Symposium CI
Ceramic Thin Films and Coatings for Protective, Tribological and Multifunctional Applications

Session CI-1 - Advances in Deposition, Surface Modification and Characterisation Techniques

CI-1:IL01  Use of Raman Spectroscopy and Synchrotron Micro-Diffraction to Investigate Stress In Thermal Oxide Films: A Multiscale Approach
J.L. GROSSEAU-POUSSARD¹, M. GUERAIN¹, P. GOUDEAU², G. GEANDIER³, B. PANICAUD⁴, N. TAMURA⁵, M. KUNZ⁵, C. DEJOIE⁵, J.S. MICHA⁶, ¹LEMMA, Université de La Rochelle, France; ²PPRIME CNRS-ENSMA Université de Poitiers, France; ³IJL CNRS-Université de Loraine, France; ⁴LASMIS CNRS Université Technologique de Troyes, France; ⁵ALS Lawrence Berkeley National Laboratory, USA; ⁶DSM, INAC/SP2M/NRS-ESRF, France

Ability of Chromia-former alloy to form a thermal oxide scale allows reducing oxidation kinetics of the materials. Durability of the metal/ceramic system depends on the mechanical integrity of this scale, and also of the scale damage which could appear during oxidation or cooling. These scale damages are closely correlated to the residual stress magnitude in the oxide and to the microstructure. In this work, an accurate determination of residual stress magnitude in both Ni-30Cr and Fe-47Cr alloys at macroscopic scale in the adherent oxide and at local scale through damaged area allows a comparison with models describing thin film delamination. A multi-scale approach is proposed:
At macroscopic scale, residual stress magnitudes are determined thanks to conventional XRD and Raman spectroscopy. The influence of metallurgical parameters on scale microstructural states and damage is studied. At microscopic scale, residual stress map through different types of delamination are performed thanks to Raman micro spectroscopy and Synchrotron micro diffraction. Stress release modes by diffusional creep or delamination are studied and quantified. Morphological information and associated residual stresses allows confrontation to buckling mechanic and calculation of the interface toughness.


CI-1:IL02  Low Temperature Growth and Patterning of Metal Oxide Thin Film by photo-induced Chemical Solution Deposition for Printable Electronics
T. TSUCHIYA, T. NAKAJIMA T. SHINODA, T. NAKAMURA, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, Tsukuba, Ibaraki, Japan

Printed electronics is creating many new products given the benefits of the technology compared to conventional electronics, such as thickness, flexibility, cost, ease of manufacture, fast production turn around, "green" technology, power efficiency and more. Therefore, the development of a low temperature processing for oxide thin film would be necessary. For this purpose, we have developed the photo-induced chemical solution process such as excimer laser-assisted metal organic deposition (ELAMOD) and photo reaction of nano-particle method (PRNP) for the preparation of patterned metal oxide thin film on organic, glass and single crystalline substrates.
In the case of using PRNP, the ITO film was prepared on glass substrate at room temperature. The resistivity of the film was 5.94×10-4 Ωcm. The sheet resistance of the ITO film on glass and PET by using the PRNP method was 50 and 100Ω/sq.
To prepare the epitaxial oxide films at room temperature, it was found that the direct excimer laser irradiation was effective for the improvement of the crystallinity and electrical properties at low temperature. Detailed results of the thin film processing using PRNP and ELAMOD will be presented.


CI-1:L03  Influence of Application Technology in the Structural Characteristics of Ceramic Coating with Advanced Anticorrosive and Tribological Properties
D. VELEZ, J.M. MUÑOZ, J.A. DÍEZ, Fundación Cidetec, San Sebastián, Spain

Electrophoretic deposition (EPD) of ceramic frits is shown to be a useful coating method for different metal surfaces and geometries since it allows obtaining very smooth surface finishes with precise control of their thickness. By the other hand, these kind of coatings show differences with the coatings obtained by conventional wet application methods as dipping, flow-coating, slushing and spraying.
At this point, CIDETEC has used an own advanced ceramic coating based on no commercial enamels to determine the best application method to obtain an excellent anticorrosive coating on carbon steel.
In view of possible scaling up to particular industrial applications, a detailed characterization of the microstructure, morphology, physical, chemical and mechanical properties of the coatings was performed. The preliminary studies show that EPD system improves the characteristics of this coating.


CI-1:L04  X-ray Nanodiffraction Characterization of Residual Stresses and Microstructure in Thin Films
M. STEFENELLI¹, R. DANIEL², A. RIEDL¹, M. BURGHAMMER³, C. MITTERER², J. TODT⁴, J. KECKES⁴, ¹Materials Center Leoben Forschung GmbH, Leoben, Austria; ²Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Leoben, Austria; ³European Synchrotron Radiation Facility, Grenoble, France; ⁴Erich Schmid Institute of Materials Science, Austrian Academy of Sciences and Department of Materials Physics, Montanuniversität Leoben, Leoben, Austria

Nanocrystalline thin films usually exhibit pronounced microstructure and residual stress depth gradients which decisively influence their physical and functional properties. Recently, we developed a synchrotron X ray nanodiffraction approach which allows characterizing those gradients with a resolution of 100 nm in transmission geometry. The new approach allows mapping the structural properties at sub-micron scale and in combination with finite-element evaluation of residual stress gradients for the individual sub-layers of the films. In this contribution, results from CrN, TiAlN and CrN/Cr thin films characterized at the nano-focus extension of the ID13 beamline of ESRF in Grenoble will be presented. The measurements were used to evaluate depth profiles of crystallographic texture, strain, composition and grain morphology in the films. The results are correlated with the actual deposition conditions, thermal history and mechanical properties of the film. The data document that the microstructure and residual stresses can be tuned at the nano-scale by using dedicated deposition recipes. Additionally, mechanical tests performed using nanoindentation and bending tests on micro-cantilevers demonstrate the correlation between thin film mechanical properties and their microstructure.


CI-1:IL05  High Power Pulsed Plasma Enhanced Chemical Vapor Deposition
H. PEDERSEN¹, D. LUNDIN^{2, 3}, ¹Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden; ²Laboratoire de Physique des Gaz et Plasmas, UMR 8578 CNRS, Université Paris Sud-XI, Orsay Cedex, France; ³Division of Space and Plasma Physics, School of Electrical Engineering, Royal Institute of Technology, Stockholm, Sweden

A novel plasma enhanced chemical vapor deposition (PECVD) technique called High Power Pulsed PECVD (HiPP-PECVD) has been developed. [1,2] The main feature of HiPP-PECVD is the use of a high power pulsed power scheme characterized by short (few tens of µs) pulses with a high (several kW) peak-power and a duty cycle of a few percent to generate a process plasma with a significantly higher plasma density compared to traditional PECVD. This power scheme is similar to what is used in high power impulse magnetron sputtering (HiPIMS), which is known to generate plasma densities on the order of 1018-1919 m-3 resulting in at least 50 % ionization of the material flux.
In this contribution we will show that the higher plasma density in HiPP-PECVD leads to a more reactive plasma chemistry, which results in a higher rate of dissociation of the precursor molecules, leading to a more efficient use of the precursors. The high plasma density also leads to a higher degree of ionization of the growth species, enabling the possibility to guide the growth species to the substrate or applying an energetic bombardment of the growing film by applying a substrate bias.
References
[1] H. Pedersen et al., Surf. Coat. Technol., 206, 4562 (2012).
[2] D. Lundin and H. Pedersen, Phys. Proc., 46, 3 (2013).


