Loading...
Search for:
coating
0.008 seconds
Total 688 records
Simulation of melt flow in coated mould cavity in the casting process
, Article Journal of Materials Processing Technology ; Volume 142, Issue 2 , 2003 , Pages 493-507 ; 09240136 (ISSN) ; Esmaeileian, H ; Serajzadeh, S ; Varahram, N ; Davami, P ; Sharif University of Technology
2003
Abstract
In this investigation, simulation of the 3D flow of incompressible molten metal in a mould cavity has been carried out. A code has been developed to include heat transfer and permeability of coating utilizing the finite difference method (FDM). To achieve this, solid and free boundary conditions have been modified and a new algorithm has been proposed to calculate the effect of coating permeability during mould filling. In this algorithm, the effect of coating permeability on the filling pattern has been modelled and compared with an experiment. The modelling of molten metal flow and the location of free surfaces has been simulated based on the SOLution Algorithm-Volume Of Fraction...
Percolation of cadmium across a mercury film
, Article Materials Chemistry and Physics ; Volume 78, Issue 3 , 2003 , Pages 796-799 ; 02540584 (ISSN) ; Gobal, F ; Sharif University of Technology
2003
Abstract
Electrodeposition/dissolution of cadmium onto a film of mercury shows some deviations from the natural liquidity of mercury caused by the reduction of Cd onto it. Percolation and fractal analyzes were done on the surface and the bulk of the mercury film during diffusion of Cd species (atoms). These show that the fractal dimensions of the Cd-inserted mercury film are about 2.11 and 2.54 near the surface of the mercury film and at deeper points inside the film, respectively. The insertion process has a negligible effect on the surface morphology of the mercury film and there is a phase transition in the bulk, as well as a geometrical transition during the Cd-insertion (de-insertion) process....
Anodizing of titanium in NaOH solution and its corrosion resistance in PBS physiologic solution
, Article Scientia Iranica ; Volume 10, Issue 3 , 2003 , Pages 361-366 ; 10263098 (ISSN) ; Vaezi, M. R ; Sharif University of Technology
Sharif University of Technology
2003
Abstract
Titanium is a highly reactive metal with an inclination to compose with oxygen. In order to increase its corrosion resistance and application, therefore, a thin layer of titanium oxide is produced on the surface by chemical and electrochemical methods. In the present research, titanium has been anodized in 20 M of NaOH solution under potentiostatic conditions at constant voltages of 25 and 35 V. The microstructure of the anodic layers has been studied by the use of a Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD). The results indicated that the structure of the anodic layers is amorphous with low porosity and that thickness increases with an increase in anodizing voltage. The...
Electrodeposition of graphite-brass composite coatings and characterization of the tribological properties
, Article Surface and Coatings Technology ; Volume 148, Issue 1 , 2001 , Pages 71-76 ; 02578972 (ISSN) ; Mazaheri, M ; Khangholi, K ; Kharazi, Y ; Sharif University of Technology
2001
Abstract
Co-deposition of Cu(Zn) and graphite powders with size less than 10 μ was studied. Electrocomposite coatings were prepared by means of the conventional electrodeposition (CECD) and the sediment co-deposition (SCD) techniques. Brass electroplating cyanide bath has been selected out of electrodeposition brass. The effect of parameters such as rate of agitation and current density on the composition of electrodeposition brass and also the effect of the concentration of graphite particles in brass bath, air agitation rate on graphite incorporation within brass matrix and deposition efficiency were studied. The wear and friction properties of G-Cu(Zn) composite coatings containing different...
Synthesis and Investigation of Hybrid Nanoparticles Based on Metal-Organic Framework on the Properties of Polymeric Coatings
, M.Sc. Thesis Sharif University of Technology ; Shojaei, Akbar (Supervisor) ; Molavi, Hossein (Co-Supervisor) ; Nematollahzadeh, Ali (Co-Supervisor)
Abstract
In this study, MOF / PAN hybrid nanoparticles have been used as active anti-corrosion inhibitors for the first time. At first, UIO-66, PANI, and hybrid nanoparticles were synthesized based on different weight percentages of UIO-66. Their functional groups, crystal structure, nanoparticle morphology, porosity structure, stability and thermal performance were investigated using FT-IR, XRD, FE-SEM, BET, and TGA analyses, respectively. The type of nanoparticle structure formation was investigated by TEM images. The particle size distribution along with their surface charge was determined using DLS analysis. Inhibitory properties of nanoparticles were evaluated by TOEFL polarization method and...
