Loading...
Search for:
aluminum-coating
0.006 seconds
Total 37 records
Functional Design of a Coating System for the Telescope Mirrors, A Recognition to Telescope of Iranian National Observatory
, M.Sc. Thesis Sharif University of Technology ; Moshfegh, Alireza (Supervisor) ; Khosroshahi, Habib (Co-Advisor)
Abstract
Functional design of coating system for the primary mirror of the Iranian National Observatory (INO) is done. This telescope has a 3.4 m primary mirror in diameter, made of Zerodur from Schott. Although similar coating systems are in use since years ago, this is the first attempt to design a system for such a large surface case in Iran. Systematic approach led us first to clarify and identifying the design requirements. Lower limit of 80% for reflectance on all wavelength range from 325-1000 nm, thickness of 100 nm with un-uniformity of 5 nm, adhesion enough to pass the selotape test and surface roughness of less than 8 nm. Study of the available methods for coating and selection of the best...
Influence of pulse parameters on electrocodeposition of Cr-Al2O3 nanocomposite coatings from trivalent chromium bath
, Article International Heat Treatment and Surface Engineering ; Volume 6, Issue 4 , December , 2012 , Pages 178-184 ; 17495148 (ISSN) ; Sadrnezhaad, S. K ; Salehi Doolabi, D ; Asadirad, M ; Sharif University of Technology
2012
Abstract
Cr and Cr-Al2O3 coatings were electrodeposited from Cr(III) bath with both pulsating and direct current onto copper substrates. Pulsating current resulted in homogeneous films of higher Al2O3 content and lower particle agglomeration than the direct current. Differences were more tangible at shorter duty cycles and pulse frequencies. Pulsating current improved both microhardness and corrosion resistance. The presence of alumina nanoparticles resulted in greater current efficiency, higher film microhardness and better corrosion resistance. Maximum current efficiency, highest microhardness and densest electrodeposited coatings were achieved at current density of 20 A dm-2, duty cycle of 40% and...
Influence of aluminide diffusion coating on the tensile properties of the Ni-base superalloy René 80
, Article Surface and Coatings Technology ; Volume 202, Issue 8 , 2008 , Pages 1385-1391 ; 02578972 (ISSN) ; Nategh, S ; Sharif University of Technology
2008
Abstract
Ni-base superalloy René 80 is widely used in manufacturing aircraft turbine blades. The service temperature of this alloy is in the range of 760-982 °C. Although this alloy possesses suitable mechanical, oxidation and hot corrosion properties, it is coated in order to increase its wear, oxidation, erosion and hot corrosion properties against harmful environmental service conditions. In this paper the influence of applying diffusion coating (CODEP-B) on the tensile properties of René 80 has been studied in the temperature range of 22-982 °C. Experimental results show that the tensile properties of the coated specimens are relatively lower than that of uncoated ones in the same conditions. But...
Characterization of Ni-P-SiO2-Al2O3 nano-composite coatings on aluminum substrate
, Article Materials Chemistry and Physics ; Volume 189 , 2017 , Pages 207-214 ; 02540584 (ISSN) ; Afshar, A ; Sadreddini, S ; Ghanbari, A. A ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
In the present work, nano-composites of Ni-P-SiO2-Al2O3 were coated on a 6061 aluminum substrate. The surface morphology of the nano-composite coating was studied by field emission scanning electron microscopy (FESEM). The amount of SiO2 in the coating was determined by Energy Dispersive Analysis of X-Ray (EDX) and the crystalline structure of the coating was examined by X-ray diffractometer (XRD). All the experiments concerning the corrosion behavior of the coating carried out in 3.5%wt NaCl solution and evaluated by electrochemical impedance spectroscopy (EIS) and polarization technique. The results showed that an incorporation of SiO2 and Al2O3 in Ni-P coating at the SiO2 concentration of...
Development of a structured monolithic support with a CNT washcoat for the naphtha HDS process
, Article Journal of the Taiwan Institute of Chemical Engineers ; Vol. 45, issue. 3 , May , 2014 , p. 887-895 ; Kazemeini, M ; Rashidi, A. M ; Jozani, K. J ; Sharif University of Technology
Abstract
An acid treatment of the cordierite monolith followed by coating of the CNT onto it by means of catalytic decomposition of methane was performed. The resulting material utilized as the support for the CoMo catalyst. The characterization outcomes showed that the CNTs were distributed uniformly on the surface of the monolith leading to a high BET surface area and relatively good adhered mesoporous layer of CNTs. Moreover, the catalytic activity of the resulting catalysts determined in an HDS reaction of naphtha. It was concluded that the activity of the CoMo catalyst over the CNT coated monolithic support (FACNT) was higher than that of the CoMo deposited onto the acid-treated monolith and...
