Influence Of Alumina Research Articles

Influence of alumina on the performance of Ag/ZnO based catalysts for carbon dioxide hydrogenation

We study silver-zinc oxide type catalysts with and without the addition of alumina and perform structural analysis and activity tests for the hydrogenation of carbon dioxide. Adding alumina has a dispersing effect on the zinc oxide without structurally altering the silver phase. An alumina-surface enriched ZnO/Al2O3 phase is observed with an increased surface reducibility. Ag/ZnO has a high selectivity towards carbon monoxide (63 ± 12 %) and methane (24 ± 3 %) and low selectivity towards methanol (13 ± 0.5 %). Operando infrared (SSITKA-FTIR) and mass spectrometric product detection indicate methane formation via an adsorbed carbon monoxide (COads) intermediate. The selectivity changes gradually with increasing alumina content, up to 80 ± 3 % toward methanol, and 20 ± 4 % carbon monoxide without methane detection, combined with a tripling of the space time yield to 0.65 ± 0.02mmolMeOH*gcat-1*h−1 at 250 °C and 30 bar. Kinetic analysis suggests that the selectivity change originates from hindering the CO-pathway, while the formate pathway leading to methanol remains active.

Influence of alumina and PMMA on mechanical properties and aging behavior of 3D printed PLA composites: A comparative study

AbstractThis study intends to investigate the mechanical, thermal, and aging behaviors of 3D‐printed PLA (polylactic acid)‐blend with 10% polymethyl methacrylate (PMMA) and 10% alumina polymer composites for biomedical applications using compressive, DSC, and DMA analysis. The experimental results revealed that aged PLA blend with alumina samples increased compressive strength by 60.1% and 37.8% during hydrolytic and enzymatic degradation, respectively, compared to aged PLA samples. Also, it was reported that the PLA blend with PMMA samples increased compressive strength by 51.1% and 24% after hydrolytic and enzymatic degradation, respectively, as compared to aged PLA samples. Furthermore, DSC analysis revealed that alumina blended samples had a higher Tg than pure PLA and PMMA blended samples. In addition, DMA investigation revealed that the Tg of aged neat PLA, PLA/PMMA, and PLA/alumina increased by 4.38%, 4.8%, and 4.6%, respectively, compared to unaged polymer composites. Additionally, PLA/alumina‐aged samples exhibited stronger aging properties than neat PLA and PLA/PMMA blended‐aged samples. It was reported that the weight loss of PLA/Alumina was lowered by 10.7% and 15.6% compared to aged PLA/PMMA samples, for hydrolytic and enzymatic aging respectively. It was found that PLA alumina has better mechanical, thermal, and degradation resistance than PLA materials.Highlights Alumina and PMMA materials were blended with PLA. Examined the aging and mechanical properties of PLA blended composites. Utilized hydrolytic and enzymatic aging for biomedical applications. Evaluated mechanical strength performance of aged and unaged samples. DSC and DMA were utlised for this research.

Influence of alumina on emission characteristics of Gd3+ ions in lead silicate glasses

Influence of alumina on emission characteristics of Gd3+ ions in lead silicate glasses

Influence of Alumina, Ferric Oxide, and Mn as Composites on the Properties of Recycled Aluminium Alloy

Recycling of aluminium alloys is gaining significant attention due to its economic and environmental benefits. However, close loop recycled aluminium alloys can be adversely affected by impurities and alloying elements present in the recycled feedstock. In this study, the influence of three composites, namely alumina (Al2O3), ferric oxide (Fe2O3), and manganese (Mn), on the properties of recycled aluminium taldon scraps was investigated to enhance the tensile behaviour of the alloys. The effects of these composites on the mechanical properties, microstructure, and corrosion behaviour of the recycled aluminium alloys were evaluated through experimental characterization techniques. The results showed that the addition of these composites had a significant influence on the properties of recycled aluminium alloys, providing insights into the potential for improving the performance of recycled aluminium alloys through composite additions. The addition of Al2O3 enhanced the tensile strength by 44.18 % and the variation can be attributed to the strengthening of the dendritic zones by the formation of α-Al.

