Increasing Aluminum Content Research Articles

Influence of Varying Amounts of Alumina (Al2O3) on the Wear Behavior of ZnO, SiO2 and TiO2 Compounds

This study aimed to exploit the superior properties of TiO2, ZnO, SiO2 and Al2O3 inorganic materials to combine them under pressure and investigate their mechanical properties. The hot pressing technique was used to produce new materials. Varying amounts of alumina such as 0, 5, 10, 20 and 30 wt% in compounds was considered. The produced materials were characterized by SEM, EDS and XRD analyses. The microhardness properties of the materials were studied, and their tribological properties under different wear loads, i.e., 10 N, 20 N and 30 N, were investigated for every specimen. In XRD analysis, it was observed that no significant new peaks were formed regarding increasing alumina content. The SEM and EDS characterization analyses showed that the materials had a two-phase structure with complex boundaries, and no clear grain boundaries were formed. Moreover, the elements in the EDS analyses and the compounds in the XRD analyses were found to be in line with each other. In wear tests, it was seen that as the wear load increased, the depth and width of the wear track increased. The highest weight loss under different wear loads was obtained for the Ti55Si15Zn20Al10 material. It was determined that as the Al2O3 wt% increased over 10 wt%, the weight losses decreased. It was observed that there was an increase in the microhardness value generally depending on the increase of alumina content in compounds.

Experimentally and Numerically Investigate of the Critical Diameter of Aluminized DNAN/RDX Melt-Cast Explosive

This study experimentally investigates the effect of RDX particle size and crystal quality, as well as aluminum particle size and content on the critical diameter of aluminized DNAN/RDX melt-cast explosive using the continuous wire method. Ultimately, the critical diameter increases when the particle size of both RDX and aluminum, as well as RDX crystal quality increases. Contrastingly, the critical diameter decreases when the aluminum content increases. Besides, we employed the Ignition and Growth reaction flow model to simulate the effect of RDX particle size and crystal quality, as well as aluminum particle size and content on the critical diameter.

Effects of Heat Treatment on the Interface Microstructure and Mechanical Properties of Friction-Stir-Processed AlCoCrFeNi/A356 Composites

Equiatomic AlCoCrFeNi high-entropy alloy (HEA) has gained significant interest in recent years because of its excellent mechanical properties. A356 aluminum alloy reinforced by AlCoCrFeNi HEA particles was fabricated by friction stir processing (FSP) and subsequent heat treatment. Solution and aging treatments were specially performed for the composites to control the interface microstructure, and interfacial microstructure and tensile properties were explored at different conditions. The interface between the matrix and HEA particles showed a dual-layered core-shell structure and the thickness of the shell region increased with the solution time. The microstructure located in the shell layers consisted of a solid solution with increasing aluminum content, in which a radial-shaped solid solution phase formed in the region close to the core of the HEA particle and scattered solid solution grains with high Ni content formed in the region close to the matrix alloy. The gradient of composition and microstructure across the HEA/Al interface can be obtained through heat treatment, and an optimal interface bonding state and mechanical property were obtained after solution treatment for 2 h. Compared with FSPed A356 aluminum alloy, the FSPed composite enhanced the tensile stress by 60 MPa and the stain by 5% under the optimized conditions. The overgrowth of the shell layer decreased both the tensile strength and the ductile greatly due to the formation of a radial-shaped solid solution phase in the shell region.

Impact-abrasive wear resistance of high alumina ceramics and ZTA

In transport of raw materials abrasive wear resistance is a requirement, which can be met with alumina ceramics. At certain locations additional impact load occurs, exacerbating the wear loss. As literature on impact-abrasive wear of ceramics is scarce this topic will be researched in this work.We selected a variety of commercial alumina ceramics (90–96% Al2O3) and according to literature much more impact resistant – and substantially more expensive – Zirconia Toughened Alumina (ZTA, 20–25% Zr) used for wear resistant linings in impact dominated systems. We selected the Impeller-Tumbler test, an impact-abrasion test for wear evaluation of highly loaded ceramic edges. Two load regimes were evaluated for the abrasive, either corundum particles for severe load or steel balls for extreme load conditions. Correlation of wear results with the fracture toughness (K1C) and Vickers hardness of the materials is intended – material parameters used as measure for brittle failure of ceramics and wear resistance, respectively.The various ceramic materials showed very different wear behaviour under the impact-abrasive load. The 90% Al2O3 was least wear resistant under both load conditions. Interestingly large differences between the 92% types were found at extreme load conditions. The increase of alumina content to 95–96% showed remarkable benefits in both wear regimes. Best wear resistance against severe load was achieved by 25% ZTA, while it is comparable to the 95–96% high alumina types at extreme load.