CI-1:L06  Impedance and Dielectric Spectroscopy of Thin Films
R. GERHARDT, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, USA

Impedance and Dielectric Spectroscopy is an electrical characterization method that uses alternating current to probe the electrical response of materials and devices at all length scales(i.e. from macroscopic dimensions down to the nanoscale). It can be used to measure the electrical behavior of insulating, dielectric, semiconducting as well as conducting materials and their mixtures. As a result, it is an excellent technique for determining the properties of all types of thin film materials regardless of their end application. However, in the materials community, characterization of the electrical properties is generally an afterthought, which is often compounded by the wide availability of turn key measurement systems that give a false sense of accuracy. The challenge is that there are some measurement limitations related to the equipment used, the contacting method as well as the film thickness, degree of homogeneity and electrical characteristics of the films themselves. In this talk, examples will be provided that will illustrate under what conditions one can safely measure the properties of the materials in question and the importance of using the proper length scale for detecting all of the elecrical phenomena present in the samples.


CI-1:L07  Amorphous Alumina Coatings on Glass Bottles using Direct Liquid Injection MOCVD: A Barrier Layer for Packaging Applications
P.-L. ETCHEPARE¹, H. VERGNES², D. SAMÉLOR¹, C. BRASME³, B. CAUSSAT², C. VAHLAS¹, 1Centre Interuniversitaire de Recherche et d'Ingénierie des Matériaux, ENSIACET/INPT, Université de Toulouse, France; ²Laboratoire de Génie Chimique, ENSIACET/INPT, Université de Toulouse, France; ³SGD, Mers-les-Bains, France

In the field of packaging, barrier coatings are commonly applied in order to avoid interactions between the container and its content. For glass bottles, application of a barrier film on the internal surface prevents the alkaline ions release into the liquid phase and consequently the alteration of its properties, e.g. organoleptic or pharmaceutical.
In this presentation, we propose an innovative way to apply amorphous alumina coatings on glass bottles by direct liquid injection metalorganic chemical vapour deposition, using tri-isopropoxide aluminium (ATI) as precursor. A numerical model is developed using the Computational Fluid Dynamics (CFD) code Fluent to integrate thermal profile, fluid flow and kinetic reactions of this process. Sub-micrometric alumina films are deposited on the internal surface of the glass container at reduced pressure in a temperature range between 415°C and 600°C.
Thickness profiles of alumina are determined on cross sections over the length of the bottle by scanning electron microscopy (SEM) and are compared with simulated ones.
Finally, the hydrolytic resistance is determined for uncoated and for coated glass containers to quantify the barrier property of the films.


CI-1:IL07b  Temperature Dependent 4-, 5- and 6-fold Coordination of Aluminum in MOCVD-grown Amorphous Alumina Films: From Local Coordination to Material Properties
A.N. GLEIZES, CIRIMAT, CNRS-Université de Toulouse, Toulouse, France

Alumina is not a glass-forming oxide. The structure of amorphous alumina can be studied either from the melt or from thin films grown at relatively low temperature. In both approaches, the samples are difficult to isolate for a clean submission to structural study techniques. Another approach consists in modeling the structure through theoretical calculations. Do these different approaches give comparable results? How do the technique of preparation and the experimental conditions influence the structure of amorphous films? The results presented here partly answer these questions.
A series of MOCVD-prepared thin films were submitted to very high-field (20 T) solid state 27Al 1D MAS and 2D MQMAS NMR spectroscopy (CEMHTI-CNRS, Orléans). The films were deposited on silicon substrates at deposition temperatures (Td) ranging from 360 to 720 °C. Depending on Td, film composition is either AlO1+x(OH)1-2x (x≤0.5) or Al2O3. From the NMR study, the films grown between 360 and 600 °C contain between 38 and 43 at.% of 5-fold coordinated aluminum sites ([5]Al). The at.% of [6]Al and [4]Al sites vary spectacularly, being respectively minimal (5 at.%) and maximal (54 at.%) around 515 °C. These results will be discussed and compared with those of studies on the melt and of calculated structures.


CI-1:IL08  Development and Durability of Thermal Barrier Systems with Pt-rich Gamma-Gamma prime Bond coatings
D. MONCEAU, M. BOIDOT, S. SELEZNEFF, P. AUDIGIÉ, D. OQUAB, C. ESTOURNES, A. ROUAIX-VANDE PUT, CIRIMAT, CNRS, Université de Toulouse, France; S. HAMADI, A. MALIÉ, SNECMA-SAFRAN, France

The design of innovative coating solutions requires testing a large number of alloy compositions as they need to be adapted to the aggressive environment but also to the substrate with which they interdiffuse. In this paper, we report a method to develop new coating compositions for the protection of structural alloys against high temperature oxidation. The use of spark plasma sintering (SPS) for the fabrication of a large range of coating compositions was associated with the use of thermal cycling for a quantitative evaluation of oxidation kinetics. This method was applied to the specific case of Pt-modified gamma-gamma prime bond coatings for thermal barrier systems on Ni-base superalloys. SPS allowed combining powders and pure metal foils deposited on a superalloy substrate in order to obtain multilayered coatings in a single short process step. Fabrication of Pt-rich gamma/gamma prime phases and their alpha-AlNiPt or beta-(Ni,Pt)Al precursors, alloyed with reactive elements or minor metallic additions was performed. Thermal cycling was used to select coating compositions and similar coatings were fabricated using classic methods, i.e. Pt electro-deposition followed by vapor phase aluminization. Cyclic oxidation with a quantitative evaluation of aluminum consumption kinetics was then applied to optimize the compositions. This paper will focus on the method with its advantages and will discuss the difficulties which appeared during this work and the solutions found.


