SCC Behaviour of X-70 Pipeline Steel in Near-Neutral pH Solutions

The stress corrosion cracking (SCC) behaviour of X-70 pipeline steel in near-neutral pH solutions was studied via slow strain rate testing (SSRT). The results showed that the cracking mode of X-70 pipeline steel in near-neutral pH solutions was transgranular at different temperatures and applied potentials with the feature of quasi-cleavage. The pH value of the solution decreased with increasing the addition of CO2, which increased the susceptibility to SCC. SCC susceptibility increased as the applied potential moved towards the cathodic direction, suggesting that hydrogen induced cracking (HIC) dominated the cracking process at cathodic potentials. The slight decrease of pH values with decreasing temperature of the solution increased the susceptibility to SCC, which attributed to the change of solubility of CO2 in the solution at different temperatures. The propagating directions of SCC cracks were different at different potentials. At rather negative cathodic potentials, the cracks were almost perpendicular to the tensile axis, while at free corrosion potential and near anodic potentials, cracks were nearly at 45 degree, and in the range of moderate cathodic potentials both propagating directions could be observed.

Effect of Cyclic Loading on Cracking Behaviour of X-70 PipelineSteel in Near-Neutral pH Solutions

The cracking behaviour of X-70 pipeline steel in near-neutral pH solutions was studied under different modes of cyclic loading. The crack propagation process of X-70 pipeline steel under low frequency cyclic loading condition was controlled mainly by stress corrosion cracking （SCC） mechanism. Under mixed-mode cyclic loading, both higher tensile stress and shear stress made cracks easier to propagate. Applied cathodic potentials and high content of carbon dioxide in solutions also promoted the propagation of cracks. The propagation directions of cracks were different under different cyclic loading conditions. Under mode I （pure tensile stress） cyclic loading condition, cracks were straight and perpendicular to the tensile stress axis, while under mixed-mode 1/111 （tensile/shear stress） cyclic loading,cracks were sinuous and did not propagate in the direction perpendicular to the main tensile stress axis. Under the mixed-mode cyclic loading, cracks were much easier to propagate, suggesting that shear stress intensified the role of tensile stress. In addition, shear stress promoted the interaction between cracks, resulting in easier coalescence of cracks.

Efficient removal of Al(Ⅲ)and P507 from high concentration MgCl_(2)solution based on in-situ reaction strategy

For a highly efficient recycling of a wastewater containing a high concentration of MgCl_(2),Al(Ⅲ)and P507 were scheduled to be removed in advance.In this study,the in-situ removal of Al(Ⅲ)and P507 from a high concentration MgCl_(2)solution at different pH values and Al/P molar ratios was investigated.The results showed that P507 formed organic complexes of Al_(x)(OH)_y^(Z+)-P507 at pH of 2.0-4.0.At pH of 4.0-5.0,Al(Ⅲ)precipitated and transferred into Al(OH)_(3)with a flocculent amorphous morphology.Active sites on the Al(OH)_(3)surface enhanced the removal efficiency of P507.At pH of 6.0-6.5,Al(Ⅲ)and Mg(Ⅱ)formed layered crystalline Al(OH)_(3)and MgAl_(2)(OH)_(8with)small pore channels and fewer active sites,resulting in a reduced removal efficiency of P507.When the Al/P molar ratio exceeded 13 and the pH was between 4.0 and 5.0,the removal rates of both Al(Ⅲ)and P507 were higher than98%,while the concentration loss of Mg(Ⅱ)was only 0.2%-0.9%.

Effects of Nutrient Solution pH on the Growth of Seedlings of Sugarcane

The impacts of pH on roots growth of sugarcane seedlings were explored by a pot test. The nutrient solution with three pH levels, Le., 5.0, 7.0 and 8.5 were applied to culture five combination seedlings, including A （RB85-5156 × YR05-407）, B （YR06-3501 ×Tolodo）, C （YT94-128 × GZ75-65）, D （ROC6 × YR05-733） and E （VMC87-95 ×YR05-171）. The result indicated that root length, root surface, root volume and root diameter were all in the largest in B combination with solution pH= 7.0, and the root length, root surface, root volume were in the largest in combination A, C, D and E with solution pH=8.5. Root activity in combination C, D and E were in the highest with solution pH=5.0, while it was in the highest for combination B when pH=7.0. In general, the root growth and morphology in all five combinations were better in the solutions with pH of 7.0 and 8.5.

