ICMCTF2006 Session AP: AP Poster

Thursday, May 4, 2006 5:00 PM in Room Town & Country
Thursday Afternoon

Time Period ThP Sessions | Topic A Sessions | Time Periods | Topics | ICMCTF2006 Schedule

AP-1 Thermal Stability of the Elevated Temperature Protecting Films Deposited by Ion Beam Assisted Magnetron Sputtering Method
J.-K. Kim, J.-W. Choi, S. Lee, E. Byon, D.-G. Kim (Korea Institute of Machinery and Materials (KIMM), Korea)
Iridium based alloy films, used for elevated temperature coating of tools to enhance their mechanical and thermal properties, and the interlayer films, such as Cr and Cr/CrN, improving the adhesion of Ir based protecting coatings to substrate were prepared by means of ion beam assisted magnetron sputtering method. In this work, we investigated the thermal and oxidation behaviors of the Ir based films depended on interlayer films such as Ir based film/Cr/substrate and Ir based film/CrN/Cr/substrate. The microstructure and the surface morphology were analyzed by X-ray diffraction and Scanning Electron Microscopy. Auger depth profiling is used to examine chemical composition variation with the samples annealed at high temperatures. The micro hardness indentation and ball-on-disc tribology test have been also utilized to take the mechanical properties of the samples. The results showed that the local exfoliation and surface oxidation on the samples of conventional Ir based/Cr films were easily affected by means of the out-diffusion of Cr atoms from interlayer through Ir based film to the surface, while the samples of Ir based/CrN/Cr showed the good thermal and mechanical properties due to the resistance of the out-diffusion of the Cr atoms.
AP-2 Magnesium Phthalocyanine(mgPc) Thin Films as Nanomaterials
M. Puri (IIT, India)
MgPc is a promising candidate for photovoltaic applications. It can be easily synthesized and is non-toxic to the envioronment. It is a self assembly molecule developed from deep-blue-green pigment. It exhibits a characteristic structural self organization which is reflected in an efficient energy migration in the form of extinction transport. MgPc relates to the similarity with chlorophyll. In the present work thin films of MgPc have been prepared on glass substrate under strict vacuum conditions(10-6 torr),thickness of few nanometers .Absorption spectra in Visible and IR regions have been observed which is good for fabrication of Photovoltaic cells and Nanostructures for Photodynamic Cancer Therapy .Appreciable amount of cytotoxicity can be observed while using MgPc as photosensitizers which is a promising PDT agent .The films thus prepared have been studied for their electrical and optical characterizations .Investigations have been made from different stacking positions of molecular MgPc thin films for studying their self-assembling nature that can be useful for their applications as Molecular-Recognition in Drug delivery and sensors which is one of the key features of Nanotechnology.
AP-3 Filter Effect on TiAlN/TiN Duplex Coatings by Cathodic Arc Deposition
C.-H. Hsu, C.-C. Lee (Tatung University, Taiwan)
Cathodic arc deposition (CAD) coatings such as TiN and CrN have been successfully applied in metal forming industries for their excellent wear resistance. There has been interest in applying such coatings to the surface of molding materials in order to reduce the friction coefficient and extend mold life. However, CAD process possesses a higher deposition speed compared to other PVD methods, but the coating by CAD has a rougher surface due to depositing the bigger particles. In this study, thus, TiAlN/TiN duplex coatings were deposited on DC53 molding steel by utilizing CAD facilities with/without an attached filter. The structure, chemical composition and morphology of the coatings were respectively analyzed using X-ray diffractionmeter (XRD), Auger electron spectroscopy (AES), and SEM. In addition, the corrosion and wear tests were carried out for evaluating the filtered coatings effect on DC53 steel. The results showed that the use of the filter for TiAlN/TiN coatings resulted in the decrease of depositing speed, but they were smoother compared with the coatings without the filter. Moreover, in both cases of corrosion and wear resistance, the TiAlN/TiN filtered coatings behaved the better performance than the ones without using filter.