Experimental Investigations of Using Aluminum Oxide (Al2O3) and Nano-Graphene Powder in the Electrical Discharge Machining of Titanium Alloy.

In the present study, a comprehensive parametric analysis was carried out using the electrical discharge machining of Ti6Al4V, using pulse-on time, current, and pulse-off time as input factors with output measures of surface roughness and material removal rate. The present study also used two different nanopowders, namely alumina and nano-graphene, to analyze their effect on output measures and surface defects. All the experimental runs were performed using Taguchi's array at three levels. Analysis of variance was employed to study the statistical significance. Empirical relations were generated through Minitab. The regression model term was observed to be significant for both the output responses, which suggested that the generated regressions were adequate. Among the input factors, pulse-off time and current were found to have a vital role in the change in material removal rate, while pulse-on time was observed as a vital input parameter. For surface quality, pulse-on time and pulse-off time were recognized to be influential parameters, while current was observed to be an insignificant factor. Teaching-learning-based optimization was used for the optimization of output responses. The influence of alumina and nano-graphene powder was investigated at optimal process parameters. The machining performance was significantly improved by using both powder-mixed electrical discharge machining as compared to the conventional method. Due to the higher conductivity of nano-graphene powder, it showed a larger improvement as compared to alumina powder. Lastly, scanning electron microscopy was operated to investigate the impact of alumina and graphene powder on surface morphology. The machined surface obtained for the conventional process depicted more surface defects than the powder-mixed process, which is key in aeronautical applications.

Influence of alumina on the formation process and morphology of silicon nitride whisker

β-Si3N4 whiskers were synthesized by heat treatment of α-Si3N4 and Y2O3 mixed powder, and different content of Al2O3 powder was introduced to adjust the synthesis condition and L/D. Introducing Al2O3 significantly accelerated the phase transformation from α-Si3N4 to β-Si3N4. The phase transformation can be completed at 1650 °C by introducing only 0.3 wt% Al2O3, and the phase transformation temperature was reduced by about 100 °C after 1.8 wt% Al2O3 was introduced. Y2O3 orients β-Si3N4 grain growth, while the role of Al2O3 is to reduce liquid viscosity, promote mass transfer, and accelerate grain growth. Introducing a small amount of Al2O3 and appropriately extending the holding time at a lower treatment temperature has been proven to be an effective method to obtain β-Si3N4 whiskers with higher length and diameter ratio (L/D) under mild conditions. High purity β-Si3N4 whiskers (99 wt%) were proved to be synthesized at low temperature (1650 °C) without pickling.

The optimization of Carreau model and rheological behavior of alumina/linear low-density polyethylene composites with different alumina content and diameter

Abstract The influence of alumina (Al2O3) content and diameter on the viscosity characteristics of the alumina/linear low-density polyethylene (Al2O3/LLDPE) composites was discussed. The composites were fabricated by melt mixing with the two-rotor continuous mixer. The equivalent surface average particle diameter ( d ¯ A {\bar{d}}_{\text{A}} ) of Al2O3 was calculated by the scanning electron microscopic (SEM) images of samples. The steady-state and dynamic rheological measurements were used to study the evolution of viscosity parameters. With the Carreau model fitting to the steady-rate rheological data, zero-shear viscosity η 0, time constant λ, and power law index n of composites were obtained. On this basis, an optimized Carreau model was established by studying the changes of these parameter values. The rheological result presented that the parameter values (η 0, λ, and n) were linearly proportional to the filling content of Al2O3 particles for nano-Al2O3/LLDPE composites. However, these parameters were, respectively, related to d ¯ A {\bar{d}}_{\text{A}} , d ¯ A 2 {\bar{d}}_{\text{A}}^{2} , and d ¯ A 3 {\bar{d}}_{\text{A}}^{3} for micron-Al2O3/LLDPE composites.

