coatings composed of ~3 nm thin c-AlN layers are able to provide resistance against crack propagation. Hence, they allow for significantly higher loads during the tests. Detailed structural investigations, in-situ and after the tests, suggest that the cubic AlN layers, which are stabilized by coherency strains in the CrN/AlN multilayer coatings, phase transform when experiencing additional strain fields and thereby hinder crack propagation.
10:40 AM B5-1-9 Hardness of CrAlSiN nanocomposite coatings at elevated temperatures
Shiyu Liu, Sandra Korte (Gordon Laboratory, Department of Materials Science and Metallurgy, University of Cambridge, UK); XingZhao Ding, Xianting Zeng (Singapore Institute of Manufacturing Technology, Singapore); William Clegg (Gordon Laboratory, Department of Materials Science and Metallurgy, University of Cambridge, UK)

Cr-based nanocomposite coatings are attracting increasing attention for use as protective coatings in dry machining and aerospace applications where the components are consistently exposed to high temperatures. In this report, CrAlSiN nanocomposite coatings have been deposited with different silicon contents and at different substrate bias voltages using a lateral rotating cathode arc technique. Their composition, microstructure and mechanical properties were characterized using EDS, XRD and nanoindentation respectively and compared with CrN and CrAlN coatings deposited under the same conditions. The flow behaviour around the indent has been studied using AFM and TEM. The mechanical behaviour of the coatings has been determined both from room temperature tests after annealing at elevated temperatures and hot stage nanoindentation, allowing the hardness to be measured at temperatures up to 600 °C. The evolution of the structure and internal stress has been measured in both cases allowing the two approaches to be compared.

11:00 AM B5-1-10 Hard nanocrystalline Zr-B-C-(N) films prepared by pulsed magnetron sputtering
Jiri Kohout, Petr Steidl, Jaroslav Vlcek, Radomir Cerstvy (University of West Bohemia, Czech Republic)

Hard Zr-B-C-(N) films were deposited on Si(100) substrates by pulsed magnetron co-sputtering of a single B4C-Zr target (127 x 254 mm2) in various nitrogen-argon gas mixtures. The target was formed by a B4C plate overlapped by Zr stripes which covered 15 or 45 % of the target erosion area. The N2 fractions in the gas mixture were in the range from 0 to 50 % at the total pressure of the gas mixture of 0.5 Pa. The planar rectangular unbalanced magnetron was driven by a pulsed DC power supply (Rübig 120 MP) operating at the repetition frequency of 10 kHz and the average target power of 500 W in a period with a fixed 85% duty cycle. The substrates were at a floating potential and were heated to 450˚C. The target-to-substrate distance was 100 mm. The elemental composition of the films was determined by Rutherford backscattering spectrometry. X-ray diffraction measurements of as-deposited samples were carried out using a PANalytical X’Pert PRO diffractometer. Hardness, reduced Young’s modulus and elastic recovery were determined by a Fischerscope H-100B ultramicroindenter. Electrical resistivity was measured by four-point method. Hard (37 GPa) nanocrystalline Zr-B-C films with very low compressive stress (0.4 GPa) and high electrical conductivity (resistivity of 2.3×10-6 Ωm) were deposited in argon discharge at the 15 % Zr fraction in the target erosion area. Hard (37 GPa) nanocomposite Zr-B-C-N films with low compressive stress (0.6 GPa) and even higher electrical conductivity (resistivity of 1.7×10-6 Ωm) were deposited at the 45 % Zr fraction in the target erosion area and 5 % N2 fraction in the gas mixture.

11:20 AM B5-1-11 Magnetron co-sputtered hard and ductile TiB2/Ni coatings
Huaiyong Wang (Anhui University of Technology, China); Fangfang Ge (Ningbo Institute of Materials Technology and Engineering, China); Ping Zhu, Shengzhi Li (Anhui University of Technology, China); Feng Huang (Ningbo Institute of Materials Technology and Engineering, China)
Titanium diboride (TiB2) coatings were alloyed with nickel (Ni) in order to improve their ductility. The coatings were co-sputtered from two magnetron sources, with a constant mid-frequency dc and a variable dc powers applied to the TiB2 and Ni targets, respectively. The microstructure, mechanical properties, as well as tribological tests were obtained. While the effect of Ni addition on the grain size is mixed, more Ni alloying clearly improves the ductility. When the amount of Ni addition is more than 20%, the coating shows clearly ductile behavior in tribological tests, and a high hardness >30 GPa.
11:40 AM B5-1-12 Comparative investigation of boride and boronitride hard coatings produced by magnetron sputtering of MeBx (Me: Mo, Cr, Ti) SHS-targets
Philipp Kiryukhantsev-Korneev, Alexander Sheveyko (National University of Science and Technology “MISIS”, Russian Federation); Boris Mavrin (Institute of Spectroscopy of RAS, Russian Federation); Evgeny Levashov, Dmitry Shtansky (National University of Science and Technology “MISIS”, Russian Federation)

Many engineering materials require a combination of properties: wear-, corrosion-, and oxidation-resistance, thermal stability, high fatigue strength, and low friction coefficient. These properties can be achieved in hard coatings based on borides or boronitrides of transition metals. In the present work, Mo-B-(N), Cr-B-(N), and Ti-B-(N) coatings were deposited by magnetron sputtering of MoB, CrB2, and TiBx (x=1 and 2) targets in an Ar atmosphere or reactively in a gaseous mixture of Ar+15%N2. To evaluate oxidation resistance, the coatings were annealed in the range of 800-12000C in air. The structure of coatings was studied by means of X-ray diffraction, transmission and scanning electron microscopy, Raman and X-ray photoelectron spectroscopy, and glow discharge optical emission spectroscopy. The mechanical properties of the coatings were measured using nanoindentation and scratch-testing. The tribological properties were evaluated in air using both conventional and high-temperature ball-on-disc tribometer. The electrochemical tests were performed in 5N H2SO4 medium. The milling, drilling, and turning tests of the coated WC-Co and HSS tools were also performed.

The results obtained show that the coatings with optimal structure and elemental composition had hardness up to 55 GPa, elastic recovery up to 70%, friction coefficient against WC-Co ball below 0.5 and wear rate <10-5 mm3N-1m-1. The tribological properties of coatings were shown to be stable in the temperature range of 20-5000C. The reactively deposited coatings showed the better corrosion and oxidation resistance than that of the nitrogen-free coatings. The lifetime of cutting tools coated with Ti-B-(N) and Cr-B-(N) coatings was increased by 1.5-2.5 times compared with the TiN coating.

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