Effect of Fly Ash on Frost-Resistance and Chloride Ions Diffusion Properties of Marine Concrete

It is necessary to pay more attention to the durability of concrete undergoing freeze-thaw cycles and seawater attack simultaneously.Investigated are the effects of water-binder ratio,fly ash（FA）contents and air-entraining agent on resistance to frost and chloride diffusion of marine concrete blended with FA in natural seawater.The results show that fly ash does not improve the frost resistance of concrete but can improve its resistance to chloride diffusion by addition of less than 30%.The resistance to frost and chloride diffusion of FA concrete can be improved with the decrease of water-binder ratio,and FA may improve both of them simultaneously only being mixed with air-entraining agent.A ratio（named as R）of the frost-resisting durability factor to chloride diffusion coefficient can be used to evaluate the durability of marine concrete.Scanning electron microscope（SEM）analyses are consistent with the evaluations by the value of R.

Effect of temperature, chloride ions and sulfide ions on the electrochemical properties of 316L stainless steel in simulated cooling water

The influence of temperature, chloride ions and sulfide ions on the anticorrosion behavior of 316L stainless steel in simulated cooling water was studied by electrochemical impedance spectroscopy and anodic polarization curves. The results show that the film resistance increases with the solution temperature but decreases after 8 days’ immersion, which indicates that the film formed at higher temperature has inferior anticorrosion behavior; Chloride ions and sulfide ions have remarkable effects on the electrochemical property of 316L stainless steel in simulated cooling water and the pitting potential declines with the concentration of chloride ions; the passivation current has no obvious effect; the rise of the concentration of sulfide ions obviously increases the passivation current, but the pitting potential changes little, which indicates that the two types of ions may have different effects on destructing passive film of stainless steel. The critical concentration of chloride ions causing anodic potential curve’s change in simulated cooling water is 250 mg/L for 316 L stainless. The effect of sulfide ions on the corrosion resistance behavior of stainless steel is increasing the passivation current density Ip. The addition of 6 mg/L sulfide ions to the solution makes Ip of 316 L increase by 0.5 times.

Invading track of chloride ions in cemented-based materials

Invading track of chloride ions and chloride ion distribution rule in cement-based materials were investigated by partially soaking in 3.5% （mass fraction） NaCl solution and fully immerging in 3.5% and 5.0% （mass fraction） NaC1 solution, respectively, and relevant invading mechanisms were discussed. Results indicate that under full immerging condition, the invading track of chloride ions in cement mortar is similar to beeline that is vertical to chloride ion invading direction, and chloride ion content decreases rapidly with the increase of chloride ion invading depth. Under partial soaking condition, the invading track of chloride ion in cement mortar is similar to the shape of concave parabola, and chloride ion content decreases slowly along the lengthway direction of cement mortar samples in the distance of 20-80 mm from the bottom. Lots of chloride ions accumulate in cement mortar surface layer under the effect of capillary rise and evaporation and then invade cement mortar by diffusion effect. Under partial soaking condition, cement mortar is distinguished by four areas, i.e., immerging area, wet area, crystallization area and dry area.

Tetrahydro-dibenzo[a,d]Annulene-5,11-Dihydrazone and Magnesium Oxide Used to Control the Corrosion of Aluminium in Chloride Ions Environment

Chloride ions interact with aluminium in marine atmosphere to form corrosion cell.Due to this corrosion reaction occurs on their surface,aluminium is oxidized into Al3+.The corrosion reaction accelerates deterioration in metal and it produces galvanic,pitting,stress,crevice,intergranular corrosion.Chloride ions decrease internal and external strength of aluminium metal.It is a very important metal so used in different appliances for e.g.road,water,air transports,housing,railways and other fields.Nanocoating and electrospray techniques used to check the corrosion of aluminium metal.For nanocoating and electrospray materials applied tetrahydro-dibenzo[a,d][7]annulene-5,11-dihydrazone and MgO.Both materials formed composite barrier and developed a passive surface for Cl-ions.This barrier reduced the corrosion rate of aluminium.Nozzle spray and chemical vapour deposition technique used for coating process.The corrosion rate of metal was determined by gravimetric method.Corrosion potential and current density were calculated by potentiostat.The composite barrier formation was confirmed by activation energy,heat of adsorption,free energy,enthalpy and entropy.These thermal parameters were obtained by Arrhenius equation,Langmuir isotherm and Transition state equation.The adsorption of tetrahydro-dibenzo[a,d][7]annulene-5,11-dihydrazone and MgO electrospray on aluminium surface was depicted by Langmuir,Frundlich and Temkin isotherm.The results of surface coverage area and coating efficiency were noticed that both materials were mitigated the corrosion rate of aluminium in chloride ions environment.