The Effect of the pH of Ammonum Nitrate Solution on the Susceptability of Mild Steel to Stress Corrosion Cracking (SCC) and General Corrosion

This work investigates the relative aggressiveness of nitrate solutions at different pH values on mild steel towards stress corrosion cracking (SCC) and general corrosion. Electrochemical behavior and stress corrosion cracking sus-ceptibility measurements were carried out in 52 Wt% ammonium nitrate solutions at 368° K and various pH values ranging from 0.77 to 9.64. Constant load stress corrosion test at 90% yield stress was conducted. Tested specimens were prepared and examined using the scanning electron microscope (SEM). The potentiodynamic polarization curves for different pH values again emphasized the validity of the gravimetric measurements and hence the mechanism of cracking was attributed to the stress that assisted the dissolution process.

THE INFLUENCES OF SOLUTION PH AND CURRENT DENSITY ON COERCIVITY OF ELECTROPLATING CoNdNiMnP PERMANENT MAGNETIC ALLOY FILM ARRAYS

The influences of plating bath solution PH and current density on coercivity of electroplating CoNdNiMnP permanent magnetic film arrays were studied. The experiment results show that both for solution PH and current density there were the best depositing parameters. Too high and too low plating bath solution PH or current density both result in decreasing of the film array coercivity. When solution PH is 3.5 and current density is 5mA/cm2, the prepared film array coercivity can reach the maximum.

Oxygen permeability of soft contact lenses in different pH, osmolality and buffering solution

AIMTo determine the effect of pH, osmolality, and buffering system on the oxygen permeability (Dk) of soft contact lenses.METHODSTwo hydrogel lenses (nelfilcon A and etafilcon A) and 2 silicone hydrogel lenses (lotrafilcon A and balafilcon A) were used in the study. These lenses were incubated in phosphate-buffered saline (PBS) and borate-buffered saline (BBS) solutions adjusted by 0.8 pH increments to a pH in the range of 5.8-9.0 or in hypotonic (280 mOsmol/kg), isotonic (310 mOsmol/kg) and hypertonic (380 mOsmol/kg) PBS solutions. Polarographic method was used for measuring the Dk and lenses were stacked as 4 layers to correct the boundary effect.RESULTSDk values of all contact lenses measured in BBS solutions were more stable than those in PBS solutions. Especially the etafilcon A lens showed a relative big change compared with other types of contact lenses at the same conditions. When the osmolality of PBS solution increased from hypotonic to hypertonic, Dk of all contact lenses decreased. Variations in Dk existed depending on lens materials, etafilcon A lens was the most affected and nelfilcon A was the least affected by osmolality.CONCLUSIONFrom the result obtained, it is revealed that Dk of contact lenses is changed by the pH, osmolality, and buffering condition of tear. Thus, Dk of contact lens can be varied by the lens wearers' physiological and/or pathological conditions.

In-situ pH Measurement at the Electrode/Solution Interface

In this paper a pH microprobe technique was developed to measure in-situ the pH value at the electrode/solution interface. Iridium oxide was used as a pH sensitive material with good response behavior in the measured solutions. The experimental results indicated that the interfacial pH increased with the applied potential, first jumped to a maximum, then slowly decreased at the controlled potential during the electrodeposition process of functional ceramics.

Electrochemical Study on Hydrogen Evolution and CO2 Reduction on Pt Electrode in Acid Solutions with Different pH

Hydrogen evolution reaction(HER)is the major cathodic reaction which competes CO2 reduction reaction(CO2 RR)on Pt electrode.Molecular level understanding on how these two reactions interact with each other and what the key factors are of CO2 RR kinetics and selectivity will be of great help in optimizing electrolysers for CO2 reduction.In this work,we report our results of hydrogen evolution and CO2 reduction on Pt(111)and Pt film electrodes in CO2 saturated acid solution by cyclic voltammetry and infrared spectroscopy.In solution with pH>2,the major process is HER and the interfacial pH increases abruptly during HER;COad is the only adsorbed intermediate detected in CO2 reduction by infrared spectroscopy;the rate for COad formation increases with the coverage of UPD-H and reaches maximum at the onset potential for HER;the decrease of COad formation under HER is attributed to the available limited sites and the limited residence time for the reduction intermediate(Had),which is necessary for CO2 adsorption and reduction.

