مجله مواد و فناوری های پیشرفته
سال چهارم شماره 4 (زمستان 1394)

In this research to rich nano structure bond coat uses in TBC, firstly with ball milling process the micron size NiCrAlY convert to nano particle size NiCrAlY, and after agglomeration nano particle NiCrAlY, powder were deposited upon stainless steel 420 substrate with atmospheric plasma spray (APS) process. Injection distance of powder, hydrogen rate, and utilizationof argon shroud parameters were investigated for suitable deposition agglomeration nano NiCrAlY particles. The result shown, utilization of argon shroud in nano NiCrAlY bond coat was decreased oxidation salient. Also increase of injection distance of powder and hydrogen rate cause to oxidation enhancement. Moreover the nano particle NiCrAlY in comparison micron NiCrAlY toward oxidation was very tender.

In this paper, to improve the electronic parameters of silicon nanowires, the influence of As and P dopants are investigated. These electronic parameters include transmission spectra, mobility, mean free path and energy band diagram. To study the conduction mechanism and mobility of the Sinanowires, carrier transport along the long nanowires in presence of many defects (including dopant, vacancy, disorderly and surface roughness) has been investigated. In this paper, to simplify the calculations, short Si nanowires with small amount of defects are considered. Therefore, short length silicon nanowires have been doped by As and P and the effects of the dopants have been analyzed. Simulation results demonstrate that, by increasing the energy, transmission spectra increases. It is shown that mobility decreasesin carrier concentration more than and for concentration less than this value, mobility is approximately constant.

In this study the effect of electroplating bath temperature on the behavior of nickel-Graphene composite coating and also on the morphology and corrosion properties were investigated. For this reason nickel sulfamate additive free bath with grapheme were used. Electroplating process was carried out with DC generator and at three temperatures (35, 45, 55 C ). surface morphology and crystallographic texture of electroplating nickel- grapheme were investigated with Field Emission Scanning Electron Microscope(FESEM).Corrosion behavior of nickel-Graphene coating were investigated with potential dynamic polarization test results.Results shown that to increases intemperature also will cause increases in Graphene Nano particles absorptionbut up to 50 C the absorption of graphene reduce. Also increases in temperature will cause Graphene Nano particles agglomerated and lack of uniformity in the coating. As a result the corrosion resistance of the coating is reduced.

In this study, the cracking sensitivity of deposited weld of E8010-P1 cellulosic electrodes as a function of base metal thickness and interpass temperature was analyzed. For this purpose, different welded samples (different base metal thickness and interpass temperature) were subjected to the bending test according to the SEP-1390 bohler specification. Studies illustrated an increase in the minimum interpass temperature from 80?C to 120?C is required with increasing base metal thickness from 20mm to 30mm to prevent weld cracking. Increasing of interpass temperature not only decreases the welding cooling rate but also reduces the heat sink effect of base metal and therefore decreases the cracking sensitivity. Structural studies indicated that the main cause of E8010-P1 weld metal cracking is development of undesirable phases such as grain boundary and widmanstaten ferrite in the weld metal. In addition, optimum cooling time between 800-500?C (?t8/5) for preventing E8010-P1 weld metal cracking determines to be around 18010s.

One of the main problems of the use of stainless steels is related to low strength of steels to pitting corrosion in chloride-containing environments such as sea water. In this paper, the corrosion resistance of the cerium oxide coating on stainless steel is investigated. Potentiodynamic polarization and impedance spectroscopy was used to study the corrosion behavior of the coating. In addition, microstructural and phases of the cerium oxide coatings were studied using a scanning electron microscope, FTIR and X-ray diffraction. The results showed that the formation of cerium oxide coatings on the stainless steel causes an increase in the corrosion resistant and the best corrosion resistant of the coating was obtained when the heat treatment was applied at 300 C.

In this study, performance corrosion protection of simultaneous self assembled thin layer copper phthalocyanine sulfonated together with nanostructured hybrid inorganic- organic coatings on carbon steel in acidic solution was investigated. Hybrid sol was synthesized via acid catalyzed hydrolysis and condensation of methacryloxypropyl trimethoxysilane (TMSM) and tetraethoxysilane (TEOS) at the molar ratio of 1:1. The morphology and composition of carbon steel coated with hybrid coating and self assembled CuPh was examined by SEM, EDX and FTIR. The performance corrosion protection of the hybrid coatings was investigated with polarization scans and electrochemical impedance spectroscopy (EIS) in aerated 0.5 mol L-1 HCl solution. Self assembled CuPh films coated under the hybrid coating showed a strong influence on its corrosion resistance, mainly when the samples have 24h immersion time and 1 mM concentration. Addition of inhibitor to anti corrosion system, improved the protection of carbon steel in HCl 0.5M solution up to 94%. Th

The production of microalloy steel plates is associated with the combination of heat treatments and hot working known as thermo-mechanical process. Superior mechanical properties of the milled products could be obtained by controlling the microstructural evolution during hot rolling process and accurate identification of phase transformation temperatures. In this paper, the influence of austenitizing time and temperature, cooling rates, banded structure of ferrite and perlite and microalloying element on the phase transformation of austenite in API-X70 steel were investigated. The dilatometry test and microstructure analysis were carried out on the samples with different direction (RD, TD and ND) to the steel plate. The results indicate that increasing of austenitizing time and temperature decrease of the start and the finish temperature of austenite decomposition; this was associated with changing of microstructure from ferrite-perlite to ferrite-bainite. The impact of small changes of cooling rate was found to be insignificant on the phase transformation temperatures. However, by increasing the cooling rate, the microstructure becomes bainitic and the critical temperatures decrease rapidly. Both the dilatometry data and the microstructure micrographs prove that the sample direction has negligible effect on critical temperatures.

The use of soil additives in the management and conservation of soil resources is becoming increasingly important. Examples of these additives, polymer materials which are in the category of copolymers based on acrylamide and acrylic acid due to ease of synthesis and availability of raw materials has attracted much attention. In this study, copolymer based on acrylamide and acrylic acid was synthesized by chain polymerization in the water system. Fourier transform infrared spectroscopy revealed that the carboxylic acid and amide functional groups were successfully polymerized in the material. The amount of each component was measured by thermogravimetric analysis. To calculate the negative charge density and molecular weight of samples, titration method and laser light scattering analyzer were used which showed soil stabilization with increment in negative charge density. The use of acrylamide monomer plays a major role in the copolymerization to increase the molecular weight. Finally, soil loss was determined using 0.4, 0.6, 1, 2, 3, 4 and 6 gr/m2 of copolymers in water and solutions sprayed on the soil surface before implementation of artificial rainfall, also its continuity in 30min rainfall was studied.