On the influence of alumina as a binder on the performance of Pt-Beta catalyst during the transalkylation of toluene and 1,2,4-Trimethylbenzene

The influence of the addition of 20–50 wt% alumina binder on the physical, chemical and catalytic properties and performance of zeolite Beta loaded with 0.08 wt% Pt for the transalkylation of 1,2,4-trimethylbenzene (124-TMB) with toluene was studied. The catalytic tests were conducted in a fixed-bed reactor at WHSV of 5 h−1, 400 °C and 10 bar with a mixture of toluene and124-TMB feed in 50:50 wt % ratio. The catalyst and binder mixture reduced the overall activity with increasing amount of binder. The progressive addition of the binder had a more negative effect on toluene conversion than 124-TMB which is explained by the increase in isomerization and disproportionation side reactions. The results suggested that Pt-Beta is responsible for the dealkylation reactions as the light products were decreased with increased binder contents. The xylenes yield was reduced upon addition of the binder from 39.5 to 30.5 wt %. This can be explained by the increase of amount of coke formation per unit area of Pt-Beta over the catalysts and by the re-distribution of platinum particles.

Influence of alumina and zirconia incorporations on the structure and wear resistance of titania-based MAO coatings

In the present work, the influence of alumina (Al2O3) and zirconia (ZrO2) incorporation on the structural properties and wear resistance of titania (TiO2) based micro-arc oxidation (MAO) coatings fabricated on Ti6Al4V alloy was studied. For this purpose MAO was employed in a silicate-based electrolyte with and without additions of Al2O3 and ZrO2 particles. The structural properties were determined via X-ray diffraction (XRD) and X-ray photoelectron (XPS) spectroscopy analysis and an energy dispersive spectrometer (EDS) equipped scanning electron microscope (SEM). Furthermore, thermochemical simulations were made by using FactSage 7.3. Mechanical properties of the MAO coatings were determined by hardness measurements and dry sliding reciprocating wear tests. Structural examinations revealed that the MAO coatings fabricated in Al2O3 and ZrO2 added electrolytes comprised of these oxides and their complex forms (Al2TiO5 and ZrTiO4, respectively) along with TiO2 and amorphous silica (SiO2). Although incorporations of Al2O3 and ZrO2 did not remarkably improve the hardness of the MAO coatings, the highest wear resistance was obtained from the one formed in the ZrO2 added electrolyte. On the other hand, the MAO coating fabricated in the Al2O3 added electrolyte exhibited lower wear resistance than that of fabricated in the particle-free silicate-based electrolyte.

The Influence of Alumina Filler on Mechanical, Thermal and Electrical Properties of Bulk Moulding Compounds (BMCs) Composite

Bulk moulding compounds (BMCs) are composite materials of thermosetting polymer matrix reinforced by short glass fibers. BMCs have known as the alternative of the traditional materials thanks to their optimal properties such as lightweight, durability, corrosion under certain environment, formable, high electrical resistance... The previous study mentioned the process of manufacturing composite materials BMCs from unsaturated polyester resin reinforced with short glass fiber and CaCO3 filler by Z axis mixer and applying in the circuit breaker bottom, [1, 2]. To improve the thermal resistance of BMCs under high temperature condition in the industry, in this research, alumina filler was added to investigate the influence of alumina with the different content of 15wt.% and 20wt.% on the mechanical, thermal and electrical properties of BMCs. Specimens manufactured with and without alumina filler content were compared. The results show clearly that adding alumina could improve the thermal properties whereas this might decrease the tensile strength of BMCs. The experimental results also indicated the influence of mass fraction of alumina filler content on properties of BMCs.

Correlation of Mechanical and Electrical Behavior of Polyethylene Oxide-Based Solid Electrolytes for All-Solid State Lithium-Ion Batteries

Mechanical and electrochemical stability are key issues for large-scale production of solid state Li-ion batteries. Polymer electrolytes can provide good ionic conductivity, but mechanical strength needs to be improved. In this study, we investigate the correlation of mechanical and electrical properties of poly (ethylene oxide) (PEO)-based solid electrolytes for Li-ion batteries. The influence of alumina and LiClO4 addition are investigated. Differential scanning calorimetry (DSC) is used to study the thermal behavior of salt-free and salt-containing samples and to identify the melting temperature. Dynamic mechanical analysis reveals the elastic properties as a function of temperature. Electrochemical properties are investigated using impedance spectroscopy. It is found that addition of alumina increases mechanical strength, while LiClO4 decreases it. Addition of LiClO4 and Al2O3 increases ionic conductivity and improves mechanical properties. However, there is no overlapping window of high mechanical strength and high ionic conductivity.