CI-1:IL09  Molecular Thin Film Technology Based on Oxide Nanosheets
M. OSADA, T. SASAKI, International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan

In designing functional thin films, we focus on 2D oxide nanosheets (such as Ti1-δO2, MnO2, perovskites), which are obtained by delaminating a layered compound into its single layers. 2D nanosheets, which possess atomic or molecular thickness and infinite planar lengths, have increasingly attracted fundamental research interest because of their potential to be used as conductors, semiconductors, insulators, and even ferromagnets, depending on their chemical composition and how their atoms are arranged. Another attractive aspect of nanosheets is that nanosheets can be organized into various film architectures by applying solution-based synthetic techniques involving electrostatic layer-by-layer assembly and Langmuir-Blodgett deposition. It is even possible to tailor superlattice assemblies, incorporating into the nanosheet galleries with a wide range of materials such as organic molecules, polymers, and inorganic/metal nanoparticles. We utilized oxide nanosheets as a building block in the bottom-up assembly, and successfully developed various functional thin films such as high-k dielectrics, capacitors, artificial ferroelectrics, all nanosheet FET, ferromagnetic superlattices, magneto-optical materials, and electrodes for Li-ion battery.


CI-1:L10  Fabrication and Characterization of Optical Ceramic Layers using the Aerosol Deposition Method
T.N.H. NGUYEN, S. DENNELER, M. AHLSTEDT, C. SCHUH, Corporate Technology, Siemens AG, Munich, Germany; R. MOOS, Lehrstuhl Funktionsmaterialien, Universität Bayreuth, Germany

The Aerosol Deposition Method (ADM) is a coating process which has the remarkable advantage of enabling the manufacture of dense layers at room-temperature directly from ceramic powder. In this method, ceramic particles are dispersed with a gas to form an aerosol, which is accelerated onto a substrate to form dense layers. The aim of this work was to investigate how the process parameters affect the optical properties (e.g. transmittance) of aluminum oxide and yttrium aluminum garnet layers on glass substrates. As-deposited layers were characterized including microstructure and phase analysis as well as optical measurements. For aluminum oxide dense and crack-free layers with thicknesses up to 50 µm were obtained, whereas yttrium aluminum garnet layers exhibited lower density and integrity. Layer characteristics and deposition procedures are discussed with respect to the entire processing procedure to derive a deeper understanding of the intrinsic deposition mechanisms and critical parameters.


CI-1:L11  Synthesis by CVD and Characterization of Monolithic SiC Tubes for High Temperature Structural Applications
P. DRIEUX, T. CALAIS, G. COUÉGNAT, S. JACQUES, G. CHOLLON, LCTS, CNRS, Pessac, France

SiC/SiC composites have excellent mechanical behavior under irradiation but their porosity prevents their use as fuel claddings in the future nuclear plants. A high strength and gas-tight SiC sheath could complete the composite structure and provide an efficient barrier to fissile products.
The aim of this work was to prepare long, free standing and high strength SiC tubes using a rapid and near net shape manufacturing process. The SiC tubes were produced by chemical vapor deposition (CVD) at atmospheric pressure using CH3SiHCl2/C3H6/H2 precursor mixtures. Sliding the heating system along the substrate allowed the continuous deposition of long and a few micrometer-thick CVD-SiC sheaths. Their composition, microstructure and surface morphology were analyzed in details. C-ring specimens were cut from the tubes and submitted to compressive tests to assess the room temperature failure properties and the high temperature mechanical behavior.
The deposition rate, Si/C ratio, crystalline state and surface roughness of the CVD-SiC tubes are related to the gas phase reactions along hot zone. The smooth outer surface leads to fairly high failure strength. The high temperature properties can be improved by adjusting the through-thickness composition gradient.


Session CI-2 - High Temperature Protective Coatings in Oxidising and Harsh Environments

CI-2:IL02  Self-adaptive Lubrication Mechanisms in Hard Coatings for Different Temperature Regimes
R. FRANZ, C. MITTERER, Department Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Leoben, Austria

In the field of hard coatings, a multitude of coating materials are nowadays available. However, the ever increasing demand for reducing the manufacturing costs of industrial goods makes the development of new coating materials and designs a necessity. In particular, the reduction in the usage or the complete absence of lubricants during cutting operations places high demands on the wear resistance of the coatings. Friction control plays a crucial role in order to reduce or limit the rise in temperature in the tribological contact zone. In the absence of external lubricants, this functionality has to be included in the protective coating.
Depending on the expected operation temperature, different lubricating effects can be utilised. At room to medium temperature, carbon containing coatings are commonly applied, but also other lubricating phases, e.g. transition metal dichalcogenides, showed promising results. The incorporation of soft metals can offer lubricating effects at medium to high temperature. The choice of lubricating phases for high-temperature applications is limited. However, lubricious oxides that form during operation represent a possible solution. The strategies for reducing the friction at different temperature levels will be presented and discussed.


CI-2:IL03  Novel Approaches to Erosion-resistant Ceramic Coatings
C. LEYENS, Technische Universität Dresden, Institute of Materials Science, Chair of Materials Engineering, Dresden, Germany

In aero engines, coatings are facing severe attack under multiple loading conditions. Sand erosion, e.g., can cause great damage to turbine hardware in the compressor, while hot corrosion and oxidation are of concern in the hotter parts of the engines. Today, coatings are widely applied to protect high pressure turbine airfoils, however, their use in the compressor and the low pressure turbine is scarce yet.
The paper will review recent developments in the field of erosion protection of aerospace alloys such as titanium and nickel alloys indicating that coatings can substantially improve the component lifetimes under erosion attack. Moreover, examples of coatings for intermetallic titanium aluminide alloys will be addressed. These alloys are the latest aerospace materials brought into service by General Electric in their GEnx for stage 6 and 7 of the low pressure turbine.
It has been shown that the Mn+1AXn phases Ti2AlC and Cr2AlC exhibit good erosion protection due to their combination of metallic and ceramic properties. Furthermore, Cr2AlC has excellent oxidation resistance, particularly if doped with Y. Recently , for this MAX phase autonomous self-healing behaviour was demonstrated which fostered significant research efforts in this area. The current aim of ongoing research is to assess the potential of Cr2AlC MAX phase coatings as erosion resistant autonomous self-healing material by understanding the basic physical and chemical principles governing multiple crack closure to heal erosion damage.


CI-2:IL06  High-speed Coating by Laser Chemical Vapor Deposition
T. GOTO, A. ITO, H. KATSUI, Institute for Materials Research, Tohoku University, Sendai, Japan

CVD (Chemical Vapor Deposition) has been used for preparing thin films due to low deposition rate less than several µm/h. Although auxiliary energy such as laser (termed LCVD)can effectively enhance the deposition rate, LCVD can increase the deposition rate only at a localized area. It has been thought that high-speed, wide-area and thick coating would be impossible by LCVD.
We have developed a new LCVD and the deposition rates in volume of our LCVD are several orders higher than those of conventional LCVD. YSZ (Yttria stabilized zirconia) film was prepared by LCVD at a deposition rate of 230 µm/h. Vertically elongated columnar grains with (100) orientation was prepared. WC-Co cutting tools are generally coated by alpha-Al2O3 film using halide CVD. The deposition temperature of alpha-Al2O3 by halide CVD has commonly been above 1273 K, and the deposition rate was less than 1 µm/h with insignificant orientation. By the LCVD, hexagonal facets were observed on the surface with significant (0001) orientation. A high deposition rate of gamma-Al2O3 film of 600 µm/h was obtained around 950 K, and the deposition rates of alpha-Al2O3 film was about 200 µm/h at 1050 K. These values were several 100 times higher than those of conventional halide CVD.