Cation-Induced Disruption of the Local Structure of Water in Faujasite

The changes in the structure of water confined in faujasite were resolved by a series of ab initio molecular dynamic simulations of explicit water molecules in faujasite with varying Si/Al ratio and counterions present. Radial distribution functions of water oxygen atom pairs, as well as counterions to Al pairs, were calculated to quantify the structure of water in faujasite and the distribution of counterions in the water-filled faujasite pores. Radial distribution functions reveal that confinement without counterions results in more water molecules hydrogen bound to each other. In hydrogen-exchanged faujasite, the increase in aluminum content led to the disruption of the confined water structure as charge-compensating protons dissociated from Al tetrahedra and entered the liquid water in the pores. In addition, a potential of mean force of proton transfer shows that protons are thermodynamically favored to be in the liquid water rather than bound on Al tetrahedra. Exchanged Na+ and La3+ counterions, which remain closer to Al tetrahedra in liquid water than H+, also disordered the confined water structure. Two La3+ ions disrupted water less than did six Na+ ions, suggesting that, for the alkali and lanthanide ions, the number of counterions in FAU has a larger effect on the structure of water than the charge of the ion itself.

Hatchability and Survival of Lamproglena clariae Fryer, 1956 Exposed to Increasing Concentrations of Aqueous Aluminium

The effect of increased aluminium concentration on the hatchability and survival of Lamproglena clariae is unknown. During October 2019 and October 2020, infected C. gariepinus were collected from the Vaal River and transferred to a controlled aquarium room. Parasite infection was established on acclimated C. gariepinus. Adult female parasites (F2 and F3 generation) on live fish were inspected for egg strings. Viable egg strings were removed, leaving females attached to produce more eggs. Bioassays were performed in varying concentrations of Al (control, 5 µg/L, 30 µg/L, 60 µg/L, and 120 µg/L). Egg development was monitored. In situ physical and chemical water quality parameters were measured, and water samples were collected every 24 h for metal analysis using inductively coupled mass spectrometry. The experiment terminated when all juveniles perished. Five percent of exposed eggs did not hatch in the control solution, compared to 26% in 120 µg/L Al. Hatchability and survival of L. clariae were negatively affected by increased Al concentrations. By removing this ectoparasite from living fish, the need to euthanise the host organism is eliminated, emphasising the usefulness of L. clariae as a bioindicator for metal pollution.

Effect of Al2O3 on the Structural Properties of Water-Quenched Copper Slag Related to Pozzolanic Activity

Water-quenched copper slag (WCS) modified with alumina (Al2O3) has been proven as a cement substitute; however, the effect of Al2O3 on structural properties of WCS related to pozzolanic activity has not been well investigated. The structural properties and the pozzolanic activity of WCS with different amounts of Al2O3 are characterized by X-ray diffraction, differential scanning calorimetry, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and the uniaxial compressive strength test. The results show that only amorphous exists in copper slag, and the stability of amorphous first increases and then decreases with the increase in the alumina content. The addition of alumina significantly improves the pozzolanic activity of WCS at 7 and 28 days, but it has little effect on the pozzolanic activity of WCS when the slag’s curing age is 3 days. The results also show the increase in the non-bridging oxygen content, the decrease in the degree of polymerization, and the transition from Q2 and Q4 to Q3 with the increase of alumina content. Moreover, the addition of aluminum will convert Si-O-Si into Si-O-Al. These experimental results show that the addition of alumina can improve the pozzolanic activity of WCS, which can be used to partially replace cement.