Effect of anodic dissolution and passivation on X80 steel in NaHCO_(3) solution

The effects of extreme stray current on the anodic dissolution and passivation of X80 steel in NaHCO3 solution were investigated using measurements of polarization curves and EIS,AFM and SEM techniques.Under the interference of anodic current(i=0~200 A/m2),main constituents of corrosion products of X80 steel were FeO(OH)and Fe3 O4.A double-layer film formed at i=00 A/m2,in which FeOOH was in outer and Fe3 O4 lied in inner.The formation mechanism of Fe3 O4 was confirmed and described by the electrochemical reaction in various regions on anodic potentiodynamic polarization curve.

碳化条件下混凝土中钢筋腐蚀pH阈值研究

目的 确定碳化条件下几种典型缓冲溶液及模拟混凝土孔隙液中钢筋的腐蚀pH阈值范围。方法 采用电化学阻抗谱法,对不同pH、不同配制方法的缓冲溶液及模拟混凝土孔隙液中的钢筋试片进行电化学测量,选用不同的等效电路进行拟合,对测量中钢筋试片发生的电化学过程进行简要阐述。结合阻抗谱测量结果、等效电路拟合结果及工作电极典型宏观形貌,判断钢筋试片腐蚀状态,给出不同溶液对应的钢筋腐蚀pH阈值范围。结果离子环境不同,各缓冲溶液及模拟混凝土孔隙液中钢筋腐蚀pH阈值均存在一定差异,位于9~10.5不等。结论 混凝土碳化引入的HCO_(3)^(–)和CO_(3)^(2–)对钢筋腐蚀有促进作用。混凝土孔隙液pH越低,钢筋腐蚀越容易发生。因此,仅根据pH判断混凝土中钢筋腐蚀状态的方法并不可靠。

Leaching of Silver from Boorchi Ag-Pb Ore in Mongolia with Acidic Thiourea Solution

A hydrometallurgical process to extract silver from the silver-lead ore in Boorchi,Mongolia by using thiourea leaching solution is studied in this work.Through the observation of optical and scanning electron microscopes,and energy spectral analysis,it is determined that 5 kinds of silver minerals exist in the ore,including argentite,Ag-tetrahedrite,Ag-Zn-Sb-tetrahedrite,freibergite and acanthite.The experimental results of direct thiourea leaching of the ore show that 56%～60% of silver is leached.The main reason for the low leaching rate is due to silver minerals enveloped in galena and other minerals,even though the ore is ground to the particle size of 75μm.When the ore is pretreated with ammonium carbonate solution under oxidation,the experimental results of thiourea leaching show that the leaching rate of silver increases to near 75% with the pretreatment.Based on the leaching experiments,a principle hydrometallurgical technological route to extract silver from the Ag-Pb ore is proposed.

Hydrogen Permeation Behaviors of X52 Pipeline Steel in NACE A Solution with Saturated H_2S/CO_2

With the aid of hydrogen permeating devices, the hydrogen permeation behaviors of X52 pipeline steel in NACE A solution with saturated H2S/CO2 were studied under the conditions of different ambient temperatures and pH values, and the hydrogen permeation behaviors of X52 pipeline steel in weld seam zone were comparatively studied. The experimental results show that the hydrogen permeation coefficient value is directly proportional to the time required for reaching the saturation anode current and inversely proportional to the saturation anode current, and the hydrogen permeation coefficient is influenced by the corrosion scales; the temperature is directly proportional to the saturation anode current, and the hydrogen permeation coefficient is influenced by the temperature and corrosion scales, heat-affected zone and matrix zone in NACE A solution with saturated H2S/CO2 at normal temperature. The hydrogen permeation coefficient in weld seam zone is larger than that in heat-affected zone which is further larger than that in matrix zone.