CI-2:L07  Influence of the Carbon Content on the Structural Properties of Polysilylcarbodiimide-derived SiCN Coatings
A. KLAUSMANN, G. MERA, E. IONESCU, R. RIEDEL, Technische Universität Darmstadt, Darmstadt, Germany

Due to their outstanding structural properties like oxidation, creep and crystallization resistance up to high temperatures, silicon carbonitrides (SiCN) were identified in the last time as excellent candidates for high temperature applications. They are intrinsically heterogeneous materials, consisting of amorphous silicon nitride, silicon carbide and segregated carbon. Especially the carbon phase (e.g., content, crystallinity, sp3/sp2-hybridization, etc.) was shown to strongly affect the properties of the polymer-derived SiCN.
In the present work, SiCN-based ceramics derived from polysilylcarbodiimides were developed as coatings for the environmental protection of metallic substrates. Three preceramic polymers with different carbon content were synthesized and the coatings were applied by spin coating of polymer solutions. After ceramization in argon at 1100°C, amorphous, crack-free and dense SiCN coatings with thickness up to 1 micron were produced. High temperature annealing experiments were performed in order to assess their thermal stability. Moreover, the prepared coatings were exposed to oxidative/corrosive conditions at high temperatures and the influence of the carbon phase on their environmental performance was assessed.

 
Session CI-3 - Thermal Barrier Coatings

CI-3:IL01  Fundamental Challenges in Designing Next Generation Thermal Barrier Coating Systems
C.G. LEVI, Materials Department, University of California, Santa Barbara, CA, USA

Gas turbine technology is at a cross-roads, with demands for increased engine performance and fuel flexibility translating into higher material temperatures, ≥1300°C, and chemically more aggressive environments for the gas path components.  Coatings are now considered enabling to new engine designs, but state-of-the-art systems based on ZrO2-7±1wt%Y2O3 (7YSZ) are fundamentally limited at the prospective operating temperatures.  Developing new materials requires an understanding of the interplay between chemistry, microstructure and the critical attributes that govern performance and durability.  Key issues arise from the need for simultaneously improving toughness and resistance to the environmental attack, especially by molten silicate deposits, while maintaining or improving attributes such as low thermal conductivity and strain tolerance.  While higher temperature materials with either improved toughness or improved resistance to silicates have been identified, to this date there is no material with the full spectrum of desirable attributes.  This presentation discusses the challenges in achieving the requisite behavior because of the divergence in the chemical approaches to reach the different goals, as well as those arising from processability.  The issues are illustrated with recent work on zirconia and hafnia based materials.


CI-3:IL02  Design of Thermal Barrier Coatings for Gas Turbine Applications
P. NYLEN, M. GUPTA, N. CURRY, N. MARKOCSAN, University West, Trollhattan, Sweden

Thermal barrier coating (TBC) systems have been used in the gas turbine industry since the 1980s. The future needs both the air and land based turbine industry involve higher operating temperatures with longer lifetime on the component so as to increase power and efficiency of gas turbines. The objective of this research was to investigate relationships between coating microstructure and thermo-mechanical properties of TBCs, and to utilize these relationships to design an optimized microstructure. Experimental as well as simulation techniques were used to achieve this goal. Important microstructural parameters influencing the performance of TBCs were identified and coatings with the identified microstructural parameters were designed, modelled and experimentally verified. The interface roughness between the bond-coat and the topcoat was given particular interest since this interface has been shown to play a major role in the development of induced stresses and lifetime of TBCs. Modelling of real surface topographies was here utilized to understand the effect of roughness on induced stresses. Different thermally grown oxide layer thicknesses were evaluated. The modelling results were also compared with existing theories established on simplified profiles published in earlier works.


CI-3:IL03  Advanced Processing Methods for TBCs
R. VASSEN, Forschungszentrum Jülich GmbH, IEK-1, Jülich, Germany

Thermal barrier coating systems are an important feature of modern gas turbines as they increase their efficiency and can prolong the lifetime of the components. The ceramic top coatings are in most cases produced by atmospherical plasma spraying (APS), mainly for highly loaded parts in aero-engines also electron beam physical vapor deposition (EB-PVD) is used. Recently, new thermal spray methods as suspension plasma spraying (SPS) and plasma spray physical vapor deposition (PS PVD) reveal a high potential for the application of TBCs.
In the SPS process suspensions are used as liquid feedstock. These feedstocks allow the manufacture of highly segmented or even columnar microstructures, which result in excellent thermal cyclic properties. In the PS PVD process a powerful plasma spraying gun is operated in a low pressure (about 1 mbar) atmosphere. Under these conditions injected particles are not only molten but also evaporated. Hence, the microstructure of the deposited coatings can show a columnar structure as in PVD coatings - depending on the used deposition conditions.
In the paper the different processes are described in detail and the properties of the coatings are compared with the properties of standard APS coatings.


CI-3:L04  Effect of Bondcoat Composition on the Interface Chemistry of YSZ including Re-oxide for TBC by Electron Beam PVD
YOON-SUK OH¹, CHAN-YOUNG PARK^{1, 2}, YOUNG-HWAN YANG¹, SEONGWON KIM¹, SUNG-MIN LEE¹, HYUNG-TAE KIM¹, DAE-SOON LIM², BYUNG-KOOG JANG³, ¹KICET, Icheon, Gyeonggi-do, Korea; ²Korea University, Korea; ³NIMS, Korea

Thermal barrier coating(TBC) consisting of two different layer of ceramic and alloy materials has been developed as a protective layer on surface of metallic components for gas turbines especially operating in high temperature condition. Typically 4 mol% yttria stabilized zirconia (4YSZ) has been most widely used for commercial TBC application. With increasing of operating temperature of gas turbines, more durability is required as well as low thermal conductivity of TBC materials. EB PVD (Electron beam physical vapor deposition) and Re-oxide added zirconia have been studied for the improvement of thermal durability of TBC at high temperature for their remarkable structural and compositional stability compared to conventional plasma spray method and YSZ material over 1300℃.
In this study, 4YSZ coatings including Re-oxides such as La2O3 with different bondcoat composition are fabricated by electron beam evaporation. Phase evolution, microstructure, adhesion of coating, thermal conductivity and durability are examined. Under a particular processing condition, a different interlayer formation through diffusion of bondcoat elements such as Ni, Co to interface was observed.


