Oxidation Kinetics of Aluminum Powders in a Gas Fluidized Bed Reactor in the Potential Application of Surge Arresting Materials

In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arresting materials are discussed. Theoretical calculations of oxidation of spherical aluminum powders in a typical gas fluidization bed are demonstrated. Computer software written by the author is used to carry out the basic calculations of important parameters of a gas fluidization bed at different temperatures. A mathematical model of the dynamic system in a gas fluidization bed is developed and the analytical solution is obtained. The mathematical model can be used to estimate aluminum oxide thickness at a defined temperature. The mathematical model created in this study is evaluated and confirmed consistently with the experimental results on a gas fluidization bed. Detail technical discussion of the oxidation mechanism of aluminum is carried out. The mathematical deviations of the mathematical modeling have demonstrated in great details. This mathematical model developed in this study and validated with experimental results can bring a great value for the quantitative analysis of a gas fluidization bed in general from a theoretical point of view. It can be applied for the oxidation not only for aluminum spherical powders, but also for other spherical metal powders. The mathematical model developed can further enhance the applications of gas fluidization technology. In addition to the development of mathematical modeling of a gas fluidization bed reactor, the formation of oxide film through diffusion on both planar and spherical aluminum surfaces is analyzed through a thorough mathematical deviation using diffusion theory and Laplace transformation. The dominant defects and their impact to oxidation of aluminum are also discussed in detail. The well-controlled oxidation film on spherical metal powders such as aluminum and other metal spherical powders can potentially become an important part of switch devices of surge arresting materials, in general.

Design and Analysis of MEMS Based Aluminum Nitride (AlN), Lithium Niobate (LiNbO₃) and Zinc Oxide (ZnO) Cantilever with Different Substrate Materials for Piezoelectric Vibration Energy Harvesters Using COMSOL Multiphysics Software

Interest in energy harvesters has grown rapidly over the last decade. The cantilever shaped piezoelectric energy harvesting beam is one of the most employed designs, due to its simplicity and flexibility for further performance enhancement. The research effort in the MEMS Piezoelectric vibration energy harvester designed using three types of cantilever materials, Lithium Niobate (LiNbO3), Aluminum Nitride (AlN) and Zinc Oxide (ZnO) with different substrate materials: aluminum, steel and silicon using COMSOL Multiphysics package were designed and analyzed. Voltage, mechanical power and electrical power versus frequency for different cantilever materials and substrates were modeled and simulated using Finite element method (FEM). The resonant frequencies of the LiNbO3/Al, AlN/Al and ZnO/Al systems were found to be 187.5 Hz, 279.5 Hz and 173.5 Hz, respectively. We found that ZnO/Al system yields optimum voltage and electrical power values of 8.2 V and 2.8 mW, respectively. For ZnO cantilever on aluminum, steel and silicon substrates, we found the resonant frequencies to be 173.5 Hz, 170 Hz and 175 Hz, respectively. Interestingly, ZnO/steel yields optimal voltage and electrical power values of 9.83 V and 4.02 mW, respectively. Furthermore, all systems were studied at different differentiate frequencies. We found that voltage and electrical power have increased as the acceleration has increased.

Theoretical and experimental investigation of gas metal arc weld pool in commercially pure aluminum:Effect of welding current on geometry

Effects of welding current on temperature and velocity fields during gas metal arc welding(GMAW) of commercially pure aluminum were simulated. Equations of conservation of mass, energy and momentum were solved in a three-dimensional transient model using FLOW-3 D software. The mathematical model considered buoyancy and surface tension driving forces. Further, effects of droplet heat content and impact force on weld pool surface deformation were added to the model. The results of simulation showed that an increase in the welding current could increase peak temperature and the maximum velocity in the weld pool. The weld pool dimensions and width of the heat-affected zone(HAZ) were enlarged by increasing the welding current. In addition, dimensionless Peclet, Grashof and surface tension Reynolds numbers were calculated to understand the importance of heat transfer by convection and the roles of various driving forces in the weld pool. In order to validate the model, welding experiments were conducted under several welding currents. The predicted weld pool dimensions were compared with the corresponding experimental results, and good agreement between simulation and preliminary test results was achieved.

