فصلنامه مواد پیشرفته و پوشش های نوین
پیاپی 18 (پاییز 1395)

One of the big challenge in the oil, gas, petrochemical industries is equipment wearing. Tackling this process ,a new coating process using mechanical milling, have been proposed.This study has been done in a method of mechanical alloying in order to build a coating using copper , nickle powders and silica nonoparticles, on the steel plat form , at theroom , tempeerature and under the enviranment space with the use of grinder bullets for different periods of time (1,3,5,10,20 and 30 hours) for the samples of series 1 (30%containing copper) and samples of series 2 (30% containing nickle).The mutual diffusion of the elements during milling which led to the formation of a Ni–Cu solid solution and the creation of Ni–Cu coating on the surface of samples was studied.Micro-structural characterization of the coating surface using optical microscope, electron rubshi microscope (FESEM), spectroscopy of X.ray with the scattered energy and analysing the roughness and abrasion of the surface were studied. ,the thickness of coating layer is formed on the series 1(30%copper) is more than series 2(30%nickel)and at the long time periods of milling X-ray diffraction (XRD) results revealed the formation of nanocrystalline solid solutions.

In this study, coating process was carried out using micro-arc oxidation (MAO) on aluminum AA1230 substrate. The specimens have been coated with and without SMAT pre-process in the phosphate based electrolyte and in the existence of silicon nitride nanoparticles (Si3N4). Then, in order to study how to distribute of nanoparticles and the elements within the coating, morphology of the samples' surface was investigated by scanning electron microscopy (SEM) and they were studied using EDS analysis and elemental maps of different components obtained. potentiodynamic polarization method was used to determine the coating's corrosion resistance. Also, wettability test has been performed for all samples through deionized water solution and contact angle was computed. The value of coating surface roughness was also measured by roughness measuring device. The results of this study showed that the contact angle mean in all samples with nano-crystallization pre-process is increased approximately 27% compared to the ones without pre-process. Furthermore, the consequences of study demonstrated that developing nano-crystallization process on the specimens prior to coating culminate in adsorbing more nanoparticles and causes to increase corrosion resistance of the coatings. But, increasing in the intensely impact of balls resulting from getting larger of their diameter result in much more increases in plastic deformation on the surface of the specimens and gives rise to the increase of cracks and pores in the sample surface which reduces corrosion resistance.

In this study particulate composite based on polypropylene/ talc containing different amount of titan dioxide were produced. Titan dioxides powders were incorporated in nano and micro size. The effect of micro and nano size of titan dioxide were studied via mechanical (tensile and impact properties) and color matching tests. The samples were obtained using a co-rotating twin screw extruder. The results showed that the presence of titan dioxide has not considerable effect on melt flow index of the samples in both sizes. However, the different meaningful results were obtained in mechanical and optical testes due to different size (micro and nano) for the samples. The samples containing nano size titan dioxide showed better mechanical and optical test due to higher surface/volume ratio.

Adhesion dysfunction of organic coatings on the plastic substrates arise from less surface energy of these surfaces. To improve the adhesion, the surface energy should be increased or with some modifications in the structure of coatings, the strength of the attraction forces should be improved. In this research, acrylic polymers were designed and synthesized with various functional groups and their functions were investigated to evaluate adhesion. The thermoplast part of the resins were prepared from methyl methacrylate and butyl methacrylate monomers and acrylamide, acrylic acids and 2-hydroxy ethyl methacrylate functional monomers. The physical, chemical and mechanical properties of the synthesized resins were analyzed such as viscosity, solid percent, … Then, the synthesized polymers were coated on the polypropylene substrates and the physical and chemical properties of surfaces were analyzed. The adhesion of coatings were analyzed with cross cut method and their mechanical properties with crust hatch cut examination. In addition, the results of this research showed that with optimization of polymer compounds, the surface of polyethylene was improved coated with synthesized resins. Therefore, they can be effective coatings on the plastic surfaces.

Poly lactic acid (PLA) films were prepared using different mass% of a network polymer by casting method and water vapor and oxygen permeability of prepared films were investigated. The network polymer was synthesized from 2-acrylamido-2-methylpropanesulfonic acid and N,N′-methylenebisacrylamide by radical polymerization and its structure was confirmed by fourier transform infrared spectroscopy (FTIR). The result of X-ray analysis was indicated that the network polymer structure had been a desirable interaction with poly lactic acid. By increase network polymer content to PLA, the water vapor permeability and oxygen transmission rate have decreased. The water vapor permeability was decreased from 0.243 ± 0.012 g/m2.24h for neat PLA to 0.235 ± 0.01 and 0.229 ± 0.013 g/m2.24h for the PLA films containing 2 and 6 mass% of network polymer, respectively.

One of the most common methods to removed contaminations from different substrates is to use the photocatalysis properties of a thin TiO2 nanoparticles coating on that substrate. A thin layer of TiO2 nanoparticles are usually applied on any surface using the Solgel method. Polyester fabrics were modified with TiO2 and TiO2/SiO2 nanocomposites through a low-temperature sol–gel method, so the self-clean properties of TiO2/SiO2 hybrid coatings on polyester fibers were studied. Silica was used to reduce the tendering effect of TiO2 nanoparticles. Sol-gels from TiO2, SiO2, and their blends in different weight ratios of 20:80, 50:50 and 80:20 were prepared and coated on the fibers surfaces by immersion, padding, and curing. FTIR and ATR results confirm the appearance of TiO2 and SiO2 nanoparticles in the solgels adnd chemical bonds between the coating and fibers after the deposition of the TiO2/SiO2 solgels. XRD experiment revealed that the nano silica treatment only influenced the surface properties of TiO2 nanoparticles and not the morphology and crystalline structure. Surface morphology of polyester samples was analyzed through the SEM images and it is shown that adding SiO2 resulted in a more uniform coating with a higher thickness. Contact angle measurements showed higher hydrophilicity by increasing nano SiO2 content. The highest self-clean property under UV radiation was also seen for the 50:50 SiO2/TiO2 composition. Finally, the mechanical properties of coated fibers dropped under UV radiation and it is shown that SiO2 incorporation in the coating formulation resulted in a slower rate of decrease in mechanical properties upon UV radiation.

In this restructure CoFe2O4 nanoparticles were first synthesized via precipitation method by various natural capping agents such as lactose, glucose and sucrose. Then CoFe2O4 / poly aniline nanocomposites then were prepared using an easy polymerization method in low temperature for surface coating of military equipment (invisible they radars) for microwave absorber and obviation it. The prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectroscopy. Magnetic property studies of the products were carried out using an alternating gradient force magnetometer (AGFM) and the results illustrated super- paramagnetic behavior of CoFe2O4 nanoparticles.