Sharif Digital Repository

Electroplating is an appropriate method for co-deposition of metallic, non-metallic and polymeric fine particles onto a metal matrix for production of functional coatings. In this study, chromium and Cr–Al2O3 composite coatings are electrodeposited from trivalent chromium bath by using DC and square pulse current. Dependence of the amount of Al2O3 nano-particles trapped into the coatings on the Al2O3 bath concentration, average current density, particle size, agitation rate and type of the current is investigated. These parameters are optimized for the highest co-deposition amount of the Al2O3 onto chromium layer. Optimum values are 20g/l Al2O3, 200 rpm stirring rate and 25A/dm2 current... 

The aim of this thesis was creating Titania/RGO coating with electrophoretic method to evaluate the corrosion resistance of stainless steel 316. At first Graphene Oxide were synthesized with modified Hammers method and their physical, chemical and morphological properties have been investigated using XRD, FTIR, EDX, TGA, UV-Vis and Raman analysis. then Graphene Oxide was added to the bath of titanium and was deposited on 316 stainless steel substrates. Moreover, corrosion protection of coating has been examined using Poarization test and Electrochemical Impedance Spectrometry. The effect of deposition parameters on corrosion properties of composite coatings were examined. The key variables... 

This research focuses on finding an appropriate method for increasing wear and corrosion resistance of hard coating TiN PVD and chromium. The substrate was made up of 42CrMo4 (DIN) steel (used for marine industries) and coated by TiN Arc PVD process and hard chromium electro-deposition. The results of these two coatings are compared and the better coating which is TiN Arc PVD is suggested. To find the best method for coating, several test studies are organized such as: the mechanical and tribological properties of TiN PVD and hard chromium coatings for wear and corrosion resistance applications are organized. The potentiodynamic polarization technique was used to measure the corrosion rate... 

Considering the importance of biocompatibility of implantable prothesis’, metallic alloys have weaker corrosion resistance than ceramics. In order to extend usage of nanomaterials to improve the bio-properties of materials, Nano-structured ceramic coatings are being suggested to improve corrosion resistance and biocompatibility of prosthesis. Meanwhile, very good properties of TiN, such as corrosion resistance and mechanical properties as a thin film coating are undeniable. In this study, TiN and Ti2N thin film were deposited on Ti-based substrate, using PVD and Magnetron sputtering at different argon to nitrogen ratio. The crystal structure of the films was examined using Grazing XRD... 

In this thesis Blackening of electroless nickel-phosphorous coating and the effect of TiO2 anti-reflection coating on optical properties of coating was investigated. In the first step, electroless nickel coatings with different amounts of phosphorous on 1050 aluminium substrate deposited. In second step, blackening of coatings by chemical and electroche-mical methods have studied and in final step, effect of TiO2 antireflection coatings with different amount of Pluronic F127 on the optimum black surface and properties of coating investigated. Chemical blackening performed in nitric acid and effect of acid concenteration, Blackening time and temperature studied. optimized condition was... 

Today, the process of corrosion and compensation of minor injuries, without the need for tracing or any other physical interference, has become one of the subjects of interest to researchers. Inhibitors have been considered as one of the anti-corrosion agents. In this research, safflower extract as a green inhibitor in sodium chloride corrosive environment was used to evaluate the rate of corrosion of mild steel. Also the MoS2 nanoparticles were used as carrier of this green inhibitore in the epoxy coating to allow the activation of the coating in a scratched state in sodium chloride solution of 3.5%. In the first step, the extract of the safflower was prepared to reach the best part of this... 

In this study, antistatic waterborne polyurethane coating containing zirconia nanoparticles is made and applied on 304 stainless steel substrates at weight percentage of 0.66, 1.3, 3, 4.5 and 6% zirconia nanoparticles. For synthesis of hydrophilic isocyanate prepolymer, isocyanate prepolymer is modified by hydrophilic polyethylene glycol with molecular weight 600, 1000 and 4000. For ensuring of modification condition and stability of hydrophilic isocyanate prepolymer in aqua solution, FTIR and stability tests are employed, respectively. In order to create antistatic properties of these coatings, semi - conductive zirconia nanoparticles are used. To improve the distribution of zirconia... 

The highest efficiency of Perovskite solar cells that is attained up to now, is around 24%. This champion solar cell is prepared under vacuum. This method suffers from low rapidity, small deposition area and high cost which are not compatible with commercialization. Printing method has a special position in mass production of electronic equipment, such as solar cells. This method has the potential of high rapid, low cast and repeatable deposition. In this thesis, I introduce a novel deposition method, named Capillary Adhesion Coating, which is based on capillary concept. The novel deposition method coats infinite perfect thinfilms with high rapidity and low cost. After the introducing of... 

The aim of this study was electrodeposition of Zn-Ni-P/Zn-Ni multilayer coatings by single-bath method from a citrate bath to produce a sacrificial coating with high barrier properties compared to Zn-Ni monolayer coating. The coatings that were prepared at 10 mA/cm2 was Zn-Ni-P (Ni-rich and percentage of zinc, nickel and phosphorus, respectively: 40, 50 and 10 %), and the alloy deposited in 60 mA/cm2 were practically Zn-Ni (Zn-rich, 85% zinc) and almost phosphorus free. Galvanostatic pulse deposition method through switching of the current density between the two values mentioned in monolayers (10 and 60 mA/cm2) in different time periods to create bilayers corresponding to the monolayers,... 

To protect mild steel against corrosion, an intelligent self-healing epoxy (EP) coating including carbon nanofiber (CNF) modified with polydopamine (PDA)-La (III) complex was successfully fabricated. The high aspect ratio and unique thermal and electrical characteristics of CNF made it an ideal physical barrier against the penetration of corrosive ions. Due to the poor dispersion of CNF, its surface was modified using PDA. PDA, which contains functional groups such as catechol, amine, and imine, can mitigate corrosion reaction by generating the Fe-Catechol complex and also boost the coating's adherence to the metal surface, in addition to anchoring La3+ inorganic corrosion inhibitor.... 

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... 

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... 

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... 

The aim of this project is electrodeposition of Cu/Ni-P multi-layer coating and investigating the nucleation and growth mechanisms of the deposits. To evaluate the effect of the selected bath on the kinetics of the process and deposition, cyclic voltammetry and chronoamperometry studies were conducted and electrodeposition mechanism was obtained three-dimensional instantaneous nucleation and growth controlled by diffusion. Potentiostatic pulse-deposition method with potential steps -0.3 and -1.1 V vs SCE was selected for deposition of Cu/Ni-P multi-layers. In order to demonstrate the effect of monolayer thickness on the properties of the final coating, multiple layers with various monolayers... 

Electrochemical deposition of multilayer coatings is one of the surface engineering techniques to create thin surface layers with a controlled structure in order to create desirable surface properties. In this research, the nickel-iron-silicon carbide multilayer coating is deposited from a single bath with a sulfate composition and by changing the current density between two values (10 and 40 mA/cm2). The number of layers in multilayer coating was 4, 8, 16, 32.The effect of current density and the number of layers on chemical composition, surface morphology, phase structure, corrosion resistance, nano hardness measurement, wear resistance of multilayer coatings respectively using electron...