CI-3:IL05  Advanced Characterisation of Thermal Barrier Coatings
F. CERNUSCHI, RSE Spa Ricerca sul Sistema Energetico, Milano, Italy

It is known that the thermal diffusivity of plasma sprayed coatings is quite sensitive to the specific microstructure and to operating conditions, namely to the operation atmosphere composition and its pressure. This occurrence makes in principle possible to get information from thermal diffusivity measurements on TBCs microstructure and its evolution as a function of time.
The application of this approach to some as sprayed and sintered freestanding atmospheric plasma sprayed YPSZ TBC samples will be outlined.
Anisotropy of thermo-physical properties of TBC are significantly affected by the microstructure. It is therefore worth studying the thermal properties along the different directions. A thermographic technique able to estimate in a single experiment both in-plane and in-depth thermal diffusivity of TBC will be presented and results will be compared with the in-plane elastic modulus as measured by the three point bending test.
The possibility to estimate the overall porosity content of APS TBC by measuring thermal diffusivity is also discussed.
Furthermore, an approach for a semi-quantitative estimation of cracks at the interface of APS TBCs from thermal diffusivity measurements by using a single side thermographic technique will be presented.


CI-3:L07  Structures and Thermal Conductivities of Lanthanum/Gadolinium Zirconate TBCs Fabricated by Suspension Plasma Spray
SEONGWON KIM¹, CHANG-SUP KWON¹, YOON-SUK OH¹, SUNG-MIN LEE¹, HYUNG-TAE KIM¹, BYUNG-KOOG JANG², ¹Engineering Ceramic Center, Korea Institute of Ceramic Engineering and Technology, Icheon, Korea; ²High Temperature Materials Unit, National Institute of Materials Science, Tsukuba, Japan

Among candidate materials for future TBCs, zirconate-based oxides with fluorite and/or pyrochlore are prevailing ones. While the cubic fluorite phase of rare-earth oxide has the space group of Fm3(-)m, the cubic pyrochlore phase corresponds to the space group of Fd3(-)m. Furthermore, the pyrochlore structure is characterized by the cation occupancy of the special crystallographic sites and the oxygen vacancy at the 8a site. This ordering of cations in the pyrochlore structure results in additional peaks from superlattice in XRD compared with the fluorite structure. Besides, modification of plasma spray by using suspension or solution source is in demand in order to enhance the thermal durability of TBCs.
In this study, Lanthanum/gadolinium zirconate coatings are fabricated by suspension plasma spray. Lanthanum/gadolinium zirconate systems are comprised by selecting La3+ /Gd3+as A-site ions and Zr4+ as B-site ions in A2B2O7 pyrochlore structures. Phase formation, microstructures, and thermal conductivities are examined with the deposited coatings of lanthanum/gadolinium zirconate compositions. The possibilities of these coatings for TBC application are also discussed.

 
Session CI-4 - Tribological Thin Films and Coatings

CI-4:IL01  State of the Art and Recent Advancements of Thermally Spray Hardmetal Coatings
L.-M. BERGER, Fraunhofer IWS, Dresden, Germany

Thermal spray can be considered as a technology which allows to realise the functionality of hardmetals with a coating thickness in the
range 100-500 µm on the surface of large parts and components, which can not be produced by powder metallurgy for technical and economical reasons. This contribution reviews different spray processes, with focus on the currently most important high velocity oxy-fuel and high-velocity air fuel processes, and the properties of the different feedstock powders in a historical context. The properties of the most important hard phases, namely, WC and Cr3C2 and TiC as an alternative, are discussed. Commercially available hardmetal compositions are reviewed. Since the spray process influences the chemical and phase compositions, coating formation and microstructures are discussed. Methods of coating characterization with growing importance, e.g. Young's modulus and indentation fracture toughness; and thermophysical properties are presented. Corrosion properties, the influence of heat treatments on coating microstructure and the oxidation in service are reviewed. Wear protection (abrasion, erosion and sliding wear resistance) and potential new applications are discussed.


CI-4:IL02  Nanoindentation Cartography and Tomography for the Determination of Local Mechanical Properties
C. TROMAS, X. MILHET, J.C. STINVILLE, C. TEMPLIER, P. VILLECHAISE, Institut Pprime, Département de Physique et Mécanique des Matériaux, UPR 3346 CNRS - Université de Poitiers - ENSMA, SP2MI, Chasseneuil Futuroscope Cedex, France

During the last two decades, nanoindentation testing has become a commonly used technique for mechanical property measurements at surfaces. One of the most popular applications of nanoindentation is probably the determination of hardness or elastic modulus of thin films. With devices equipped with a motorized X-Y table, it is now possible to perform large regular nanoindentation arrays. This method is particularly interesting to study heterogeneous materials. A statistical analysis, associated to mathematical deconvolution methods allows identifying the properties of each individual phase. Furthermore, hardness or elastic modulus maps can be then established and compared to other local properties such as microstructure, crystallographic orientation or chemical composition. Several examples will be detailed in this presentation.
Furthermore, by performing successive indentation arrays in a same area after removing thin material layers by chemo-mechanical polishing, hardness and elastic modulus cartographies can be reconstructed in 3D. This method will be presented in a study of the elastic and plastic anisotropy of a plasma nitrided stainless steel, across the nitrogen concentration profile.


CI-4:IL03  Supra-lubrication of Zinc Oxide Coatings
M. TOSA, M. SASAKI, M. GOTO, A. KASAHARA, H. SUZUKI, H. HONDA, National Institute for Materials Science (NIMS), Tsukuba, Japan

We have successfully synthesized low frictional zinc oxide coating by using a combinatorial sputter coating system. High expectations are placed on zinc oxide (ZnO) as a stable material under oxidizing atmospheres, as it is an abundant raw material, does not contain harmful substances, and is suitable for use as a high temperature material, having a sublimation temperature of more than 1300°C. However, ZnO sinters have a high friction coefficient (μ) of approximately 0.6. The high friction coefficient (μ= approximately 0.3) of ZnO films has been obtained by conventional sputter coating without any optimization. Using a combinatorial approach, we found that a large reduction of μ is possible if the crystal preferred orientation of the ZnO coating can be best optimized with high accuracy. We also discovered that this ZnO might generate an electrical polar interaction in oil, and was successful in further reducing friction by molecular addition into oil.