Zeta-potential investigation and experimental study of nanoparticles deposited on rock surface to reduce fines migration
, Article SPE Journal ; Volume 18, Issue 3 , February , 2013 , Pages 534-544 ; 1086055X (ISSN) ; Habibi, A ; Pourafshary, P ; Ayatollahi, S ; Sharif University of Technology
2013
Abstract
Finesmigration is a noticeable problem in petroleum-production engineering. Plugging of throats in porous media occurs because of detachment of fine particles from sand surfaces. Thus, the study of interactions between fines and pore surfaces and the investigation of governing forces are important factors to consider when describing the mechanism of the fines-release process. The main types of these forces are electric double-layer repulsion (DLR) and London-van der Waals attraction (LVA). It may be possible to alter these forces with nanoparticles (NPs) as surface coatings. In comparison with repulsion forces, NPs increase the effect of attraction forces. In this paper, we present new...
Characterization of line nanopatterns on positive photoresist produced by scanning near-field optical microscope
, Article Journal of Nanomaterials ; Volume 2015 , September , 2015 ; 16874110 (ISSN) ; Yasrebi, N ; Rashidian, B ; Sharif University of Technology
Hindawi Publishing Corporation
2015
Abstract
Line nanopatterns are produced on the positive photoresist by scanning near-field optical microscope (SNOM). A laser diode with a wavelength of 450 nm and a power of 250 mW as the light source and an aluminum coated nanoprobe with a 70 nm aperture at the tip apex have been employed. A neutral density filter has been used to control the exposure power of the photoresist. It is found that the changes induced by light in the photoresist can be detected by in situ shear force microscopy (ShFM), before the development of the photoresist. Scanning electron microscope (SEM) images of the developed photoresist have been used to optimize the scanning speed and the power required for exposure, in...
A non-catalytic vapor growth regime for organohalide perovskite nanowires using anodic aluminum oxide templates
, Article Nanoscale ; Volume 9, Issue 18 , 2017 , Pages 5828-5834 ; 20403364 (ISSN) ; Waleed, A ; Gu, L ; Zhang, D ; Tavakoli, R ; Lei, B ; Su, W ; Fang, F ; Fan, Z ; Sharif University of Technology
Royal Society of Chemistry
2017
Abstract
In this work, a novel and facile synthesis process to fabricate single crystalline organometal halide perovskite nanowires has been successfully developed. Nanowires were grown in a high density ordered array from metal nanoclusters inside anodic aluminum oxide templates using a non-catalytic chemical vapor deposition method. Specifically, perovskite NWs were grown as a result of the reaction between methylammonium iodide (MAI) and the Pb/Sn (Pb or Sn) metal in anodic aluminum oxide templates under optimal conditions. The characterization results show that there is a reaction zone at the interface between the perovskite material and metal, at the bottom of the anodic aluminum oxide...
Superhydrophobic surfaces with a dual-layer micro- and nanoparticle coating for drag reduction
, Article Energy ; Volume 125 , 2017 , Pages 1-10 ; 03605442 (ISSN) ; Moosavi, A ; Nouri Borujerdi, A ; Daeian, M. A ; Vafaeinejad, S ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
We propose a facile and cost effective method for fabricating superhydrophobic surfaces with significant drag reduction in a wide velocity range. A dual structure superhydrophobic aluminum surface with a hydrophobic Al2O3micro- and nanoparticle coating and also another superhydrophobic surface with a nanoparticle layer coating are fabricated. Then, the resulted drag from each of these surfaces is measured carefully in different velocities and compared with the drag of the as-received aluminum surface. Our results reveal that the surface with the dual structure experiences drag reduction in a wider velocity range compared with the nanoparticle coated sample. Drag reduction of the dual...
Mechanism of Al-Si codeposition on In738LC through single-step diffusion process
, Article International Journal of Surface Science and Engineering ; Volume 11, Issue 1 , 2017 , Pages 1-11 ; 1749785X (ISSN) ; Abdi, M ; Rastegari, S ; Sharif University of Technology
Abstract
The out-of-pack cementation method was applied to coat the Nickel-based super alloy IN738LC with Si-modified aluminide. Different mixtures of the pack containing pure Al, Si, alumina powders as an inert filler, and NH4Cl as a halide salt activator were used for co-deposition at 950 and 1,050°C. The results showed although the amount of subhalide vapour pressures of Al and Si were equal at 1,050°C, Al atoms diffused only after Si atoms had been deposited. Before heat treatment, the coating thickness formed by the pack containing 2.3 wt.% Al was 6 μm more than that containing 3.5 wt.% Al. After heat treatment, thickening coatings formed within the pack containing 2.3 wt.% Al was less than that...
