Engineering Commons^™

Oxidation Modeling By Means Of Molecular Dynamics, Chaiyod Soontrapa

UNLV Theses, Dissertations, Professional Papers, and Capstones

Oxidation modeling is normally engineered to study systems at macroscopic scales, mostly in analytical forms based on diffusion theories. The associated time scale is usually in months, days, or minutes, and the length scale is in the order of microns. In this dissertation, oxidation modeling is performed at atomistic scale with the time and length scales in picoseconds and angstroms, respectively, using molecular dynamics. Molecular dynamics simulations generate trajectories of each atom or particle in a system according to the laws of physics. Studying oxidations under the atomistic point of view can offer new insights on atomic behaviors and influencing …

Study Of Corrosion Of Materials In The Sulfur-Iodine Hydrogen Production Cycle, Thao Trung Ho

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen is of great interest since the availability of traditional fossil fuels is in decline. Strictly speaking, hydrogen is not a primary source of energy but is an energy carrier, since energy typically must be used from another source (electricity, natural gas, coal, etc.) to produce it. Of hydrogen production techniques, the Sulfur-Iodine thermochemical water splitting process (S-I cycle), which was proposed by General Atomics (GA), is promising with its simplicity and high efficiency. Most of the chemicals are recycled except water. However, the S-I cycle operates in a harsh, corrosive environment in the presence of a mixture of iodine …

Corrosion Inhibition Of Magnesium Alloy In 3.5% Nacl Medium By Tungstate, Ling-Jie Li, Zhi-Ming Yao, Jing-Lei Lei, Dong-Hai He, Sheng-Tao Zhang, Fu-Sheng Pan

Journal of Electrochemistry

Electrochemical impedance spectroscopy(EIS),Tafel polarization curves and scanning electron microscopy(SEM) were used to study the corrosion inhibition of AZ61 magnesium alloy in 3.5% NaCl medium with tungstate.Results showed that tungstate demonstrates strong inhibition to the corrosion of AZ61 magnesium alloy.At the concentration of 0.01 mol/L,tungstate has a high inhibition efficiency 75.5%.Tungstate is an anodic inhibitor that mainly inhibited the anodic reactions of magnesium alloy through forming a compact protective layer that covered the magnesium alloy surface active sites.

Corrosion Electrochemical Behavior Of Az31 And Az61 Magnesium Alloys In Simulated Sea Water, Ling-Jie Li, Sheng-Hai Yu, Jing-Lei Lei, Chuan-Pu Liu, Sheng-Tao Zhang, Fu-Sheng Pan

Journal of Electrochemistry

Tafel polarization curves and electrochemical impedance spectroscopy(EIS) techniques were employed to investigate the corrosion electrochemical behavior of AZ31 and AZ61 magnesium alloys.Scanning electron microscopy(SEM) was used to observe the alloy microstructure and corrosion morphology.The variation of the bulk corrosive medium pH with immersion time was recorded during the exposure of the alloys to simulated sea water.Results show that AZ61 magnesium alloy exhibits much better anti-corrosion ability than AZ31 magnesium alloy.The different corrosion behavior between the two magnesium alloys is correlated with their different content of Al alloying element.The higher content of Al in AZ61 alloy leads to the homogenerous microstructure …

Supercritical Water Oxidation Process And Its Application In Treatment Of Industrial Wastewater (Persian Paper), N. Daneshvar, S. Aber, Mir Saeed Seyed Dorraji, M. Zarei, M. H. Rasoulifard

Mir saeed Seyed Dorraji

In the last two decades, supercritical water has become an interesting medium for chemistry. One of its most investigated applications is the oxidative treatment of aqueous wastes containing organic compound in the so-called “supercritical water oxidation”. In this technology, supercritical water acts as a non-polar solvent. Consequently, even non-polar organic compounds and gases like oxygen become completely miscible with the supercritical fluid. During the supercritical water oxidation (SCWO) process, the organic compounds react completely with oxidant –mostly oxygen- in a single phase reaction forming CO2 and H2O. The hetero-atoms present in the organic wastes are transformed into the mineral acids. …

Study On Electrochemical Impedance Spectroscopy Of Carbon Steel Eroded In Methyldiethanolamine Solution, Dong-Ping Wei, Rong-Zong Hu, Dan-Mei Pan, Wei-Xiong Huang, Rui Dong

