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Chromate conversion coating is applied on aluminum 6061. The optimum conditions for chromate bath composition and immersion time are also obtained for standard requirements provision such as corrosion resistance in salt spray test, electrical resistance and coating quality. The applied coatings are electrochemically tested in sea and distilled water. According to Tafel and cyclic polarization curves, the protection mechanism are evaluated in said environments. This evaluation has shown the formation of passive film layer, contains chromate and alumina on the base. The proper behavior of corrosion and electrical conductivity is probably due to this mechanism.

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Research subject: In this research we studied the anti-corrosion properties of epoxy coating containing anti-corrosion pigment zinc phosphate with hydrophobic nano silica with different percentage also for determine the optimal conditions for preparation of nanocomposite Taguchi experimental design method was used.
 
Research approach: Anti-corrosion properties of epoxy coating under the influence of very important factors such as the percentage of nano silica, anticorrosive pigment and pigment to resin ratio according to model L9 taguchi method was studied and analyzed. Anti-corrosion properties of epoxy coatings were studied by electrochemical impedance spectroscopy test (EIS) in 3/5% NaCl aqueous solution and salt fog test (salt spray). To investigate the distribution of nano silica particles in epoxy resin were analyzed by transmion electron microscope (TEM) and scanning electron microscope (SEM). The results show that using from zinc phosphate and nano-silica was able to improve the corrosion resistances.
 
Main results:Results shows that addition of zinc phosphate and nano silica to epoxy resin caused a decrease in number of blisters and corrosion products after exposure to corrosion test based on the results in Nyquist and Bode plots, also the similarity in results was observed for the epoxy coating loaded according to the optimum conditions with 8% zinc phosphate, 3% nano silica and pigment to resin ratio of one according to salt spary. The significance levels of the experimental parameters, which indicate how the factors affect the compressive addition of zinc phosphate and nano silica to epoxy resin, were determined by using variance (Anova) method.

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Research subject: Regarding to temperature effect on the rate of corrosion in absorption tower of gas refineries, it is very useful to examine and invest on new methods to decrease the temperature in mentioned towers.
Research approach: By studying different types of corrosion in amine processes and the influence of different variables on them, the dominant effect of temperature on the rate of corrosion in absorption towers was determined. Due to decreasing temperature in the absorption tower the surface tension of amine solvent and corrosion rate decrease. The reduction in surface tension reduces the foaming and flooding in the tower, which reduces the concentration of sour gases CO₂ and H₂S from the natural gas outlet. Various methods of reducing temperature in the absorption tower such as increasing flow rate of circulation amine solvent, opening the insulated tower wall and injecting amines into the middle of the tower have been studied. Aspen- HYSYS software was used to investigate the effects of amine injection into the middle of the tower.
Main result: According to the simulation results, the maximum temperature in the two-feed absorption tower was reduced to about 3°C and in the three feedstocks the maximum temperature was reduced to about 10°C. Also, as the CO₂ and H₂S concentration of the gas outlet decreases, the amount of Spent Caustic and catalyst in the lower part of the tower will decrease. Finally, it was found that among the above methods, injection of amine into the middle of the tower had the highest efficiency in decreasing the temperature of it. However, a combination of the above methods can be used to further reduce the temperature in the tower.
 

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Ohmic heating has an advantage over conventional indirect heating methods because heater (electrode) surfaces temperatures are comparatively lower as heat is generated within bulk fluid. Conventional ohmic heating under typical low frequency alternating current (50 or 60 Hz) could cause hydrogen and oxygen evolution due to electrolysis of water. This process could develop the electrodes decay or corrosion. Any decay or corrosion of electrodes shorten the life time and contaminate the food. The main objective of this study was to investigate the rate of the electrodes corrosion in the ohmic heating process. For this purpose the concentrations of Fe, Cr, Ni, Mn, and Mo from the stainless steel electrode migrated into ohmic and conventionally treated soup were measured. In this study migration of the major key metal ions from stainless steel measured by Atomic Absorption. The results showed that overall ohmic treatment yielded the same migration residues of all metal ions, compared to the conventional retorting with similar electrodes. Concentrations of all metal ions migrated into food samples after ohmic treatment were far lower than dietary exposure levels so that this technique can ensure the safety and quality of food supplies.  