Optical properties for N,N’-bis (lnaphyhly)N,N’-diphenyl-1,1’-biphenyl-4,4’-diamine and tris (8-hydroxyquinolinato) aluminum in organic light emitting devices

The optical properties of N,N’-bis (Inaphthyl)N,N’-diphenyl-1,1’-biphenyl-4,4’-diamine (NPB) and tris (8-hydroxyquinolinato) aluminum (Alq3) organic materials used as hole transport and electron transport layers in organic light-emitting devices (OLED) have been investigated. The NPB and Alq3 layers were prepared using thermal evaporation method. The results show that the energy band gap of Alq3 is thickness independence while the energy band gap of NPB decreases with the increasing of sample thickness. For the case of photoluminescence the Alq3 with thickness of 84 nm shows the highest relative intensity peak at 510 nm.

Review on laser directed energy deposited aluminum alloys

Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al parts.As a mainstream AM technique,laser-directed energy deposition(LDED)shows good scalability to meet the requirements for large-format component manufacturing and repair.However,LDED Al alloys are highly challenging due to their inherent poor printability(e.g.low laser absorption,high oxidation sensitivity and cracking tendency).To further promote the development of LDED high-performance Al alloys,this review offers a deep understanding of the challenges and strategies to improve printability in LDED Al alloys.The porosity,cracking,distortion,inclusions,element evaporation and resultant inferior mechanical properties(worse than laser powder bed fusion)are the key challenges in LDED Al alloys.Processing parameter optimizations,in-situ alloy design,reinforcing particle addition and field assistance are the efficient approaches to improving the printability and performance of LDED Al alloys.The underlying correlations between processes,alloy innovation,characteristic microstructures,and achievable performances in LDED Al alloys are discussed.The benchmark mechanical properties and primary strengthening mechanism of LDED Al alloys are summarized.This review aims to provide a critical and in-depth evaluation of current progress in LDED Al alloys.Future opportunities and perspectives in LDED high-performance Al alloys are also outlined.

A modified Johnson–Cook model for 7N01 aluminum alloy under dynamic condition

Tensile tests at different strain rates(0.0002, 0.002, 0.02, 1000 and 3000 s^(-1)) were carried out for 7N01 aluminum alloy. Low strain rate experiments(0.0002, 0.002 and 0.02 s^(-1)) were conducted using an electronic mechanical universal testing machine, while high strain rate experiments(1000, 3000 s^(-1)) were carried out through a split Hopkinson tensile bar. The experimental results showed that 7N01 aluminum alloy is strain rate sensitive. By introducing a correction scheme of the strain rate hardening coefficient, a modified Johnson–Cook model was proposed to describe the flow behaviors of 7N01 aluminum alloy. The proposed model fitted the experimental data better than the original Johnson–Cook model in plastic flow under dynamic condition. Numerical simulations of the dynamic tensile tests were performed using ABAQUS with the modified Johnson–Cook model. Digital image correlation was used together with high-speed photography to study the mechanical characters of specimen at high strain rate. Good correlations between the experiments results, numerical predictions and DIC results are achieved. High accuracy of the modified Johnson-Cook model was validated.

Revisiting aluminum current collector in lithium-ion batteries:Corrosion and countermeasures

With the large-scale service of lithium-ion batteries(LIBs),their failures have attracted significant attentions.While the decay of active materials is the primary cause for LIB failures,the degradation of auxiliary materials,such as current collector corrosion,should not be disregarded.Therefore,it is necessary to conduct a comprehensive review in this field.In this review,from the perspectives of electrochemistry and materials,we systematically summarize the corrosion behavior of aluminum cathode current collector and propose corresponding countermeasures.Firstly,the corrosion type is clarified based on the properties of passivation layers in different organic electrolyte components.Furthermore,a thoroughgoing analysis is presented to examine the impact of various factors on aluminum corrosion,including lithium salts,organic solvents,water impurities,and operating conditions.Subsequently,strategies for electrolyte and protection layer employed to suppress corrosion are discussed in detail.Lastly and most importantly,we provide insights and recommendations to prevent corrosion of current collectors,facilitate the development of advanced current collectors and the implementation of next-generation high-voltage stable LIBs.

Soil Profile Concentration Distributions of Aluminum, Gallium, Indium and Thallium across Southeastern Missouri

The soil chemistry of gallium, indium, and thallium is not well defined, particularly with emerging evidence that these elements have toxic properties and may influence food safety. The purpose of this investigation was to estimate the soil concentrations of gallium, indium, and thallium and determine if these elements have a soil chemistry like aluminum and therefore demonstrate significant concentration correlations with aluminum. Twenty-seven soil series were selected, and the elemental concentrations were determined using aqua regia digestion with analytical determination performed using inductively coupled plasma emission-mass spectroscopy. The concentrations of gallium, indium, and thallium generally compared with the known literature. Aluminum-gallium and aluminum-thallium exhibited significant concentration correlations across the soil horizons of the sampled soils. Aluminum, gallium, and thallium did demonstrate concentration increases in soil horizons having illuviation of phyllosilicates, implying these phyllosilicates have adsorption and isomorphic substitution behaviors involving these elements.