Urban mining of precious metals via oxidizing copper smelting

Recycling of precious metals from end-of-life electronics is a key factor for sustainable and efficient raw material usage. Simultaneously with the depletion of natural ore resources, the urban mines are storing increasing amounts of valuable and, more importantly, rare metals. To fulfill the targets of sustainability and move towards circular economy, the liberation of these valuables from wastes back to production and use needs to be improved. This study investigates the recoveries and behavior of gold, silver, palladium and platinum in copper smelting conditions at 1300 °C and pO2 = 10−5–10−7 atm. The investigated system includes a copper alloy with three different type of slags in silica saturation: pure iron silicate, iron silicate with 10 wt% alumina and iron silicate with 10 wt% alumina and 5 wt% lime, providing information on the influence of alumina and lime on precious metal recovery possibilities. A highly advanced equilibration-quenching technique, followed by EPMA and sensitive LA-ICP-MS analyses, has been adopted to execute the experiments. Results show that gold, platinum and palladium are recovered very efficiently in copper, as their distribution coefficients between copper and slag, LCu/s, were greater than 104 under every experimental condition studied and with all slag compositions. Silver distributed 30–60 times more in copper phase than was lost to slag. The addition of alumina into the slag somewhat decreased the distribution coefficient of silver, whereas gold and palladium distribution coefficients were increased. Lime addition improved the recovery of every precious metal (Pt unclear) into the copper phase. The concentrations of platinum in the slags were mainly below the detection limit of the used LA-ICP-MS, providing a minimum distribution coefficient of 106.

Effects of alumina nanoparticles on dynamic impact responses of carbon fiber reinforced epoxy matrix nanocomposites

The influence of alumina (Al2O3) nanoparticles addition upon low-velocity impact behaviors of carbon fiber (CF) reinforced laminated epoxy nanocomposites have been investigated. For this purpose, different amounts of Al2O3 nanoparticles ranging from 1 to 5 wt% were added to the epoxy resin in order to observe the effect of nanoparticle loadings. CF reinforced epoxy based laminated nanocomposites were produced using Vacuum Assisted Resin Infusion Method (VARIM). The low velocity impact (LVI) tests performed according to the ASTM-D-7136 standard under 2, 2.5 and 3 m/s impact velocities. After LVI testing, the damage formations within composites were examined by using scanning electron microscopy (SEM). The results of this study showed that addition of Al2O3 nanoparticles provided a significant improvement in impact damage resistance. The highest damage resistance and minimum energy absorption were observed for 2 wt% Al2O3 nanoparticles loadings. As a result, we can confidently claim that the addition of the Al2O3 nanoparticles in CF/epoxy composites has considerably affected the dynamic response of the nanocomposites.

Influence of the properties of blast furnace slag on cast iron heating at pulverized coal injection

In the course of the studies at two industrial blast furnaces, we established a change in the characteristics of slag mode and cast iron heating, resulting from the transition to the pulverized coal fuel injection with a decrease in basicity of CaO/SiO 2 slag from 1.16 to 1.10 and from 1.20 to 1.12 units. It was shown that depending on a particular influence of alumina and magnesia in the slag composition, as well as on their ratio, a decrease in slag basicity can be accompanied by both an increase and a decrease in viscosity. During the research, the dependence between slag viscosity at the temperature of 1,400 °C and chemical heating of cast iron heating at the outlet was established. According to obtained data, an increase in slag viscosity by 0.1 Pа∙s was accompanied by an increase in silica concentration in cast iron by 0.08–0.1 %. The relation of physical heating of metal with slag basicity and stoichiometry was established. It was shown that a decrease in basicity of (CaO+MgO)/SiO 2 by 0.1 units led to a decrease in cast iron temperature by 30 °C. Such a substantial effect of basicity of metal heating indicates the need to take this influence into account not only to control the blast furnace process, but also to state the thermal balance of steel smelting. It was shown that in the studied range of slag compositions, the influence of magnesia on heating of cast iron is limited. A slight influence of MgO on physical heating of metal was pronounced at a magnitude of the ratio Al 2 O 3 /MgO that is close to unity. Results of present research could be used to improve control over blast furnace smelting in terms of taking into consideration slag influence on heating of cast iron.