DILUTE SOLUTION BEHAVIOR OF CHITOSAN IN DIFFERENT ACID SOLVENTS

Dilute solution behavior of chitosan was studied in formic acid, acetic acid, lactic acid andhydrochloric acid aqueous solution under different pH values. The reduced viscosities, η_(sp)/C,ofchitosan solutions were dependent on the properties of acid and pH value of solvents. For a givenchitosan concentration, η^(sp)/C decreased with the increase of acid concentration, or decreasing pHof solvent, indicating shielding effect of excessive acid similar to adding salt into solution. Thestabilities of dilute chitosan solution in formic acid and lactic acid were better than that in acetic acid and hvdrochloric acid.

Corrosion behavior of Cu/Al casting-rolled clad plates in different alkaline solution

The effect of pH value and different kinds of anions on the corrosion behavior of Cu/Al casting-rolled clad plates in the alkaline solution was evaluated by means of scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),weight loss analysis,3D confocal laser scanning microscopy(CLSM)and electrochemical test.Results show the corrosion mainly occurs on the aluminum side.The corrosion resistance of the Cu/Al decreases as the pH value increases.When pH≥12,the dissolution of the film layer is faster than the passivation process.The addition of Cl^(-)ions reduces the corrosion resistance of the Cu/Al clad plates,which leads to pitting corrosion.The higher the concentration of Cl^(-)ions,the more prone the pitting to occur.The addition of SO_(4)^(2-)ions causes the denudation of the samples.The corrosion resistance of the Cu/Al is better in the alkaline solution containing NO_(3)^(-)ions than that in the solution containing Cl^(-)ions or SO_(4)^(2-)ions.When adding SO_(4)^(2-),NO^(3)^(-)and Cl^(-)to the pure alkaline solution,the corrosion resistance of the Cu/Al clad plates decreases.

Softswitch Based Solution to Make Network Intelligent

The factors, such as the network optimization or the network amelioration by fixed telecommunication network operators, the convergence of the Personal Handy-phone System (PHS) network and the Public Switched Telephone Network (PSTN), the integration of PSTN and the Third Generation Mobile Communication (3G) Network, the broadband and multimedia based communication networks, causes the requirement for fixed network’s intelligentization. The Softswitch is a feasible approach to meet this kind of requirement. The solution to make the network comprehensively intelligent based on Softswitch is highly advantageous, which enriches communication services and promotes Fixed and Mobile Convergence (FMC).

焦化生化废水处理pH值调节技术研究与应用

拜城县众泰煤焦化有限公司现有焦化废水处理采用A^(2)/O工艺技术,采用固体碳酸钠作为调节废水pH的药剂。由于碳酸钠为固体,在调节p H的过程中存在调整不及时导致p H指标超标、人工劳动强度增大的弊端。通过实验发现,采用30%的氢氧化钠溶液代替碳酸钠固体调节生化废水pH,能有效解决原有工艺技术存在的弊端,调节效果非常明显,且每年节约废水处理药剂费用约40万元。

Formulation of the System of Isohydric Solutions

The isohydricity (pH constancy) as the property referred to mixtures of acids or bases, is illustrated on a simple example of the solutions: HL (C0, mol/L) and HL (C mol/L) mixed according to titrimetric mode (pH titration). A new derivation of the Michalowski formula C0=C+C2·10PK1 expressing this property is presented, and its applicability for determination of pK1 = – logK1 value is indicated. The principle of the isohydric method of pK1 determination is also outlined.

缓冲液pH值对单晶冰糖色值检测的影响

采用《冰糖试验方法》(QB/T 5010—2016)中的分光光度计法测定单晶冰糖的色值,并研究缓冲溶液p H值对单晶冰糖色值检测结果的影响。结果表明,缓冲溶液pH值为7.0时,单晶冰糖色值的检测结果更为准确。

聚铁溶液pH值及盐基度的相关性研究

对聚铁溶液进行 p H值和盐基度的分析和估算 ,给出了聚铁溶液的极限 p H值和极限盐基度与总溶解铁浓度的关系曲线。最终计算结果表明 :在平衡条件下 ,聚铁溶液的 p H值和盐基度具有相关性 ,即当其中一个参数发生变化时 ,另一个参数必然要发生相应的改变。随着总溶解铁浓度的不断升高 ,极限 p H值单调下降 ,而极限盐基度却单调递增。对于铁含量为 1 60 g/L的标准聚铁溶液 ,其最大 p H值为 1 .31 4,最高盐基度为 1 9.99%。