Papers

ICMCTF2011 Session PD: Post Deadline Discoveries and Innovations

Thursday, May 5, 2011 1:30 PM in Room Tiki Pavilion

Thursday Afternoon

Start	Invited?	Item
1:30 PM		PD-1 Superhard Transition Metal Diboride Coatings V.A. Ravi, A. Schissler, B. Harrison, A. Ly, J. Koch (California State Polytechnic University); A. Lech, R. Kaner (University of California, Los Angeles) The diboride of the transition metal rhenium has been reported to have hardness values high enough to classify it as a superhard material and has been shown to scratch diamond. This superhard material has been synthesized in bulk form; however, the development of coatings of this material is still ongoing. Pack cementation techniques were implemented to form rhenium diboride coatings on rhenium substrates and a series of experiments are currently underway to examine the kinetics of rhenium diboride coating growth for several pack compositions. Thus far, coatings have been produced with thicknesses up to ~13 µm and Vickers microhardness values of up to ~43 GPa. X-ray diffraction was used to confirm the predominant phase as ReB₂. This talk will summarize the current status of the work on rhenium diborides; mention will also be made of the work underway on tungsten tetraboride coatings. This work was supported by the National Science Foundation under Grant No. DMR 0805357
1:50 PM		PD-2 Intelligent Self-Healing Corrosion Resistant Vanadia Coating of Flower-Like Morphology for AA2-24 and Novel Magnesium Alloys Abdel Salam Hamdy (Max Planck Institute, Germany & King Fahd University, Saudia Arabia); I. Doench, H. Möhwald (Max Planck Institute, Germany) Environmentally acceptable vanadia based coatings of self-healing properties were developed for improving the corrosion protection performance of Aluminum Alloy 2024 and some newly developed magnesium alloys for possible application in automotive and aerospace industries. The optimum vanadia solution concentrations and pH that can offer the best corrosion resistance of aluminum or magnesium substrate in chloride containing solutions were measured by mean of electrochemical impedance spectroscopy and polarization techniques. A flower-like coating morphology of self healing properties was observed to improve the localized corrosion resistance in 3.5% NaCl solution. Surface morphology, composition and microstructure of vanadia conversion coatings were examined by AFM, XPS, SEM-EDS and macroscopic imaging techniques.
2:10 PM		PD-3 Life Time Analysis of MCrAlY Coatings for Industrial Gas Turbine Blades (Calculational and Experimental Approach) P. Krukovsky (Institute of Enbineeering Thermophysics, Ukraine); K. Tadlya (Institute of Engineering Thermophysics, Ukraine); A. Rybnikov (Polzunov Central Boiler and Turbine Institute, Russia); Vladislav Kolarik (Fraunhofer ICT, Germany) A calculational and experimental approach was developed for life time analysis of MCrAlY coatings for industrial gas turbine blades. This approach based on a model that describes the main diffusion and oxidation processes within the coating-base metal system as well as experimental data for specimens after different short time exposures at different temperatures. In comparison with existing models the proposed model describes the interdiffusion zone between coating and base alloy. The model’s adequacy to represent physical processes is provided by identifying model parameters from short-time experimental data for coating – base alloy systems. The measured Al concentration profiles were used as input values for model parameters estimation and a calculational prediction of the long term diffusion and oxidation behaviour of the coating was performed. The model, calculational and experimental approach as well as MCrAlY life time estimation results for 10000 h at 950°C are presented. These results were obtained with short time experimental data for Al concentration profiles across the coating thickness measured after 300 and 1000 h. The predicted and measured -phase content in the coating during oxidation for coating thickness 200 micron at 900, 950 and 1000 °C are presented too. The dissapearance of -phase in the coating was assumed as the corrosion life time criterion.