Corrosion resistances of metallic materials in environments containing chloride ions:A review

Corrosion,more specifically,pitting corrosion happening extremely in marine environments,leads to lifespan of materials drastically decreasing in service,which causes enormous economic loss and even environmental disaster and casualties.In the past decade,increasing efforts have been made to study the corrosion behaviors of materials in chloride-containing aqueous environments.Herein,this work provides an overview of recent progress in understanding the degradation mechanism and improving the corrosion resistance and corrosion-wear resistance of materials from bulk metal to surface treatment involving organic coating,metal and its alloy or compound coating.The particular emphasis is given to the periodic layered structures(PLSs),whose anti-corrosion properties outperformed others to some extent,wherever in terms of bulk metal or surface treatment,regardless of aggressive environment(corrosion or corrosion-wear conditions).Numerical simulation based on kinds of models at different scales is introduced to deeply understand the process of corrosion and/or corrosion-wear in chloride-containing aqueous environment.Combined experimental result with numerical simulation,the micro-galvanic corrosion dominated degradation mechanism of PLSs is critically analyzed.Types of setups to realize corrosion-wear in laboratory are also summarized.At last,future research and development are prospected,offering to develop a basic application of PLSs designed by corrosion protection methodology in the near future.

Diffusion of Chloride Ions in Soils:I.Influences of Soil Moisture, Bulk Density and Temperature

Diffusion coefficients of chloride ions in four soils of different texture with varying effective moisture content and varying bulk density from 1.1 to 1.6 g cm3 under three different temperatures were determined by the diffusion-cell method using 36Cl-labelled CaCl2 solution. The results showed that activation energy decreased with water content, which indicated that the threshold for diffusion was lower at a higher soil moisture rate. Therefore, the diffusion coefficient (D) of chloride ions in soil increased consistently with soil moisture. Although a near linear increase in the diffusion coefficient with increasing soil moisture or bulk density in all the soils was observed, the increase rate in different soils was not the same. The D value increased with temperature, and with temperature increased by 10℃ in the range from 5 "C to 45℃ theD valve increased by 10%～30%, averaging about 20%.

Diffusion of Chloride Ions in Soils: Ⅱ. Kinetic and Thermodynamic Characteristics

The amounts of chloride ions diffused in four soils of different textures at the same water content under different temperature and at varied time were measured by the diffusion cell method using 36Cl-labelled CaCl2 solution. Five kinetic models were used to fit the dynamic process of the diffusion of chloride ions in the soils. It was found that Elovich equation or power function equation was the best model to describe the process. The pseudothermodynamic parameters, i. e. the net reaction energyl the activation entropy,activation enthalpy and activation free energy of the diffusion, were derived from the absolute reaction-rate theory. The results showed that these parameters decreased in the order of loessal soil > black in soil >lou soil > yellow cinnamon soil, which indicated that the force and the heat-energy barrier to be overcome for diffusion decreased, the diffusion rate increased and the disorder of the soil-solution-ion system due to diffusion decreased successively with the texture becoming heavier in the four soils.

M-T Scheme for Predicting Effective Diffusion Coefficient of Chloride Ions in Cement-based Materials

To investigate the transport characteristics of chloride ions in cement-based materials, the Mori-Tanaka (M-T) prediction scheme of the effective diffusion coefficient in composites containing single-phase and multi-phase inclusions is systematically deduced based on the theory of composite mechanics and porous medium. The volume fraction, morphology and distribution of aggregates, as well as the interfacial transition zone (ITZ) are fully taken into consideration in this proposed model. The results show that the algorithm of M-T prediction scheme with high accuracy is relatively simple.