Influence of alumina and silica addition on the physico-mechanical and dielectric behavior of ceramic porcelain insulator at high sintering temperature

The high-strength electrical porcelain insulator plays a vital role in the power industry. The present study investigates the effect of alumina and silica addition on the physico-mechanical and electrical properties of porcelain bodies over high sintering temperatures. The pallets were prepared in different shapes and dimensions with the help of hydraulic press machine by pressing at 160MPa for a period of 10-min. Different characterizations techniques such as; dilatometer, X-ray diffraction (XRD), and scanning electron microscopy (SEM) used to evaluate the thermal, structural, and microstructural changes, respectively by increasing the concentration of silica (0–20wt.%) and decreasing alumina (45–25wt.%) concentration for the base composition of porcelain insulator. The measurement of mechanical strength and physical behavior were analyzed for all the samples prepared with different compositions of alumina and silica with varying sintering temperature (1250 and 1350°C). The sample with a composition having silica 10wt.% of alumina 35wt.% and sintered at 1350°C, shows the maximum density of 2.55g/cc with water absorption of 0.94%. This sample also shows the highest value of bending and compressive strength of 129±5 and 202±5MPa respectively. The highest dielectric value of 5.75 and minimum dielectric loss of 0.05 at a frequency (2–20GHz) is achieved for the same composition with silica 10wt.% of alumina 35wt.% sintered at 1350°C. The composition having silica 10wt.% with alumina 35wt.% sintered at 1350°C, has enormous potential to serve as a high strength refractory and a dielectric ceramic material for microwave applications.

Structuration and Dynamics of Interfacial Liquid Water at Hydrated γ-Alumina Determined by ab Initio Molecular Simulations: Implications for Nanoparticle Stability

Liquid water/solid interfaces are central in catalytic nanomaterials, from their preparation to their chemical stability under harsh catalytic conditions such as the hot aqueous medium used in biomass valorization. Here we report an ab initio molecular dynamics (AIMD) study of the γ-Al2O3 (110)/water interface using the most recent surface model available in the literature. The size of the simulation box and the duration of the AIMD simulation enables us to characterize the whole interface at the atomic scale. The simulation evidences a redistribution of protons within the chemisorbed water layer. The influence of γ-Al2O3 (110) is also important on the water molecules that are not bound to the surface: it is only above 10 A that water recovers its bulk liquid behavior. The influence of alumina is structural, with preferred angular orientations for water molecules, and also dynamical. The translational self-diffusivity of water is diminished by up to 2 orders of magnitude, and the angular relaxation time i...

Effect of Al2O3 nanoparticles in biodiesel-diesel-ethanol blends at various injection strategies: Performance, combustion and emission characteristics

The current experimental work focusses on influence of Alumina (Al2O3) nanoparticle on various injection strategies. Experiments were conducted with three different injection timings (IT) namely, original timing (ORG IT) of 23deg bTDC, advanced timing (ADV IT) of 27deg bTDC and retarded timing (RET IT) of 19deg bTDC. The base fuel used is a blend of biodiesel (20%), diesel (70%), and ethanol (10%) (known as BDE). Alumina nanoparticles were synthesized, characterized by SEM and XRD analysis and blended with BDE blend at a fraction of 25ppm using ultrasonicator. The effect of 25ppm Al2O3 in BDE blend at ORG IT, ADV IT and RET IT were experimented in a single cylinder diesel engine and the following results were obtained. Al2O3 addition at ADV IT resulted in higher peak pressure and heat release rate occurring nearer to TDC, higher hydrocarbon (HC), higher carbon monoxide (CO), lower carbon dioxide (CO2), higher nitrogen oxides (NOx), higher exhaust gas oxygen (EGO), higher combustion duration (CD) and lower ignition delay (ID). Whereas, Al2O3 addition in RET IT causes lower cylinder pressure and heat release away from TDC, followed by simultaneous reductions of HC, CO, NOx and smoke opacity. In addition, higher levels of EGO and ID along with lowered brake specific fuel consumption (BSFC) and CD were observed with Al2O3 addition in RET IT. Overall, the influence of 25ppm Al2O3 in RET IT of 19deg bTDC resulted in better engine performance, combustion and emission characteristics.

