Search for: coating
Total 639 records
Microstructure-corrosion resistance relationship of Direct and Pulse Current electrodeposited Zn-TiO2 nanocomposite coatings, Article Ceramics International ; Vol. 41, issue. 1 , 2014 , pp. 217-224 ; ISSN: 02728842 ; Ghorbani, M ; Afshar, A ; Sharif University of Technology
Zinc-TiO2 nano-composite coatings were synthesized by Direct Current (DC) and Pulse Current (PC) electrodeposition techniques. The effects of the plating parameters on the microstructure, codeposition percentage of TiO2 and corrosion behavior were investigated. The coatings morphology presents hexagonal grains perpendicularly oriented to the surface. Under DC conditions, TiO2 content of the coatings decreased with increasing TiO2 concentration of the electrolyte. Increasing applied current and TiO2 concentration in the bath leads to a fine microstructure with corrosion currents as low as 2.7 μA/cm2. Under PC conditions, incorporation rate of nanoparticles tends to increase with increasing...
Corrosion behaviour of Ni-Co alloy coatings at Kish Island (marine) atmosphere, Article Bulletin of Materials Science ; Vol. 37, issue. 3 , May , 2014 , p. 713-719 ; Ghorbani, M ; Sharif University of Technology
In this study, the corrosion behaviour of Ni-Co alloys with low Co content, electroplated on steel substrate in sulphate bath, was investigated. The morphology of coatings was studied by optical and SEM microscopy. The corrosion products were analyzed using EDX. The results showed that Ni-1%Co coatings had a better corrosion resistance 0.30, 0.92 and 3.75 mpy for atmospheric, salt spray and polarization tests, respectively. These are 0.41, 1.20 and 5.40 mpy for pure nickel coatings that indicate the least corrosion resistance. Surface analysis revealed the presence of oxides, sulphides and chlorides in corrosion products
Photocathodic protection of 316L stainless steel by coating of anatase nanoparticles, Article Protection of Metals and Physical Chemistry of Surfaces ; Volume 49, Issue 1 , January , 2013 , Pages 109-112 ; 20702051 (ISSN) ; Faghihi Sani, M. A ; Ghasemi, H ; Sharif University of Technology
Uniform nanostructure anatase films were coated on 316L stainless steel by the sol-gel dip coating method. Sols with different values of pH were applied. The corrosion protective behavior of coated samples was investigated by electrochemical measurements in 0.5 molar NaCl solutions on samples placed under UV illumination and dark condition using Tafel curves. It was found that in addition to acting as a physical barrier, anatase thin films are more protective under UV illumination due to photocathodic protection. Neutral sols give better protection due to formation of more uniform and less defective coatings
Effects of various parameters on the coating of substrates with trenches, Article 2012 International Conference on Advanced Materials Design and Mechanics, ICAMDM 2012, Xiamen, 5 June 2012 through 7 June 2012 ; Volume 569 , 2012 , Pages 219-222 ; 10226680 (ISSN) ; 9783037854808 (ISBN) ; Moosavi, A ; Sharif University of Technology
We investigate thin liquid film coating of substrates with trenches via lattice Boltzmann method. The effects of different parameters such as the capillary number, the contact angles and geometric parameters on the results are studied. Our results indicate that for trench depths greater than a critical size coating of the trench is not successful. The critical depth increases by decreasing the capillary number. Moreover we find height, width, capillary number and contact angle under which the coating is successful. The results have been compared with the available results and very close agreement has been achieved
MAO-derived hydroxyapatite/TiO 2 nanostructured multi-layer coatings on titanium substrate, Article Applied Surface Science ; Volume 261 , 2012 , Pages 37-42 ; 01694332 (ISSN) ; Golestani Fard, F ; Rezaie, H. R ; Mirhosseini, S. M. M ; Sharif University of Technology
In this study, titanium substrates which previously oxidized through Micro arc oxidation method, was coated by Hydroxyapatite (HAp) coating once more by means of the same method. Morphology, topography and chemical properties as well as phase composition and thickness of layers were studied to reveal the effect of the electrolyte concentration on coating features. According to results, the obtained coatings are consisted of HAp and titania as the major phases along with minor amounts of calcium titanate and α-tri calcium phosphate. Ca and P are present on surface of obtained layers as well as predictable Ti and O based on the XPS results. Thickness profile of coatings figured out that by...