Journal of Electrochemistry

Corrosion behavior of carbon steel in methyldiethanolamine(MDEA) solution was investigated by Electrochemical Impedance Spectroscopy(EIS).The results were showed that the corrosion rate of carbon steel in solution containing dissolved oxygen is higher than that in solution removed of dissolved oxygen before cathodic activation.They were reversed after cathodic activation.The corrosion rate is increased at first and then decreased when the concentration of MDEA is increased in the blank solutions.In the simulated solutions containing quantities of!heat-stable salts(HSS),the corrosion rate is decreased monotonously with increase of the MDEA concentration.As anodic polarization potential is increased,the EIS of carbon steel in HSS simulated solution showed characteristics …

Corrosion Electrochemical Behavior Of Aluminum Flake Pigmented Water-Borne Epoxy Coating On Carbon Steel In Nacl Solution, Li-Li Xue, Li-Kun Xu, Qing-Fen Li, Hong-Qing Song, Wen-Juan Zhou, Guang-Zhang Chen

Journal of Electrochemistry

The corrosion electrochemical behavior of a water-borne epoxy coating pigmented with aluminum flake on carbon steel with artificial scratch defect was studied in 3.5% NaCl solution using electrochemical impedance spectroscopy(EIS)and scanning vibrating electrode technique(SVET).The results indicated that the defect presented anodic electroactivity at the initial stage of immersion,which extended gradually with time from the scratch into the neighboring coating,lowering the coating impedance.With further immersion,however,the electroactivity of the coating/steel interface decreased significantly due to the self-repairing of the corrosion products,causing an obvious increase of the coating impedance.In the later period of immersion,more scattered electroactive areas appeared under the coating because of …

Effect Of Cracks On Corrosion Of Rebar In Concrete Studied By Wire Beam Electrode, Guo-Xi Li

Journal of Electrochemistry

The effects of crack and ethanolamine on corrosion of rebar in concrete were studied by measuring the distribution of corrosion potential and polarization resistance of iron wires in 10% NaCl solution.The results showed that the diffusion of water,oxygen and chloric ion toward concrete was accelerated by the crack which intensified the nonuniform corrosion of iron wire with the regions near to crack as anode and the uncracked regions as cathode.Ethanolamine could diffuse into the body of concrete and absorb on the surface of iron wire,which reduced iron corrosion evidently and successfully inhibited the nonuniform corrosion caused by crack without changing …

Polymer-Derived Si-Al-C-N Ceramics:Oxidation, Hot-Corrosion, And Structural Evolution, Yiguang Wang

Electronic Theses and Dissertations

Polymer-derived ceramics are a new class of materials synthesized by thermal decomposition of polymer precursors. Previous studies have shown that the materials exhibit excellent thermo-mechanical properties and can be stable at temperatures up to 2000oC. Furthermore, the novel polymer-to-ceramics process enables the manipulation of the ceramic structures at the atomic/nano level by designing the chemistry of polymer precursors and controlling the pyrolysis conditions, thereby, the properties of ceramics. In this dissertation, oxidation/hot-corrosion behavior and the structural evolution of Si-Al-C-N ceramics have been studied. The structural evolution and crystallization behavior of the SiCN and SiAlCN ceramics are investigated using FT-IR, XRD, …

A Study Of Three Corrosion Inhibitors For Reinforcing Steel In Sps Solution By Electrochemical Methods, Bing Zhao, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

Some electrochemical techniques such as linear polarization,electrochemical noise and EIShave been employedto study the inhibition behavior of N-lauroyl sarcosinate,β-sodium glycerophosphate and D-sodium gluconate for the reinforcing steel immersed in simulated concrete pore solution(SPS) with NaCl addition.The results show that D-sodium gluconatehas an obvious inhibitive effect for the reinforcing steelin containingCl~(-)SPS solution.It has been proposed that the corrosion inhibition of D-sodium gluconate is due to its competitive adsorption and precipitation on steel surface in the simulated concrete environment.

Corrosion Behavior Of Sml,Erw Pipeline Steels Exposed To Seamud, Wei Hua

Journal of Electrochemistry

The corrosion behavior of API Spec X60 pipeline steels, including electric resistance welding(ERW) and Seamless (SML) types,in sea mud gathered fromYangtse River estuaryof the East China Sea was investigatedthrough linear polarization resistance, potentio-dynamic polarizationand electrochemical impedance measurements.The result indicate the improved corrosion resistance of SML in sea mud. The oxygen diffusion in the cathode zone determines the corrosion behavior of pipeline steel in sea mud.

