Abstract Two-phase matrix carbide ductile irons are a new idea i  ired by the processes of producing two-phase matrix ductile irons and producing austempered carbide ductile irons containing free carbide. As an emerging align="left" dir="LTR" >Keywords: Intercritical austenite, carbide ductile iron, austemper temperature, corrosion behavior, two-phase contex.

Developing the scope of application of new material depends on understanding the behavior of these in different environments and also gaining knowledge on the effect of various factors such as heat treatment parameters on their properties.   With regard to this issue we focused on the investigation the effect of partial austenitizing duration on creating a matrix with a dual structure of ferrite-ausferrite, corrosion resistance, bending strength, time to failure in crosive media under applied bending loads and stress corrosion threshold stress of a carbidic austempered ductile iron (CADI) which has been known as new family of ADI. In this regard, cast parts from a non-alloy carbidc cast iron were first subjected to ferritizing annealing to obtain full ferritic matrix. Then, the samples were partially austenitized at 870 ?C for 10, 15, and 20 minutes, followed by austempering in a molten salt bath at 350 ?C for one hour. After it, samples microstructures were examined with an optical microscope. In the next step, electrochemical corrosion tests were performed with Tafel polarization method. Then, by preparing notched and smooth C-ring samples, the loads leading to their failure were determined under the bending tests in air. Finally, the behavior of C-ring samples in corrosive caustic soda solution were investigated under bending loads. According to the obtained results, with the increase of the partial austenitizing time, the ausferrite phase fraction increased according to the JMAK equation. The creation of dual matrix structure of ferrite-ausferrite caused the corrosion resistance of the samples to be weakened compared to the samples with fully ferritic matrix and conventional ADI. As the partial austenitizing time increased, the corrosion resistance, bending tensile strength in air and time to failure in corrosive media under constant load, increased. The bending loads leading to the failure of notched samples in air were significantly lower than those of smooth samples. The results of stress analysis in C-ring samples under bending test in air showed that the reduction of cross-sectional area, change the outer effective radius and neutral radius of the samples, and stress concentration are three contributing factors in reducing the tolerable bending load without occouranse failure with the contribution of 35%, 35% and 30%, respectively. The notch strength ratio (NSR) was independent of the effect of partial austenitizing time and it was about 0.87. All the smooth samples endured 100 hours of stress-corrosion testing under maximum applied loads (equivalent to 85% of failure load in air) without occurrence of failure. By decreasing the applied load in the corrosive environment, the time to failure of all samples increased greatly. There was a power relationship between the stress-corrosion threshold stress and the ultimate tensile strength of the samples. Also, during stress-corrosion testing the gradual fracture along with growth of cracks was not observed and failure of all samples in both environments air and caustic soda occurred via very rapid crack propagation in a completely brittle mode over the whole range of the applied loads.   

  هدف،

   Due to the decreasing trend of fossil resources and increasing global warming, the crisis of energy shortage, and with the aim of reducing the carbon footprint and the need to pay attention to the use of renewable energies, which has become more important in global societies, it is necessary to pay attention to this matter. Is.    The construction sector is one of the major consumers of fossil fuel; Optimizing architectural design with a climate compatible approach can have a great effect in reducing fossil fuel consumption and using renewable energies. Computational design in the initial stages is one of the methods that plays a significant role in optimizing architectural design because in this stage of design, basic decisions are made to achieve the goals of building design, including energy performance, cost, environmental effects, thermal comfort, and so on. It is taken as Therefore, optimization studies should be done in the initial stage of design, where most of the architectural decisions have not been taken yet. Therefore, the aim of this study is to investigate the effect of architectural and construction parameters on improving energy consumption in the initial stages of designing a high-rise residential building in Tehran. The approach used in this research is quantitative and the research method is simulation and modeling. At first, the climate data of Tehran city was analyzed with the Ladybug plugin and static climate design solutions were presented. In the next step, to find the optimal form and proper orientation in the Ladybug plugin, the building form was analyzed with regard to solar radiation. And the optimal option was selected. From the optimal forms obtained according to the architectural needs (physical program, standards and such), an option was selected and an architectural plan was drawn. The architectural plan in the Honeybee plugin was converted into thermal zones for simulating energy, and by determining the range of changes in architectural parameters (window-to-wall ratio, window type, thermal insulation thickness, optimal canopy depth) and the effect of each of them on energy consumption, The parametric form was analyzed and studied. In the end, according to the results, a high-rise residential building was designed in the desired site. The building that was designed has 20 floors, the 15th floor of which was chosen as a sample floor for study. According to the background of the research, it was determined that the most efficient energy simulation engine is Energy Plus software. According to the results obtained from the sensitivity analysis, among the architectural parameters affecting energy consumption, the window-to-wall percentage ratio (bedroom and kitchen - hall and reception) and the type of glass had more sensitivity than other parameters; And the depth of the shade and the material of the internal walls were the least effective options, and among the considered parameters, the optimal modes were selected. The results show that by increasing the window-to-wall ratio, the heating load decreases and the cooling load increases. Also, the total energy has a decreasing trend up to 50% and after that it starts to increase. So 50% was chosen as the optimal percentage. In terms of window type, the upvc window with low-e glass was considered as the most optimal window among several different types.

