ICMCTF2014 Session B1-1: PVD Coatings and Technologies

Monday, April 28, 2014 10:00 AM in Room Royal Palm 1-3

Monday Morning

Time Period MoM Sessions | Abstract Timeline | Topic B Sessions | Time Periods | Topics | ICMCTF2014 Schedule

Start Invited? Item
10:00 AM B1-1-1 Composition Control in Zr-Cu-Ni-Al Thin Film Metallic Glass for Improvement of Mechanical and Anti-microbial Properties
Joseph Lee, KaiChieh Hsu, JenqGong Duh (National Tsing Hua University, Taiwan)
This study focuses on the correlations among the compositions of Zr-Cu-Ni-Al thin film metallic glass (TFMG) and corresponding mechanical as well as anti-microbial properties. The TFMG was prepared by DC magnetron co-sputtering technique with Zr-Cu and Ni-Al targets. By adjusting working power and pressure, thin films with various constituents were fabricated. The chemical compositions of the Zr-Cu-Ni-Al thin films were analyzed by field emission electron probe micro-analyzer (FE-EPMA). The amorphous structures were verified by X-ray diffractometer (XRD). The hardness and elastic modulus were measured by nano-indention tester. The cross-sectional morphologies of the thin films were observed by field emission scanning electron microscope (FE-SEM). With the increasing Ni and Al content in (Zr5Cu5)100-2xNixAlx system, the hardness was improved up to 50% as compared to Zr-Cu TFMG. The strengthening mainly results from the atomic radii difference, and the enthalpy of mixing among mutual atomic bonding. In pursuit of high hardness, whether the coating still belongs to a metallic glass is critical. Differential scanning calorimetry (DSC) analysis further identifies the metallic glass characteristics of films with the formation of super-cooling regions. In addition, the property difference between (Zr5Cu5)100-2xNixAlx and (Zr4Cu6)100-2xNixAlx system were investigated.

Liquid culture methods and plate counting methods are used to assess the antimicrobial performance of specimens. The antimicrobial rate against Escherichia coli (E. coli) under Japanese Industrial Standard JIS Z2801: 2000 is over 95%. The results show that the surface of SS 304 stainless steel substrate can be modified by deposited Zr-Cu-Ni-Al TFMG, and their improved anti-microbial efficiency against E. coli is attributed to their amorphous rough surface, and released copper ion.

Finally a Zr-Cu-Ni-Al TFMG with appropriate composition to exhibit improved hardness, thermal stability, and antimicrobial ability was revealed and discussed.

10:20 AM B1-1-2 Low-Temperature, High-Rate Growth of Dense, Hard and Stress-free Refractory Ceramic Alloy Coatings
Grzegorz Greczynski, Jun Lu, Jens Jensen (Linköping University, IFM, Thin Film Physics Division, Sweden); Ivan Petrov, Joseph Greene (University of Illinois at Urbana-Champaign, US); Werner Kölker, Stephan Bolz, Christoph Schiffers, Oliver Lemmer (CemeCon AG, Germany); Lars Hultman (Linköping University, IFM, Thin Film Physics Division, Sweden)

Growth of thin films by means of physical vapor deposition requires elevated substrate temperatures to ensure high adatom mobilities necessary for film densification. With no external heating applied during deposition resulting layers are underdense and exhibit poor mechanical properties. Bombardment of the growing film surface with gas ions accelerated in the intentionally applied electric field of the substrate helps to eliminate porosity through collisional increases in adatom mean free paths. [1] However, at higher incident ion energies, necessary to obtain densification, a steep price is extracted in the form of residual ion-induced compressive stress resulting from both recoil implantation of surface atoms and trapping of rare-gas ions in the lattice.

Here, we propose a new PVD method to grow dense, hard and stress-free thin films at low substrate temperature Ts, i.e., with no external heating applied. We use hybrid high-power pulsed and dc magnetron co-sputtering (HIPIMS and DCMS) [2,3] to grow Ti1‑xTaxN alloys. The Ta target driven by HIPIMS serves as the pulsed source of energetic Ta+/Ta2+ metal-ions, as determined by the in-situ ion mass spectrometry, while the Ti target operates in DCMS mode resulting in a continuous flux of metal atoms to sustain the high deposition rate. Substrate bias Vs is applied in pulses synchronized to the metal-ion phase of the HIPIMS discharge and the amplitude is varied from 20 to 280 V to investigate the effect of the bombarding Ta-ion energy on film properties. The densification of the magnetron sputtered film is achieved by pulsed bombardment with heavy Ta ions that are constituents of the alloy films and thus the excessive stresses are eliminated. The deposition rate is high (defined by the DCMS cathodes) and no external heating is used. We show that with as little as 8 mol% of TaN incorporated in the film, Ti0.92Ta0.08N alloys with high hardness can be obtained with Ts not exceeding 130 °C during the 1 h-long deposition; XTEM and STEM images reveal that upon Ta ion irradiation, the intracolumnar porosity observed in the reference TiN layer is greatly reduced. The films hardness and modulus of elasticity increase from 7.8 and 211 GPa for the reference TiN film deposited at Ts < 120 °C to 24.1 and 360 GPa for Ti0.92Ta0.08N layers prepared with Vs = 120 V.