On the rolling contact problem of two elastic solids with graded coatings, Article International Journal of Mechanical Sciences ; Volume 64, Issue 1 , 2012 , Pages 62-81 ; 00207403 (ISSN) ; Alinia, Y ; Adibnazari, S ; Sharif University of Technology
In this study, the rolling contact problem of two elastically similar cylinders coated with functionally graded materials is investigated. The singular integral equations approach is utilized to extract the governing equations of the problem. The governing equations are discretized into systems of algebraic equations by virtue of the Gauss-Chebyshev integration method. Comprehensive parametric study is performed to examine the effects of mechanical properties, coating thickness and external loads on the surface stress components, stick/slip transition, creep ratio and power loss. This study aimed to emphasize the capability of graded materials in improving the rolling contact fatigue of...
Surface modification for titanium implants by hydroxyapatite nanocomposite, Article Caspian Journal of Internal Medicine ; Volume 3, Issue 3 , 2012 , Pages 460-465 ; 20086164 (ISSN) ; Solati Hashjin, M ; Nik, S. N ; Nemati, A ; Sharif University of Technology
Background: Titanium (Ti) implants are commonly coated with hydroxyapatite (HA). However, HA has some disadvantages such as brittleness, low tensile strength and fracture toughness. It is desirable to combine the excellent mechanical properties of ZrO 2 and the chemical inertness of Al 2O 3 with respect to the purpose of this project which was coating Ti implants with HA-ZrO 2-Al 2O 3 to modify the surface of these implants by adding ZrO 2 and Al 2O 3 to HA. The purpose of this study was to evaluate the efficacy of hydroxyapatite coating nonocomposite. Methods: From September 2009 to January2011, functionally graded HA-Al 2O 3-ZrO 2 and HA coatings were applied on Ti samples. HA-Al 2O 3-ZrO...
Fabrication of low friction bronze-graphite nano-composite coatings, Article Materials and Design ; Volume 32, Issue 6 , 2011 , Pages 3548-3553 ; 02641275 (ISSN) ; Ghorbani, M ; Alfantazi, A ; Farhat, Z ; Sharif University of Technology
This paper addresses the fabrication of bronze-nano-graphite coatings containing 30. nm sized graphite particles. Addition of Poly Vinyl Pyrrolidone (PVP) and dispersing the suspension by ultrasound was utilized to stabilize the electroplating solution. Pulsed current electrodeposition was used and the deposits were characterized in terms of graphite content, particle dispersion in coating and morphology. The wear behavior of the coating was compared to bronze-micro-graphite coatings prepared with the same experimental conditions. The present coating showed improved wear resistance in comparison to bronze-micro-graphite coatings at the same graphite content
Zn-Ni Electrophosphating on galvanized steel using cathodic and anodic electrochemical methods, Article Surface and Coatings Technology ; January , 2015 ; 02578972 (ISSN) ; Afshar, A ; Aliabadi, A ; Sharif University of Technology
Electrophosphating is the novel method for accelerating the low temperature phosphating bath. This method can be performed as cathodic and anodic treatments. Both of them influence the coating deposition mechanism and therefore coating properties. In this study Zn-Ni electrophosphate coating was applied on galvanized steel using cathodic and anodic electrochemical methods. Microstructure, composition and corrosion resistance of coating were characterized by using a scanning electron microscopy, X-ray diffraction method and potentiodynamic polarization test respectively. The results of this study indicated that, by using cathodic method, compact phosphate coating with high corrosion...
Effect of current density on DC electrochemical phosphating of stainless steel 316, Article Surface and Coatings Technology ; Volume 205, Issue 7 , December , 2010 , Pages 2302-2306 ; 02578972 (ISSN) ; Afshar, A ; Hasannejad, H ; Sharif University of Technology
In this study, tri-cation phosphate coating of zinc, calcium and iron was applied electrochemically to stainless steel 316 substrates. Cathodic current was used as an accelerator for the phosphating process. The effects of current density on the microstructures of the coatings and the time necessary for the reduction of the oxide layer have been established. For this purpose, analyses such as chronopotentiometery, SEM, EDS and linear polarization were carried out. Results indicated that higher electrophosphating current densities result in finer crystal size of the coating. This effect is detrimental to the quality of the layer. In addition, chemical analyses of the layer revealed that the...
