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The Structure and Corrosion Behavior of Synthesized Zn-SiO2 Nano-composite Coating by Sol-Gel Method
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Zinc–silicanano-composite coatings were produced by successive dip coatand sintering procedure from different sol-gel solutions. The surface and cross-sectional morphologies of Zn-SiO2 nano-particles (NPs) were examined using field emission scanning electron microscopy (FE-SEM). Corrosion resistance evaluated by means of polarization and electrochemical impedance spectroscopy showed that even thin films of Zn-SiO2 in orders of 200 nm can have corrosion rates as low as conventional hot dip galvanized steels. Multi-layers coatings have been studied and showed that 10 layers coating with the thickness of 2m has the lowest corrosion rate with the passive region in anodic branch. Corrosion...
A Study on Properties of Composite Coating with Al2O3 Base Prepared by Hard Anodizing with ZrO2 Nanoparticles
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdollah (Supervisor)
Abstract
In this study anodized none composite and composite film containing ZrO2 nanoparticles were prepared on 1050 Al Alloy using hard anodizing method in sulfuric and oxalic acid mixed solution by pulse Currents. The microstructure and properties of the film were studied by field emission scanning electron microscopy with EDS analyzer and XRD diffraction and friction wear test were performed to evaluate the mechanical properties of coating . Results indicate that the composite film with ZrO2 nanoparticles have reduced friction coefficient with high micro hardness friction coefficient of composite film can be small as 0.16 which is much smaller than that 0.39 of none composite film. Micro hardness...
Recent progress in inorganic and composite coatings with bactericidal capability for orthopaedic applications [electronic resource]
, Article Nanomedicine-nanotechnology Biology and Medicine - NaoMed- NanoTechnol- Biol Med ; 2011, Vol. 7, No. 1, PP. 22-39 ; Tamjid, E ; Pishbin, F ; Boccaccini, A. R ; Sharif University of Technology
Abstract
This review covers the most recent developments of inorganic and organic-inorganic composite coatings for orthopedic implants, providing the interface with living tissue and with potential for drug delivery to combat infections. Conventional systemic delivery of drugs is an inefficient procedure that may cause toxicity and may require a patient's hospitalization for monitoring. Local delivery of antibiotics and other bioactive molecules maximizes their effect where they are required, reduces potential systemic toxicity and increases timeliness and cost efficiency. In addition, local delivery has broad applications in combating infection-related diseases. Polymeric coatings may present some...
Characterization and antibacterial performance of electrodeposited chitosan–vancomycin composite coatings for prevention of implant-associated infections [electronic resource]
, Article Journal of Materials Science and Engineering: C ; 1 August 2014, Volume 41, Pages 240–248 ; Tamjid, E ; Simchi, A. (Abdolreza) ; Sharif University of Technology
Abstract
Orthopaedic implant-associated infections are one of the most serious complications in orthopaedic surgery and a major cause of implant failure. In the present work, drug-eluting coatings based on chitosan containing various amounts of vancomycin were prepared by a cathodic electrophoretic deposition process on titanium foils. A three-step release mechanism of the antibiotic from the films in a phosphate-buffered saline solution was noticed. At the early stage, physical encapsulation of the drug in the hydrogel network controlled the release rate. At the late stage, however, in vitro degradation/deattachment of chitosan was responsible for the controlled release. Cytotoxicity evaluation of...
Long-term antibiotic delivery by chitosan-based composite coatings with bone regenerative potential
, Article Applied Surface Science ; Vol. 317, issue , 2014 , p. 56-66 ; Simchi, A ; Sharif University of Technology
Abstract
Composite coatings with bone-bioactivity and drug-eluting capacity are considered as promising materials for titanium bone implants. In this work, drug-eluting chitosan-bioactive glass coatings were fabricated by a single-step electrophoretic deposition technique. Drug-loading and -releasing capacity of the composite coatings were carried out using the vancomycin antibiotic. Uniform coatings with a thickness of ∼55 μm containing 23.7 wt% bioactive glass particles and various amounts of the antibiotic (380-630 μg/cm2) were produced. The coatings were bioactive in terms of apatite-forming ability in simulated body fluid and showed favorable cell adhesion and growth. In vitro biological tests...