[1] I. Petrov, P.B. Barna, L. Hultman, and J.E. Greene, J. Vac. Sci. Technol. 21, S117 (2003).

[2] G. Greczynski, J. Lu, M. Johansson, J. Jensen, I. Petrov, J.E. Greene, and L. Hultman, Surf. Coat. Technol. 206 (2012) 4202

[3] G. Greczynski, J. Lu, M. Johansson, J. Jensen, I. Petrov, J.E. Greene, and L. Hultman, Vacuum 86 (2012) 1036

10:40 AM B1-1-3 Estimating Metastable Phase Formation During Magnetron Sputtering
Keke Chang, Denis Music, Dennis Lange, Moritz to Baben, Hamid Bolvardi, Jochen Schneider (RWTH Aachen University, Germany)

Saunders and Miodownik [1] reported a model to predict metastable phase formation by estimating the migration distance of atoms. This model was critically appraised for the immiscible Cu–W system using both experimental and theoretical means. Cu–W thin films were synthesized by DC combinatorial magnetron sputtering. By applying X-ray diffraction, the phase formation was studied with respect to magnetron power density and substrate temperature. Then, a metastable Cu–W phase diagram was constructed. At 150 oC, it is observed that a two phase region containing bcc and fcc phases forms for Cu concentrations ranging from 73.6 and 82.4 at. %. This range broadens as the substrate temperature increases.

The random bcc and fcc Cu–W configurations were studied by ab initio calculations applying special quasirandom structures (SQS) and coherent potential approximation (CPA) approaches. The predicted lattice parameters and solubility limits are consistent with those determined by experiment.

[1] N. Saunders and A. Miodownik, J. Mater. Sci. 22 (1987) 629.

11:00 AM B1-1-4 Microstructure and Superhardness Effects of VC/TiC Nanoscale Multilayer Films
Jianling Yue, Jie Chen, XueChao Dong (Central South University, China); Geyang Li (Shanghai Jiaotong University, China)
The nanoscale multilayer films have proven great potential for the development of novel thin film materials with tailored properties due to superhardness effect. In this work, a series of VC/TiC multilayers with various bilayer modulation periods were synthesized with VC and TiC target by magnetron sputtering. The microstructure and mechanical properties of the films have been studied by x-ray diffraction, energy dispersive x-ray spectrometry, high-resolution transmission electron microscopy and nanoindentation. The results reveal that VC/TiC multilayer films grow into coherent structure when their bilayer modulation period is below a critical thickness (5 nm). Correspondingly, the hardness and elastic modulus of the multilayers increases significantly and reaches the maximum value of 41.9 GPa and 326 GPa, respectively. With further increase in the modulation period, coherent structure of multilayers are destroyed, resulting in a remarkable decrease of hardness and elastic modulus. The superhardness effect of VC/TiC naomultilayers is related to the three directional strains generated from the coherent structure.
11:20 AM B1-1-5 Recent Developments in Industrial Scale Pulsed Laser Deposition Technology for Thin Films
Jari Liimatainen, Ville Kekkonen (Picodeon, Ltd., Finland)

Despite its numerous advantages (flexibility, simple setup, coating quality), PLD is still very little utilized in real industrial coating and thin-film processes. The conventional PLD techniques, relying mainly on low repetition rate lasers and point sources, do not allow a large-scale or large-area coating with the high throughput, reliability, homogeneity, and reproducibility required in industrial processes.

Recently, thin-film coating technology has been developed which is based on ultra-short pulsed laser deposition (USPLD) enabled by the cutting edge, industrial laser technology utilized in machining. The industrial production capability and scalability of the technology is based on producing a line source of plasma instead of static point source of conventional PLD techniques. The technology is made possible by the high repetition rate and high average power of the new lasers combined with state-of-the-art, high-speed laser scanning technology. Together with the industrial approach which includes roll-to-roll production, the advantages of cold ablation (high-quality plasma, controlled ablation, reduced amount of particles) form a strong basis for scalable, high production rate ultra short pulsed laser deposition coating for variety of materials. Now, this technology has been made available with equipment. Here, we demonstrate the results produced using the equipment and the development of special coatings, especially B-C-N materials and composites based on, DLC, oxides, and metals, with the main focus in applications requiring wear resistance, tribological properties, optical quality, and/or biocompatibility.

Time Period MoM Sessions | Abstract Timeline | Topic B Sessions | Time Periods | Topics | ICMCTF2014 Schedule