CI-4:IL04  Advances in the Deposition of Well-adhered Diamond Coatings onto Co-cemented Tungsten Carbides
R. POLINI, Università di Roma Tor Vergata, Dipartimento di Scienze e Tecnologie Chimiche, Roma, Italy

Co-cemented tungsten carbides (WC-Co) are largely used to manufacture high wear resistant components in several manufacturing segments. Coating WC-Co with superhard materials like diamond CVD is of utmost interest as it can further extend their useful lifespan. However, the deposition of diamond coatings onto WC-Co tools and wear parts presents several problems due to interfacial graphitization induced by the binder phase at CVD temperatures, and thermal expansion mismatch of diamond and WC-Co. Methods used to improve film adhesion include substrate-modification processes that create a three-dimensional compositionally graded interface.
The techniques by which WC-Co can be treated to make it prone to receive diamond coatings by CVD will be reviewed.
In particular, the most recent approaches developed at the University of Rome Tor Vergata include the use of either CrN-base interlayers or high power diode laser irradiation to alter both morphology and chemical composition of the substrate surface. Surface morphology and composition of WC-Co substrates after the different pretreatments and the deposition of diamond films were studied by surface profiler, SEM, EDX and XRD. Wear performance of diamond coated WC-Co was assessed by dry sliding linear reciprocating tribological tests.

 
Session CI-5 - Smart and Multifunctional Thin Films and Coatings

CI-5:IL01  Recent Progress in the Field of Multicomponent Bioactive Nanostructured Films
D.V. SHTANSKY, E.A. LEVASHOV, I.V. BATENINA, National University of Science and Technology "MISIS", Moscow, Russia; N.A. GLOUSHANKOVA, N.Y. ANISIMOVA, M.V. KISELEWSKI, Blokhin Russian Cancer Research Center of the Russian Academy of Medical Sciences, Moscow, Russia; I.V. RESHETOV, Hertsen Moscow Oncological Research Institute, Moscow, Russia

Recent progress in the field of multicomponent biocompatible nanostructured films (MuBiNaFs) is briefly reviewed in the presentation. The films were obtained by sputtering of specially designed and fabricated via the self-propagating high-temperature synthesis method composite targets on different metal (Ti-, Ni-, and Co-based alloys), insoluble polymer, and deimmunized donor's bone substrates. An excellent combination of properties makes such MuBiNaFs very attractive materials for bioengineering and modification of metal and polymer surfaces, as well as deimmunized donor's bones. To get even better synergetic effect of implant modifications, the MuBiNaFs deposition can be combined with either a bulk material modification, for instance by a severe plastic deformation to improve mechanical properties, or a surface modification to control surface roughness and blind porosity. Another promising application is the fabrication of hybrid materials incorporated with stem cells or medicine.


CI-5:IL02  Pulsed Magnetron Sputtering of Novel Multifunctional Thin Films and Coatings
J. VLCEK, J. REZEK, J. KOHOUT, University of West Bohemia, Plzen, Czech Republic

High-power impulse magnetron sputtering with a pulsed reactive gas flow control was used for the reactive deposition of Ta-O-N films with tunable composition and properties. The depositions were performed using a strongly unbalanced magnetron with a planar Ta target in Ar-O2-N2 gas mixtures at an average target power density of up to 2.4 kWcm-2 in a pulse. An effective reactive gas flow control made it possible to adjust the film composition from Ta2O5 to a mixture of Ta3N5 and TaN. We prepared TaON films possessing appropriate band-edge levels for water splitting and a narrow optical band gap of 2.5 eV that permits a visible light absorption up to 500 nm.
Pulsed dc magnetron co-sputtering of a single target (B4C-Si, B4C-Zr or B4C-Hf-Si) in Ar-N2 gas mixtures was used for deposition of different multifunctional films. We present the results obtained for amorphous Si-B-C-N films with an exceptionally high thermal stability (above 1500°C) and very high optical transparency, for nanostructured Zr-B-C-N films with a high hardness (37 GPa) and high electrical conductivity, and for nanostructured Hf-B-Si-C films with a high hardness (34-37 GPa), high electrical conductivity and significantly improved oxidation resistance in air up to 800°C.


CI-5:L04  Hydrophilic Ceramic Glazes for Sanitary Ware for Single Firing
F. KNIES, T. GRAULE, Empa - Swiss Federal Laboratories for Materials Science and Technology, Duebendorf, Switzerland; L. Gauckler, ETH - Swiss Federal Institute of Technology, Zürich, Switzerland; W. FISCHER, Laufen Bathrooms AG, Laufen, Switzerland; C. ANEZIRIS, TU Bergakademie Freiberg, Freiberg, Germany

The average Swiss family spends 7h a week on cleaning. Due to hygienic standards esp. the bathroom is in the focus of cleaning. In order to facilitate cleaning sol-gel coatings for sanitary ware have been developed, but their durability is hampered due to aggressive cleaning agents. A new approach is the development of a ceramic glaze, which is super even to avoid contamination in the first place, but is also super hydrophilic; thereby water can easily wash the dirt away. To achieve such surfaces, photo-catalytically active oxides are introduced in the compositions of industrial glazes. Glazes with photo-catalytically active oxides show lower surface roughness (AFM) from Ra= 60nm to 20nm, while the commonly used photo-catalyst TiO2 increases roughness from
Ra= 60nm to 200nm. The water wetting angle can be decreased from 45° to 26° by adding a fluorite-structured oxide. Our final target is to lower the surface roughness to less than 5nm, the wetting angle to less than 5° and to optimize the crystallization behaviour referring to thermal expansion and mechanical resistance. The present results already now indicate that the undertaken approach is a successful strategy towards the development of robust, self-cleaning and photocatalytically active surfaces for sanitary applications.


CI-5:IL05  Novel Thin Film Nitrides for Applications as Thermoelectric Materials
P. EKLUND, S. KERDSONGPANYA, B. ALLING, Thin Film Energy Materials Group, Thin Film Physics Division, Dept. of Physics, Cehmistry and Biology (IFM), Linköping University, Linköping, Sweden

Thermoelectric devices have the potential to contribute to energy harvesting in society by directly converting heat into electricity or vice versa. However, the conversion efficiency of thermoelectric devices of today is limited. The critical material-dependent parameter is the figure of merit (ZT = S2T/rk);, where r is electrical resistivity, S is the Seebeck coefficient and k is the total thermal conductivity). In this invited talk, we present recent results from our experimental and theoretical investigations of ScN-based thin film system. ScN thin films exhibit an anomalously high power factor (S2/r)for transition metal nitrides of 2.5-3.3×10-3 W/mK2 at 800 K. We have explained this result by nitrogen vacancies generating an asymmetric sharp feature in the density of states which allows low electrical resistivity with relatively large S. Unfortunately, ScN has high thermal conductivity, thus its ZT is low (~0.2). To reduce lattice thermal conductivity, potential strategies are nanostructuring, alloying or nanoinclusion formation. To understand which alloying elements that could be of interest at elevated temperatures were diffusion can be activated, we have investigated the trends in mixing thermodynamics of ScN-based solid solutions, correlated with experiments.