铝盐聚合醇钻井液体系在辽河油田的应用

辽河油田沈北区块上部地层含大段软泥岩,易水化膨胀缩径,下部地层水化分散强,易发生周期性垮塌,常规的钻井液体系不能有效稳定井壁,常引发井下复杂情况。研制出了强抑制性铝盐聚合醇钻井液体系,该钻井液由于铝盐和聚合醇的协同作用,具有优良的润滑和抑制性能。该体系在沈625-10-22井、沈625-14-34井及沈625-18-30井钻进过程中表现出良好的抑制性,减少了钻井复杂情况,井下安全,井眼规则,与同区块使用聚合物分散体系的井相比,平均井径扩大率降低7.95%-11.77%,并且降低了钻井液的使用密度。其成功应用证明,铝盐聚合醇钻井液抑制性和井壁稳定能力强,具有明显的防塌效果,可满足沈北区块沙河街地层钻进的需要。

污水配制的Al^(3+)交联聚合物凝胶性能特征

用大庆采油二厂的污水(矿化度4013mg/L)配制不同HPAM浓度的Al3+交联聚合物凝胶,在气测渗透率1 25μm2的人造岩心上,按清水(矿化度729mg/L)—凝胶—污水或清水的注入程序,注入量>5PV,测得凝胶中HPAM浓度为0 6、0 5、0 4g/L时,残余阻力系数FRR(368 6～277 4)大于阻力系数FR(266 7～246 0),二者均随HPAM浓度减小而减小;后续注入清水时FRR较低;凝胶中HPAM浓度为0 3g/L时FRR<RR;注入用25%、50%污水稀释的0 6g/LHPAM的凝胶时,FRR略有下降而FR不变。在二维纵向非均质人造岩心上,注凝胶(0 5g/LHPAM)、注水、再注凝胶过程中,入口压力升高而中间点压力基本不变,20天后再注水时两测点压力急剧上升,两测点压力差逐渐减小,与注聚合物溶液时两测点压力升高、注水时又降低的现象形成鲜明对比。初始粘度8 8mPa·s的Al3+交联聚合物凝胶,2天时粘度最高(10 2mPa·s),60天时下降至8 4mPa·s,FR和FRR则随凝胶放置时间加长而增大,由1天时的4 92和3 32增加到10天时的192 4和271 2,FRR>FR;聚合物溶液的粘度略低,在放置过程中FR和FRR大体不变,FR和FRR值很小且FRR<FR。实验温度45℃。图2表7参6。

High corrosion and wear resistant electroless Ni–P gradient coatings on aviation aluminum alloy parts

A Ni–P alloy gradient coating consisting of multiple electroless Ni–P layers with various phosphorus contents was prepared on the aviation aluminum alloy. Several characterization and electrochemical techniques were used to characterize the different Ni–P coatings’ morphologies, phase structures, elemental compositions, and corrosion protection. The gradient coating showed good adhesion and high corrosion and wear resistance, enabling the application of aluminum alloy in harsh environments. The results showed that the double zinc immersion was vital in obtaining excellent adhesion (81.2 N). The optimal coating was not peeled and shredded even after bending tests with angles higher than 90°and was not corroded visually after 500 h of neutral salt spray test at 35℃. The high corrosion resistance was attributed to the misaligning of these micro defects in the three different nickel alloy layers and the amorphous structure of the high P content in the outer layer. These findings guide the exploration of functional gradient coatings that meet the high application requirement of aluminum alloy parts in complicated and harsh aviation environments.

Research of Crystallization of Aluminums Cast Iron

In work was researched the composition and structure of high-alloyed aluminum cast iron ЧЮ22Ш. Crystalization of cast iron ЧЮ22Ш (ЧЮ22Ш standard cast iron) was researched by phase transformation, leaking upon its harden and cooling –down. High-alloyed materials are widely applied as the heat-resistant materials. Overall content of that reaches 30-50% and more. Previous performed researches allowed to optimize the content high-alloyed aluminum cast iron ЧЮ22Ш, to research its structure, casting and operational characteristics, to develop technological mode of melting, casting and thermal / heat treatment casts, to held its industrial examination and to determine perspective direction of its application. However, in present time ability of the aluminum cast iron ЧЮ22Ш is being used not sufficiently.