AP-4 Study on Characteristics of CrxOy/CrN Duplex Coatings Deposited by Cathodic Arc Evaporation
D.-H. Huang, C.-H. Hsu, M.-C. Chiu (Tatung university, Taiwan)
In this study, the CrxOy/CrN duplex coatings deposited on SKH51 steel and silicon wafer were synthesized by cathodic arc evaporation method. The duplex coatings were designed with CrN as an interlayer and CrxOy as a top-layer. The top CrxOy layer was deposited under the different N2/O2 flow ratios at a constant working pressure. Characteristics of the duplex coatings were respectively analyzed using transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffractionmeter (XRD), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The XRD result showed that the top CrxOy layer structure mainly possessed both CrN and Cr-oxide phases. From the analyses of AES and XPS, the results further showed the top layer consisted of the constituents of CrN, CrO, Cr2O3 and Cr2O5. Thus, they indicated that CrxOy layer was formed on the top of CrN film resulting from the nitrogen being easily replaced by oxygen during the coating process. The micro-hardness of CrxOy/CrN duplex coatings was higher than that of pure CrN coating. Consequently, the coatings with the mixed constituents would enhance the substrate in surface hardness and properties.
AP-5 Thermal Stability of TaSiN Nanocomposite Thin Films at Different Nitrogen Flow Rate
C.-K. Chung, T.-S. Chen, C.-C. Peng, B.-H. Wu (National Cheng Kung University, Taiwan)
The TaSiN thin films were generally applied to diffusion barriers for Cu interconnections in ultra-large-scale integrated circuits (ULSI). The resistivity and thermal stability were the important issues in interconnections because of the RC-delay effect. In this paper, we investigated the relationship between the microstructures, resistivity and thermal stability of the TaSiN nanocomposite thin films. The TaSiN thin films were deposited on the Si(100) substrate at different nitrogen flow rate (N2% = N2 /(Ar+N2) x 100%) by magnetron reactively co-sputtering. Then the TaSiN films were annealed from 600 to 900°C for one hour in vacuum to evaluate thermal stability. The resistivity of the TaSiN films was measured by four-point probe method. The microstructure and phase transform were examined by the grazing incident angle X-ray diffraction (GIAXRD) and the morphology was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). GIAXRD results revealed that the microstructures of TaSiN films still retained amorphous phase for the as-deposited films at room temperature and annealed at temperatures up to 900°C. In addition, the broad peak in spectrum indicated the existence of nanocrystalline grains in amorphous matrix (nc/±-TaSiN). The resistivity of the as-deposited TaSiN films increase with the increasing N2 flow rate. It is small around 200- 500©cm for low N2 flow rates of 2% to 10%, while it increases abruptly to about 7700©cm at high N2 flow rate up to 20% or more. The grain size of as-deposited TaSiN films increases with the increasing N2 flow rate. The polycrystalline TaSiN films at 20% N2 flow rates have large grains with loose microstructure which reflect much high resistivity. The resistivity of TaSiN films slightly increases about 20-50©cm for low N2 flow rates after annealing at 600- 900°C. It indicates the nc/±-TaSiN films have good thermal stability in microstructure and resistivity up to 900°C.
