Sharif Digital Repository

Adding solid lubricant particles such as PTFE, Graphite and MoS2, has major influence on electroless composite nickel coatings in order to make low friction surfaces. Among these lubricants, MoS2 has attracted great attention due to its highest stability under wearing condition. In this work Ni-P-MoS2 composite coatings using MoS2 nano-particles have been made and in the next step, we evaluated tribological properties of these coatings. For exploring these coatings different experiments were utilized, like Scanning Electron Microscope study (SEM), chemical composition analysis exploiting AAS and XRF method, and thickness measurements. Two kinds of surfactants, CTAB and PVP, have been applied... 

In this study solid lubricants MoS2 nanoparticles with average size 50 nm and hard ZrO2 nanoparticles with average size 51 nm were used in watts bath and Ni/ZrO2-MoS2 composite coatings were prepared by pulse plating technique. Effect of current density, frequency, duty cycle, surfactant type and concentration of particles in the electrolyte on the amount of particles in the coatings were investigated and optimum conditions were determined to create composite coatings. Scanning Electron Microscopy (SEM) and x-ray diffraction (XRD) analysis were performed to study the morphology, structure, chemical composition of coatings. Corrosion testing of coatings by potentiodynamic polarization in... 

In this project, nonocrystalline nickel coatings with grain sizes within the range of 9-27 nanometers were produced on yellow-brass plates by electroplating in a modified Watts bath applying current densities from 2 to 6 A/dm2 and bath stirring speeds from 0 to 400 rpm. To determine crystallite size, X-ray diffraction technique (XRD) was utilized; it was observed that grain size declined continuously with increase in current density and then in bath stirring speed. The experimental results coming from XRD tests were compared with a theoretical model in order to verify their reliability; the obtained curve indicated a good correspondence between the experimental data and the theoretical... 

In the first chapter, high substituted pyrrole derivaitives were synthesized through a one pot four compounent reaction using carbonyl and amin compounds at the presence of magnetic nanoparticles of superparamagnetic ferrospinel NiFe2O4nanoparticles as catalyst.In the second chapter, NiFe2O4magnetic nanoparticles were employed in the Sonogashira reactions using phenyl acetylene as coupling partner with different types of aryle and alkyl halides in water as a green solvent. The results of these reactions were considered comprehensively  

Part 1: In the first work, the electrochemical behavior of Ceftriaxone was thoroughly investigated at the surface of a glassy carbon electrode modified with nano-diamond graphite (NDG). The surface morphology and electrochemical properties of thin film modifier are characterized by Scanning electron microscopy (SEM) and cyclic voltammetry (CV) techniques. The prepared electrode showed a considerable improvement in the peak current of Ceftriaxone compared to either glassy carbon electrode or nanodiamond (NDs) modified glassy carbon electrode. Under the optimum conditions, the modified electrode showed a wide linear dynamic range of 0.04-10 μM with the detection limit of 10 nM for voltammetric...