CI-5:L06  Transparent Layered Hybrid Films Possessing Multi-functionalities including Excellent Dynamic Dewetting, Anti-corrosion and Self-healing Properties
A. HOZUMI, C. URATA, B. MASHEDER, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya, Japan

In this study, we report the preparation of transparent layered hybrid films exhibiting multi-functionalities, including excellent dynamic dewetting behavior, anti-corrosion and self-healing properties [1-2]. Our layered hybrid films are composed of alternating alkyl chain and silica layers with nanometer-scale interval distance between the layers. Such organic/inorganic hybrid materials offer several attractive advantages; 1) the resulting coatings are highly transparent and curable at room temperature, 2) the surface of the coatings shows excellent dynamic dewettability because of the low surface energy and flexibility of the alkyl chains, 3) the layered nanostructures are capable of carrying functional molecules such as corrosion inhibitors between the layers, and are expected to show self-healing properties when the samples are subjected to harsh environments. For example, due to the coating of our layered hybrid films with corrosion inhibitors, corrosion resistance for copper and aluminum substrates has been markedly improved. All samples retained their metallic luster even after exposure to salt water for 10 days.
[1-2] A. Hozumi, et al., ACS Appl. Mater. Interfaces, 5, 154 (2013) and 5, 7899 (2013).


CI-5:L07  Catalytically Active Cobalt-copper Oxide Layers on Aluminum and Titanium
I.V. LUKIYANCHUK, V.S. RUDNEV, L.M. TYRINA, I.V. CHERNYKH, P.M. NEDOZOROV, Institute of Chemistry FEB RAS, Vladivostok, Russia

The coatings modified by cobalt and copper oxides have been obtained on titanium and aluminum by combination of Plasma Electrolytitc Oxidation (PEO) in zirconate and silicate electrolytes and impregnation in nitrate solutions. Coatings elemental and phase composition, morphology and catalytic activity in CO oxidation have been investigated. The composites based on SiO2+Al2O3/Al and those based on ZrO2+TiO2/Ti show highest and lowest total concentration of cobalt and copper, respectively. According to effect on catalytic activity cobalt-copper oxide coatings formed by combination of PEO and impregnation techniques can be arranged in series: SiO2+TiO2/Ti > SiO2+Al2O3/Al > Ce2O3+ZrO2+TiO2/Ti > ZrO2+TiO2/Ti. The correlations between coatings characteristics and their catalytic activity are discussed.

 
Session CI-6 - Modelling and Simulation of Coatings and Films

CI-6:IL02  Modeling and Measurement of Thermal Resistance at Interfaces
YIBIN XU, National Institute for Materials Science, Tsukuba, Ibaraki, Japan

Interfacial thermal resistance plays an important role in determining the thermal conductivity of hybrid material systems such as nano-composite, power device and electronic device. Evaluation of interfacial thermal resistance by measurement and simulation is essential to control and design the thermal performance of these materials or devices. In this presentation, our recent work on computation of interfacial thermal resistance by a phonon diffusion mismatch model on more than 1000 interfaces, and thermal resistance of Si/Ge interface by a molecular dynamics simulation, as well as a new method to measure interfacial thermal resistance by period heating and thermal reflectance technique and the measurement results on metal/dielectric interfaces.


CI-6:L04  Systematic Theoretical Search for Alloys with Increased Thermal Stability for Advanced Hard Coatings Applications
H. LIND, F. TASNADI, I.A. ABRIKOSOV, Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, Sweden

State-of-the-art alloys for hard coating applications, such as TiAlN are known to suffer from a decreased hardness during heat treatment in excess of 900 °С due to the formation of detrimental wurtzite AlN phases. Recent research has shown that multicomponent alloying with additional transition metals such as Cr can shift the onset of the phase transformations to higher temperatures [1], but a search for new alloys is generally time-consuming due to the large number of processes that influence material properties along with the large number of alloy compositions that have to be synthesized. To overcome this difficulty we carry out systematic first-principles calculations aimed at finding potential new transition metal (TM) aluminum nitride alloy components for advanced hard coating applications. To this end, we perform ab-initio calculations for all transition metals, considered as impurities in AlN to identify promising candidates on which further studies may be carried out.
[1] H. Lind et al, Appl.Phys.Lett. 99, 091903 [2011]


CI-6:IL06  Phase Stability and Elastic Properties of Hard Coating Phases Studied by ab Initio Calculations
D. MUSIC, J.M. SCHNEIDER, Materials Chemistry, RWTH Aachen University, Aachen, Germany

Two families of hard coatings will be discussed: M0.5Al0.5N1-xOx and MgAlB14 based phases. The influence of oxygen content and transition metal valence electron concentration (VEC) on the phase stability and elastic properties of cubic M0.5Al0.5N1-xOx (M = Sc, Ti, V, Cr; x = 0-0.5) was studied. The negative value of enthalpy of mixing was observed for all phases indicating full miscibility. Furthermore, point defects exhibit an important role in explaining the phase stability. Bulk moduli are decreased as x in M0.5Al0.5N1-xOx is increased, which may be due to an increase in the ionic character of the overall bonding. We have also explored surface processes on M0.5Al0.5N1-xOx interacting with polypropylene as well as residual and environmental gases.
The effect of VEC and size of the X element in MgXB14 (X = Al, IVA, 3d metals) on stability and elastic properties was explored. Based on the electronic structure, X elements and Mg transfer electrons to the boron network. Hence, the stability of the compounds studied increases as more electrons are transferred. We have also designed a new compound by replacing Mg with Y and probed this by sputtering. The bulk moduli for all these borides are in the range 196-220 GPa, rather close to known hard coatings such as α-Al2O3.


CI-6:IL07  Theory for Accelerated Materials Design: New Tool for the 3d Millennium Materials Science
I.A. ABRIKOSOV, IFM, Linköping University, Linköping, Sweden

We discuss a need to develop modern theory, significantly reducing number of approximations in calculations, explicitly taking into account conditions at which materials operate, and making accuracy of theoretical predictions comparable to or exceeding the experimental one. In this talk we will concentrate on applications of the theory for a knowledge-based design of advanced hard coatings. Three main directions will be considered: (i) theoretically motivated materials design in direct collaboration with experiment and industry; (ii) systematic knowledge-based search for new materials using high-throughput combinatorial processing; (iii) computer experiment to assembling data bases of materials parameters allowing for user-friendly data-mining and accelerated materials design. A successful realization of the program promises enormous benefits for materials science. Our specific goal is to shorten by half development time for new materials. Our long term goal is to change an empirical paradigm for materials development, and to give the 3d millennium materials science truly powerful tool for accelerated materials design.
 