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Abstract: The influence of cement content increase on corrosion resistant behavior in concretes containing nano-SiO2 was experimentally studied. For comparison, the chloride diffusion of plain concrete and the concrete containing nano-SiO2 was also experimentally studied. The test results indicated that the corrosion resistance of concretes containing nano-particles is significantly improved. However, the index of diffusion chloride ion in the concretes containing nano-SiO2 is directly related to cement content in the mix. The SEM oservations revealed that the microstructure of concrete with nano-SiO2 is more uniform and compact than that of normal concrete, but higher pore size distribution was observed when cement content is increased, which in turn leads to the increase in the diffusion of choloride ion.

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Abstract: The durability of concrete structures against corrosion due to high concentration of chloride ion is considered as a main concern in these kinds of structures in Persian Gulf area. However, increasing the initial temperature its effect on concrete microstructure can intensify this issue & severely increase the concrete corrosion rate. This article deals with the high initial temperature effect on chlorine ion penetration in concrete, particularly concretes consisted of silica fume. Evaluation of high initial temperature has been done by making samples in different temperature till initial setting & keeping in the same conditions in the environment temperature to simulate the environmental conditions of Persian Gulf. For this purpose, the changes of concrete micro structure due to initial temperature increase & its effect on concrete resistance properties against chloride ion penetration have been studied. In this paper, the influence of high initial temperature on chloride penetration and microstructure of concrete containing silica fume was investigated. Two different mixes at three different initial casting temperature (20-40°c) were studied: a control mix in which no cement replacement materials were added and a mix where cement was partially replaced 6% silica fume (by weight), at a constant water-to-binder ratio of 0.45 and a cement content of 400 kg/m3. High initial temperature casting was employed to simulate concrete temperature in Persian Gulf hot climate. The results show that chloride penetration at 40°c is directly related to increase in the porosity of the binder phase and the absorption of concrete. The Higher chloride penetration resistance was observed when cement is partially replaced with silica fume. From SEM result recognized silica fume particles make core sites to cement hydration, therefore make more consistency micro structure and decrease pore size distribution. It is concluded that increasing the initial temperature of the concrete in the time of casting & formation, leads to accelerating the hydration & therefore the heterogeneous distribution of products in the mixture. This phenomenon causes the bigger pores in the concrete structure by increasing the temperature and more space for chloride ion penetration. So, high casting and initial temperature leads to increasing chloride ion penetration & reduction of concrete resistance against corrosion. By adding silica fume to the mixture, size & the distribution of pores improve and the temperature increase effect on parameters of chloride penetration & corrosion decrease. Hence, the corrosion behavior (Chlorine ion penetration coefficient & electrical potential) of 40°c silica fume included specimen are improved than reference concrete.   Keywords: Initial Temperature, Corrosion, Chloride diffusion, Silica Fume

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Acoustic Emission technique is a non destructive method which can be used for detection of corrosion mechanism. In this paper the corrosion of sulfuric and hydrochloric acids solution on some kinds of stainless steel like 304, 316 and GTD-450 with and without residual stress was surveyed by acoustic emission technique. Considering tests diagrams, cumulative counts in the samples with residual stress is more than other ones due to high sensitivity of stainless steel samples to stress corrosion cracking. Also frequency in the samples with residual stress is lower than other ones. Cumulative count in the stainless steel 304 is more than stainless steel 316 for all of the samples. A sudden and intensive corrosion in the hydrochloric acid environment was observed specially in the samples with residual stress. For stainless steel 304, this event was very harmful, because, it will the cause of some pitting corrosion, which concentrates stress in these locations and finally creates crack in structure.

