Investigation of Cavitation in NaCl Solutions in a Sonochemical Reactor Using the Foil Test Method

Ultrasonic baths and sonochemical reactors are widely used in industrial applications dealing with surface cleaningand chemical synthesis. The processes of erosion, cleaning and structuring of the surface can be typically controlledby changing relevant influential parameters. In particular, in this work, we experimentally investigate theeffect of NaCl concentration (0–5.5 mol/L) on the erosion of an aluminum foil under ultrasonic exposure at afrequency of 28 kHz. Special attention is paid to the determination of cavitation zones and their visualizationusing heat maps. It is found that at low NaCl concentration (0.3 mol/L), the foil destruction rate is higher thanin distilled water. At higher concentrations of salt, cavitation takes place mainly in the upper part of the container.

NaCl aqueous solution as a novel electrode in a dielectric barrier discharge reactor for highly efficient ozone generation

Ozone(O_(3)) generated by a dielectric barrier discharge(DBD) is widely used in various industrial processes. In this study, NaCl aqueous solution was used as a novel electric power transmission electrode in a DBD reactor(instead of a traditional metal electrode) for highly efficient ozone generation. The results demonstrated that a high O_(3) yield of 242 g k Wh^(-1) with a concentration of 14.6 g m^(-3)O_(3) was achieved. The power transmission mechanism works because NaCl aqueous solution behaves as a capacitor when an alternating pulse voltage below 8 k Hz is used.Compared with the resistance of the discharge barrier and discharge space, the resistance of NaCl aqueous solution can be ignored, which ensures that O_(3) is generated efficiently. It is expected that O_(3) generation using NaCl aqueous solution as a novel electrode in a DBD reactor could be an alternative technology with good application prospects.

Corrosion behavior of tinplate in NaCl solution

The corrosion process of tinplate in 0.5 mol/L NaCl solution was investigated using the electrochemical impedance spectroscopy（EIS）,and the morphology and structure of the corrosion products were characterized by scanning electron microscope（SEM）,scanning probe microscopy（SPM）,X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）.The results showed that the resistance of tin coating,Rc,was essentially constant but the charge transfer resistance,Rct,decreased by 2 orders of magnitude,which indicated that the tin coating was not seriously corroded while the carbon steel substrate was corroded continuously.The corrosion of tinplate in 0.5 mol/L NaCl solution was mainly the dissolution of carbon steel substrate because of the defects in the tin layer and the corrosion product was mainly γ-FeOOH.

NaCl溶液浓度对磷石膏制备α-半水石膏转晶行为的影响

为提高湿法磷酸工艺排放的副产品磷石膏的利用率和附加值,采用常压水热合成法在NaCl溶液中制备α-半水石膏材料,研究了NaCl溶液浓度对α-半水石膏的结晶水含量、转晶行为、矿相组成和显微形貌的影响。研究结果表明,在温度为95℃质量分数为10.0%~20.0%的NaCl溶液中,磷石膏的结晶水含量均随着反应时间的延长逐渐降低,且降至约6%后将逐渐趋于平缓。结合XRD和SEM分析认为磷石膏在95℃质量分数为10.0%~20.0%的NaCl溶液中可脱水转晶形成稳定的六方柱状α-半水石膏。同时,磷石膏的脱水转晶速率呈现先缓慢上升而后快速升高,最后逐渐趋于平缓的变化趋势,属于典型的生长-成核动力学过程。随着NaCl溶液浓度的升高,α-半水石膏的诱导成核时间和晶体生长时间逐渐加快,总转晶时间逐渐缩短。其中,磷石膏在质量分数为20.0%的NaCl溶液中水热反应0.5 h后即可完全转变为α-半水石膏,与质量分数为15.0%的NaCl溶液相比缩短了1.38 h。因此认为,NaCl溶液浓度的提高有助于加快磷石膏的脱水转晶效率,这可为实际规模化生产α-半水石膏提供指导。

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.

Corrosion of Artificial Aged Magnesium Alloy AZ80 in 3.5 wt pct NaCl Solutions

The corrosion morphologies of aged magnesium alloy AZ80 were investigated by immersion corrosion tests, scanning electron microscopy （SEM）, electrochemical measurement. The T5 heat treatment was carried out in a vacuum furnace, holding for 16 h at 177℃, and then cooling in air. The results showed intergranular corrosion （IGC） occurred as an aged AZ80 sample was immersed in 3.5 wt pct NaCI aqueous solution for 1 h and the narrow path attack progressed predominantly along the bulk β phase in the grain boundaries or took place in the eutectic areas. IGC was attributed to the network distribution of β phase along the grain boundaries, the depleted aluminium in the precipitation areas and the breakdown potential.