Experimental investigation of the effect of copper electrodeposition on the aluminum surface and addition of ethylene glycol on boiling heat transfer coefficient
, Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; 2021 ; 09477411 (ISSN) ; Mahdi, M ; Abarghooei, A ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
In this research, the effect of surface characteristics on boiling heat transfer has been investigated experimentally. For this purpose, a device with the ability to automatically record the liquid temperature of the inlet and outlet of the test area, calculate the coefficient of boiling heat transfer, and heat flux has been developed. The automatic temperature stability of the working fluid and the ability to investigate the effect of surfaces with different characteristics (in terms of material and surface structure) on the boiling heat transfer parameters are the most important features of this device. The performance of the experimental setup was evaluated by the modified "Chen" equation...
Experimental investigation of the effect of copper electrodeposition on the aluminum surface and addition of ethylene glycol on boiling heat transfer coefficient
, Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 58, Issue 5 , 2022 , Pages 801-812 ; 09477411 (ISSN) ; Mahdi, M ; Abarghooei, A ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
In this research, the effect of surface characteristics on boiling heat transfer has been investigated experimentally. For this purpose, a device with the ability to automatically record the liquid temperature of the inlet and outlet of the test area, calculate the coefficient of boiling heat transfer, and heat flux has been developed. The automatic temperature stability of the working fluid and the ability to investigate the effect of surfaces with different characteristics (in terms of material and surface structure) on the boiling heat transfer parameters are the most important features of this device. The performance of the experimental setup was evaluated by the modified "Chen" equation...
Corrosion resistance enhancement of Ni-P-nano SiO2 composite coatings on aluminum
, Article Applied Surface Science ; Vol. 303 , 2014 , Pages 125-130 ; ISSN: 01694332 ; Afshar, A ; Sharif University of Technology
Abstract
In this study, the influences of different concentrations of SiO 2 nano sized particles in the bath on deposition rate, surface morphology and corrosion behavior of Ni-P-SiO2 Composite coatings were investigated. The deposition rate of coating was influenced by incorporation of SiO2 particles. The microstructure was investigated with field emission scanning electron microscopy (FESEM). The amount of SiO 2 was examined by Energy Dispersive Analysis of X-Ray (EDX) and amount of SiO2 nanoparticles co-deposited reached a maximum value at 4.5 %wt. Corrosion behavior of coated aluminum was evaluated by electrochemical impedance spectroscopy (EIS) and polarization techniques. The results...
Thermo-mechanical stress analysis of thermal barrier coating system considering thickness and roughness effects
, Article Surface and Coatings Technology ; Vol. 243 , 2014 , pp. 91-99 ; ISSN: 02578972 ; Azadi, M ; Farrahi, G. H ; Sharif University of Technology
Abstract
Cast aluminium-silicon alloy, A356.0, is widely used in automotive and aerospace industries because of its outstanding mechanical, physical, and casting properties. Thermal barrier coatings can be applied to combustion chamber to reduce fuel consumption and pollutions and also improve fatigue life of components. The purpose of the present work is to simulate stress distribution of A356.0 under thermo-mechanical cyclic loadings, using a two-layer elastic-visco-plastic model of ABAQUS. The results of stress-strain hysteresis loop are validated by an out of phase thermo-mechanical fatigue test. Different thicknesses from 300 to 800. μm of top coat and also roughness of the interfaces are...
Effect of NaOH on the structure and corrosion performance of alumina and silica PEO coatings on aluminum
, Article Journal of Materials Engineering and Performance ; Volume 21, Issue 10 , October , 2012 , Pages 2195-2202 ; 10599495 (ISSN) ; Ehteshamzadeh, M ; Mirhosseini, S. M. M ; Sharif University of Technology
Springer
2012
Abstract
The effect of NaOH content of electrolyte on the properties of ceramic coatings, produced in silicate solution, was studied. Morphology, chemical analysis, phase composition, and cross-section of the ceramic coatings were investigated by SEM, EDS, XRD, and OM, respectively. The corrosion resistance and corrosion mechanism were also studied using potentiodynamic polarization and electrochemical impedance spectroscopy in a 3.5% NaCl solution. To study the surface roughness, a brightness SEM image analysis method was used. Results suggested that increasing the NaOH concentration of sediment production size causes thickness and coating roughness to decrease. The lowest corrosion rate belonged to...