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Dissimilar welding between Inconel 625 nickel base superalloy and high strength quenched and tempered A517 Gr.B steel investigated by pulsed ND:YAG laser beam welding equipment. This joint has special application at submarine components. After welding, the optimized joint microstructure including the weld metal and heat affected zones were characterized by optical and scanning electron microscopy (SEM). The results showed a fine dendritic structure and existence of large amount of Niobium carbide and Laves eutectic phase in the weld metal. Energy-dispersive X-ray spectroscopy (EDS) analysis showed Nb and Mo segregation to interdendritic zones at the weld metal. Grain growth in the heat affected zone of Inconel 625 did not occur, however, ultrafine precipitations were deposited at the heat affected zone. An approximately 65 µm wide transition zone was observed at the steel and weld zone interface; consisted of a martensitic layer (10-20µm) along the weld interface and the austenite phase region with a little ferrite adjacent to the base metal. The tensile test and micro hardness test of the optimized sample was investigated. The electrochemical behavior of the weld metal was investigated at room temperature in 3.5% NaCl solution using potentiodynamic polarization. The results show that the corrosion resistance of weld metal is more than that of Inconel 625 and less than that of A517 Gr.B. It can be concluded that a proper selection of laser beam welding parameters provides sound, fully-penetrated welds.

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With respect to special conditions apply to the gas turbine, its blades are affected by many different factors such as, hot corrosion, oxidation, wear, impact of external particles, and etc. and are destroyed. Due to the reduction of their working life time, the turbine efficiency reduces and ultimately the heavy costs of periodic repairs are needed, and also new replacements of their blades are unavoidable. The aim of this study is investigation of the effects of corrosion and blade damage on flow field and gas turbine performance, by numerical simulation. In this research, a two stage turbine is modeled in the form of three dimensional and the results are validated with experimental data. To analyze of the behavior of entire flow, conservation of mass, momentum, and energy equations are solved. The numerical simulation of the turbine is done with ANSYS CFX software. Then the increased rotors tip clearance effects with decreasing thickness due to corrosion in both nozzles and blade leading edge and trailing edge were separately studied on turbine flow field and its performance in five actual different pressure ratios. The results showed that the most important factor in reducing the efficiency of gas turbine is due to rotor tip clearance increasing. Also corrosion of the blade edge respect to the trailing edge damage is a little more affected on reducing efficiency and increasing loss coefficients.

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Owing to direct contact with the machined surface, the flank surface can cause unfavorable effects on the surface integrity in high speed milling. Thus, in this study, the influences of flank wear width on the main characteristics of surface integrity like roughness, topography, microhardness and electrochemical corrosion resistance during high speed milling process is investigated. Milling tests were performed under constant cutting conditions with three repetitions and using 12 tools with flank wear widths on the AISI 4340 hardened steel. It was concluded that using the tool with flank wear width up to 0.4 mm increase roughness and microhardness, uniformly (95% for surface roughness and 6.3% for microhardness relative to new tool). However, using a tool with the flank wear of 0.6 mm increases these outputs up to 484% and 18.6%, respectively. Surface topography images also revealed that using the tool with the flank wear width of 0.6 mm can cause irregular forms of material flow on the surface. Using the tool with the flank wear of 0.4 mm or less had an insufficient effect on the in-depth microhardness distribution. In addition, electrochemical impedance spectroscopy of the milled surfaces showed that relative to new tool, using tools with 0.4 and 0.6 mm flank wear, reduce Rcorr up to 22% and 83%, respectively. It indicated lower electrochemical corrosion resistance of milled surfaces with 0.6 mm worn-out tools.