炭化液对NaCl胁迫下高丹草种子萌发和幼苗生长的影响

为探讨炭化液对NaCl胁迫下高丹草(Sorghum bicolor×sudanense)种子萌发和幼苗生长的影响,利用工程水生植物金鱼藻(Ceratophyllum demersum Linn.)和苦草〔Vallisneria natans(Lour.)Hara〕制备炭化液,研究了NaCl胁迫下2种炭化液及其稀释比例对高丹草种子萌发及幼苗生长和生理指标的影响。结果显示:在0~16 g·L^(-1)NaCl范围内,高丹草种子的发芽率、发芽势和发芽指数随着NaCl质量浓度的提高呈下降趋势,在16 g·L^(-1)NaCl条件下发芽率仅5.6%;种子萌发阶段的耐盐适应质量浓度、耐盐半致死质量浓度和耐盐极限质量浓度分别为4.00、8.03和15.06 g·L^(-1)。在4 g·L^(-1)NaCl条件下,添加金鱼藻炭化液和苦草炭化液(稀释比例1∶15)对高丹草种子发芽势、发芽率和发芽指数的影响不显著,但总体上显著(P<0.05)促进了芽长和根长;且处理10和15 d,金鱼藻炭化液处理的芽长和根长分别较苦草炭化液处理显著增加。在8~16 g·L^(-1)NaCl条件下,添加金鱼藻炭化液(稀释比例1∶15)总体上显著增加了高丹草种子的发芽势、发芽率、发芽指数、芽长和根长。在8 g·L^(-1)NaCl条件下,添加稀释比例1∶15和1∶5的金鱼藻炭化液均较对照显著增加了高丹草幼苗的株高、根长、茎长、叶长、总鲜质量、地上部鲜质量、地下部鲜质量和根冠比,显著降低了超氧阴离子含量、过氧化氢酶活性和可溶性蛋白质含量。综上所述,较高质量浓度NaCl胁迫下,添加金鱼藻炭化液显著促进了高丹草的种子萌发,有效减少了高丹草幼苗受到的氧化损伤,进而缓解了NaCl对高丹草种子萌发和幼苗生长的胁迫作用。

Study on the Electrical Conductivity of 0.025 mol NaCl Solution at 0.25-3.75 GPa and 20-370℃

The electrical conductance of 0.025 mol NaCl solution was measured at0.25-3.75 GPa and 20-370℃. As shown by the results, the conductance increases with temper-ature, and there is a liner relation between the reciprocal of temperature and the logarithm ofthe conductance but their slopes are different at different pressures. The relations between theconductance and pressure is rather complex and there are some discontinuities: in the range of2.25-3.75 GPa, the conductance increases with the pressure; in the range of 1.25-2.0 GPa, theconductance is not related to the pressure; and at a pressure of 0.75 GPa, the conductance ishigher than that at the pressures nearby. This reflects that the NaCl solution has rather differentproperties of electronic chemistry at various pressures, and probably is an important cause forthe existence of the layers with high electrical conductance and low velocity in the Earth's crustand mantle.

Role of nickel alloying on anodic dissolution behavior of zinc in 3.5% NaCl solution.Part II:Potentiodynamic,potentiostatic and galvanostatic studies

Zinc is common metal used for steel protection from corrosion.The addition of further element,such as Ni,can modify the corrosion rate and maintain sacrificial protection.The anodic dissolution behavior of Zn,Ni and Zn-Ni alloys with different Ni contents（from 0.5% to 10%,mass fraction） in 3.5% Na Cl solution was investigated using potentiodynamic,potentiostatic and galvanostatic techniques.The composition and microstructure of the corrosion layer on Zn,Ni and Zn-Ni alloys were characterized by energy-dispersive X-ray spectroscopy analysis（EDX） and scanning electron microscopy（SEM）.The galvanostatic curves show that the anodic behavior of all investigated electrodes exhibits active/passive transition and the tendency of the alloys to passivity decreases with the increase in Ni content,except for 99.5Zn-0.5Ni alloy.While the potentiodynamic curves exhibit active passive transition only for pure Zn.Surface analysis reveals the presence of oxides,chlorides and metal hydroxide chloride in corrosion products,and very small cracks are observed for 90Zn-10 Ni alloy compared with that of Zn.