 
Poster Presentations

CI:P01  Surface Modification of Ceramic Materials to Improve their Wettability by Metal
K. JACH, A. SIDOROWICZ, A. WAJLER, H. WEGLARZ, U. BRYKALA, Institute of Electronic Materials Technology, Warsaw, Poland

One of the most common techniques used for ceramic-metal composites fabrication is infiltration of the porous ceramic preforms by liquid metals. During this process, pressure is transferred to the preform and may causes its deformation. This affects both the kinetics of the process and the composite microstructure. Furthermore, application of pressure is limited by the mechanical strength of ceramic preform. The possible alternative to this process is pressure-less infiltration or sintering. However, a serious problem faced in that cases is the lack of wettability of oxide ceramic materials by metal. One of the solutions of this problem can be the use of an intermediate layer of high-melting metal exhibiting strong adhesion to ceramic preform and high wettability by the desired metal.
This paper presents the results of studies on surface modification of alumina ceramics by tungsten layer deposition (APCVD, dip-coating in a precursor solution). The resulting thin films were subjected to X-ray phase analysis (XRD) and microscopic observation (AFM, SEM). Wetting test with copper was also performed and then the contact angle measurements were made.
The work is financed by the Polish Science Funds in the years 2010-2013 as a research project no. N N507 4312 39.


CI:P05  Mullite-rare Earth Silicate EBC Coatings
KEE SUNG LEE, FAN JIE FEN, School of Mechanical Systems Engineering, Kookmin University, Seoul, Korea

Improvements of the inlet temperature of gas turbine system can be achieved using ceramic composites such as Si3N4 and SiC, from 1100 °C to 1700 °C, in order to increase thermal efficiently from 43% to 56~60%. However, one of the major problem is that Si-based ceramic is corroded under water vapor environment at high temperature. Therefore, mullite, glass-ceramics such as BSAS and rare earth silicate such as Y2Si2O5, Yb2SiO5, Yb2Si2O7, Er2SiO5, and Sc2SiO5 have been used for environment barrier coatings to protect SiC fiber reinforced composites from material loss under water environment. Mullite coatings are commonly developed for protective coating for Si-based ceramics because they have similar thermal expansion coefficient with Si-based materials and good stability. However, the coating microstructure is heterogeneous, containing micro-cracks, irregular pores and non-crystalline phases. Silicate coatings have been investigated because of lower silica activity and good phase stability. However, high cost and non-sinterability are one of the problems for EBC coatings. In this study we prepared mullite-rare earth silicate composites for EBC coatings by varying the content of silicate in the composites. The result indicates that mullite-silicate coatings are desirable for EBCs.


CI:P10  Plasma Torch for Supersonic Coatings at Atmospheric Pressure
F.R. CALIARI, D.A.P. REIS, Universidade Federal de São Paulo, São José dos Campos, SP, Brazil; G. PETRACONI, R. SILVA, Instituto Tecnológico Aeroespacial, São José dos Campos, SP, Brazil; L.I. CHARAKHOSVKI, A. ESSIPTCHOUK, Luikov Heat- and Mass Transfer Institute, Minsk, Belarus

Typical air plasma sprayed MCrAlY coatings contain many internal defects (such as irregular pores, incorporated oxides, etc.), which lowers the level of mechanical resistance in comparison with a dense HVOF coating. The objective of this study is to develop dense bond MCrAlY and ZrO2 coatings at atmospheric pressure using a supersonic plasma torch. For this purpose, an innovative plasma torch with powder injected into discharge chamber was developed and tested. The study was focused on the spray parameter optimization of deposition process of ZrO2 partially stabilized 8%Y2O3 and MCrAlY on Ti6Al4V substrate. First experiments showed the coating microstructure is look like to typical HVOF coating. Detailed characterization of samples and comparison with typical microstructure of HVOF and conventional Air Plasma Spray (APS) are presented.


CI:P11  Comparison of the Ablation Mechanism of C/C-SiC Composite under Atmospheric and Low Pressure
R.J. SILVA, H.S. MACIEL, T.M.B. CAMPOS, A.A. MARTIN, G. PETRACONI, Technological Institute of Aeronautics, Sao José dos Campos, SP, Brazil; A.M. ESSIPTCHOUK, Luikov Heat- and Mass Transfer Institute, Minsk, Belarus

Comparisons of heating tests at atmospheric pressure and low pressure by using a thermal plasma torch were performed. A constant heat flux on the sample surface was applied in the study of the oxidation mechanism of C/C-SiC composite, used in thermal protection systems. The SEM and EDS analysis show an intensive glassification at the surface, which is strongly dependent on the oxygen partial pressure and the sample surface temperature. For vacuum conditions, at maximum surface temperature of 1450 ºC and the oxygen partial pressure of about 66 Pa, a uniform passivation layer of SiO2 is formed. At atmospheric pressure, under an oxygen partial pressure of 21 kPa, the maximum surface temperature is 400 ºC higher than obtained in vacuum, reaching levels of 1850ºC. Under these conditions, the protective oxide layer is partially volatilized with time, increasing the specific mass loss rate by a sublimation of the composite, directly exposed to the plasma jet. This effect is alike to what occurs in the process of transition from passive to active oxidation of SiC.


CI:P13  Oxide Layers Formed on FeCrAl Steel Foil Coated with Pt and Al Films
K. RESZKA, Koszalin University of Technology, Institute of Technology and Education, Koszalin, Poland; Z. ZUREK, A. JARON, Cracow University of Technology, Institute of Inorganic Chemistry, Krakow, Poland; M. SZCZYPINSKI, TERMEX Ltd., Koszalin, Poland

The investigations were aimed to characterize the oxide layers (Al2O3) in terms of the crystal structure development and their impact on increase in mechanical distribution of Pt in volume of the layer, as a system predisposed to carry out catalytic processes. The morphology and phase composition of oxide layers formed on the surface of FeCrAl steel foil coated with Al and Pt films and Al / Pt composition layers after oxidation at high temperature were investigated. Films of Al or Pt, and Al / Pt were applied by magnetron sputtering. As a result of Al deposition on FeCrAl foil a layer composed of three zones was formed; the inner of which exhibited the crystalline characteristics whereas the outer zone and the one lying below the crystalline zone were amorphous in character. The Pt film was continuous and well adhered to the original Al2O3 layer. The process of simultaneous Pt and Al sputtering provided the nanolayers continuous in charakter. All samples with films were oxidized in an atmosphere containing 67% O2/Ar at 850 ° C in a period of 24 h. As a result of the oxidation processes there were formed θ-Al2O3 oxides of whiskers structure of a considerable size, while whiskers of θ-Al2O3 oxides formed on the samples coated with a Pt films were smaller but with higher density.