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Abstract Reliability analysis of steel structures subject to seawater corrosion is of considerable interest for coastal and offshore marine steel structures. These are often very expensive and have high consequential costs and implications should failure occur. Since corrosion of steel structures causes deterioration of structural strength, usually gradually with time, safety assessment is of considerable importance for new structures (those in the design stage) and also for those which are already in operation. Marine corrosion is a complex phenomenon and subject to various influencing factors each of which has its own inherent uncertainty. In any safety assessment, in principle, the uncertainty of each factor should be studied and taken into account. Since such an action is too difficult, in practice some test programs are normally conducted and all uncertainties caused by different factors are assumed to be included in the relevant corrosion measurements. In addition, in any corrosion reliability analysis for steel structures exposed to seawater, two different models must be taken into consideration: (1) A physical model indicating general corrosion behaviour as a function of exposure time and (2) A stochastic model describing probabilistic treatment of uncertainties observed in real corrosion data. The first has been traditionally treated by invoking a simple power law and in particular a linear relationship. However, using realistic long-term data, validity of such a model has recently been challenged. The second model (i.e. probabilistic modelling of corrosion process) has been dealt with in literature in different approaches, including either taking the corrosion annual rate as a random variable or proposing a stochastic process such as Gamma process. This is usually proposed as a general structural deterioration process. The second approach provides, doubtlessly, better treatment of corrosion uncertainties; however it can be shown unfortunately that the Gamma process is unable to reflect the corrosion uncertainties in some circumstances. In this paper, two sets of corrosion data collected in different seawaters around the world with different temperatures are used. This requires processing of data in such a way that the data sets remain consistent with each other and that outcome is data that can be considered as belonging to one statistical population. Herein, first, a simple algorithm is proposed to transform the whole data to one common temperature. Second, a novel Markov-chain based model is developed which meets long term second-order corrosion statistics (i.e. means and standard deviations of corrosion losses). It is based on a corrosion model that previously has been calibrated extensively to field observations of corrosion and to literature-reported realistic data. Although actual long-term field observations of marine corrosion of steel are scarce, it is shown that particularly for the standard deviation the new model is well capable to be consistent with the long-term data. It is noted that herein, only the corrosion data collected in marine immersion zones are considered (i.e. those taken in splash zones and atmospheric zones are not considered). Further, only general corrosion (i.e. not pitting corrosion) is accounted for herein. These issues, obviously, have to be addressed separately.

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This research aims to describe a novel model, namely Hybrid Adaptive-Neuro Fuzzy Inference System-Particle Swarm Optimization (ANFIS-PSO), for predicting corrosion rate of 3C steel considering different marine environment factors. In the present research, five parameters (temperature, dissolved oxygen, salinity, pH, and oxidation–reduction potential) were used as input variables, with corrosion rate being the only output variable. In the proposed hybrid ANFIS-PSO model, the PSO served as a tool to automatically search for and update optimal parameters for the ANFIS, so as to improve generalizability of the model. Eeffectiveness of the hybrid model was then compared those to two other models, namely Adaptive-Neuro Fuzzy Inference System–Genetic Algorithm (ANFIS-GA) and Support Vector Regression (SVR) models, by evaluating their results against the same experimental data. The results showed that the proposed hybrid model tends to produce a lower prediction error than those of ANFIS-GA and SVR with the same training and testing datasets. Indeed, the hybrid ANFIS-PSO model provides engineers with an applicable and reliable tool to conduct real-time corrosion prediction of 3C steel considering different marine environment factors.

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Nowadays, multilayered sheet metals are used in order to achieve a wide range of favorite mechanical, physical, thermal and electrical properties. The laser beam passage over the sheet creates extreme temperature changes which can lead to a change in chemical properties and microstructures. Due to the wide application of these materials in chemical and corrosive environments, corrosion tests were carried out on two-layered SUS304L/copper C11000 and three-layered SUS430/copper C11000/steel SUS430 sheets subjected to various laser passes. Ytterbium fiber laser is used and the governor mechanism during the process is TGM. The changes of microstructures were revealed by metallography. Corrosion resistance of steel layer in three-layered sheet subjected to laser was dropped due to the martensite and oriented ferrite grain size reduction in HAZ. There is no change in microstructure and corrosion behavior of copper layer and the second steel layer due to the HAZ low penetration depth. There is no change in microstructure and corrosion behavior of steel layer in two layered sheet due to the austenitic microstructure. Penetration depth of HAZ in two-layered sheet is limited to a small part of its steel cross section. So, there is no change in microstructure and corrosion behavior of copper, and corrosion is the same all over the copper layer in all specimens.