Influence of alumina on photoluminescence and thermoluminescence characteristics of Gd3+ doped barium borophosphate glasses

Gd3+ doped barium borophosphate glasses mixed with varying concentration of Al2O3 are synthesized. Photoluminescence, thermoluminescence and other spectroscopic studies viz., IR and EPR spectral studies, have been carried out. IR spectral studies of these glasses indicated that there is a gradual increase in the degree of depolymerization of the glass network with increase in the concentration of Al2O3 upto 3.0mol%. The EPR spectral studies revealed the lowest concentration of Gd3+ ion clusters in the glass mixed with 3.0mol% of Al2O3. The photoluminescence emission spectra exhibited strong ultraviolet blue emission at 311 under excitation at 273nm due to 6P7/2→8S7/2 transition of Gd3+ ions. The intensity of this band is found to be enhanced four times when the glass mixed with 3.0mol% of Al2O3 with respect to that of alumina free glass. The enrichment of this emission is attributed to the declustering of Gd3+ ions by Al3+ ions. Thermoluminescence (TL) characteristics of these glasses have also been investigated after irradiating them with different doses of γ-rays (in the range 0–8.0kGy). The TL emission exhibited a dosimetric peak at about 200°C. The TL output under this glow peak is observed to increase with increase of γ-ray dose. For any fixed γ-ray dose, the TL output is increased with increasing Al2O3 content up to 3.0mol% and beyond this concentration quenching of TL is observed. The mechanisms responsible for TL emission and the variation in TL output with the concentration of Al2O3 are quantitatively discussed in terms of electron and hole centers developed due to interaction of γ-rays with the glass network. The dose response of these glass samples exhibited linear behavior in the dose range 0–8.0kGy.

Influence of alumina reinforcement on nano-hydroxyapatite/biopolymer composite for biomedical applications

ABSTRACTThe foremost material that closely mimics the mineral part of the bone tissue, and is therefore suitable for bone replacement, is nano-hydroxyapatite (nHAp) which exhibits low fracture toughness, and can be used for load-bearing scaffolds in biomedical applications. Therefore, for improved biomechanical features, composite materials are developed. This work focuses on the influence and contribution of bioactive alumina and nHAp on the biopolymer, i.e., gelatin matrix for the fabrication of load-bearing bone replacement composites. Incorporation of bioceramics alumina at the strengthening phase is essential for the improvement of mechanical properties for biomedical applications. The porosity of scaffolds varied from 79 to 85%. Fourier transform infrared (FTIR) and X-ray powder diffraction (XRD) analyses showed the presence of molecular interactions and chemical linkages between gelatin matrix, alumina, and nHAp particles. The compressive strength of alumina-reinforced nanocomposites scaffolds is three times higher than those of nHAp/gelatin. The elemental composition of the chemically synthesized nHAp particles was determined by SEM, FTIR, and XRD analyses.

Influence of alumina and titanium dioxide coatings on abrasive wear resistance of AISI 1045 steel

This project aims to compare the behaviour of an AISI 1045 steel's abrasive wear resistance when is covered with aluminium oxide (Al2O3) or Titanium dioxide (TiO2), of nanometric size, using the technique of thermal hot spray, which allows to directly project the suspension particles on the used substrate. The tests are performed based on the ASTM G65-04 standard (Standard Test Method for Measuring Abrasion Using the Dry Sand/Rubber Apparatus). The results show that the amount of, lost material increases linearly with the travelled distance; also determined that the thermal treatment of hardening-tempering and the alumina and titanium dioxide coatings decrease in average a 12.9, 39.6 and 29.3% respectively the volume of released material during abrasive wear test.