车轮钢ER8在中性NaCl溶液中的电化学腐蚀行为

为研究ER8车轮钢在沿海中性氯盐环境下的腐蚀行为,通过电化学测试、腐蚀失重试验,结合扫描电镜(SEM)、X射线衍射(XRD)技术对ER8车轮钢在3种不同浓度中性NaCl溶液中的电化学腐蚀行为进行分析。极化曲线结果表明浸泡初期5.0%NaCl浓度下自腐蚀电流密度(Jcorr)最大,576 h后Jcorr在2.0%、3.5%NaCl浓度下均持续增大,腐蚀速率在2160 h时均大于0.12 mm/a。SEM结果显示腐蚀产物形貌主要为片状与团簇状结构,初期腐蚀产物形貌具有较多孔隙,难以阻碍Cl-与基体发生反应,2160 h时腐蚀产物结构更为均匀致密。XRD结果表明腐蚀产物主要由γ-FeOOH、α-FeOOH与Fe3O4组成。

Corrosion behavior of sintered zinc-aluminum coating in NaCl solution

Sintered zinc aluminum coating (SZAC) was prepared using zinc flakes, aluminum flakes and CrO 3 as main raw materials. The corrosion behavior of SZAC in 3.5%NaCl solution was studied by means of SEM, EDS, EIS and so on. Results indicate that aluminum corroded in advance of zinc to produce speculate or spherical substances, which attaches to SZAC and adds mass to it. Corrosion production passivates metal powders in SZAC, causes E corr of SZAC to increase gradually, and causes the arising of the third time constant in EIS, which corresponds to the insulation of corrosion production.

Influence of NaCl on dechromization of Cu-Cr-Al alloy in H_3PO_4 solution

The dechromization of Cu-Cr-Al alloys was investigated by a static immersing corrosion test. The influence of NaCl on the dechromization was analyzed by electrochemical test, scanning electron microscopy, optical microscopy and X-ray fluorescence spectroscopy. The results show that the dechromization of Cu-Cr-Al alloys will take place in a H3PO4 solution of 11.32 mol/L at 55 ℃. And the corrosion process occurs initially at the interface between Cu and Cr phase, and then extends inward Cr-phase inside. The addition of NaCl into H3PO4 solutions can shorten the dechromization incubation time, decrease the dechromization temperature and concentration of H3PO4 solution, and increase the tendency of dechromization. But, the NaCl scarcely has an effect on the form and structure of chromium depleted-layer.

Relationship between the Brittlement Susceptibility and H Permeation Current for UNS G11180 Steel in 5% NaCl Solution with H_2S

Sulfide stress corrosion cracking (SSCC) behaviour of UNS G11180 steel in 5% NaCl solution with H2S was studied by slow strain rate tensile test (SSRT), SEM and electrochemical hydro gen permeation technique. The results reveal different cracking mechanism and H permeation current (IH) through UNS G11180 steel plate in different concentration of H2S solution. The susceptibility to SSCC of UNS G11180 Steel in 5% NaCl solution with H2S was evaluated by the permeation current(IH, μA), which depends on the concentration (c×10-6) of H2S by the equation:IH = 8.525 ×c0.7249. lt is proved that the electrochemical H permeation method is a practical way to assess the susceptibility to SSCC.

Effect of NaCl Concentration on the Cumulative Strain and Pore Distribution of Clay under Cyclic Loading

Clay,as the most common soil used for foundationfill,is widely used in various infrastructure projects.The phy-sical and mechanical properties of clay are influenced by the pore solution environment.This study uses a GDS static/dynamic triaxial apparatus and nuclear magnetic resonance experiments to investigate the effects of cyclic loading on clay foundations.Moreover,the development of cumulative strain in clay is analyzed,and afitting model for cumulative plastic strain is introduced by considering factors such as NaCl solution concentration,con-solidation stress ratio,and cycle number.In particular,the effects of the NaCl solution concentration and con-solidation stress ratio on the pore distribution of the test samples before and after cyclic loading are examined,and the relationship between microscopic pore size and macroscopic cumulative strain is obtained accordingly.Our results show that as the consolidation stress ratio grows,an increasing number of large pores in the soil samples are transformed into small pores.As the NaCl solution concentration becomes higher,the number of small pores gradually decreases,while the number of large pores remains unchanged.Cyclic loading causes the disappearance of the large pores in the samples,and the average pore size before cyclic loading is posi-tively correlated with the axial cumulative strain after cyclic loading.The cumulative strain produced by the soil under cyclic loading is inversely proportional to the NaCl solution concentration and consolidation stress ratio.

EFFECTS OF WAVEFORM AND FREQUENCY OF CYCLIC LOADING ON CORROSION FATIGUE CRACK PROPAGATION FOR GC－4 STEEL IN 3．5％NaCl SOLUTION

Abstract Experimental investigations were carried out of the effects of waveforms includingtriangular, positive sawtooth,negative sawtooth,square and negative Pulse) and frequen-cics including l,5 and 20Hz) of cyclic loading on the fatigue crack propagation fFCPj forGC-4 (40CrMnSiMoVA) steel in neutral 3.5% NaCI solution.Test results show thatwaveform and frequency have great effect on FCP rates of GC4 steel in 3.5% NaCl solution.Moreover,test results also show that the static stress corrosion cracking(SSCC)anddynamic stress corrosion cracking (DSCC) can occur simultaneously in the corrosion fatigue ICF) process and that the DSCC may be able to occur at K(max)<KISCC.Based on theexperimental results and the analysis in this study,a modified process competition modelwas presumably proposed, which can reasonably explain the test results obtained in thisstudy.