AP-6 Oxidation Behaviour of Gamma Titanium Aluminides for High Temperature Applications
R. Braun, M. Froehlich, C. Duda, A. Ebach (DLR - German Aerospace Center, Germany); C. Leyens (Technical University of Brandenburg at Cottbus, Germany)
Numerous engineering gamma TiAl alloys have been developed in the last two decades to be used for structural applications in aerospace vehicle and automotive engines. Possessing a favorable combination of low density and attractive high temperature capability, these alloys, however, exhibit an insufficient oxidation resistance when operating at temperatures above 800°C for long time periods. In the present study, the oxidation behaviour of two laboratory alloys was investigated under isothermal oxidation conditions in the temperature range between 800 and 900°C. The alloys with the chemical compositions Ti-45Al-8Nb-0.2B-0.15C and Ti-45Al-1Cr-6Nb-0.4W-0.2B-0.5C-0.2Si were received from UES, Dayton, OH. To improve the oxidation resistance, specimens of these alloys were coated with protective layers of 4 µm thick TiAlCr and 2 µm thick Al2O3. Furthermore, the applicability of thermal barrier coatings (TBC) to gamma titanium aluminides was investigated. Using electron-beam physical vapour deposition, yttria-stabilized zirconia was deposited on specimens of the TiAl alloys pre-oxidised or coated with protective layers. The performance of thermal barrier coatings and the oxidation resistance of the protective layers were investigated through isothermal exposure in air at temperature between 800 and 900°C. Post-oxidation analysis of the coating systems was performed using a FEG SEM equipped with an EDX detector, highlighting microstructural features.
AP-7 Silicon Coating on Ferritic Steels by CVD-FBR Technology
F.J. Pérez, M.P. Hierro, J.A. Trilleros, L. Sánchez, F.J. Bolívar (Universidad Complutense de Madrid, Spain)
Silicon protective coating has been deposited on ferritic steels (9-12 % Cr) by Chemical Vapour Deposition by means of fluidized bed reactor (CVD-FBR). The process was realized at temperature below 580°C with the use of Silicon donator powder and chloride of hydrogen (HCl) activator. Thermochemical calculations were made before the experimental study to investigate the conditions for the formation of gas precursor for deposition of Si-coating. The result obtained of examination of the coated by means optical microscopy (OM), Scanning Electron Microscopy (SEM) and Energy Dispersion Spectroscopy (EDS) has show the formation of dense, homogenous and small coating consisting of an Fe3Si phase in agreement with X-ray diffraction (XRD).
AP-8 High Temperature Oxidation Resistance of 1.25Cr-0.5Mo wt% Steels by Zirconia Coating
Y.S. Baron, A. Ruiz, G. Navas (Universidad Simon Bolivar, Venezuela)
% yttria-stabilized zirconia coating was deposited by sol-gel technique. One problem with this method is that the hydrolysis of the organometallic precursors is faster than condensation; and the formation of precipitates is favored. Ethyl acetate was used to slow the hydrolysis rate, in order to obtain a more continuous layer. The air oxidation behavior of the coating was studied at 600°C and 700°C by the continuous measurement of the weight gain. The microstructural characterization was performed by optical and scanning electron microscopy, and composition was determined by energy dispersive spectroscopy (EDS). The weight gain of the 1.25Cr-0.5Mo wt% was diminished in about 70% respect to uncoated samples.
AP-9 Microstructural and Mechanical Properties Characterization of Magnetron Sputtered NiAlPtHf Coatings
X. Li, F. Huang, M.L. Weaver (The University of Alabama)
Ni-Al-Pt coatings have been claimed as promising bond coats in thermal barrier coatings systems. The reliability of systems is critically linked to the thermal expansion coefficient (CTE) and mechanical properties of bond coats such as hardness, modulus and residual stress. In this paper, the microstructure and mechanical properties of magnetron deposited Ni-Al-Pt(Hf) coatings were characterized. The modulus, CTE, and hardness were extracted by performing stress/temperature and nanoindentation studies of coatings on different substrates. The residual stress development with film thickness was quantified via the substrate curvature method. The results showed a dramatic increase of film stress with thickness for low thicknesses followed by a saturation region. X-ray diffraction tests revealed the presence of a disordered crystalline face centered cubic phase in the as-deposited coatings. The formation of a crystalline phase was rationalized through diffusion calculations. The density and cross-sectional microstructure of coatings were also investigated.
Time Period ThP Sessions | Topic A Sessions | Time Periods | Topics | ICMCTF2006 Schedule