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Catastrophic failures due to corrosion are among the most common phenomena in pre-stressed concrete pipeline, which has been reported in Iran, as well. Structural health monitoring, quick assessment and timely detection of corrosion in its early stages with active in-situ sensors is could prove vital in avoiding such hazards. Acoustic emission is a non-destructive technique that can be used to give a better insight on the structural state of such concrete structures. However, the interpretation of the AE measurements is quite challenging and may actually be even more difficult when the concrete is cracked, which would affect the material and structural properties of concrete pipes. The amplitude distribution of the acquired signals is very sensitive to micro-cracking. This paper presents the results of an experiment conducted in the laboratory of Middle East Technical University on pre-stressed concrete pipe for determining the amplitude attenuation and path of acoustic wave propagation and frequency spectrum before and after corrosion using Hsu-Nielsen pencil-lead break source and applying accelerated corrosion. The results from the laboratory tests indicate that since the changing in amplitude and wave propagation path is negligible before and after corrosion, the AE measurements can be used as an accurate method for tackling the problem mentioned above. Then the performed AE measurements are reported and results discussed.

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Corrosion of steel reinforcement has a complex process which leaded the reduction of crass section bars and degradation of concrete structure. the corroded reinforcement bars were the most important issue of the concrete permanence in the marine structures. The important effects of corrosion are in the damages made by corroded concrete structure which include all kinds of structural and non-structural damages. The first one is more important because of the reduction of the safety factor of the structure against the applied external loads. These failures include the reduction of cross-section bars and the changes in the steel mechanical behavior. Corrosion includes two processes: (1) corrosion initiation and corrosion propagation. The initiation time is when the corrosive ions receive on the surface bars and lead to activation of the steel. (2) The propagation time is when the structure loses its capability subject to the loss of the cross-sectional area of reinforcing steel bars, reduction of bond and crack initiation and propagation. The predicative models of life-service of a reinforced concrete structures should be included the two processes of corrosion. Because for new structures, the initiation time of corrosion and insurance from the long-time of corrosion initiation time, and for the existing structures, controlling the corrosion propagation is more important.
In this paper, statistical characteristics of the chloride diffusion coefficient, corrosion initiation time and corrosion rate including the best probability distribution function and its parameters are investigated based on Mont Carlo simulation of pitting corrosion data. The distribution function parameters of the corrosion variables i.e. the chloride diffusion coefficient, corrosion initiation time and corrosion rate were calculated using the Maximum likelihood method based on mathematical pitting corroded model that corrosion initiation and corrosion propagation processes are considered in this model. the probability density functions such as: Gamma, Gumbel, Lognormal, Normal, and Weibull were used in the statistical analyses of corroded pitting parameters. The best probability distribution function was selected using chi-square statistic. the Lognormal distribution function was obtained the best probability function for the threshold chloride concentration, the corrosion initiation time and the corrosion rate. The corrosion initiation time depend on four basic random variables such as: the concrete compressive resistance, the concrete cover, the threshold chloride concentration and the surface chloride concentration. Thus, their statistical effects of these random variables on corrosion initiation time are parametrically investigated using 10000 Mont Carlo simulations. It is obvious that increasing the concrete resistance leads to increasing the corrosion initiation time and standard deviation of the density function. The concrete physical and mechanical characteristics are effective variables on the corrosion initiation time but the threshold chloride concentration and the surface chloride concentration are insensitive variables on the mean of corrosion time but lead to significant changes in standard deviation of the corrosion time. Finally, Various diameters bars such as: 8, 12, 16 bars and 20 were investigated in time-depended area of the corroded steel of concrete beams. Results illustrated that and the cover depth is important variable in corroded crass section of bars. Also, increasing the bar diameter and decreasing the corrosion time period were leaded to reduce the rate of the crass section bars.