The Effect of Pomegranate Peel Extract as a Green Anti-corrosion Agent and Aluminium Oxide Nanostructured Containing Sulfur on the Anticorrosion
Performance of Epoxy Coating
,
M.Sc. Thesis
Sharif University of Technology
;
Ramazani Saadatabadi, Ahmad
(Supervisor)
Abstract
The present work focuses on the sustainable development of an intelligent self-healing anticorrosion coating using nanocontainers based on the aluminium oxide nanostructure-pomegranate peel extract-Ce3+ (Ce-PPE@Cat). The Ce-PPE@Cat nanopigment was introduced into the epoxy film (Ep) to achieve a smart barrier/ self-healing anti-corrosive property. To this end, a couple of characterization tests, including FT-IR, TGA, and, BET have been carried out to investigate the Ce-PPE@Cat nanopigment structure/composition. The effectiveness of the anti-corrosion performance of the established coatings was confirmed by EIS, FE-SEM, and accelerated salt spray test. Furthermore, EIS studies revealed that...
Investigating the Microstructure, Mechanical Properties and Corrosion Resistance of Biodegradable Mg-Li-Zn Alloys
, M.Sc. Thesis Sharif University of Technology ; Alizadeh, Reza (Supervisor) ; Tavakoli, Rouhollah (Co-Supervisor)
Abstract
Due to its biodegradability, magnesium can be a good option for making degradable medical implants that disappear in the body over time and thus there would be no need for secondary surgery. However, high rate of corrosion of magnesium in the body environment and low formability at room temperature are the two main problems of magnesium, which lead to rapid destruction of the sample in a short time and serious problems. For these reasons, much research is currently being done to improve the corrosion behavior and mechanical properties of magnesium alloys through microstructure modification. In this regard, special attention has been paid to Mg-Li alloys as the lightest magnesium alloys. The...
Fabrication and Characterization of Electrochemical Properties of Porous Ni and Ni/rGO Nanocomposite by Electrochemical Deposition for Pseudocapacitor Application
, M.Sc. Thesis Sharif University of Technology ; Abachi, Parvin (Supervisor) ; Dolati, Abolghasem (Supervisor)
Abstract
Fabrication of porous hybrid coatings, specially in combination with carbon compounds, can improve the electrochemical behavior of the coating. In this study, graphene oxide (GO) was first synthesized by tour method. After examining different methods to create a porous coating, the electrochemical coating method for simultaneous deposition of GO and nickel on the copper substrate was selected. CTAB was used to form nanometer porosity in the coating structure. In order to investigate the effect of GO on the properties of the deposited coating, two porous coatings of nickel (Ni) and nickel reduced-graphene oxide (Ni-rGO) were investigated by different analyzes. These analyzes include FESEM...
Electrochemical Deposition of Zinc/Nickel Multilayer Coating and Investigating the Effect of Morphology and Phase Structure on the Dissolution of Zinc/Nickel Alloy Coating
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
The multilayer coating (Zn-Ni)1/(Zn-Ni)2 is deposited from a single bath with a zincate-sulfate compound and by changing the current density. The effect of current density and the number of layers on the chemical composition, surface morphology, roughness, phase structure, and corrosion resistance of multilayer coatings respectively using atomic absorption spectroscopy, FE-SEM microscope, roughness tests, X-ray analysis, and electrochemical techniques such as Tafel polarization and impedance was investigated and compared with single-layer coatings. Because the amount of nickel in the composition of the coatings is less than 27%, in all the studied currents, the deposition is anomalous. The...
