Evolution of mechanical properties,localized corrosion resistance and microstructure of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging

The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,intergranular corrosion test,exfoliation corrosion test,slow strain rate tensile test and electrochemical test,and the mechanism has been discussed based on microstructure examination by optical microscopy,electron back scattered diffraction,scanning electron microscopy and scanning transmission electron microscopy.The NIA treatment includes a heating stage from 40℃to 180℃with a rate of 20℃/h and a cooling stage from 180℃to 40℃with a rate of 10℃/h.The results show that the hardness and strength increase rapidly during the heating stage of NIA since the increasing temperature favors the nucleation and the growth of strengthening precipitates and promotes the transformation of Guinier-Preston(GPI)zones toη'phase.During the cooling stage,the sizes ofη'phase increase with a little change in the number density,leading to a further slight increase of the hardness and strength.As NIA proceeds,the corroded morphology in the alloy changes from a layering feature to a wavy feature,the maximum corrosion depth decreases,and the reason has been analyzed based on the microstructural and microchemical feature of precipitates at grain boundaries and subgrain boundaries.

柠檬酸协同黄铁矿对煤矸石硅缓释及土壤砷稳定性的影响研究

煤矸石是煤炭开采和加工过程中产生的固体废弃物,通常由硅酸盐组成。其在提升硅的生物可利用性方面具有显著潜力,因此可作为农业用硅肥的潜在来源。然而,煤矸石硅的缓释性不足与植物的慢吸收速率存在天然矛盾,限制了煤矸石作为硅肥的应用。本研究探讨了柠檬酸和黄铁矿对煤矸石中硅的缓释效果,以及由此制备的复合物(C@PC-10)对土壤中砷的固化与稳定化作用。研究结果显示,C@PC-10能有效减缓煤矸石中硅的释放速率,在30 d的实验周期内,土壤中水溶态砷和有效态砷的去除效率分别达到71.3%和55.9%。此外,酸溶态砷的比例降低,而残渣态砷的比例增加。模拟酸雨实验进一步表明C@PC-10能够抑制土壤中砷的溶出。通过X射线衍射(XRD)、X射线光电子能谱(XPS)和傅里叶变换红外光谱(FT-IR)分析,本研究证实了球磨过程中黄铁矿的氧化及其向黄钾铁矾和FeOOH的转化。这些发现揭示了氧化黄铁矿对砷的吸附能力显著增强,表明C@PC-10复合物是一种高效的修复材料,能够调控硅酸盐的释放并有效阻碍土壤中砷的迁移。

Single-atom electrocatalysts for lithium-sulfur chemistry:Design principle,mechanism,and outlook

Lithium-sulfur batteries(LSBs)have been regarded as one of the promising candidates for the next-generation“lithium-ion battery beyond”owing to their high energy density and due to the low cost of sulfur.However,the main obstacles encountered in the commercial implementation of LSBs are the notorious shuttle effect,retarded sulfur redox kinetics,and uncontrolled dendrite growth.Accordingly,single-atom catalysts(SACs),which have ultrahigh catalytic efficiency,tunable coordination configuration,and light weight,have shown huge potential in the field of LSBs to date.This review summarizes the recent research progress of SACs applied as multifunctional components in LSBs.The design principles and typical synthetic strategies of SACs toward effective Li–S chemistry as well as the working mechanism promoting sulfur conversion reactions,inhibiting the lithium polysulfide shuttle effect,and regulating Li+nucleation are comprehensively illustrated.Potential future directions in terms of research on SACs for the realization of commercially viable LSBs are also outlined.

Tennantite and Enargite Rejection in the Copper Flotation—A Mini-Review

With the development of arsenic removal technologies, biological method and sulfide method have been applied in industrial fields, other methods have also been applied in arsenic-containing copper flotation, including coagulation process, ion exchange method, direct precipitation method and so on. In the paper, a short review on the progress of arsenic removal technologies of copper flotation during the last decade is presented, and the importance and the trend of arsenic removal are discussed. The existing and possible strategies of improving copper recovery in porphyry copper ores and rejection of penalty elements such as Tennantite and Enargite in copper flotation concentrates are also presented.

An Industrial Perspective on Magnesium Alloy Wheels: A Process and Material Design

Light weights wheels improve vehicle performance with respect to road handling, cornering as well providing fuel economy and reduced greenhouse gas emissions. Aluminum wheels are currently used in many models and are produced usually by low pressure assisted gravity casting. Important property requirements are fatigue strength, pressure tightness, tensile strength, impact resistance, and corrosion resistance. Many attempts have been made to convert aluminum road wheels to magnesium. Race cars and some of the high end models (Porsche, Ferrari, etc.) have used magnesium wheels. These wheels have been gravity cast or forged. Viable corrosion protection systems have been developed and magnesium wheels have been used with success on these models. To use magnesium on more modest models is a challenge due to cost issues. Higher productivity casting processes or more cost effective coating systems need to be utilized. The project consists of selecting magnesium alloys for road wheels, examining the possible cost effective casting processes and corrosion protection systems, evaluating the cost per one wheel and comparing it to aluminum wheel costs. The wheels will also be compared with respect to fatigue and impact properties, pressure tightness, and corrosion.