Effect of aluminum-based additives on the ignition performance of ammonium perchlorate-based composite solid propellants

The addition of aluminum particles in composite propellants has a positive effect on the performance of solid rocket motor, while it also brings some changes in the ignition behaviors. To clarify the ignition process and performance of aluminized propellants, a visualization experimental system was built. It is found that the ignition process of aluminized propellants mainly includes heating and melting of the solid phase, evaporation, mixing and ignition of decomposed gas. Besides, few aluminum particles agglomerate together and they are not ignited during the ignition process of propellants. According to the process of ignition, the ignition delay time can be described as the sum of pyrolysis time, mixing time and chemical reaction time. After the propellants is ignited and the stable flame is formed, the aluminum particles on the burning surface mainly undergo exposure – accumulation – fusion – separation – ignition – combustion. And the structure of the agglomerate transitions from a coral-like to an oxidized cap. At the same time, the ignition of agglomerated products occurs in the stable flame. With the increase of aluminum content and initial aluminum particle size, the ignition delay time also increases, but the proportion of these three times in the ignition delay is not very much related to the formulation of propellants. With the increase of power density of ignition, the ignition delay time decreased markedly, but the decreasing trends continuously became more gradual and eventually flattened out. As the power density of ignition increases, the percentage of pyrolysis time in the ignition delay time decreases rapidly and gradually stabilizes, while the percentage of mixing time gradually increases and the chemical reaction time does not change much. A sufficiently large and reasonable ignition energy power can reduce the ignition delay time and also reduce the impact of the differences between formulations on ignition performance.

Magnetism and EPR Spectroscopy of Nanocrystalline and Amorphous TiO2: Fe upon Al Doping

This work is devoted to the study of the magnetic properties and Electron Paramagnetic Resonance (EPR) spectroscopy of TiO2:Fe nanoparticles doped with Al in different structural states. The sol-gel methods have been used to obtain the particles in both crystalline (average size from 3 to 20 nm) and X-ray amorphous states. The electron paramagnetic resonance spectra of crystalline samples TiO2:Fe doped with aluminum besides a resonance line with g-factor ~2 exhibit a small signal with a g-factor of 4.3 from Fe3+ ions with rhombohedral distortions. The fraction of Fe3+ with rhombohedral distortions increases with increasing aluminum content. For the amorphous state at Al doping, the resonance with a g-factor of 4.3 is completely dominant in the electron paramagnetic resonance spectrum. The density functional theory calculation shows that aluminum prefers to be localized near iron ions, distorting the nearest Fe3+ environment. The complex integral electron paramagnetic resonance spectrum of all samples was fitted with sufficient accuracy by three separate resonance lines with different widths and intensities. The temperature behavior of the electron paramagnetic resonance spectrum can be described by the coexistence of paramagnetic centers (isolated Fe3+ ions including dipole-dipole interactions) and iron clusters with negative exchange interactions.

Combined Influence of Lithium Nitrate and Metakaolin on the Reaction of Aggregate with Alkalis.

The best known and effective methods for the reduction of the negative effects of an alkali-silica reaction in concrete include the application of mineral additives with an increased aluminium content and reduced share of calcium, as well as chemical admixtures in the form of lithium compounds. Because both aluminium and lithium ions increase the stability of reactive silica in the system with alkalis, it is possible to presume that the application of both corrosion inhibitors together will provide a synergistic effect in the ASR limitation. The paper presents the results of studies on the influence of combined application of metakaolin and lithium nitrate on the course of corrosion caused by the reaction of opal aggregate with alkalis. The potential synergistic effect was studied for the recommended amount of lithium nitrate, i.e., the Li/(Na + K) = 0.74 molar ratio and 5%, 10%, 15%, and 20% of cement mass replacements with metakaolin. The effectiveness of the applied solution was studied by measurements of mortars expansion in an accelerated test, by microstructure observations, and by determination of the ASR gels composition by means of SEM-EDS. The influence of metakaolin and the chemical admixture on the compressive and flexural strengths of mortars after 28 and 90 days of hardening were also analysed. The results of the studies revealed a synergistic effect for mixtures containing metakaolin at 15% and 20% cement replacement and lithium nitrate admixture in alkali-silica reaction expansion tests. It was found that corrosion processes in mortars with 5 and 10% levels of metakaolin became more severe after adding a lithium admixture to mortars with metakaolin only. The obtained results were confirmed by observations of the mortars' microstructures. There was no synergistic impact of lithium nitrate and metakaolin on compressive strength characteristics. The compressive strength of mortars containing a combination of metakaolin and lithium nitrate decreased both after 28 and after 90 days, compared to mortars with metakaolin alone.