2:30 PM		PD-5 Development of Photonic Platforms from Hybrid Sol-Gel Thin Films M. Oubaha, R. Copperwhite, A. Gorin, C. McDonagh (Dublin City University, Ireland) Over the past decade, integrated optoelectronic devices have gained increasing importance with the rising demand for higher lightwave transmission capacity. One technology that can aggressively address the increasing need for integration of electro-optical components into miniaturised systems is that of lightwave circuits (LWC) based on optical channel waveguides. The availability of LWCs on an industrial level would allow the direct integration of passive and active components such as parallel optical interconnects, Wavelength Division Multiplexer, Variable Optical Attenuators, Optical Switches, and Multianalyte Biosensors. The key components for facilitating the use of LWCs are suitable fabrication methods as well as advanced optical materials. In this paper, we show application of newly developed photocurable hybrid sol-gel materials to the fabrication of photonic devices for telecommunication, optical sensing and biosensing applications. This work will be divided into 2 parts. The first will be devoted to the material development and characterisation. The synthesis of photocurable sol-gel materials will be described and optical properties discussed and correlated to the material structure, with a particular emphasis on the photosensitivity of the materials [1]. The second part will deal with the photo-patterning of the developed thin film materials, employing both single and two photon polymerization (2PP) techniques (Fig. 1), for the fabrication of optical waveguides (Fig. 2) utilized in the development of our photonic LWCs and biosensor platforms [2] (Fig. 3), as well as novel microfluidic systems (Fig. 4). Performances of the developed systems will be discussed and compared with the state of the art. Original three-dimensional structures fabricated by 2PP technique [3,4] will also be presented showing the strong potential of these materials in the development of mechanically stable 3D structures (Fig. 5). [1] M. Oubaha et al. Journal of Material Science, 46, 2, 2011, 400-408. [2] M. Oubaha et al,. Microfluidics & Nanofluidic, In Press. [3] M. Oubaha et al.,Applied Surface Science, 257, 7, 2011, 2995-2999. [4] A. Ovsianikov, M. Oubaha et al, ACS Nano, 2008, 2 (11), 2257-2262.
2:50 PM		PD-6 Vertical Growth of Carbon Nanotubes on Bulk Copper Substrates for Charge Storage Applications G. Atthipalli, R. Epur, P.N. Kumta, Y. Tang, A. Star, J.L. Gray (University of Pittsburgh) Growth of carbon nanotubes (CNTs) on bulk copper foil substrates has been achieved by sputtering an inconel thin film on Cu substrates followed by ferrocene decomposition into iron during thermal chemical vapor deposition (CVD). The inconel film breaks up into islands acting as a catalyst and iron nanoparticles from ferrocene act as an additional vapor phase delivered catalyst. Both inconel and iron are needed for dense and uniform growth of CNTs on the copper substrates. Two hydrocarbon sources investigated were ethanol and xylene to determine the best conditions for growth of CNTs on copper. The results demonstrate the effectiveness of this simple and cost effective method of directly integrating CNTs with highly conductive copper substrates as double layer capacitors for charge storage applications. Electron microscopy, Raman spectroscopy were used to evaluate the morphology and quality of the CNTs. We report the specific capacitance and power density values of the double layer capacitors developed from the CNTs grown directly on copper substrates.
3:10 PM		PD-7 Thickness Ratio Calculation of Bi-Layer TiNi Alloys to Enhance Shape Memory Behavior using Stress-Strain Properties of the Individual Thin Films M. Mohri, M. Nili-Ahmadabadi (University of Tehran, Iran) Thin film shape memory alloy (SMA) has been recognized as promising material for being used in micro-electro-mechanical-system (MEMS) for a decade. Among various SMAs, NiTi-based alloys have received wide attention due to their ability to generate large recoverable strain. In the present study Ni-Ti thin films have been deposited on NaCl substrates by dc magnetron sputtering source fitted with a 80mm diameter alloy target. In order to obtain a variety of film compositions, several discs of alloy target, prepared by vacuum arc remelting (VAR), were used. Three types of thin films have been deposited; Ti and Ni-rich thin films were separately deposited on NaCl substrate and also a composite layer of Ni45Ti50Cu5 and Ni-rich. The as deposited Ni-Ti thin films were crystallized to change the amorphous structure to a nano-structured material to characterize shape memory and superelastic behaviors. The effect of composition on film structure, transformation temperature and mechanical behavior was studied by using X-ray diffraction (XRD), Scanning electron microscopy (SEM), electrical resistivity and nano indentation. The results of thin films behavior were used to calculate the thickness ratio of be-layer composite NiTi to obtain enhanced shape memory behavior.