Texture evolution of commercial pure Ti during cold rolling and recrystallization annealing

X-ray diffraction （XRD） was employed to analyze the texture evolution of commercial pure （CP） Ti during cold rolling and re- crystallization annealing. The texture components were measured by electron backscattered diffraction （EBSD） after recrystallization an- nealing. The CP Ti tends to form a texture with the basal pole tilted 30°-40° away from the normal direction toward the transverse direction. The texture of the initial hot-rolled plate can be classified into three kinds, i.e., the pyramid texture （1013）[5230] and （2021）[1015], the basal plane texture （0001）[2110], and the stronger_prism_texture （1120）[0001]. After cold rolling and annealing （700℃,60 min）,_the main texture components are the cold-rolled texture （1125）[1123] and the recrystallized texture （1013）[5230]. The texture （2021）[1015] is in- herited from the texture of the initial hot-rolled plate with the decrease of orientation density gradually. The volume contents of the cold-rolled texture {2115}（0110） and the recrystallized texture {1013}（1210） are calculated by EBSD. After recrystallization annealing, the specimen is rich in the recrystallized texture and inherits some of texture components from the cold-rolled texture. When the annealing time is prolonged, the anisotropic value decreases.

Effects of pre-deformation mode and strain on creep aging bend-forming process of Al-Cu-Li alloy

The bending deformation method was adopted to characterize the creep deformation behavior of Al-Cu-Li alloy in the creep aging forming(CAF) process based on a series of CAF tests, and the evolution laws of its mechanical properties and microstructures under different pre-deformation conditions were studied. The results show that the bending creep strain characterization method can intuitively describe the creep variation. With the increase of the pre-deformation strain, the creep strain of the specimen firstly increases and then decreases. The increase of the pre-deformation strain can promote the course of aging precipitation, and improve the formed alloy’s tensile properties at room temperature, the Kahn tearing properties, and the fatigue propagation properties. Pre-rolled specimens produce a slightly weaker work hardening than pre-stretched specimens, but they also create a stronger aging-strengthening effect;thus the strength, toughness and damage performance can be improved to some extent. Among all the types of specimens, the specimen with 3% rolling after CAF treatment has the best comprehensive mechanical properties.

New Approach to Cluster Synchronization in Complex Dynamical Networks

In this paper, a distributed control strategy is proposed to make a complex dynamical network achieve cluster synchronization, which means that nodes in the same group achieve the same synchronization state, while nodes in different groups achieve different synchronization states. The local and global stability of the cluster synchronization state are analyzed. Moreover, simulation results verify the effectiveness of the new approach.

Influence of original microstructure on the transformation behavior and mechanical properties of ultra-high-strength TRIP-aided steel

The transformation behavior and tensile properties of an ultra-high-strength transformation-induced plasticity （TRIP） steel （0.2C-2.0Si-I.SMn） were investigated by different heat treatments for automobile applications. The results show that F-TRIP steel, a tradi- tional TRIP steel containing as-cold-rolled ferfite and pearlite as the original microstructure, consists of equiaxed grains of intercritical ferrite surrounded by discrete particles of M/RA and B. In contrast, M-TRIP steel, a modified TRiP-aided steel with martensite as the original mi- crostlucture, containing full martensite as the original microstructure is comprised of lath-shaped grains of ferrite separated by lath-shaped martensite/retained austenite and bainite. Most of the austenite in F-TRIP steel is granular, while the austenite in M-TRIP steel is lath-shaped. The volume fraction of the retained austenite as well as its carbon content is lower in F-TRIP steel than in M-TRIP steel, and austenite grains in M-TRIP steel are much finer than those in F-TRIP steel. Therefore, M-TRIP steel was concluded to have a higher austenite stability, re- sulting in a lower transformation rate and consequently contributing to a higher elongation compared to F-TRIP steel. Work hardening be- havior is also discussed for both types of steel.

Phosphogypsum Pyrolysis by Adding Mineralization Agent:Process and Mechanism

In order to decrease energy consumption for phosphogypsum(PG)pyrolysis process,a pilot-scale vertical-retort furnace was designed initiatively,and then mineralization agent was added to pyrolysis mixture.Calcium fluoride(CaF_(2))was proven to be a suitable mineralization agent,and the optimal parameters were:pyrolysis temperature 960℃,carbon-sulfur mole ratio 0.7,reaction time 50 min,and CaF_(2)dosage 4%by weight.Under this condition,PG decomposition and sulfur dioxide(SO_(2))conversion were up to 89.6%and 67.3%,respectively.CaF_(2)could lead to the formation of fluosilicate complexes,and facilitate PG decomposition at a low temperature.During pyrolysis process,calcium sulfide(CaS)was an inevitable intermediate substance,and only a part of total sulfur in the feedstock could be converted to SO_(2).