Instrumentation Of Ysz Oxygen Sensor Calibration In Liquid Lead-Bismuth Eutectic, X. Wu, Jian Ma, Yingtao Jiang, B. Fu, W. Hang, J. Zhang, N. Li

Mechanical Engineering Faculty Research

Liquid lead-bismuth eutectic (LBE), a good candidate for the coolant in the subcritical transmutation blanket, is known to be very corrosive to the stainless steel that transports it. Such a corrosion problem can be prevented by producing and maintaining a protective oxide layer on the exposed surface of the stainless steel. Proper formation of the oxide layer critically depends on the accurate measurement and control of the oxygen concentration in liquid LBE. An oxygen sensor calibration/measurement apparatus has been designed and built to deliberately calibrate an yttria stabilized zirconia (YSZ) oxygen sensor. A detailed description of this system with its …

Study Of Anti-Corrosion Property On Poly(An-Co-Oas)/Epoxy, Qing-Wu Wang, Geng-Chao Wang

Journal of Electrochemistry

polyaniline, polyanisidine and their copolymer poly(An-co-oAs) were synthesized via the solution chemical oxidative polymerization of aniline and anisidine in an acidic aqueous medium, and their properties and structure were characterized. The electrochemical method were applied to evaluate the corrosion behavior of tined iron uncoated or coated by polyaniline, poly(An-o-oAs), polyanisidine and poly(An-co-oAs)/epoxy blend in acid or saline aqueous solution. The result showed that with the increase of anisidine content, the solubility of polymers is improved apparently but their oxidation extent decreases accordingly. It is also founded that polyaniline, poly(An-co-oAs) and polyanisidine all have good anti-corrosion properties, and their anti-corrosion capacity …

Electrodeposition Nanolaminated Growth Of Zinc, Ying Cao, Tian-Hui Shen, Jing-Yuan Yao, Gui-Fu Ding

Journal of Electrochemistry

Nanolaminated growth of the electrodeposition of zinc was studied. The structure and size of crystalline in zinc coatings were investigated by using FEG-TEM and XRD. The corrosion tests of the zinc deposition and the Coatings-Neutral salt spray test were performed, the capability in corrosion resistance of the nanolaminated growth was better than that of others.

The Localized Corrosion Behavior Of 6% Mo And 316l Stainless Steels In Chloride Media And The Effect Of Applied Mechanical Stress, Houssam El-Din Sabry Ahmed

Archived Theses and Dissertations

Electrochemical techniques were applied to study the crevice corrosion resistance of two types of stainless steel alloys namely, conventional 316L and super austenitic 6% Mo in acidified 3% NaCl solution at room temperature. Potentiodynamic results showed that 6% Mo alloy possessed a remarkable resistance to crevice corrosion compared to 316L alloy when tested in the same solution. The breakdown potential at which passivity broke down for 316L alloy was 0.00 m V, SCE, the corresponding value for 6% Mo alloy could not be reached up to the potential value of 700 m V, SCE. 316L alloy suffered extremely from crevice …

Effect Of Dissolved Oxygen On The Corrosion Behavior Of Coalesced Copper And Stainless Steel-206 In Acetic Solutions, Rong-Zong Hu, Xiong-Cao Zhao, Yu-Hua Weng, Chang-Jian Lin

Journal of Electrochemistry

Linear sweeping technique and dissolving oxygen sensor were used to study the effect of dissolved oxygen and relating factors on the corrosion behavior of coalesced copper and stainless steel-206 in acetic solutions. It was found: 1. The existing of dissolved oxygen is one of the important factors, which strongly influenced the corrosion behavior of coalesced copper and stainless steel-206 in acetic solution. 2. The existing of dissolved oxygen is benefitial to the preventing stainless steel-206 from corrosion in acetic solutions, but damage to the preventing coalesced copper from corrosion. 3. At the high temperature since the dissolved oxygen was escaping …

Electrochemical Techniques For Measuring Anti-Corrosion Behavior Of The Thin Corrosion Inhibitor Layer To The 907a Steel, Yong-Tao Zhao, Jian-Hua Wu, Fan-Cai Chen, Zhong-Ping Gao, Jia Wang, Chang-Jiu Zhao

Journal of Electrochemistry

The corrosion inhibiting behavior of 907A steel,which was covered with thin inhibitor layers in moist seawater atmosphere,was studied.The electrochemical measurements,including EIS method and the coulostatic method,were used to atmospheric corrosioed monitor(ACM)under thin inhibitor layers to determine its corrosion rate.The results shown that the application of electrochemical methods such as the coulostatic technique and EIS could readily detect the on going process of film formation. Hence, the rapid evaluation of the thin inhibitor layers for 907A steel might be possible.

