Effect of Graphite Nodule Diameter on Water Embrittlement of Austempered Ductile Iron

Effects of graphite nodule diameter on the water embrittlement of austempered ductile iron (ADI) is studied. The water embrittlement mechanism is discussed. Due to water adhesion, local embrittlement occurs on the surface of ADI specimen, resulting in early fracture and significant reduction in tensile strength and elongation. The water embrittlement is the cracking of stress induced martensite formed during tensile deformation caused by hydrogen diffusion decomposed from water and as a result tensile strength and elongation of ADI are remarkably reduced. The segregation of alloying elements in ductile iron is weakened with decreasing nodule diameter, reducing the residual austenite in grain boundaries, then decreasing the amount of stress induced martensite during tensile plastic deformation and finally restraining ADI water embrittlement.

Water oxidation electrocatalysis with iron oxide nanoparticles prepared via laser ablation

Iron oxide nanoparticles（FeOx NPs, 5–30 nm size） prepared via laser ablation in liquid were supported onto Indium Tin Oxide conductive glass slides by magnetophoretic deposition（MD） technique. The resulting Fe O x@ITO electrodes are characterized by a low amount of iron coverage of 16–50 nmol/cm^2,and show electrocatalytic activity towards water oxidation in neutral phosphate buffer pH 7 with 0.58 V overpotential and quantitative Faradaic efficiency towards oxygen production. XPS analysis on the oxygen region of the FeOx films reveals a substantial hydration of the surface after catalysis, recognized as a crucial step to access reactivity.

Influencing factors and mechanism of water absorption process of iron ores during sintering

The appropriate content and distribution of sinter moisture play an important role in the granulation of iron ores. In this study, the effects of porosity, size distribution, and particle shape on the water absorption rate （WAR） of four types of iron ores were analyzed by using the immersion method and capillary water absorption method. In addition, the mechanism underlying the water absorption process in iron ores was unraveled. It is found that the WARs of iron ores decrease quickly with the increase in water absorption time at the initial stages of water absorption. With further increase in absorption time, the WARs decrease gradually, until near 0. Iron ores with higher porosity, smaller particle size, and plate-like structure have the higher WARs. Compared with pores in the single-particle iron ore, voids among particles in the multi-particle iron oxide play an important role at the initial stages of water absorption. The water absorption mechanism of all single-particle and multi-particle iron ores analyzed in this study includes four steps, wherein the first three steps play a significant role in the sintering pro-cess.

Effect of Different Water Management and Nitrogen Forms on Characteristics of Iron Nutrition of Rice Cultivated Under Aerobic Condition

Although available iron is usually abundant for the growth of rice cultivated in waterlogged condition, the rice crop may suffer from its deficiency when cultivated in aerobic soil since the soil properties are totally different from waterlogged. Solubility of iron is very low in soils with high Eh and/or high pH. A field experiment with five different depth (10, 20, 30, 40 and 50 cm) of groundwater, and a pot experiment with five treatments of ammonium nitrate ratio (100/0, 75/25, 50/50, 25/75 and 0/100) were conducted to study the characteristics of iron nutrition of rice in non full irrigation condition. Moreover, the contents of iron extracted by 1 mol L 1 HCl of rice plant samples of 8 cultivars from both aerobic and waterlogged cultivation were analyzed to study the effect of water regimes on iron content of rice plants. The results were as follows: (1) The average content of available Fe (2.70 mg kg 1 ) of 5 layers of the soil treated with 10 cm depth of groundwater was significantly higher than that (0.83 mg kg 1 ) with 50 cm depth of groundwater, and the iron concentration of rice plant of the former was much higher than that of the later. (2) Iron deficiency of rice became much severe when high ratio of nitrate (more than 75 percent) in nitrogen fertilizer applied at different intervals in aerobic cultivation. (3) The iron concentrations of 3 cultivars, Wuyujing3 (99 mg kg 1 ), Yangdao4 (87 mg kg 1 ) and 9520 (95 mg kg 1 ), of rice plants cultivated in aerobic condition were significantly less than those(195, 197 and 175 mg kg 1 ) respectively in waterlogged condition at tillering stage. And even much significant differences existed in the iron concentrations of different cultivars growing in the aerobic and waterlogged condition at maturity.