Effect of Al2O3 particles on the mechanical and wear properties of Al base composites

In this study as its novelty, Al/Al2O3 composites have been fabricated combined stir casting and accumulative roll bonding (ARB) process. Then, the next step was the investigation of the effect of Nano Al2O3 Vol.% on mechanical, wear and microstructural properties of these kind of composites. After the 4th cycle, an excellent particle distribution through the aluminum matrix has been achieved. Then, mechanical properties, wear resistance and microstructural properties have been investigated. The results showed that by higher the alumina Vol.% contents, the strength of these composites were enhanced and the elongation of samples decreased. Also, by increasing alumina content into the Al matrix through stir casting process, a significant increase in wear resistance was achieved.

Effective radiative recombination coefficient of p-AlGaAs for varying aluminium concentrations

The effective radiative recombination coefficient of p-AlGaAs was experimentally determined for different sample geometries and compositions. Double-heterostructures with varying active layer thicknesses and aluminium concentrations between 0.08 and0.23 were grown using metalorganic vapor phase epitaxy. Combining injection-dependent and time-resolved photoluminescence measurements allowed to compute the effective radiative efficiency as a function of excess carrier density and to extract the effective radiative recombination coefficient. For increasing active layer thickness and for increasing aluminium content the effective radiative recombination coefficient decreases in agreement with numerical modelling. Optical interference effects, in particular for thin samples, make the results susceptible to small variations in sample thickness and additional layers underneath the double-heterostructure. The extracted non-radiative lifetimes imply the existence of three different defects, independent of composition and thickness, that are dominant in different carrier injection regimes. A sensitivity analysis of the presented method revealed that the low-injection carrier lifetime and the doping concentration are the two most critical input parameters whose combined uncertainties amplify the error on the obtained effective radiative recombination coefficient.

Investigation of microstructure evolution and properties in silica‐based ceramic cores with alumina as a mineralizer

AbstractIn this work, silica‐based ceramic cores with alumina as a mineralizer were prepared via an injection molding method, and the effects of alumina on the microstructural evolution and properties at 1450°C (simulating the process of equiaxed castings) and 1550°C (simulating the process of columnar/single crystal castings) were investigated. It was found that alumina promoted the cristobalite crystallization of fused silica refractory during sintering but inhibited the devitrification rate in the subsequent heating. The flexural strength of silica‐based ceramic cores at an ambient temperature and 1450°C improved with an increasing alumina content, whereas the opposite trend appeared at 1550°C. The creep resistances of silica‐based cores were improved significantly and then slightly deteriorated with an increasing alumina content from 5% to 20%, depending on the competition effects of alumina hindering the viscous flow of liquid silica (favorable), but suppressing the devitrification rate (unfavorable). The results of this work show that silica‐based cores need to follow different compositional design principles for equiaxed and columnar/single‐crystal turbine blade castings.