Corrosive Electrochemical Behavior Of Carbon Steel In Microbiological Medium, Jing Liu, Hong-Bo Fan, Hai-Ping Xu, Jia-Shen Zheng, Li-Ming Xu, Zong-Qiang Mao

Journal of Electrochemistry

Sulfate_reducing bacteria(SRB)grows and propagates, PH of the solution is dropped from 7.5 to 5.8,and forms the biofilms on carbon steel in culture medium.The micro_environment on the surface of carbon steel is changed under the biofilms,the factors accelerate the formation of the pitting corrosion. When the biofilm on carbon steel is cleaned out,the surface of carbon steel have the non_uniform pitting corrosion. The activity of SRB and the porous structure of biofilms induced the initiation and development of the pitting corrosion of carbon steel.The process of microbiologically induced corrosion(MIC) involves the development of SRB activity,which promotes the permeation of gydrogen into …

Studies On The Anti-Corrosion Behavior Of Corrosion Inhibitor To The Ship Building Steel In Moist Air, Yong Tao Zhao, Jian Hua Wu, Jia Wang

Journal of Electrochemistry

The anti corrosion behavior of 907A steel, which were covered with thin inibitor layers in moist air, were simulated, The electrochemical measurements, including EIS method and the coulostatic method, were used to atmospheric corrosion monitor(ACM)under thin inhibitor layers to study the mechanism of rust preventiion. the results shown that the mechanism of inhibiting corrosion was different from the steel immersed in inhibitor solutin, the anodic reaction process under thin inhibitor layers had the advantage over that of cathodic for blocking the speed of corrosion. At the later stage of soaking, the blend feature due to the electrochemical process and the …

Corrosion Behavior Of Reinforcing Steel In Concrete, Rong Du, Gui Gui, Rong Hu, Feng Zu Gang, Tan Jian De, Lin Chang Guang, Jian Jian

Journal of Electrochemistry

The corrosion behavior of reinforcing steel in concrete in chloride free and chloride contaminated simulated concrete solutions was studied by electrochemical technique.The results showed that the reinforcing steel exhitibted different corrosion characteristics in the different solutons.In general ,the steel in concrete was protected in the test solutions with no salt or the lower concentration of NaCl.When the concentration of NaCl is larger than 70%,however,the corrosion behavior of the steel varied considerably,and the corrosion rate increased as pH fell and the concentration of Cl - increased.

Synthesis And Application Of Polymeric Corrosion Inhibitor For Reinforced Concrete, Weiwei Lin, Shengxian Wang, Jianqing Zhang

Journal of Electrochemistry

A new polymer E Twas synthesized and used as a corrosion inhibitor for reinforced concrete. The inhibitive behavior and mechanism were studied with linear polarization ,Tafel polarization,EIS and XPS method in simulated pore solution system with concrete samples.The result showed that the polymer was a mixing type inhibitor. A 1% dosage was sufficient to imhibit the corrosion of steel in simulated pore solution system. The salt endurance was enhanced from 0.02 mol/L to 0.10 mol/L.The result also showed the good synergetic effect of NaNO 2,especially in low NaNO 2 concentration.The EIS showed that E_T has dual function on reinforced concrete,i.e.,densifying …

Corrosion Characteristics Of Electrodeposited Ni Mo P Alloy Immersed In Nacl Solution, Yue Zeng, Hongxin Huang, Xiaoming Xiao, Shixun Lian

Journal of Electrochemistry

The corrosion characteristics of electrodeposited Ni Mo P alloy immersed in 5wt.% NaCl solution were investigated using immersion, anodic polarization curves, XPS and AES analysis. The corrosion rates of amorphous Ni Mo P alloys are lower than that of crystalline Ni Mo P alloys. Anodic polarization curve experiments show that for the electrodeposited Ni Mo P alloys, the nickel mol fraction of which has in between 0.719 and 0.868, the corrosion potential moves to positive with the increase of P content, and the peak current value of active region increase with the increase of Mo content in alloys, though the …

Mechanical Properties, Structure, And Corrosion Characteristics Of Al And Al-Zn Coated Steel Sheets, Farraj El Shammari

Archived Theses and Dissertations

No abstract provided.

Characterization Of Iron Oxides And Atmospheric Corrosion Of Steel, Sei Jin Oh

Physics Theses & Dissertations

The study of corrosion behavior was performed using three different analytical techniques, which provided information on the formation, development and layering of iron oxides on the corrosion products as a function of atmospheric conditions, exposure time and type of steel. In particular, the protective layer formed on weathering steel was investigated as a function of different amounts of alloying elements in the steel, atmospheric conditions and exposure times. Combined together, the results provided a better understanding of the atmospheric corrosion behavior of steel, and formed a part of database of the atmospheric corrosion characteristics.