The effect of material property grading on the rolling contact stress field
, Article Mechanics Research Communications ; Vol. 55, issue , 2014 , p. 45-52 ; Guler, M. A ; Adibnazari, S ; Sharif University of Technology
Abstract
This paper investigates the subsurface stress field induced by a rigid cylinder rolling over a functionally graded coating-substrate system. The Fourier transform is employed to extract the stress components within the graded coating and the homogeneous substrate. The distributions of the stresses are given through the depth and along the coating-substrate interface. The contour plots of normalized Von Mises stresses are provided as well. The results indicate that continuous variation of the shear modulus substantially reduces the difference between the in-plane stresses along the interface. Also, the softening coating leads to the minimum value of the stress concentration near the contact...
Double layer bioglass-silica coatings on 316L stainless steel by sol-gel method
, Article Ceramics International ; Volume 40, Issue 1, Part A , January 2014 , Pages 993–1000 ; Afshar, A ; Sharif University of Technology
Abstract
The application of bioglass coatings on metallic implants provides link between bone and materials and prevents corrosion of metallic implants in body fluid. Therefore, in this research, 45S5 bioglass-silica coatings on 316L stainless steel were prepared by the sol-gel method and were characterized by different techniques. According to X-ray diffraction (XRD) results, by sintering 45S5 bioglass at 600 C for 5 h, coatings containing both amorphous phase and Na2Ca2Si3O9 crystalline phase were obtained. Scanning electron microscopy (SEM) results showed that coatings prepared via appropriate sol aging and substrate preparations are crack-free. Potentiodynamic polarization tests in simulated body...
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...
Recent advances in surface engineering of superparamagnetic iron oxide nanoparticles for biomedical applications
, Article Journal of the Iranian Chemical Society ; Volume 7, Issue SUPPL. 1 , 2010 , Pages S1-S27 ; 1735207X (ISSN) ; Simchi, A ; Imani, M ; Sharif University of Technology
2010
Abstract
Superparamagnetic iron oxide nanoparticles (SPIONs) are promising materials for various biomedical applications including targeted drug delivery and imaging, hyperthermia, magneto-transfections, gene therapy, stem cell tracking, molecular/cellular tracking, magnetic separation technologies (e.g. rapid DNA sequencing), and detection of liver and lymph node metastases. The most recent applications for SPIONs for early detection of inflammatory, cancer, diabetes and atherosclerosis have also increased their popularity in academia. In order to increase the efficacy of SPIONs in the desired applications, especial surface coating/characteristics are required. The aim of this article is to review...
Recent advances in surface engineering of superparamagnetic iron oxide nanoparticles for biomedical applications
, Article Journal of the Iranian Chemical Society ; Volume 7, Issue 2 , July , 2010 , pp. S1-S27 ; 1735-2428 ; Simchi, A. (Abdolreza) ; Imani, M ; Sharif University of Technology
Abstract
Superparamagnetic iron oxide nanoparticles (SPIONs) are promising materials for various biomedical applications including targeted drug delivery and imaging, hyperthermia, magneto-transfections, gene therapy, stem cell tracking, molecular/cellular tracking, magnetic separation technologies (e.g. rapid DNA sequencing), and detection of liver and lymph node metastases. The most recent applications for SPIONs for early detection of inflammatory, cancer, diabetes and atherosclerosis have also increased their popularity in academia. In order to increase the efficacy of SPIONs in the desired applications, especial surface coating/characteristics are required. The aim of this article is to review...
Molten salt synthesis of a SiC coating on graphite flakes for application in refractory castables
, Article Ceramics International ; 2016 ; 02728842 (ISSN) ; Bavand Vandchali, M ; Golestani Fard, F ; Nemati, A ; Sharif University of Technology
Elsevier Ltd
Abstract
A silicon carbide coating was formed on the surface of graphite flakes by reaction of molten Si with carbon at 1100-1300. °C in a 95%KCl-5%NaF molten salt under Ar atmosphere. The effect of temperature and Si/graphite ratio in the initial mixture on the quality and the amount of SiC were investigated by XRD and SEM/EDS analyses. Also, the water wettability, oxidation resistance and zeta potential of un-coated and coated graphite were examined by TGA analysis and sedimentation test. The results show the amount of coating to increase in the coated flakes with increasing temperature and Si/graphite ratio. The SiC coating improves water wettability of graphite and acts as a protective layer to...