MINEROL IN THE PROBABLE PREVENTION OF TOXIC IMPACT OF ION ALUMINIUM ON BONES IN RATS

Background. The use of a variety of aluminium-containing medications, occupational exposure to alumina dust and fumes, and heavily contaminated water sources have been associated with an adverse effect on the organism, in particular, on bone system. The search for a preventive means against the impact of aluminium on the state of bones is topical. Objective. To assess the probable prophylactic effect of sorbent Minerol on the skeletal system of white rats in long-term AlCl3 intoxication. Materials and methods. In the 2-month study, male rats were grouped into: intact animals; AlCl3-induced toxicity model (240 mg/kg of w.b.); and animals administered daily with Minerol 1g/kg of w.b. on the background AlCl3 intoxication. Density and content of mineral and organic components were determined in the femurs and lumbar vertebrae, with atrophy of the alveolar process being determined in the jaws. The aluminium content was determined in the femoral bones. Results. A long-term exposure to AlCl3 resulted in the 2.5-fold increase in aluminium content in femoral bones, 17.1% increase of alveolar bone atrophy, the slight decrease of the density of femoral bones and the slight increase of the density of lumbar vertebrae. The following changes in the content of the mineral-organic complex of bones were indicated: in femurs – the decrease due to both mineral and organic fractions, and in lumbar vertebrae – the increase due to significant increase in the organic fraction. Minerol reduced the aluminium content in femurs by 20.7%, caused a decrease in the density, mineral-organic component and mineral fraction of bone tissue of the femur and lumbar vertebrae, and additionally increased the degree of atrophy of the alveolar bone against the background of AlCl3 intoxication. Conclusions. In addition to the sorption effect, the dose of Minerol used in the study probably bound the nutritional components required for bone remodelling, i.e. protein, calcium, phosphorus etc. The results imply further investigations of the sorption properties of Minerol in prevention of the negative impact of AlCl3 in higher dose of the said sorbent and in combination with calcium, phosphorus and protein preparations.

Correlation between the concentration of chemical elements in wool and the quantitative and qualitative characteristics of the semen in Holstein bulls

The effect of concentrations of 25 chemical elements in wool on the quantitative and qualitative characteristics of sperm was studied in Holstein sires (n = 55), age 3-4 years, in the conditions of JSC "Nevskoye" by breeding work in Leningrad region. Wool samples were collected from the top of the withers and determined by the AES-ISP method. The interrelation of quantitative and qualitative characteristics of the sperm was revealed with two chemical elements: calcium and aluminum. Thus, as the calcium concentration in wool increases from 604±194.8 mg/kg to 3690±460.3 mg/kg, the volume of native sperm increases by 55.8% (P?0.01), spermatozoa activity increases by 0.14 points (Р?0.05), diluted semen yield – by 95.1% (Р?0.01), number of frozen doses – by 82.6% (Р?0.05). An increase in aluminum concentration from 1.89 mg/kg to 8.46 mg/kg is accompanied by a decrease in the concentration of spermatozoa by 20.4% (P?0.001), activity - by 0.21 points (P?0.05), number of frozen doses - by 55.4% (P?0.01).

Belite clinkers with increasing aluminium content: Effect of calcium aluminates on calcium silicate hydration

Belite cements (BCs) could have advantages over Portland cements concerning durability, low heat development and the use of less demanding raw materials. The activation of BCs by sulfur addition at the clinkering stage and by fast cooling is well established. However, the reaction rates of the calcium silicate phases, mainly belite, are still not fully understood. This is partly due to the interplay between factors including: i) belite activation during clinkering; ii) role of the calcium aluminates at early hydration ages; and iii) role of the sulfates. In the research reported here, three belite clinkers were prepared with constant values of lime saturation factor, and SO3, Fe2O3 and CaF2 contents. The varied parameter was the amount of Al2O3. The resulting clinkers have overall crystalline reactive calcium aluminate contents of 0.4, 7.9 and 16.7 wt%, respectively. Cements were prepared with similar particle sizes and constant anhydrite content. Here, it is shown that calcium silicate reactivities, both alite and belite, strongly depend upon the calcium aluminate contents. As these amounts increase, the degree of hydration of alite at 1 day decreases: 85, 65 and 50 %. Furthermore, the degree of hydration of belite at 7 days was 50, 35 and 0 %. Thus, there is a strong influence of aluminates in calcium silicate rates of hydration. Moreover, comparing the mechanical properties of the cements with 0.6 and 8.2 wt% amounts of calcium aluminates, the improvements due to the higher reactivity of calcium aluminates at very early ages, seem to be counterbalanced by the lower reactivity of the silicate phases. The reported findings may allow further optimization of early age reactivity of active BCs.