Determination of Iron in Water Solution by Time-Resolved Femtosecond Laser-Induced Breakdown Spectroscopy

The influence of the energy of femtosecond laser pulses on the intensity of Fe I （371.99 nm） emission line and the continuous spectrum of the plasma generated on the surface of Fe^3＋ water solution by a Ti： sapphire laser radiation with pulse duration 〈45 fs and energies up to 7 mJ is determined. A calibration curve was obtained for Fe3＋ concentration range from 0.5 g/L to the limit of detection in water solution, and its saturation was detected for concentrations above 0.25 g/L, which is ascribed to self-absorption. The 3σ- limit of detection obtained for Fe in water solution is 2.6 mg/L in the case of 7 mJ laser pulse energy. It is found that an increase of laser pulse energy insignificantly affects on LOD in the time-resolved LIBS and leads to a slight improvement of the limit of detection.

FATIGUE PROPERTIES OF AUSTEMPERED DUCTILE IRON(ADI)IN WATER ENVIRONMENT

The acicular ferrite in austempered ductile iron (ADI) matrix around graphite wascorroded preferentially in wet condition, promoting crack origination and propagationand resulting in the disappearance of ADI fatigue limit. ADI fatigue strength wasgradually reduced with increasing the time of test and was reduced by 50% in wetcondition at 10~7 cycles compared with the fatigue limit in dry condition. The fatiguestrength variation of ferritic ductile iron in wet condition was similar to that of ADI.The ferritic ductile iron, however, has better corrosion resistance so that the fatiguestrength was lowered only by 10% in wet condition at 10~7 cycles compared with thefatigue limit in dry condition. On the other hand, the fatigue limits of ADI and ferriticductile iron were dropped by 32% and 25% in tap water dipping 480h/dry conditionrespectively compared with those in dry condition. The reduction of fatigue limit wasattributed to corrosion pits formation correlated with stress concentration, resultingin origination and propagation of fatigue crack.

Low Mantle Perovskite:Solid Solution, Spin State of Iron and Water Solubility

Silicate perovskites（（Mg, Fe）SiO 3 and CaS iO 3） are believed to be the major constituent minerals in the lower mantle. The phase relation, solid solution, spin state of iron and water solubility related to the lower mantle perovskite are of great effect on the geodynamics of the Earth＇s interior and on ore mineralization. Previous studies indicate that a large amount of iron coupled with aluminum can incorporate into magnesium perovskite, but this is discordant with the disproportionation of（Mg,Fe）SiO 3 perovskite into iron-free MgS i O3 perovskite and hexagonal phase（Mg0.6Fe0.4）SiO 3 in the Earth＇s lower mantle. MnS iO 3 is the first chemical component confirmed to form wide range solid solution with Ca SiO 3 perovskite and complete solid solution with MgS i O3 perovskite at the P-T conditions in the lower mantle, and addition of Mn Si O3 will strongly affects the mutual solubility between Mg Si O3 and CaS iO 3. The spin state of iron is deeply depends on the site occupation of the Fe3＋or Fe2＋, the synthesis and the annealing conditions of the sample. It seems that the spin state of Fe2＋ in the lower mantle perovskite can be settled as high spin, however, the existence of intermediate spin or low spin state of Fe2＋ in perovskite has not been clarified. Moreover, different results have also been reported for the spin state of Fe3＋ in perovskite. The water solubility of the lower mantle perovskite is related with its composition. In pure Mg SiO 3 perovskite, only less than 500 ppm water was reported. Al–Mg Si O3 perovskite or Al–Fe–MgS iO 3 perovskite in the lower mantle accommodates water of 1100 to 1800 ppm. Further experiments are necessary to clarify the detailed conditions for perovskite solid solution, to reliably analyze the valence and spin states of iron in the coexisting iron-bearing phases, and to compare the water solubility of different phases at different layers for deeply understanding the geodynamics of the Earth＇s interior and ore mineralization.