Sources of the Laoxiongdong carbonate-hosted Pb–Zn deposit in Southwest China:constraints from S–Pb–Zn isotopic compositions

The Sichuan-Yunnan-Guizhou(SYG)Pb-Zn mineral province,which has significant Pb-Zn repositories in China,is situated in the western Yangtze Block.Despite decades of research,the Pb-Zn source of deposits is still disputed between the basement rocks,sedimentary wall rocks,or the Emeishan flood basalts.The newly-discovered Laoxiongdong Pb-Zn deposit is hosted by the Late Ediacaran Dengying Formation in the SYG province.Moreover,the Laoxiongdong orebodies lie between regional deep faults and close to the Proterozoic basement and Emeishan basalts.Hence,this deposit represents a good case study on the ore-forming material source for the regional Pb-Zn mineralization.The Laoxiongdong Pb-Zn ores are massive,vein,or disseminated and have mainly sphalerite,galena,pyrite,quartz,and calcite.In this paper,we present new sulfide S-Pb-Zn isotope data of the deposit.The sulfideδ34SCDT values(+11.8 to+16.5‰)suggest that the reduced sulfur was mainly sourced from evaporites in the Late Ediacaran-Cambrian sequences.Pb isotopic ratios(206Pb/204Pb=18.004-18.107,207Pb/204Pb=15.652-15.667,and 208Pb/204Pb=38.037-38.248)suggest that the lead metal was primarily originated from the basement rocks.The sphaleriteδ66Zn values(+0.16 to+0.37‰)are also highly similar(within error)to those of basement rocks(+0.10 to+0.34‰),suggesting a basement-rocks zinc source with minor contributions from the carbonate host rocks and Emeishan flood basalts.The narrow sphalerite Zn isotopic range(0.21‰)also indicates that the Zn isotopic fractionation between the sphalerite and initial fluid was limited during the sphalerite ore precipitation.Therefore,we propose that both the Late Ediacaran Dengying Formation rocks and Proterozoic basement rocks were important ore-forming material source for the Laoxiongdong deposit,whereas the Emeishan flood basalts represent only a minor ore-material source.

Effect of Bauxite Aggregate on Properties of Al_2O_3-SiC-C Iron Trough Castables

A1203-SiC-C iron trough castables were prepared using high alumina bauxite clinker GL-90 （ 〉 1 mm ） or homogenized bauxite GL-88 to replace the traditional brown corundum aggregates （ 〉 1 mm ） to reduce the cost of iron trough castables. Effects of the two bauxite aggregates on properties of iron trough eastables were investigated. The results show that the two kinds of bauxite affect flowability, bulk density, strength and slag corrosion resistance of trough castables differently. Compared with homogenized bauxite, high alumina bauxite clinker is more suitable to substitute brown corundum. The castables prepared from the bauxite clinker have similar performances with those prepared from brown corundum, especially used in medium or small blast furnaces with weak thermal impact and lower temperature hot metal. However, in large blast furnaces with severe thermal impact and high temperature hot metal, the performances of the two castables are significantly different. So it is suggested to use the brown corundum based castables in the front gyral zone of the slag skimmer.

A CFD model for gas uniform distribution in turbulent flow for the production of titanium pigment in chloride process

The fluid dynamic behavior of feeding gas （TiCI4） in an annular channel affects the combination of 02 and TiCI4 in an oxidation reactor, a key piece of equipment in titanium pigment production. The numerical procedure was validated by a 3-dimensional gas flow in the annular channel. Applying the validated model, the flow character- istics of TiCl4 in the oxidation reactor with a tangential inlet were simulated and characterized. The flow distribu- tion with five rectifying rings of different structure was simulated and analyzed. The results showed that the rectifying ring improved the distribution uniformity of the pressure and outlet velocity. Compared to the original case without a rectifying ring, the non-uniformity of the pressure and outlet velocity could be reduced by up to 91% and 69% respectively. The rectifying ring #5, which can be installed and adjusted easily, is more effective in realizing even distribution. In addition, installation of the rectifying ring effectively reduced the circulating flow in an annular channel as well as the total energy loss.