Development of Nanostructured Lithium-Rich Cathode Material
, Ph.D. Dissertation Sharif University of Technology ; Sadrnezhaad, Khatiboleslam (Supervisor)
Abstract
This research is divided in three parts. In the first part of this research, we report the one-pot synthesis of carbonate-coated nanostructured LLO (Li2CO3@LLO) through a polyol-assisted method as a Li-ion battery cathode. Carbonate protects the cathode from adverse reactions with the electrolyte, also reduces the layered-to-spinel phase transition, thereby stabilizing the cathode structure. LLO nanostructure provides a fast Li+ diffusion. The target material exhibits excellent long-term stability with 77% capacity retention after 1000 cycles at 0.2C-rate. In the second part of research, Li(Na-doped)-Mn-Ni-O oxides were synthesized by different LiOH.H2O amount, type and amount of reducing...
Optimization of Morphology in Order to Produce Polypropylene Antistatic Fiber Containing Polyaniline
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor)
Abstract
In this study, the synthesis conditions of polyaniline were optimized in order to produce a blend based on polypropylene (PP) containing polyaniline (PANI) with the electrical conductivity in the antistatic range. A form of PANI that has adequate electrical conductivity and thermal stability, which is suitable for melt-mixing and melt-spinning conditions, was synthesized. Thermal stability and electrical conductivity of polyaniline were investigated by thermal gravimetric analysis (TGA), differential calorimetric analysis (DSC) and high-temperature electrical conductivity. It was found that the synthesized PANI has required thermal stability and electrical conductivity (106 ohm.cm) at the...
Deposition and Properties of ZIF-8/SiO2 Hydrophobi Anti-Corrosion Coating
, M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem (Supervisor)
Abstract
In this research, a coating was created on the steel surface using the network structure of zeolite imidazolate-8 (ZIF-8) and its effect on the corrosion behavior of steel was investigated. Then, the effect of two coupling agents, mercaptopropyltriethoxysilane (MPTES) and aminopropyltriethoxysilane (APTES) on the coating and its anti-corrosion properties was investigated. Then, in order to make a hydrophobic coating, the substrate was first coated with ZIF-8 and then a combination of silica nanoparticles plus hexamethyldisilazane (HMDS) and polymethylhydrogensiloxane (PMHS) was added to the initial solution and then coating was done. As a result of this process, the contact angle of water...
Investigation And Fabrication Super Hydrophobic Coating On Building Facades
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdullah (Supervisor)
Abstract
According to the creation of high-rise buildings and structures due to the increase in urbanization and population concentration in cities and attention to the beauty of these structures and the impact of this beauty on the morale of urban people, owners or municipalities costs a lot of money for cleaning the building facade every year. On the other hand, removing contaminants from high-rise buildings facades is difficult and lifethreatening. Today, with the advancement of science and the use of self-cleaning super hydrophobic coatings, many of these costs, as well as threats to life, can be prevented. On the other hand, protection of ancient structures as a cultural capital of a country,...
Fabrication and Evaluation of Anti-Corrosion Properties of Epoxy/Modified Graphitic Carbon Nitride (g-3N4) Nanocomposite on Mild Steel
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadatabadi, Ahmad (Supervisor)
Abstract
In order to protect the corrosion of steel, a self-healing epoxy nanocomposite containing modified graphite carbon nitride (g-C3N4) and ZIF-67 was made along with benzotriazole (BTA) and cerium inhibitors. To increase the efficiency and also to increase the duration of use of inhibitors, it is better to load these inhibitors on containers such as MOFs. One of the useful MOFs for this purpose is ZIF-67, which has a high specific surface area that allows the transport of inhibitors with high capacity. But these containers fail after some time, so to improve the physical properties of the coating systems, g-C3N4 was also used as a mineral material, which of course was also used as a filler....
Production of New Nanocomposites for Neutron and Gamma Shielding and Modeling of the Attenuation Phenomena Using Computational Methods
, M.Sc. Thesis Sharif University of Technology ; Outokesh, Mohammad (Supervisor) ; Vosoughi, Naser (Supervisor) ; Kiani, Mohammad Amin (Co-Supervisor)
Abstract
If nuclear radiation is not weakened and absorbed, it can cause serious damage to human devices or the environment. Dual-purpose dry casks are one of the sources of nuclear radiation production as a place to keep the spent fuel assemblies. One of the ways to protect against them is to use shield. One of the most common of them is composite shield. The composite used in this study has a polymer matrix. The matrix of the used polymer is epoxy resin. In this study, two separate composites have been made to attenuate neutron and gamma radiation. In this thesis, first, by using the MCNPX code, the necessary simulations for the design and construction of composite shields have been carried out....