Formation of Iron Sulfide in Water-Body Sediment and Its Influence on Environment

Iron sulfide is an important reductive pollutant in aquatic sediment,so that increasing attentions have been paid to it in recent years.In this paper,the formation of iron sulfide in water-body sediment was introduced.Moreover,its adverse influences upon environment were summarized,including direct contribution to deficiency of dissolved oxygen in water,association with eutrophication in water-bodies and impact on geochemical sulfur cycle.Since conventional chemical analysis for iron sulfide has several disadvantages,new technique for rapid determination of iron sulfide on-line was prospected.

Kinetics of the water-gas shift reaction in Fischer-Tropsch synthesis over a nano-structured iron catalyst

Based on formate and direct oxidation mechanisms,three Langmuir-Hinshelwood-Hougen-Watson （LHHW） kinetic models of the water-gasshift （WGS） reaction over a nano-structured iron catalyst under Fischer-Tropsch synthesis （FTS） reaction conditions were derived and compared with those over the conventional catalyst.The conventional and nanostructured Fe/Cu/La/Si catalysts were prepared by co-precipitation of Fe and Cu nitrates in aqueous media and water-oil micro-emulsion,respectively.The WGS kinetic data were measured by experiments over a wide range of reaction conditions and comparisons were also made for various rate equations.WGS rate expressions based on the formate mechanism with the assumption that the formation of formate is rate determining step were found to be the best.

Iron stability in drinking water distribution systems in a city of China

A field study on the estimation and analysis of iron stability in drinking water distribution system was carried out in a city of China. The stability of iron ion was estimated by pC-pH figure. It was found that iron ion was unstable, with a high Fe （OH）3 precipitation tendency and obvious increase in turbidity. The outer layer of the corrosion scale was compact, while the inner core was porous. The main composition of the scale was iron, and the possible compound constitutes of the outer scale were α-FeOH, γ-FeOOH, α-Fe2O3, γ-F2O3, FeCl3, while the inner were Fe3O4, FeCl2, FeCO3. According to the characteristics of the corrosion scale, it was thought that the main reason for iron instability was iron release from corrosion scale. Many factors such as pipe materials, dissolved oxygen and chlorine residual affect iron release. Generally, higher iron release occurred with lower dissolved oxygen or chlorine residual concentration, while lower iron release occurred with higher dissolved oxygen or chlorine residual concentration. The reason was considered that the passivated out layer of scale of ferric oxide was broken down by reductive reaction in a condition of low oxidants concentration, which would result more rapid corrosion of the nine and red water phenomenon.

Adsorption Kinetics and Evaluation Study of Iron Oxide Nanoparticles Impregnated in Polyurethane Matrix for Water Filtration Application

A polyurethane (PU) foam composite, loaded with iron oxide nanoparticles (IONPs), was developed for arsenic removal from drinking water at low concentrations. The effect of various synthesis parameters such as the size of IONPs and the foam shape, on the performance of the adsorbents in removing arsenic was investigated. To examine the surface adsorption of arsenic species, Energy Dispersive X-ray Microscopy (EDX) was utilized. Mercury Porosimetry was used to analyze the porosity and density of the PU-IONPs nanocomposites. Atomic Absorption Spectrometry (AAS) was conducted to measure the arsenic concentration in the treated solutions. Kinetic models were applied to determine the mechanisms which control the adsorption process. A pseudo-second-order model was found to be the best fit model for the adsorption data. Experimental results revealed that decreasing the size of IONPs from 50 - 100 nm to 15 - 20 nm yields a higher removal capacity. In addition, granular adsorbents exhibit higher removal capacity compared to cubical shaped adsorbents in the order of 20% - 100%.