Evolution of Morphology of Nano-Scale CuO Grown on Copper Metal Sheets in 5 wt% NaCl Solution of Spray Fog Environment

Nano-scale copper oxide with various morphologies is synthesized via the thermal oxide method and growth in a 5 wt% NaCl solution of spray fog environment. The nano-scale copper oxide is grown on copper metal sheets via the thermal oxide method at 650℃ for 60 minutes. Nano-scale copper oxide grains and nanowires are induced on copper metal sheets then placed in 5 wt% NaCl solution of salt spray fog environment. Significant changes in particle size and mor-phology are observed with increasing salt spray fog treatement time. The morphology of nano-scale copper oxide varies from nanograins to nanowires, Ctahedron, and icositetrahedron. The morphologies and structures of the obtained nano-scale copper oxide are investigated by scanning electron microscopy and energy-dispersive spectroscopy. Possible growth mechanisms are discussed.

Anodic Behavior of Zn-Al-Be Alloys in NaCl Solution and the Influence of Be on Structure

Potentiodynamic results of anodic behavior of Zn5Al and Zn55Al alloys, alloyed with Beryllium in the ambience of NaCl electrolyte and their microstructures are studied. They showed that a small addition of Beryllium (0.005 - 0.05 wt%) improves the corrosion resistance of Zn5Al and Zn55Al original alloys to 2 - 3 times by changing grains shape to spherical and changing sizes to small grains. The proposed composition of Zinc-Aluminum alloy, which contains of Beryllium, can be used as anodic coatings to protect steel products and constructions against corrosion.

Experimental and quantum chemical studies of carboxylates as corrosion inhibitors for AM50 alloy in pH neutral NaCl solution

Sodium salts of mono-and di-carboxylic acids(glycolic,fumaric and benzoic acid)were studied as corrosion inhibitors for AM50 alloy in pH neutral aqueous NaCl environment.Hydrogen evolution,electrochemical and surface characterization techniques were employed to reveal their corrosion inhibition mechanism,whilst the molecular features of inhibitors were investigated by quantum chemical calculation.All inhibitors reduced anodic dissolution of AM50 and their efficiency generally increased with time and concentration from 5 mM to 100 mM.The inhibition mechanism can be described as physisorption of inhibitive molecules on the surface of the intrinsic oxide layer followed by chemisorption with Mg^(2+)and Al^(3+),and the difference in inhibition action among these inhibitors was explained on the molecular scale.

Corrosion Inhibition of Copper in 3% NaCl Solution by Derivative of Aminotriazole

The inhibiting effect of N-decyl-3-amino-1,2,4-triazole (TN10) against Copper corrosion in aerated 3%NaCl, has been developed. Potentiodynamic measurements and electrochemical impedance spectroscopy have been applied to determine the corrosion rate. Scanning electron microscopy (SEM) studied surface morphology has been also used to characterize electrode surface. The obtained results indicate that TN10 acts as a good mixed-type inhibitor retarding both anodic and cathodic reactions. An increase of TN10 concentration leads to a decrease of corrosion rate and inhibition efficiency increase.

U71Mn钢轨在中性NaCl溶液中的初期腐蚀行为探析

为研究钢轨腐蚀行为与NaCl溶液浓度及腐蚀时间的关系,以U71Mn钢轨为对象,采用全浸试验和电化学测试方法探究了钢轨材料浸泡在1.0%、2.0%、2.5%、3.5%、4.0%和5.0%不同浓度的中性NaCl溶液中144 h及在中性3.5%NaCl溶液中浸泡12、48、96、144、192和288 h的初期腐蚀行为和机理。结果表明:初期钢轨材料的平均腐蚀速率与NaCl浓度和浸泡时间均呈正相关关系。随着NaCl浓度的增加,钢轨试样的E_(corr)从-0.651 V负向移动至-0.717 V,J_(corr)从5.71μA/cm_(2)增大至67.48μA/cm_(2);随着腐蚀时间的延长,钢轨试样的E_(corr)从-0.692 V负向移动至-0.720 V,J_(corr)从7.54μA/cm_(2)增大至74.59μA/cm_(2),其中腐蚀产物γ-FeOOH的还原会破坏原有稳定的锈层结构,最后造成腐蚀的加速。