Zn–Ni electrophosphating on galvanized steel using cathodic and anodic electrochemical methods, Article Surface and Coatings Technology ; Volume 306 , 2016 , Pages 497-505 ; 02578972 (ISSN) ; Afshar, A ; Aliabadi, A ; Sharif University of Technology
Elsevier B.V 2016
Electrophosphating is the novel method for accelerating the low temperature phosphating bath. This method can be performed as cathodic and anodic treatments. Both of them influence the coating deposition mechanism and therefore coating properties. In this study Zn–Ni electrophosphate coating was applied on galvanized steel using cathodic and anodic electrochemical methods. Microstructure, composition and corrosion resistance of coating were characterized by using a scanning electron microscopy, X-ray diffraction method and potentiodynamic polarization test respectively. The results of this study indicated that, by using cathodic method, compact phosphate coating with high corrosion...
A two-step spin-spray deposition processing route for production of halide perovskite solar cell, Article Thin Solid Films ; Volume 616 , 2016 , Pages 754-759 ; 00406090 (ISSN) ; Alizadeh, A. H ; Moshaii, A ; Gharibzadeh, S ; Alizadeh, A ; Mohammadpour, R ; Fathi, D ; Sharif University of Technology
We report on fabrication of halide perovskite solar cells using a two-step spin-spray coating rout. The applied method is one of the most straight forward procedures for fabricating uniform stoichiometry and crystalline perovskite cells. To fabricate a high quality perovskite layer, various concentrations of methyl-ammonium iodide (CH3NH3I) were sprayed on a spin coated PbI2 layer using a simple airbrush gun. The characterization results indicate that the size of cuboid perovskite morphology depends on the concentration of methylammonium iodide in the spray procedure. The photovoltaic performance of the fabricated solar cells has been measured and a high dependency on the cuboid sizes was...
Surface modifications of titanium implants by multilayer bioactive coatings with drug delivery potential: antimicrobial, biological, and drug release studies, Article JOM ; Volume 68, Issue 4 , 2016 , Pages 1100-1108 ; 10474838 (ISSN) ; Petrova Zustiak, S ; Simchi, A ; Sharif University of Technology
Recent strategies to locally deliver antimicrobial agents to combat implant-associated infections—one of the most common complications in orthopedic surgery—are gaining interest. However, achieving a controlled release profile over a desired time frame remains a challenge. In this study, we present an innovative multifactorial approach to combat infections which comprises a multilayer chitosan/bioactive glass/vancomycin nanocomposite coating with an osteoblastic potential and a drug delivery capacity. The bioactive drug-eluting coating was prepared on the surface of titanium foils by a multistep electrophoretic deposition technique. The adopted deposition strategy allowed for a high...
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
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...
Gas turbine oxidation life assessment and monitoring, Article Oxidation of Metals ; Volume 90, Issue 5-6 , 2018 , Pages 691-711 ; 0030770X (ISSN) ; Alizadeh, M ; Akheratdoost, H ; Khaledi, H ; Sharif University of Technology
Springer New York LLC 2018
Gas turbine hot-section parts can be very expensive components with a finite lifetime. Their durability is strongly dependent on the operating service conditions which control the maintenance intervals and associated expenses. Blade damage is the most frequent reason for failures in gas turbine engines and also oxidation is one of the most critical degradation mechanisms when the power system operates in partially loading condition. This paper describes the methodology of oxidation life assessment for uncoated and coated blades with various metallic coatings in the first stage of a typical gas turbine engine. The resultant weight-change curves were validated by comparing them with the...
Isothermal LCF behavior in aluminide diffusion coated Rene 80 near the DBTT, Article Materials and Design ; Volume 30, Issue 4 , 2009 , Pages 1183-1192 ; 02641275 (ISSN) ; Nategh, S ; Sharif University of Technology
Ni-base superalloys such as René 80 are widely used for aircraft turbine blades manufacture, due to possesses suitable mechanical, oxidation and hot corrosion properties. It is usually coated in order to increase its wear, oxidation, erosion and hot corrosion properties against environmental degradation. One the most important properties of coatings is its DBTT. In this paper the behavior of uncoated and coated (CODEP-B) René 80 has been studied near the DBTT (871 °C), R = (εmin/εmax) = 0 and strain rate of about 2 × 10-3 s-1. Experimental results show that in coated specimens while the total cyclic strain is lower than 1%, coating leaves longer fatigue life, at this condition the nucleation...