Annealing temperature dependent catalytic water oxidation activity of iron oxyhydroxide thin films

Nanostructured iron oxyhydroxide（Fe OOH） thin films have been synthesized using an electrodeposition method on a nickel foam（NF） substrate and effect of air annealing temperature on the catalytic performance is studied. The as-deposited and annealed thin films were characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）, field emission scanning electron microscopy（FE-SEM） and linear sweep voltammetry（LSV） to determine their structural, morphological, compositional and electrochemical properties, respectively. The as-deposited nanostructured amorphous Fe OOH thin film is converted into a polycrystalline Fe;O;with hematite crystal structure at a high temperature. The Fe OOH thin film acts as an efficient electrocatalyst for the oxygen evolution reaction（OER） in an alkaline 1 M KOH electrolyte. The film annealed at 200 °C shows high catalytic activity with an onset overpotential of 240 m V with a smaller Tafel slope of 48 m V/dec. Additionally, it needs an overpotential of 290 mV to the drive the current density of 10 m A/cm;and shows good stability in the 1 M KOH electrolyte solution.

Synthesized Goethite and Natural Iron Oxide as Effective Absorbents for Simultaneous Removal of Co(II) and Ni(II) Ions from Water

This study reports on the adsorption efficiency of a natural iron oxide from Mballam-Cameroon in comparison with synthesized goethite to simulta-neously remove cobalt and nickel ions from aqueous solutions. Chemical analysis on the natural iron oxide sample revealed iron as the main element and hematite (58.52%) goethite (19.42%), kaolinite (12.69%) and quartz (7.79%) as the component phases in the iron oxide sample. The iron oxide was found to be microporous (BET surface area 43.27 m2/g) with fairly spherical polydisperse particles. Results show maximum absorption for Co(II) and Ni(II) ions for both adsorbents occurred at an equilibrium contact time of 80 mins, dose rate of 0.1 g/L, and pH = 7. Goethite was slightly more efficient at removing target metal ions with maximal adsorbed quantities at 117.8 mg/g of Co(II) and 100.6 mg/g of Ni(II), and 103.9 mg/g of Co(II) and 85.2 mg/g of Ni(II) ions for natural iron oxide. Equilibrium modelling presented the Freundlich isotherm as the best fit model for both adsorbents and metal ions, indicating heterogeneity of the surface binding sites during adsorption. The pseudo-second order kinetic model was the best-fit model, indicating chemical adsorption between the adsorbent surface and metal ions, hence a good correlation between equilibrium and kinetics. The findings indicate that the efficacy of the natural iron oxide from Mballam is almost equivalent to that of synthetic goethite, validating its applicability for the simultaneous removal of cobalt and nickel ions from aqueous solution.

Evaluation of Corrosion Behaviour of Grey Cast Iron and Low Alloy Steel in Cocoa Liquor and Well Water

Corrosion behaviour of cast iron and low alloy steel in cocoa liquor and well water was investigated. The average weight losses of the specimens were measured using digital weighing balance. The results showed that the weight losses of both cast iron and low alloy steel in both media increases with time. Corrosion rate of cast iron in cocoa liquor increases rapidly with time for up to 336 hours (1000 μm/yr), but in well water the rapid rate of corrosion only lasted up to 187 hours (1160 μm/yr) thereafter it continuously dropping until 264 hours (667 μm/yr) after which it remains constant. Low alloy steel corroded faster in cocoa liquor up to 264 hours (200 μm/yr), whereas the initial rapid corrosion rate only lasted up to 168 hours (180 μm/yr) in well water environment. The results revealed that low alloy steel exhibited better corrosion resistance in both media, with cocoa liquor been more aggressive. Thus, low alloy steel will be a better material for piping and pumping system in cocoa processing industries.

Forecasting of water yield of deep-buried iron mine in Yanzhou, Shandong

This paper compares analytical and numerical methods by taking the forecasting of water yield of deep-buried iron mine in Yanzhou, Shandong as an example. Regarding the analytical method, the equation of infinite and bilateral water inflow boundary is used to forecast the water yield, and in the case of numerical simulation, we employed the GMS software to establish a model and further to forecast the water yield. On the one hand, through applying the analytical method, the maximum water yield of mine 1 500 m deep below the surface was calculated to be 13 645.17 m3/d; on the other hand, through adopting the numerical method, we obtained the predicted result of 3 816.16 m3/d. Meanwhile, by using the boundary generalization in the above-mentioned two methods, and through a comparative analysis of the actual hydro-geological conditions in this deep-buried mine, which also concerns the advantages and disadvantages of the two methods respectively, this paper draws the conclusion that the analytical method is only applicable in ideal conditions, but numerical method is eligible to be used in complex hydro-geological conditions. Therefore, it is more applicable to employ the numerical method to forecast water yield of deep-buried iron mine in Yanzhou, Shandong.