A novel method for improving cerussite sulfidization

Evaluation of flotation behavior, solution measurements, and surface analyses were performed to investigate the effects of chloride ion addition on the sulfidization of cerussite in this study. Micro-flotation tests indicate that the addition of chloride ions prior to sulfidization can significantly increase the flotation recovery of cerussite, which is attributed to the formation of more lead sulfide species on the mineral surface. Solution measurement results suggest that the addition of chloride ions prior to sulfidization induces the transformation of more sulfide ions from pulp solution onto the mineral surface by the formation of more lead sulfide species. X-ray diffraction and energy-dispersive spectroscopy indicate that more lead sulfide species form on the mineral surface when chloride ions are added prior to sulfidization. These results demonstrate that the addition of chloride ions prior to sulfidization can significantly improve the sulfidization of cerussite, thereby enhancing the flotation performance.

Impact toughness of a gradient hardened layer of Cr5Mo1V steel treated by laser shock peening

Laser shock peening（LSP） is a widely used surface treatment technique that can effectively improve the fatigue life and impact toughness of metal parts.Cr5Mo1 V steel exhibits a gradient hardened layer after a LSP process.A new method is proposed to estimate the impact toughness that considers the changing mechanical properties in the gradient hardened layer.Assuming a linearly gradient distribution of impact toughness,the parameters controlling the impact toughness of the gradient hardened layer were given.The influence of laser power densities and the number of laser shots on the impact toughness were investigated.The impact toughness of the laser peened layer improves compared with an untreated specimen,and the impact toughness increases with the laser power densities and decreases with the number of laser shots.Through the fracture morphology analysis by a scanning electron microscope,we established that the Cr5Mo1 V steel was fractured by the cleavage fracture mechanism combined with a few dimples.The increase in the impact toughness of the material after LSP is observed because of the decreased dimension and increased fraction of the cleavage fracture in the gradient hardened layer.

Lattice Constants of R-Co Permanent Magnet Alloys

The lattice constants of Sm-Co permanent magnet alloy have been determined by means of X-ray diffraction measurement. The lattice constants of R-Co alloy systems (R = rare earth) have been investigated with Bragg-williams (B-W) approximation and their expressions are given. It is pointed out that the lattice constants of RCo5 phase depend only on the alloy composition, and that the lattice constants of R2Co17 phase are related to the order parameter as well as the alloy composition. In this paper the relationship between the lattice constants of RCo5 and those of R2Co17 is discussed, and the values calculated by the expressions are compared with experimentally determined for Sm-Co alloys.

Global Synchronization of Directed Networks with Fast Switching Topologies

Global synchronization of a class of directed dynamical networks with switching topologies is investigated.It is found that if there is a directed spanning tree in the fixed time-average of network topology and the time-averageis achieved sufficiently fast,then the network will reach global synchronization for sufficiently large coupling strength.

Effects of element additions on the microstructure and mechanical properties of Al-Si-Cu filler metals

For the development of a Iow-melting-point filler metal for brazing aluminum alloys, a series of Al-Si-Cu-（ Ni, Sn, Zn ） filler metals have been studied. Through differential thermal analysis （DTA）, the melting temperatures of such Al-Si-Cu- （ Ni, Sn, Zn） filler metals were determined. The results show that the addition of 3 wt. % - 5 wt. % Sn into the Al-6Si-15Cu filler metal causes its solidus temperature to decrease by about 12℃. The filler metal with the composition Al-6Si-15Cu-2Ni is proposed, which possesses a melting temperature range of 512℃ to 520℃ and a microstrueture that includes an Al-Cu eutectic phases, Al-Si-Cu eutectic phases, silicon particles and Cu2Al, AlNi3 , Al7 Cu4Ni and Al3Ni2 intermetallic compounds. An addition of 5 wt. % -7 wt. % Zn into such A1-Si-Cu filler metals cause their solidus temperatures to drop further to a value lower than 498℃. Metallographic observations indicate that the addition of Zn into the Al-Si-Cu filler metal inhibits the formation of the Al-Si, Al-Cu and Al-Si-Cu eutectic phases. The remaining phases are a A12 Cu intermetallic compound, an α- Al solid solution and silicon particles.

Performance of High Thermal Conductivity Dense Silica Bricks and Their High Thermal Conductivity Mechanism

High thermal conductivity dense silica bricks have the higher thermal conductivity than ordinary silica bricks,which is conducive to the realization of energy saving and emission reduction in the iron and steel industry.The performance of ordinary silica bricks and high thermal conductivity dense silica bricks was compared,and the high thermal conductivity mechanism was analyzed.The results show that(1)compared with ordinary silica bricks,high thermal conductivity dense silica bricks have the characteristics of higher thermal conductivity,lower apparent porosity,higher tridymite content,higher compressive strength,and higher thermal expansion;(2)by increasing the tridymite content and reducing the porosity,the close packing of honeycombα-tridymite improves the density and continuity of the SiO_(2)frame structure of the silica bricks,and the larger area perpendicular to the heat transfer direction improves the thermal conductivity of the bricks;(3)the densification of the silica bricks also increases the thermal expansion of the bricks,but they still meet the standard requirements.