Accurate characterization of the iron oxides …

Electrochemical Study Of The Corrosion Behavior Of Coalesced Copper And Sw-206 Stainless Steel In The Acetic-Acid Solution, Rongzong Hu, Changjian Lin, Jianguang Tan

Journal of Electrochemistry

In order to provide a theoretic and experimental consideration for the material selection and anit-corrosion in the petrochemical industries the corrosion behavior of coalesced copper and sw-206 stainless steel in the acetic acid solution was studied by electrochemical impedance spectroscopy and polarization techniques. The effects of the temperature,acetic acid concentration and solubilized oxygen in the acetic acid solution on the corrosion process of this two metals were analyzed. It was found that these effects obviously accelerate corrosion process for the coalesced copper,but no apparent influnce for the sw-206 stainless steel.In the the acetic acid solution,containing water and oxygen were beneficial …

The Inhibition Of Amphipathic S- And N-Containing Compounds On Carbon Steel Corrosion, Wei Xing, Yibin Shan, Du Guo, Tianhog Lu, Shiquan Xi

Journal of Electrochemistry

Ordered monolayers of S- and N-containing amphipathic corrosion inhibitors were depoitod onto the surfaces of carbon steel electrode with super-molecular assembly technique. The effect of molecular aggregation of monolayers on carbon steel corrosion in 0. 05 mol dl￣(-3)H_2SO_4 and the mechanisms of these inhibitors were discussed in details. It was found that the transport of hydrated hydrogen ion to the surface of steel depends strongly on the inhibitor molecular aggregation in the monolayers.

Optical Fiber Fourier Transform Infrared Evanescent Wave Absorption Spectroscopy Of Aluminum Hydroxide And Natural Corrosion, Juock S. Namkung

Electrical & Computer Engineering Theses & Dissertations

A new technique for continuous, real-time, in-situ detection of natural corrosion of aluminum alloys is presented. The technique is a generalized version of attenuated total reflectance (ATR) spectroscopy, that combines optical fibers and a Michelson interferometer spectrometer to make evanescent wave absorption measurements. Aluminum hydroxide is one of the major corrosion products of aluminum. Absorption spectra of powdered samples of aluminum corrosion, in the spectral region around three micrometers have been studied and compared with the spectra from pure powdered aluminum hydroxide. A chalcogenide optical fiber was used as an attenuated total reflectance (ATR) optical element. The same samples were …

The Composition Structure And Corrosion Resistance Of Al-Mn Alloy Plating, Jiaju Guo

Journal of Electrochemistry

The Al-Mn alloy plating was electrodeposition from low temperature molten salts(below 200℃),its chemical composition control,corrosion resistance as well as the relationshipbetween chemical composition and structure were studied.The results indicate that the main effect onchemical composition of Al-Mn alloy plating is Mn ion concentration in molten salts.The Mn contentin the range of 25～40(wt)%, Al-Mn alloy plating has amorphous structure. In 0.5 mol/L H_2SO_4and NaCl solution ,corrosion resistance of the alloy plating is much better.When the alloy hasamorphous structure,corrosion resistance of plating has been remarkably increased.

Application Of Inhibitor To Improve The Anticorrosion Performance Of Electrophoretic Coating, Changshou Cai, Fangteng Su, Bihuan Liu, Guomou Wen, Jingdong Guo

Journal of Electrochemistry

To improve the anti-corrosion performance of electrocoating,organic andinorganic inhibitors are applied in an anodic electrophoretic-coating.The results show that thedeposition of polymer with zinc phospate exhibits a high inbihition efficiency.The inhibitionmechanism of the inhibitor in electrocoating has been studied.

Long-Term Effects Of Neutron Absorber And Fuel Matrix Corrosion On Criticality, William Culbreth, P. Zielinski

Mechanical Engineering Faculty Research

Proposed waste package designs will require the addition of neutron absorbing material to prevent the possibility of a sustained chain reaction occurring in the fuel in the event of water intrusion. Due to the low corrosion rates of the fuel matrix and the Zircaloy cladding, there is a possibility that the neutron absorbing material will corrode and leak from the waste container long before the subsequent release of fuel matrix material. An analysis of the release of fuel matrix and neutron absorber material based on a probabilistic model was conducted and the results were used to prepare input to KENO-V, …