Dynamic Behaviour of Cast A356/Al₂O₃Aluminum Metal Matrix Nanocomposites

The present work includes the study of the dynamic properties of the nanocomposites specimens. The dynamic properties of A356/Al2O3 nanocomposites were investigated through different fabrication conditions. The A356/Al2O3 nanocomposites specimens were fabricated using a combination between the rheocasting and squeeze casting routes. The composites were reinforced with Al2O3 particulates of 60 and 200 nm and different volume fractions up to 5 vol.%. The dynamic properties of the A356/Al2O3 nanocomposites were investigated through measuring the dynamic properties of specimens. Free vibration method is used to measure frequency response (fn ), and damping factor (ξ). The viscoelastic properties such as loss factor η, storage modulus (E'), and loss modulus (E") were obtained. The results concluded that, the dynamic properties of nanocomposites were improved by increasing the volume fractions of nanoparticulates and decreasing the nanoparticulates size. The results indicated also that, the damping factor, and the related parameters (η, E' and E") was strongly affected by increasing both volume fraction and the particulates.

Synthesis of Organic-Inorganic Hybrid Aluminum Hypophosphite Microspheres Flame Retardant and Its Flame Retardant Research on Thermoplastic Polyurethane

Aluminum hypophosphite microspheres(AHP) were synthesized by hydrothermal method using NaH2PO2·H2O and AlCl3·6H2O as raw materials, and then the AHP microspheres were polymerized by surface polymerization of micro-nanospheres with cyclic cross-linked poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol)(PZS). A new organic-inorganic poly(phosphonitrile)-modified aluminum hypophosphite microspheres(PZS-AHP) were synthesized by encapsulation and applied to flame retardant thermoplastic polyurethane(TPU). The microstructure and chemical composition of the PZS-AHP microsphere were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray spectroscopy. The thermal stability of PZS-AHP microsphere was explored with thermogravimetric analysis. Thermogravimetric data indicate that the PZS-AHP microspheres have excellent thermal stability. The thermal and flame-retarding properties of the TPU composites were evaluated by thermogravimetric(TG), limited oxygen index tests(LOI), and cone calorimeter test(CCT). The TPU composite achieved vertical burning(UL-94) V-0 grade and LOI value reached 29.2% when 10 wt% PZS-AHP was incorporated. Compared with those of pure TPU, the peak heat release rate(pHRR) and total heat release(THR) of TPU/10%PZS-AHP decreased by 82.2% and 42.5%, respectively. The results of CCT indicated that PZS-AHP microsphere could improve the flame retardancy of TPU composites.

Improvement of Microstructure and Mechanical Properties of Rapid Cooling Friction Stir-welded A1050 Pure Aluminum

Two-mm thick A1050 pure aluminum plates were successfully joined by conventional and rapid cooling friction stir welding(FSW), respectively. The microstructure and mechanical properties of the welded joints were investigated by electron backscatter diffraction characterization, Vickers hardness measurements, and tensile testing. The results showed that liquid CO_(2) coolant significantly reduced the peak temperature and increased the cooling rate, so the rapidly cooled FSW joint exhibited fine grains with a large number of dislocations. The grain refinement mechanism of the FSW A1050 pure aluminum joint was primarily attributed to the combined effects of continuous dynamic recrystallization, grain subdivision, and geometric dynamic recrystallization. Compared with conventional FSW, the yield strength, ultimate tensile strength, and fracture elongation of rapidly cooled FSW joint were significantly enhanced, and the welding efficiency was increased from 80% to 93%. The enhanced mechanical properties and improved synergy of strength and ductility were obtained due to the increased dislocation density and remarkable grain refinement. The wear of the tool can produce several WC particles retained in the joint, and the contribution of second phase strengthening to the enhanced strength should not be ignored.