Mechanism of influence of chloride ions on electrogenerative leaching of sulfide minerals

A dual cell system was used to study the influence of chloride ions on the electrogenerative leaching of sulfide minerals. The results show that the influences of chloride ions on a series of electrogenerative leaching system are similar, and chlorine ion is involved in the electrogenerative leaching process of sulfide minerals directly. The output power increases with the increase of Cl^- concentration. The influence on the electrogenerative leaching rate decreases when the Cl^- concentration reaches a certain value. The mechanisms of anodic reaction are deduced based on the reasonable hypothesis, and kinetic equations with respect to chlorine ions for each sulfide mineral are obtained. The kinetic equations show that when concentration of Cl^- is relatively low, the electrogenerative leaching rates are predicted to have 2/5,3/7,1/3 and 1/3 order dependence on Cl^- concentration for chalcopyrite concentrate,nickel concentrate, sphalerite and galena. As concentration of Cl^- increases, the correlative dependence of electrogenerative leaching rate on concentration of Cl^- becomes weak.

Development of a Rapid Test Bar for Quantitative Detection of Chloride Ions in Fresh Concrete

Due to the shortage of natural raw materials,many practitioners proposed to make concrete from desalinated sea sand.To reduce the risk of abuse of uncleaned sea sand,we proposed a new rapid test bar to detect chloride ions in fresh concrete quantitatively.The test bars were prepared by mixing silver chromate with cotton fiber.By virtue of the high liquid-absorbent capacity of cotton fiber,the chloride-contained liquid in fresh concrete will rapidly enter into the test bar and react with the silver chromate to finally show a certain coloring height,which corresponds to the actual chloride content.In order to optimize the preparation process,the color rendering,testing time and stability of test rods under different mixing ratios and conditions were investigated.The relationship between color height and chloride content was established,and an auxiliary card is prepared for user-friendly calculation of chloride content.The results showed that the best performance of the test bar was obtained under the following conditions:mass concentration of silver chromate 5.0g/L,soaking time 1 min,drying temperature 50℃and content of discolored silica gel 0.5g/root.

Coupling Effect of Cryogenic Freeze-Thaw Cycles and Chloride Ion Erosion Effect in Pre-Cracked Reinforced Concrete

Chloride (Cl−) ion erosion effects can seriously impact the safety and service life of marine liquefied natural gas(LNG) storage tanks and other polar offshore structures. This study investigates the impact of different low-temperaturecycles (20°C, –80°C, and −160°C) and concrete specimen crack widths (0, 0.3, and 0.6 mm) on the Cl−ion diffusion performance through rapid erosion tests conducted on pre-cracked concrete. The results show thatthe minimum temperature and crack width of freeze-thaw cycles enhance the erosive effect of chloride ions. TheCl− ion concentration and growth rate increased with the increasing crack width. Based on the experimental modeland in accordance with Fick’s second law of diffusion, the Cl− ion diffusion equation was modified by introducingcorrection factors in consideration of the freeze-thaw temperature, crack width, and their coupling effect.The experimental and fitting results obtained from this model can provide excellent reference for practical engineeringapplications.

Chloride ion battery:A new emerged electrochemical system for next-generation energy storage

In the scope of developing new electrochemical concepts to build batteries with high energy density,chloride ion batteries(CIBs)have emerged as a candidate for the next generation of novel electrochemical energy storage technologies,which show the potential in matching or even surpassing the current lithium metal batteries in terms of energy density,dendrite-free safety,and elimination of the dependence on the strained lithium and cobalt resources.However,the development of CIBs is still at the initial stage with unsatisfactory performance and several challenges have hindered them from reaching commercialization.In this review,we examine the current advances of CIBs by considering the electrode material design to the electrolyte,thus outlining the new opportunities of aqueous CIBs especially combined with desalination,chloride redox battery,etc.With respect to the developing road of lithium ion and fluoride ion batteries,the possibility of using solid-state chloride ion conductors to replace liquid electrolytes is tentatively discussed.Going beyond,perspectives and clear suggestions are concluded by highlighting the major obstacles and by prescribing specific research topics to inspire more efforts for CIBs in large-scale energy storage applications.