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Reinforcement inside the concrete is protected from corrosion and its damages until several years after the construction. After corrosion initiation, the Cross Section of Reinforcement begins to reduce and often load bearing of the reinforced concrete structure will be reduced significantly. Corrosion of reinforcements in concrete in polluted and contaminated areas can be occurred in two ways: Chloride and Carbonation. Chloride ion ingress is one of the major problems that affect the durability of reinforced concrete structures such as bridge decks, concrete pavements, and other structures exposed to harsh saline environments. Corrosion occurrence and development in reinforced concrete structures increase the steel volume and produce products with volume of about 2-7 times the steel initial volume. This volume increase, which is due to cracks, reduces the compressive and tensile strengths in reinforced concrete structures. Therefore, durability based design of concrete structures in marine areas has gained great significance in recent decades and various mathematical models for estimating the service life of reinforced concrete have been proposed. In spite of comprehensive researches on the corrosion of reinforced concrete, there are still various controversial concepts. Effect of environmental conditions on durability of concrete structures is one of the most important issues. Hence, regional investigations are necessary for durability-based design and evaluation of the models proposed for service-life prediction. The Persian Gulf is one of themost aggressive regions of the world because of elevated temperature and humidity as well as high content of chloride ions in seawater. Corrosion of reinforcement due to chloride ions attack causes enormous damages to structures in severe condition of marine environments. Normally, high alkaline property of concrete (PH≈13) forms a protective oxide layer on the steel surface. This is called a passive protection. The dioxide existing in the atmosphere or the chloride in the concrete environment along with the moisture and the oxygen can penetrate via the concrete pores and cracks and can reach the armature surface; then, by reducing concrete alkalinity, they cause armature corrosion inside the concrete by destroying the protective oxide layer on the steel. Chloride ions reach the passive layer according to the explained pattern and they begin to react in the passive layer when the amount of chloride ions go beyond the critical value and cause perforation corrosion. Since each influencing factor in the life time of the structure is subject to random variability and inherent uncertainties, a stochastic approach is utilized to predict the time for initiation of the corrosion. Based on Fick’s law, time for corrosion is a function of surface chloride, critical chloride, concrete cover thickness, and diffusion coefficient. The most common models service-life prediction of reinforced concrete structures under load chloride, only produce a limited definite time for the start of corrosion. In this paper monte carlo simulation use for service-life prediction of reinforced concrete structures of predict the time of corrosion initiation, and shown the influence of mean and standard deviation variations for each of the parameters that affect the occurrence of corrosion, on the time of initiation corrosion and impact of these factors on the probability initiation corrosion.

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Corrosion in spiral steel prestressed wires tensioned around core are one of the major weaknesses of prestressed concrete pipes which their untimely detection can cause sudden failure and damages. To date, these kinds of pipes are used and produced in Iran and their abrupt failure due to corrosion has been experienced. In this study acoustic emission monitoring in prestressed concrete was used to investigate the corrosion. An approximately full-scale experimental sample pipe is made in Middle East Technical University laboratory. The pipe is loaded by internal water pressure and accelerated corrosion applied to the sample and the resulted acoustic emission signals are recorded using piezoelectric sensors during corrosion. The sample is tested under wetting and drying cycles frequently for corrosion detection in which during the experiment, pipe inside pressure was fluctuated and Kaiser Effect was studied in different conditions. Experimental results show significant changes in some gained acoustic emission parameters as the pipe work pressure increases to higher amounts. It is shown that the changed AE parameters can be used for damage prediction, condition assessment and corrosion detection of prestressed concrete pipelines.

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Equal channel angular rolling process (ECAR) is one of the newest processes in the severe plastic deformation methods (SPD) that changes the mechanical properties of the sheet metal. In this study, the effects of ECAR process have been investigated on the corrosion behavior of the pure commercial copper samples. Five routs have been applied on the samples to investigate the mentioned parameters. Also, the corrosion rates were examined by the polarization and electrochemical impedance methods. The results show that the process has destructive effect on corrosion resistance of the samples. The results from SEM examination indicates that, with increasing the number of passes, the surface corrosion increases too and with increasing the passes pitting corrosion is clearly visible. Although with increasing the number of passes the uniformity of corrosion can be seen and positional mode is exited. Generally, the corrosion increases from the first pass to the second pass. Also, the more diameter and depth of corrosion is observed with increasing the pass number. The corrosion increase at the third pass and the corrosion type is pitting corrosion and uniform corrosion in the sample.