Due to their favorable biocompatible properties, titanium and its alloys are used as popular raw materials for making all kinds of implants. Therefore, the efficiency of the implant is always being developed in order to better adapt to the biological tissue and increase its retention time in the place of cultivation, in different ways that lead to the creation of an oxide layer on the surface. The aim of this research is to investigate the biocompatibility of titanium in different morphologies obtained from anodizing in alkaline and acidic electrolytes.  

Review : There are various methods of surface coating to deal with corrosion and wear and other surface damage. One of the easiest and most economical coating methods is electroplating or electroplating. In the past, the best element for electroplating coating was chromium, but today, due to the toxicity of the ions obtained from the chrome plating bath, nickel is used instead of this element. Nickel coating is alloyed with elements such as tungsten, molybdenum, cobalt, etc. for better properties. One of the innovations that has led to the production of coatings with better properties and performance is composite coating through the deposition of base and reinforcing nanoparticles. TiO2 and SiC hard nanoparticles are among the most widely used nanoparticles for creating composite coatings. The simultaneous presence of these Nanoparticles in the coating, if they are properly dispersed, can give the coating good chemical and physical properties. In this research, nickel-tungsten coating along with TiO2 and SiC nanoparticles were applied with direct plating current on the substrate of low carbon steel and their wear and corrosion behavior was investigated. The effect of variable Ph parameters, plating time, plating current density, the amount of nanoparticles in the plating bath, and the presence of ultrasonic waves during plating were investigated. In order to check the wear resistance of the pin on the disk, the corrosion resistance of the polarization test was used to determine the existing phases as well as the grain size by X-ray diffraction patterns (XRD) and to check the microstructure of the coating by field emission scanning electron microscope (FESEM). The results showed that for nickel-tungsten coating, the optimal pH is 7.5 ± 0.5 and the optimal current is 200 mA/cm2. Adding TiO2 nanoparticles to the plating bath increased the wear and corrosion resistance as well as the hardness of the coating and reduced the size of the crystals. Adding SiC nanoparticles to the bath led to an increase in hardness and wear resistance, as well as a decrease in crystal size and corrosion resistance. Coating in the presence of ultrasonic waves with powers of 40 and 60 led to an increase in the abrasion properties and hardness of the coating, but the increase in the power of the ultrasonic waves led to a decrease in these properties, which is due to the distortion and removal of particles from the surface of the coating due to the high power of the ultrasonic waves. is. In all the powers of the ultrasonic waves, the corrosion resistance decreased due to the cracks in the microstructure.   

   Abstract Today, pollution of aquatic ecosystems with a wide range of organic and inorganic pollutants has become one of the biggest human challenges, so that research studies examining techniques and the use of effective attractants in reducing and Or the elimination of some of these harmful pollutants, including arsenic, has many study priorities. The aim of this study was to optimize the adsorption conditions of arsenic heavy metal from water using magnetite-chitosan composite nanosorbent. The advantage of using chitosan coating is higher adsorption capacity and higher stability of adsorbent nanoparticles and its easy separation from aqueous solution. In this study, first magnetite nanoparticles were synthesized by co-precipitation method of iron (II) and (III) chloride ions and the obtained nanoparticles were first identified by FT-IR spectrum, then UV-Visible spectrum, TEM, XRD, VSM. , DLS, Zeta potential were obtained. After reviewing the results and obtaining the result, carboxymethylcytosans were sonochemically bonded to the surface of the modified magnetite nanoparticles and the surface of the magnetite nanoparticles was coated with carboxymethylcytosane. Magnetite-chitosan composite nanoparticles were taken by material analyzers, first FT-IR, UV-Visible, XRD which showed the presence of magnetite with chitosan coating, then TEM, VSM images, magnetic saturation change of nanoparticles after coating Delivery, DLS particle size distribution and Zeta potential surface load were investigated. Then, the adsorption test was performed using Design Expert software and the experiment was designed with Taguchi model from four factors: adsorbent dose, pH, temperature and time, and arsenic solution with an initial concentration of 1 ppm. Residual arsenic concentration was measured by ICP-Mass and statistical operations were performed on the test results and the effect of various factors on the adsorption efficiency was shown as contours so that the adsorption efficiency increased with increasing adsorbent dose and with increasing pH of The adsorption efficiency increased from 3.5 to 8.5 at a certain dose and the increase in temperature and time also increased the adsorption. Dose was 0.0300 g and pH = 3.5, contact time was 1440 min and temperature was 35 ° C. The optimal absorption point with 99.3% yield was obtained at a dose of 0.0283 g and pH = 6.4, and the contact time was 976 min and the temperature was C38, and the validation test showed a value of 99.4%. The weight ratio of chitosan to magnetite was synthesized in four different ratios of 1: 1, 2: 1, 3: 1 and 4: 1, and in optimal adsorption conditions, a test was performed. . Using the linear, nonlinear Langmuir equations and then the linear and nonlinear Friendlich isotherms, the isotherm that was consistent with the adsorption process and showed the highest correlation coefficient was the linear Langmuir and Friendlich isotherms, which obtained the maximum absorption capacity from the equation. The magnetite-chitosan composite was calculated to show 313.57 mg / g. According to the obtained results, the synthesized nanocomposite can be used for water filtration and arsenic adsorption under optimal conditions.