Evolution of the Rust Layers Formed on Carbon and Weathering Steels in Environment Containing Chloride Ions

To clarify the correlation between alloy elements and growth pattern of the rust layers, the rusting evolution of the carbon and weathering steels was investigated by using the gold markers method. The corrosion experiments were carried out in a simulated environment containing chloride ions. The results indicate that Ni, Cu, Cr and Mo elements in the weathering steel suppress the rust crystallization and impede the rust layer growth to an internal development, and the suppression function benefits the formation of a protective rust layer. Moreover, c-FeOOH is mainly located in the outer rust layer, while b-FeOOH is mainly located in the inner rust layer, and the distribution of the rust compounds in the rust layer is closely related to the growth pattern of the rust layer.

Role of Chloride Ion and Dissolved Oxygen in Electrochemical Corrosion of AA5083-H321 Aluminum-Magnesium Alloy in NaCl Solutions under Flow Conditions

Flow-induced corrosion consists electrochemical and mechanical components. The present paper has to assessed the role of chloride ion and dissolved oxygen in the electrochemical component of flow induced corrosion for AA5083-H321 aluminum-magnesium alloy which is extensively used in the construction of high-speed boats, submarines, hovercrafts, and desalination systems, in NaCI solutions. Electrochemical tests were carried out at flow velocities of 0, ：2, 5, 7 and 10 m/s, in aerated and deaerated NaCI solutions with different sodium chloride concentrations. The results showed that the high rate of oxygen reduction under hydrodynamic conditions causes an increase in the density of pits on the surface. The increase of chloride ions concentration under flow conditions accelerates the rate of anodic reactions, but have no influence on the cathodic reactions. Thus, in the current work, it was found that under flow conditions, due to the elimination of corrosion products inside the pits, corrosion resistance of the alloy is increased.

Cellular Automata-based Chloride Ion Diffusion Simulation of Concrete Bridges under Multi-factor Coupling Actions

In order to accurately simulate the diffusion of chloride ion in the existing concrete bridge and acquire the precise chloride ion concentration at given time, a cellular automata （CA）-based model is proposed. The process of chloride ion diffusion is analyzed by the CA-based method and a nonlinear solution of the Fick＇s second law is obtained. Considering the impact of various factors such as stress states, temporal and spatial variability of diffusion parameters and water-cement ratio on the process of chloride ion diffusion, the model of chloride ion diffusion under multi-factor coupling actions is presented. A chloride ion penetrating experiment reported in the literature is used to prove the effectiveness and reasonability of the present method, and a T-type beam is taken as an illustrative example to analyze the process of chloride ion diffusion in practical application. The results indicate that CA-based method can simulate the diffusion of chloride ion in the concrete structures with acceptable precision.

THE SYNERGISTIC INHIBITION STUDIES OF SEVERAL AMINES AND CHLORIDE ION ON IRON IN THE ACIDIC PERCHLORIDE SOLUTIONS

The effect of chloride ion on the corrosion inhibition of iron caused by dencylamine(DA), dipentylamine(DDA) and dodecylamine(DPA) has been investigated by measuring the inhibitory coefficients for the anodic and cathodic processes at corrosion potential. It has been shown that the major synergistic inhibition effects between amines and chloride ions occur in the cathodic process, very weak in the anodic process. The anodic inhibition mechanism follows the competing adsorptive model, while the cathodic inhibition mechanism follows the cooperative adsorptive model.

1-Hydroxyethylidene-1,1-diphosphonic Acid (HEDP) as a Corrosion Inhibitor of AISI 304 Stainless Steel in a Medium Containing Chloride and Sulfide Ions in the Presence of Different Metallic Cations