In-Situ Synthesis of Zif-8 Nanocomposite Coating on Carbon Steel and Investigating the Effect of Adding Mbt on Corrosion Behavior and Sic Nanoparticles on Mechanical Properties
, M.Sc. Thesis Sharif University of Technology ; Abachi, Parvin (Supervisor) ; Dolati, Abolghasem (Supervisor)
Abstract
Nowadays, metal-organic frameworks have received a lot of attention due to their properties and characteristics such as controllable structure, high specific surface area and the tunable porosity size and have found many applications. One group of metal-organic frameworks are zeolitic imidazolate frameworks which ZIF-8 is a member of this family, and many studies have been conducted on it. In the present study, ZIF-8 nanocomposite coating was applied to the plain carbon steel substrate by synthesis at room temperature and immersion method, and its corrosion behavior and mechanical properties were investigated. The effect of Mercaptobenzothiazole (MBT) inhibitor on corrosion behavior and...
Fabrication of Oleophobic Coating
, M.Sc. Thesis Sharif University of Technology ; Mousavi, Ali (Supervisor) ; Nouri Borujerdi, Ali (Supervisor)
Abstract
Wettability is the cause of many interactions today and is definitely effective in almost all processes where liquid and solid phases are in contact. Wetting controls by surface engineering can accelerate the process in the industry or improve the quality of daily life. Therefore, the fabrication of complex surfaces with a specific purpose and different wettability has attracted the attention of researchers. In this thesis, silica nanoparticles were synthesized to create roughness and reduce contact between surfaces and liquids at first. Then, using chemical compounds to reduce the surface energy, a transparent (94.20%) superhydrophobic and oleophobic coating was created on the glass. The...
Produce of Nano composite Antibacterial Coating of PDMS+TiO2+ Ag3PO4 on 316SS Using Sol-Gel Methods and its Properties
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdullah (Supervisor)
Abstract
The aim of this research is to create coatings with antibacterial and superhydrophobic properties. To evaluate this, the sourness angle test, bacterial culture and halo diameter test have been used. The results show that 316L stainless steel containing PDMS+TiO2+7%Ag3PO4 coating, which is applied by immersion method on the substrate, has a water contact angle of 152 degrees, the number of bacteria cfu.cm2 is 44000 and the halo diameter is 24 mm. which has the best performance among other examples. In order to increase the adhesion of coatings on 316L stainless steel, first heat treatment was performed and then the samples were placed in H2SO4:H2O2 solution for 1 hour to form its OH- groups...
Improving Mechanical and Biological Behavior of Mg-2ag Alloy: Effects of Y Addition, Heat Treatment and Coating
, M.Sc. Thesis Sharif University of Technology ; Alizadeh, Reza (Supervisor)
Abstract
Biodegradable Mg-Ag alloys are promising implants for bone tissue regeneration due to their unique ability to reduce inflammation and infection after implantation with the presence of silver. However, their biological performance, including biodegradability, needs further improvement. In this regard, the effects of adding yttrium element, solution heat treatment and coating on the microstructure, biodegradability behavior, mechanical properties and biological characteristics of a cast Mg-2Ag alloy were studied. Addition of 1 wt% of yttrium caused grain refinement in the microstructure and solid solution heat treatment led to a significant decrease in the volume fraction of secondary phases....
Study of Self-Cleaning Silica Nano Coatings
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdollah (Supervisor)
Abstract
It has always been a challenge to make self-cleaning coatings based on super-hydrophobic properties that can provide the necessary features to be operational in the industry. One of these necessary features is the ability to easily apply the coating on the substrate and reduce the cost by finding the optimal amount of consumables. Therefore, in this research, at first, it was tried to produce silica nanoparticles with a particle size of less than 011 nm using the Stober method, and then the surface of the synthesized nanoparticles was coated with HDTMS (Hexadecyltrimethoxysilane) to make the silica particles, which are hydrophilic in nature, hydrophobic. According to the conducted studies,...