MCDM selection of pulse parameters for best tribological performance of Cr–Al2O3 nano-composite co-deposited from trivalent chromium bath
, Article Journal of Alloys and Compounds ; Volume 727 , 2017 , Pages 286-296 ; 09258388 (ISSN) ; Salehi Doolabi, M ; Sadrnezhaad, S. K ; Zafarani, H. R ; Salehi Doolabi, D ; AsadiZarch, M ; Sharif University of Technology
Abstract
Optimum operating parameters for pulse co-deposition of nano-Al2O3 with Cr from a trivalent chromium bath onto Cu cathode are selected by using “technique for order performance by similarity to ideal solution” (TOPSIS), “VIšekriterijumsko KOmpromisno Rangiranje” (VIKOR), “elimination and choice expressing the reality” (ELECTRE) and “complex proportional assessment” (CORPAS) accompanied with analytic hierarchy processing (AHP) to compare methods for achievement of the best tribological coating performance. Criteria for appropriate selection include wear loss, corrosion resistance, micro-hardness, bath condition and current efficiency. Results ascertain the best Cr–Al2O3 nano-composite coating...
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...
Global sensitivity analysis of backside coating parameters on dynamic response of AM-AFM
, Article Mechanika ; Volume 23, Issue 2 , 2017 , Pages 282-290 ; 13921207 (ISSN) ; Zohoor, H ; Habibnejad Korayem, M ; Sharif University of Technology
Kauno Technologijos Universitetas
2017
Abstract
Influence of backside coating parameters on dynamic response of AM-AFM is modeled. Timoshenko based beam model is used and the general nonlinear interaction force is enclosed. The coupled ODEs of motion are achieved. The mode shapes are determined for coated cantilever and the natural frequency of each mode is validated with experimental results. It is showed a shorter cantilever with tip mass have better accuracy and inelastic and massless assumptions are not proper choice for modelling of the coating. The assumed mode method is used to determine time response of system for faraway and scanning condition of AM-AFM. Amplitude of response is calculated by FFT of time domain. Sensitivity...
Microstructural investigation of the coatings prepared by simultaneous aluminizing and siliconizing process on γ-TiAl
, Article Journal of Mining and Metallurgy, Section B: Metallurgy ; Volume 55, Issue 2 , 2019 , Pages 217-225 ; 14505339 (ISSN) ; Azadeh, M ; Sharif University of Technology
Technical Faculty in Bor
2019
Abstract
In this research, formation of aluminide/silicide diffusion coatings on γ -TiAl[Ti-48Al-2Nb-2Cr (at.%)] alloy using gasphase diffusion pack cementation process has been investigated. The application of powder mixtures with various chemical compositions in the pack cementation process performed at 1000°C for 6 hours in order to achieve simultaneous diffusion of Al and Si, showed that the composition of the powder mixture could have a significant effect on the structure and thickness of the aluminide/silicide coatings. The identification and analysis of aluminide/silicide microstructures formed as a result of simultaneous diffusion of Al and Si, which was comprehensively and qualitatively done...
Investigation of interfacial and mechanical properties of alumina-coated steel fiber reinforced geopolymer composites
, Article Construction and Building Materials ; Volume 288 , 2021 ; 09500618 (ISSN) ; Nemati, A ; Khodabandeh, A. R ; Baghshahi, S ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In this study, alumina coated steel reinforced geopolymer composites were successfully fabricated and their interfacial and mechanical properties were investigated. The fiber–matrix interface characteristics were assessed using single-fiber push-out and water contact angle experiments as well as SEM-EDS analysis. Finally, the role of alumina coating on the compressive, flexural and toughness of the geopolymer composites was investigated. The morphological studies revealed that alumina coating on steel can chemically bonded and microstructurally integrated with the surrounding matrix. The push-out test showed that the interfacial shear strength was increased approximately 150% in composites...