A new approach for preparation of semi-transparent superhydrophobic coatings by ultrasonic spray hydrolysis of methyltrimethoxysilane, Article Progress in Organic Coatings ; Volume 135 , 2019 , Pages 248-254 ; 03009440 (ISSN) ; Sabour Rouh Aghdam, A ; Nazari, M ; Bayat, A ; Saievar Iranizad, E ; Sharif University of Technology
Elsevier B.V 2019
A novel nebulizing spray hydrolysis approach was used for preparation of semi-transparent superhydrophobic coatings. Methyltrimethoxysilane was dissolved in water:ethanol mixture and ultrasonically sprayed on different substrates. Superhydrophobic coatings with a contact angle (CA) as high as 164° and a sliding angle below 5° were obtained. FESEM and AFM revealed a hierarchical micro-nano binary structure with nanometric roughness of the coatings. The coated glass substrate exhibited transmittance close to 80%. The prepared coating showed great self-cleaning and water jet repellency behaviors. The superhydrophobicity of the samples was remained after subjecting to ambient conditions for 50...
Grit blasting of Ti-6Al-4V alloy: Optimization and its effect on adhesion strength of plasma-sprayed hydroxyapatite coatings, Article Journal of Materials Processing Technology ; Volume 194, Issue 1-3 , 2007 , Pages 15-23 ; 09240136 (ISSN) ; Ziaei Moayyed, A. A ; Mesgar, A. S. M ; Sharif University of Technology
Elsevier BV 2007
The effect of grit blasting parameters on the surface roughness of Ti-6Al-4V alloy as the substrate for plasma-sprayed hydroxyapatite (HA) coatings was examined using the factorial and Taguchi designs of experiments. In this study, two grit materials (Al2O3 and SiO2) each at two sizes, and two types of blasting systems (pressure and suction) were used. An equivalent surface roughness of 3.51 μm was obtained in three optimum conditions. The results of the Taguchi designed experiments were analyzed using signal to noise ratio. The tensile bonding strength of HA coatings deposited on the roughened substrates at the three different optimum conditions was measured by the standard adhesion test...
Drag reduction in internal turbulent flow by fabricating superhydrophobic Al2O3/waterborne polyurethane coatings, Article Surface and Coatings Technology ; Volume 421 , 2021 ; 02578972 (ISSN) ; Moosavi, A ; Nouri Boroujerdi, A ; Najafkhani, H ; Najafpour, S ; Sharif University of Technology
Elsevier B.V 2021
Nowadays, increasing the CO2 emissions are one of the inevitable challenges in the world. In addition, in many industries, fossil fuels are the main source of energy demands which worsen the problem. Since in most applications, the performance and energy loss are highly affected by the drag force, many investigations have been proposed to improve the surface properties to moving surface against the water, and consequently, increasing drag reduction. To this end, one effective way is utilizing superhydrophobic coatings. In this study, we prepare two different superhydrophobic coatings using Al2O3 nanoparticles (NPs) modified by HMDS (1,1,1,3,3,3-Hexamethyldisilazane) and PDMS...
Electrodeposition and characterization of Ni-Co/SiC nanocomposite coatings, Article Journal of Alloys and Compounds ; Volume 509, Issue 39 , 2011 , Pages 9406-9412 ; 09258388 (ISSN) ; Dolati, A ; Ahmadi, M. R ; Sharif University of Technology
Ni-Co/SiC nanocomposite coatings were electrodeposited in a modified watt type of Ni-Co bath containing 20 nm SiC particles to be codeposited. Potentiodynamic polarization tests were conducted to study the effect of the SiC particulates on the electrodeposition of Ni and Co. Scanning electron microscopy was used to assess the morphology of the Ni-Co alloy and Ni-Co/SiC nanocomposite coatings. The distribution of the particulates in the matrix was considered by means of transmission electron microscopy. Applying nanomechanical testing instruments coupled to atomic force microscopy, mechanical properties of the alloy and composite coatings were studied and compared. The presence of 11 vol.%...