Effect of nano Al2O3 particles on the mechanical and wear properties of Al/Al2O3 composites manufactured via ARB

Abstract This study first tried to fabricate AA1060/Al2O3 composites via the stir casting and accumulative roll bonding process. Then, the effect of nano Al2O3 Vol% on mechanical, wear, and microstructural properties of these kinds of composites have been investigated. An excellent particle distribution through the aluminum matrix has been achieved after the fourth cycle. Then, mechanical properties, wear resistance, and microstructural properties have been investigated. The results showed that the strength of these composites was enhanced and the elongation of samples decreased by higher alumina Vol% contents. Also, there is a significant increase in wear resistance by increasing alumina content in the Al matrix through the stir casting process.

Influence of external fields on the exciton binding energy and interband absorption in a double inverse parabolic quantum well

Ground-state binding energy and optical absorption coefficient of exciton in a symmetric double inverse parabolic quantum well system in the presence of external electric and magnetic fields are investigated theoretically. Numerical calculations have been carried out with the variational technique considering the single-band effective mass approximations. Results reveal that the excitonic binding energy and interband optical absorption depend on significantly on the geometrical and structural parameters defining carriers’ double inverse parabolic confinement potential, the aluminum concentration at the well center, the electric field, and the magnetic field. The exciton binding energy is a decreasing (increasing) function of the electric field (magnetic field). The increase in aluminum concentration creates a blueshift at the resonance peak positions. As a result, the tunability of the excitonic effects is expected to be of importance in developing stable and high-efficiency nanoscale excitonic optoelectronic devices . • Analyses of double inverse parabolic quantum well. • Exciton binding energy. • Interband transitions. • Electric and magnetic field effects.

Optimization of biocorrosion resistance and mechanical properties of PM Ti–XAl–2Fe–3Cu alloys by response surface methodology

In the current study, the biocorrosion resistance and mechanical properties of the Ti–XAl–2Fe–3Cu (wt%) (X = 6, 4, 2 wt%) alloy produced by powder compact extrusion of blended elemental powders were optimized by using the response surface methodology in order to gain the best combination of processing parameters. To run the optimization process, central composite design with three equal levels of oxygen, hydrogen and aluminum was used and, by employing ANOVA, the analysis of variance was implemented. The results showed that the content of aluminum has a significant effect on the microstructure, mechanical properties, biocorrosion resistance and fracture behavior of the extruded rods. The highest aluminum content corresponds to the highest alloy strength and biocorrosion resistance. This was due to the reduction of the lamella thickness and of the material colonies as the aluminum content increases. Also, by running the experimental and optimization tests, the mechanical properties resulted 1245 MPa in yield strength and 1340 MPa in ultimate tensile strength with 0.1 µAcm−2 in corrosion current.

Effect of FeSi Alloy Additions and Calcium Treatment on Non-Metallic Inclusions in 304 Stainless Steel during AOD and LF Refining Process

Non-deformable inclusions are detrimental to the surface quality and mechanical properties of stainless-steel plates. Plant trials were conducted to investigate the effect of different ferrosilicon alloys and calcium treatment during argon oxygen decarburization (AOD) and ladle furnace (LF) refining on inclusions in Si-killed 304 stainless steel. The inclusions were examined by scanning electron microscope with energy dispersive spectrometer. The results show that both the contents of soluble aluminum in molten steel and Al2O3 in slag increase with the increase of aluminum content in FeSi alloy. The content of soluble aluminum in liquid steel could be limited to lower than 0.004% when using ultra-purity FeSi alloy. When the calcium wire addition is 2 m/t, inclusions are located in the low-melting-temperature region, and the inclusion rating of hot rolled plates is mainly C-class. Industrial application shows that, by decreasing the soluble aluminum content in liquid steel, decreasing the MgO and Al2O3 in slag in AOD, and applying low basicity refining slag as well as calcium treatment, the inclusions are low melting point silicates. The inclusion rating of hot rolled plates is mainly fine C-type with a small amount of class-A, and surface polishing qualification rate is increased from 17.8% to more than 88.7%.