  First, by reviewing the scientific literature, suitable conditions for the electrodeposition of nickel-tungsten nano-coatings are determined, and after preparing a suitable coating, nitriding operations are performed on the samples. Further erosive corrosion of pure steel, nickel and tungsten nickel coating were investigated .The electron microscope and X-ray diffraction studies are performed at each step.   

    Erosion-corrosion is a main type of damage mechanisms taking place in equipment and hydraulic components exposed to corrosive flowing fluid. Hence, in order to applications of dual phase steels for such engineering components, it is essential to have a comprehensive understanding of their erosion-corrosion behavior and involved affecting variables. The microstructure of dual phase steels is governed by the heat treatment variables like temperature of medium in which the samples are rapidly quenched from intercritical austenitizing temperature. As a results, the change in quenching medium temperature is expected to have a significant impacts on the erosion-corrosion resistance of dual phase steels. The purpose of this work was to provide comprehensive information on this issue and to evaluate erosion-corrosion correlation with the hardness and erosion resistance of dual phase steels. In this regard, several sets of samples of Ck45 steel were austenitized at 730 oC for 60 min, then quenched and held 120 min in water and/or salt bath with different temperatures ranging of 25 to 400 oC to obtain dual structures with ~40 vol. % fraction ferrite. Optical microscopy and scanning electron microscopy utilized to characterize the samples microstructures. The hardness of specimens were evaluated using Brinell hardness test method. Erosion and erosion-corrosion tests were carried out by immersion of samples in a solution of distilled water, 3.5 wt% NaCl and 1 wt% Al2O3 and rotating them with 715 rpm (9 m/s) for durations of 24-120 h. The slope of variation of mass loss various duration test was determined as erosion or erosion-corrosion rate. The obtained results revealed that increasing the quenching medium temperature from 25 to 400 ?C leads to a reduction in hardness and erosion resistance. The erosion rate was correlated with quenching medium temperature as a power model with exponents of 5.7. The rate of erosion-corrosion was raised with increasing quenching medium temperature from 25 to 325?C, while austempering at higher temperature resulted to improvement of erosion-corrosion resistance when compared to specimen austempered at 325 oC.   The power model was valid for correlation between the erosion rate and Brinell hardness, while there was no significant correlation between erosion-corrosion rate with hardness and rate of pure mechanical erosion. Compared with pure mechanical erosion in non-corrosive fluid, the degradation rates were higher than 193% to 305% and 21% to 132% for samples austempered at temperatures below and above 325 oC, respectively, when the erosion tests were performed in the aggressive condition. The erosion-corrosion resistance of ferrite-bainite samples prepared by austempering at temperature of 400 oC was similar to ferrite-martensite sample provided by quenching into water at temperature of 90 oC and had the best results compared to the rest of the specimens, except for quenched samples in water at 25 ° C.   While the pure mechanical erosion resistance of later was approximately  three time  greater  tha  that of former. These results indicate that the type of hard phase in the dual phase steel does not have much effect on its efficiency in the corrosive flowing fluid, if the appropriate temperature was selected for the quenching medium. But, ferritic-martensitic dual-phase steel is preferred for use in the non-corrosive environment and/or when the samples are subjected to cathode protection.

synthesis and Characterization of core-shell nanoparticles(YSZ@Ni nanoparticles)

study

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