The novelty of this paper is the analysis in a medium containing sulfide ion due to the generation of this ion in petroleum industries, in the refining stage (the sulfide ion is also present on the produced water). The performance of 1-hydroxyethylidene-1,1-diphosphonic acid inhibitor (HEDP) was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy, and weight loss measurements in a dissolution of AISI 304 stainless steel immersed in a solution containing chloride and sulfide ions. The protection of the stainless was increased with the addition of divalent cations (Ca2+, Zn2+, and Mg2+). Potentiodynamic polarization studies have shown that the inhibitor alone has anodic protection, but the addition of Ca2+ (10 mg·L-1) favors the cathodic protection, and the addition of Zn2+ (20 mg·L-1) and Mg2+ (10 mg·L-1) mixed-type is observed. Electrochemical impedance spectroscopy was performed at three distinct potentials: -0.3 [V vs. SCE], Ecorr [V vs. SCE], and 0.1 [V vs. SCE]. This revealed that calcium is responsible for favoring the formation of the film and the other elements (zinc and magnesium) favor the stabilization of the protective film. Scanning electron microscopy analysis revealed that the addition of cations provided the adsorption of HEDP on the metal surface. Weight loss results showed that the presence of zinc in a solution containing HEDP favored greater inhibitor efficiency (Zn2+ ηm = 85.2% and for Mg2+ ηm = 70.4%).

Potentiometric Determination of Chloride and Cyanide Ions in Nanoliter Samples with Capillary Indicating Electrodes

The samples of 25 nL of chloride and cyanide were determined with a kind of glass capillary indicating electrodes by potentiometry. Silver was deposited by the silvermirror reaction on the inner surface of the glass capillary with a volume of 25 nL. The AgCl film and the AgI film were formed by the treatment of the capillary with a FeCl 3 solution and further with a KI solution. The samples were collected automatically into the capillary by the capillary ascension. The procedure in the measurement was merely to place a reference electrode and a capillary indicating electrode vertically on a strip filter paper containing a 01 mol/L NaNO 3 solution. The various i.d. of the capillary electrodes were used to determine samples ranging from 25 nL to dozens of microliters. The ranges of the linear response to chloride and cyanide were 32×10 -4 —22×10 -1 mol/L and 10×10 -5 —10×10 -1 mol/L with an average slope of 552 and 52—62 mV/decade , respectively. The samples with various concentrations of chloride and cyanide were determined, and the relative standard deviations were less than 7%.

Adsorption and reduction of platinum(Ⅳ) chloride complex ions on activated carbon

The adsorption kinetics of platinum（IV） chloride complex ions on the activated carbon Norit GF40 was investigated. Experiments were carried out at different initial concentrations of Pt（IV） chloride complex ions, temperature, rate of mixing and pH. It was found that the value of activation energy of the studied process is equal to 19.7 kJ/mol. From the ICP MS analysis it was confirmed that platinum ions （Pt（IV） and Pt（II）） are removed from the solution due to the adsorption and are further reduced to the metallic state. Such mechanism was confirmed by XPS analysis which showed that on the carbon surface three forms of platinum species, i.e. Pt（0）, Pt（II） and Pt（IV）, exist. The presence of platinum in the solution at different oxidation states was also confirmed spectrophotometrically by identification of their characteristic absorption bands. The metallic form of Pt present on the surface of activated carbon was observed in the form of small spherical islands with the diameter not exceeding 500 nm. Those islands consist of smaller, flake-shape particles with a thickness of about 35 nm.

Chloride transport and its sensitivities to different boundary conditions in reclaimed soil solutions filled with fly ash

Chloride ion transport in reclaimed soil solutions filled with fly ash （FA） was investigated by measuring the hydraulic parameters （i,e. water retention curves and hydraulic conductivity） of three substrates, namely GSL, GFA, and CFA. Similar simulations were carried out under certain weather conditions. The different boundary conditions of chloride transport were also discussed from FA texture, cover soil thickness, groundwater table level, and initial chloride concentration. Furthermore, the sensitivities of chloride ions to these effect factors were analyzed. The results show that the different top soil thickness and initial chloride concentration have no effect on salinity of topsoil solution in the monitoring points, but they can clearly change the chloride concentration of FA layers. The sensibilities from top soil thickness and initial chloride content are exceedingly weak to the salinity balance based on two dimensions of the time and concentration. While the different FA texture and groundwater table not only affect the salinity equilibrium process of the whole reclaimed soil profile, but also change its balance state. Generally, coarse FA particles and high groundwater table can defer the salinity balance process of the reclaimed soil solution, and they also increase the chloride concentration of FA layer solutions, and even topsoil ones.