Enhanced corrosion resistance of porous NiTi with plasma sprayed alumina coating
, Article Corrosion Engineering Science and Technology ; Volume 50, Issue 8 , 2015 , Pages 595-600 ; 1478422X (ISSN) ; Akbarinia, S ; Mohammadyani, D ; Sadrnezhaad, S. K ; Sharif University of Technology
Maney Publishing
2015
Abstract
In this study, corrosion behaviour of porous NiTi modified by plasma sprayed alumina coating has been investigated. Scanning electron microscopy and X-ray diffraction techniques were applied for the morphology and microstructure characterisation, while linear sweep voltammetry and electrochemical impedance spectroscopy were used for investigation of corrosion behaviour of coated and uncoated NiTi specimens. Induced couple plasma was conducted to measure ion release of the specimens in simulated body fluid at 37°C. The plasma sprayed Al2O3 coating on the porous NiTi improved the surface characteristics for biomedical applications. The alumina coating significantly hampered Ni ion release from...
Tribological properties of Ni–P–SiO2 nanocomposite coating on aluminum
,
Article
Colloid Journal
;
Volume 77, Issue 5
,
September
,
2015
,
Pages 628-634
;
1061933X (ISSN)
; Afshar, A
; Jazani, M. A
;
Sharif University of Technology
Maik Nauka Publishing / Springer SBM
2015
Abstract
In this study, the effects of different concentrations of SiO2 nanosized particles in the bath on deposition rate, surface morphology and wear behavior of Ni–P–SiO2 composite coatings were investigated. The rate of coating deposition was influenced by the incorporation of SiO2 particles. The observations of microstructural morphology were performed with field emission scanning electron microscopy. The amount of deposited SiO2 was examined by X-ray energy dispersive analysis. The results showed that for the coating produced at 12.5 g/L of nanoparticles, the amount of co-deposited SiO2 nanoparticles and microhardness reached their maximal...
Structural ordering, morphology and optical properties of amorphous AlxIn1- xN thin films grown by plasma-assisted dual source reactive evaporation
, Article Journal of Alloys and Compounds ; Volume 632 , May , 2015 , Pages 741-747 ; 09258388 (ISSN) ; Ganesh, V ; Mehdipour, H ; Nazarudin, N. F. F ; Goh, B. T ; Shuhaimi, A ; Rahman, S. A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Amorphous aluminum indium nitride (AlxIn1- xN) thin films were deposited on quartz substrates by plasma-assisted dual source reactive evaporation system. In-rich (x = 0.10 and 0.18) and Al-rich (x = 0.60 and 0.64) films were prepared by simply varying an AC voltage applied to indium wire. The X-ray-diffraction patterns revealed a small broad peak assigned to Al0.10In0.90N (0 0 2) plane, but no perceivable peaks assigned to crystalline AlxIn1- xN were observed for the films with x = 0.18, 0.60 and 0.64. The morphology of the film was changed from clusters of small grains to uniformly shaped particles with decrease of x. The band gap energy of the films increased from 1.08 eV to 2.50 eV as the...
Damage prediction for un-coated and coated aluminum alloys under thermal and mechanical fatigue loadings based on a modified plastic strain energy approach
, Article Materials and Design ; Volume 66, Issue PB , 2015 , Pages 587-595 ; 02613069 (ISSN) ; Farrahi, G. H ; Winter, G ; Huter, P ; Eichlseder, W ; Sharif University of Technology
Abstract
In this article, a novel energy-based lifetime prediction model has been presented for uncoated and coated aluminum alloys, subjected to thermal and mechanical fatigue loadings. For this objective, isothermal and thermo-mechanical fatigue tests were performed on the A356.0 alloy, with and without thermal barrier coating systems. This model, which was based on the plastic strain energy, had three correction factors including temperature, strain and mean stress effects. The predicted lifetime showed a proper agreement with experimental data. By the present model, higher accuracy was obtained in comparison to other existed approaches. Besides, the present model had lower number of material...
Modification of nanostructured anodized aluminum coatings by pulse current mode
, Article Surface and Coatings Technology ; Volume 278 , 2015 , Pages 48-55 ; 02578972 (ISSN) ; Afshar, A ; Sharif University of Technology
Elsevier
2015
Abstract
In this study, the effects of pulse current mode on corrosion resistance and mechanical properties of anodized coatings were explored. Thickness and hardness measurements, polarization and electrochemical impedance spectroscopy were employed to take mechanical and corrosion behaviors of the anodized coatings into consideration. Also, field-emission scanning electron microscopy (FE-SEM) was utilized to characterize the surface morphology of the coatings. It was shown that in short anodizing times, coating thickness is controlled by the heat concentrated on coating. Although at prolonged anodizing times, the coating thickness is affected by average current density. Hardness measurements showed...