Silicon Mitigates Aluminum Toxicity of Tartary Buckwheat by Regulating Antioxidant Systems

Aluminum (Al) toxicity is a considerable factor limiting crop yield and biomass in acidic soil. Tartary buckwheatgrowing in acidic soil may suffer from Al poisoning. Here, we investigated the influence of Al stress on the growthof tartary buckwheat seedling roots, and the alleviation of Al stress by silicon (Si), as has been demonstrated inmany crops. Under Al stress, root growth (total root length, primary root length, root tips, root surface area, androot volume) was significantly inhibited, and Al and malondialdehyde (MDA) accumulated in the root tips. At thesame time, catalase (CAT) and ascorbate peroxidase activities, polyphenols, flavonoids, and 1,1-diphenyl-2-picrylhydrazyl(DPPH) and 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) free-radical scavenging abilitywere significantly decreased. After the application of Si, root growth, Al accumulation, and oxidative damage wereimproved. Compared to Al-treated seedlings, the contents of ·O2− and MDA decreased by 29.39% and 25.22%,respectively. This was associated with Si-induced increases in peroxidase and CAT enzyme activity, flavonoidcompounds, and free-radical scavenging (DPPH and ABTS). The application of Si therefore has positive effectson Al toxicity in tartary buckwheat roots by reducing Al accumulation in the roots and maintaining oxidationhomeostasis.

激光焊接ZL114A/5A06异种铝合金接头组织及性能

采用激光焊接ZL114A/5A06异种铝合金,通过参数优化以获得性能优良的焊接接头,利用光学显微镜(OM)、拉力试验机、高温疲劳试验机、SEM和EDS对接头的显微组织、力学性能和拉伸断口进行了研究。结果表明:焊缝中心区的金相组织为等轴晶;接头焊后不经热处理,抗拉强度可达到265 MPa,为母材强度的80%以上,并有很好的抗疲劳性能;断口分析显示断裂位置在ZL114A母材一侧的熔合线附近;在保证焊透的前提下,激光功率越小,晶粒越细小,接头强度越高。对框架蒙皮结构铝合金贮箱产品试验件进行了焊接,试验件达到了产品各项性能指标要求。

Effect of Heat Treatment on Microstructure and Mechanical Properties of Multiscale SiC_p Hybrid Reinforced 6061 Aluminum Matrix Composites

The performance of solid solution aging treatment on aluminum matrix composites prepared by powder metallurgy and reinforced with 6061 aluminum alloy powder as matrix;meanwhile, nano silicon carbide particles(nm Si Cp), submicron silicon carbide particles(1 μm Si Cp) and Ti particles were studied. The Al/Si Cp composite powder was prepared by high-energy ball milling, and then cold-pressed, sintered, hotextruded, and then heat-treated with different solution temperatures and aging times for the extruded composites. Optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy(EDS), X-ray diffractometer(XRD) and extrusion testing were used to analyze and test the microstructure and mechanical properties of aluminum matrix composites. The results show that after the multi-stage solid solution at 530 ℃×2 h+535 ℃×2 h+540 ℃×2 h, the particles are mainly equiaxed grains and uniformly distributed. There is no reinforcement agglomeration, and the surface is dense and the insoluble phase is basically dissolved. In the matrix, the strengthening effect is good, and the hardness and compressive strength are 179.43 HV and 680.42 MPa, respectively. Under this solution process, when the aluminum matrix composites are aged at 170 ℃ for 10 h, the hardness and compressive strength can reach their peaks and increase to 195.82 HV and 721.48 MPa, respectively.

Ar压强对硅基Al膜应力和微结构的影响

用直流磁控溅射法在室温Si基片上制备了溅射时间分别为5min和10min,氩气压强分别为0.7、3、6Pa的6种Al膜,用光学相移法和X射线衍射法对Al膜的应力和微结构随着压强的变化进行了研究。应力分析表明在同一溅射时间,随着氩气压强的减小,Al膜厚度增大,在相同选区范围内,Al膜的应力差变小,应力分布趋于均匀。结构分析表明制备的Al膜呈多晶状态,晶体结构仍为面心立方,在相同溅射时间下,压强为0.7Pa的Al膜结晶度最好。随着压强的减小,平均晶粒尺寸和晶格常数增大。

Influence of samarium content on microstructure and mechanical properties of recycled die-cast YL112 aluminum alloys

The influence of Sm(Samarium) content on microstructure and mechanical properties of recycled die-cast YL112 aluminum alloys was investigated.The results show that many small Sm-rich particles form in the recycled die-cast YL112 alloys with Sm addition.At the same time,the secondary dendrite arm spacing in the YL112 alloys modified with Sm is smaller than that of the unmodified alloy.The eutectic Si of recycled diecast YL112-xSm alloys transforms from coarse acicular morphology to fine fibres,Mechanical properties of the investigated recycled die-cast YL112 aluminum alloys are enhanced with Sm addition,and a maximal ultimate tensile strength value(276 MPa) and elongation(3.76%) are achieved at a Sm content of 0.6wt.%.Due to the modification of eutectic Si by Sm,numerous tearing ridges and tiny dimples on the fractures of tensile samples are observed.