In vitro study: Evaluation of mechanical behavior, corrosion resistance, antibacterial properties and biocompatibility of HAp/TiO2/Ag coating on Ti6Al4V/TiO2 substrate
, Article Surfaces and Interfaces ; Volume 24 , 2021 ; 24680230 (ISSN) ; Asadpourchallou, N ; Koozegar Kaleji, B ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Biocompatibility materials such as Ti6Al4V alloy have many medical applications, but their corrosion resistance and antibacterial properties are low, which limits their medical application. Therefore, to improve these challenges in this study, HAp + 15 wt% TiO2 + 5 wt% Ag nanocomposite coating was applied on Ti6Al4V/TiO2 substrate by sol-gel dip method and sintered at 550 °C. The TiO2 layer was pre-formed on the Ti6Al4V substrate using the gel-sol process. The results showed that the nanocomposite was synthesized correctly, and the particle size was in range of 40–90 nm. The evaluation of the coatings developed showed that TiO2/HAp + 15 wt% TiO2 + 5 wt% Ag coating had higher adhesion...
In vitro study: Evaluation of mechanical behavior, corrosion resistance, antibacterial properties and biocompatibility of HAp/TiO2/Ag coating on Ti6Al4V/TiO2 substrate
, Article Surfaces and Interfaces ; Volume 24 , 2021 ; 24680230 (ISSN) ; Asadpourchallou, N ; Koozegar Kaleji, B ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Biocompatibility materials such as Ti6Al4V alloy have many medical applications, but their corrosion resistance and antibacterial properties are low, which limits their medical application. Therefore, to improve these challenges in this study, HAp + 15 wt% TiO2 + 5 wt% Ag nanocomposite coating was applied on Ti6Al4V/TiO2 substrate by sol-gel dip method and sintered at 550 °C. The TiO2 layer was pre-formed on the Ti6Al4V substrate using the gel-sol process. The results showed that the nanocomposite was synthesized correctly, and the particle size was in range of 40–90 nm. The evaluation of the coatings developed showed that TiO2/HAp + 15 wt% TiO2 + 5 wt% Ag coating had higher adhesion...
Atmospheric corrosion evaluation of silver coating using simulating technique test
, Article European Corrosion Conference: Long Term Prediction and Modelling of Corrosion, EUROCORR 2004, Nice, 12 September 2004 through 16 September 2004 ; 2004 ; Afshar, A ; Sharif University of Technology
2004
Abstract
A standard simulating technique test was investigated to assess the atmospheric corrosion behavior of silver coating. The rates of formation of corrosion products were measured in the simulating atmospheres of 100% humidity containing SO 2,H 2S and a complex atmosphere consist of SO 2,H 2S and NO 2 gases ,based on the mass increase method. The concentrations of corrosive gases were chosen according to real world conditions. XRD, SEM and EDS were used to examine the morphology and to determine the composition of the corrosion products under different experimental conditions. Results revealed the formation of Ag 2SO 4 and Ag 2S on the silver coating surfaces in the SO 2 and H 2S containing...
Investigation and Optimization of Ni-P-Zn Electroless Alloy Coatings
, M.Sc. Thesis Sharif University of Technology ; karam, SaeedAllah (Supervisor) ; Dolati, Abolghasem (Supervisor)
Abstract
An optimization condition for obtaining Ni-Zn-P electroless alloy coating has been developed. The sulphate bath with sodium hypophosphate as a reducer and sodium citrate and ammonium chloride as complexing agents were used. The effect of variation in the pH level , temperature , time of deposition and reactants concentration on stability of bath, coating composition, microstructure, microhardness and corrosion resistance of coatings was investigated. The composition of coatings was obtained by using the EDAX analysis. To investigate coating morphology, SEM images were taken and to study the corrosion behavior of coatings potentidynamic polarization, Electrochemical Impedance Spectroscopy...