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The surface protection materials have effective results to prevent concretes from corrosion. Reinforced concrete structures have the potential to be very durable and capable of withstanding a variety of adverse environmental conditions. However, failure in the structures does still occur as a result of premature reinforcement corrosion. There are corrosion protection systems and methods to extend the long-term durability of steel reinforced concrete. For example, application of zinc rich or cement based protective primers to reinforcement, surface protection systems of concrete, Cathodic protection using sacrificial zinc anodes, and conductive anode overlays within an impressed current cathodic protection system. In general, the main duty of surface protection is controlling both physical and chemical damages to concrete in order of preventing or reducing from steel bar corrosion and creating a coat of safekeeping against penetration of chloride ion, carbon dioxide, oxygen, and most importantly water. According to European Norm, three types of protection materials are existed based on function mechanism. Coating, hydrophobic impregnation, and impregnation materials are these systems, and two types of them used in this study. In this study, two materials of surface protection have used on the surface of three types of concrete. Two types of self compacting concrete with different w/c ratio and one ordinary concrete with similar mixture design to one of those SCC were used for estimating of durability of concrete. Epoxy resin and silane-siloxane were two types of surface treatment materials used in this study. SEM analysis and water contact angle test were done to study the function mechanism of surface protection material. The other tests are water vapor permeability, corrosion potential, and corrosion intensity. Some of the results of this study is that using this materials have effective impact on declining of corrosion potential, decreasing of corrosion intensity, and after all increasing durability of concrete. As shown in this paper, all of the protected samples except one, until 49th week did not have a sign of corrosion active phase. Increasing in ratio of W/C in the substrate makes weakness in function of this materials. In the other hand, results of half-cell potential of unprotected samples show SCC2 with 0.55 w/c ratio and NC with 0.45 w/c ratio shift from passive to active state in first days and SCC1 with 0.45 w/c ratio attained its active state in 5 weeks. However once corrosion has started in SCC2-EP in 8 weeks, corrosion rate was lower than unprotected samples. In the presence of surface protection systems, due to their ability to reduce water ingress in concrete, the corrosion intensity in all samples were lower than 0.23 µA/ cm^2. The results of water vapor permeability test showed that epoxy can decrease the water vapor permeability up to 65% instead of unprotected concrete. In the meantime, silane-siloxane doesn't have effective results in concrete breathability and have a similar performance to unprotected concrete. The results show using SCC don't have much different effect on quality of the materials function instead of ordinary concrete. Another important result is that protection materials which don't let to enough evaporate, are cause of much corrosion in compare of those that let concrete to breath.

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Ti-6Al-4V alloy due to excellent mechanical properties mainly is used in the aerospace, automobile and biomedical industries. Electrical discharge machining (EDM) are used extensively for machining of this alloy. Due to the thermoelectric nature of this process, unwanted changes happen on machined surface such as development of residual stresses and the change in the corrosion resistance. The aim of this study is the experimental investigation of the effect of input parameters (discharge current and pulse on time) on the amount and distribution of residual stresses and corrosion resistance changes of the machined surface in EDM process of Ti-6Al-4V alloy. For this purpose, samples of Ti-6Al-4V alloy were machined by EDM process and residual stresses induced successive sparks in different setting (different discharge currents and pulses on time) were measured by nanoindentation method and SEM images of machined surface used to better assess of samples surface integrity. TOFL measurement method used to determine the corrosion resistance of the samples. Results indicate that at this process tensile stresses is formed on surface and mentioned stresses increase with depth initially and after reaching a maximum dropping out and eventually leads to pressure stress. By increasing pulse on time and discharge current, maximum tension residual stress only slightly increases and is near ultimate tensile strength of work piece material. Comparison of corrosion results indicated that the corrosion resistance of EDMed samples, was less than the not machined specimens.