Numerical modeling of water yield of mine in Yangzhuang Iron Mine, Anhui Province of China

This study develops a three-dimensional heterogeneous numerical model to simulate the water inrush process and predict the water yield for mineral exploration in Yangzhuang Iron Mine in Anhui Province. To identify the hydrogeological parameters of the aquifer in the study area, the model was calibrated and validated using the observed heads through the integrated trial-and-error and automated techniques. Also, the sensitivity analysis of the model was performed to evaluate the uncertainty associated with the calibrated model. According to the mine construction plan at different mining levels of-500 m,-600 m, and-700 m, the calibrated model was then applied to predict the water yields dependent on the different mining levels. As indicated by the prediction results, the numerical simulation model can systematically describe the groundwater system in the mining area and determine the source of water inrush in this iron mine. In conclusion, numerical analyses carried out in this study can provide guidance to decision-makers in balancing the iron ore mining and mine dewatering in the future.

铁尾矿废石免烧透水砖制备及性能研究

以铁尾矿废石、水泥和铁尾矿粉为原材料,静压成型制备铁尾矿废石免烧透水砖,研究了成型压力、保压时间、养护时间、水胶比、孔隙率对透水砖抗压强度、透水系数的影响,通过SEM分析样品的微观形貌。结果表明:配合比设计参数为设计孔隙率20%,水泥10%,铁尾矿粉10%,铁尾矿废石80%,水胶比0.4,减水剂掺量为1.5%;透水砖的最佳工艺条件为成型压力8 MPa,保压时间50 s,标准养护28 d,在此条件下制得的透水砖抗压强度为10.4 MPa,透水系数为2.24×10^(-2) cm/s。

电解水析氢反应的铁基非晶合金薄带催化剂研究进展

Pt基电催化剂是析氢反应的基准,然而低丰度和高成本制约了此类贵金属基催化剂的大规模应用,从而促使了替代材料的探索。铁基非晶合金具有无序原子排布结构,表现出独特的物理化学性质。受碱性溶液中的高效析氢反应启发,简述了铁基非晶合金薄带电催化剂的常见反应机理和设计策略,旨在为制备高性能电催化剂提供指导,包括杂原子掺杂、异质面构筑、应变及空位缺陷构建等。此外,原位表征技术和密度泛函理论在铁基非晶合金薄带电催化剂理论设计、反应过程、动态结构演变和机理揭示等方面发挥了重要作用。最后简要介绍了铁基电催化剂目前存在的挑战和未来的研究方向。

载铁沸石制备及在水处理中的应用进展

载铁沸石因具有比表面大、离子交换性强、选择吸附性和高吸附量等特点被广泛应用于水处理领域。本文介绍了载铁沸石的理化性质,总结了载铁沸石的制备方法及其在水处理中的应用情况,并对其作用机理进行了阐述。对载铁沸石的应用前景进行了展望,以期为科研人员提供载铁沸石在水处理中的研究进展。

国内外钢铁工业水污染物排放标准对比及启示

钢铁工业是国民经济重要的基础产业,其用水量大,涉及的生产工艺流程长,排放的污染物种类也较多。为了加强钢铁工业的水污染物排放管理,美国、德国、欧盟等国家(地区)以及世界银行均针对钢铁工业制定了水污染物排放标准,各钢铁工业水污染物排放标准具有各自的特点。梳理了国内外钢铁工业水污染物排放标准,对各标准的适用范围、污染物项目以及排放限值、超标判定要求等主要技术内容进行了对比研究。最后,为了完善我国钢铁工业水污染物排放标准,提出了相关工作建议。