Presence Of Al2O3 Research Articles

Recovery of Cr from chrome-containing leather waste and its utilization as reinforcement along with waste spent alumina catalyst and grinding sludge in AA 5052-based metal matrix composites

The present investigation deals with the development of AA 5052-based metal matrix composites (MMCs) by utilizing industrial wastes, spent alumina catalyst, chrome-containing leather waste, and grinding sludge as a reinforcement material. The chrome-containing leather waste has been utilized to extract the collagen powder, which is a form of chromium oxide. The presence of Al2O3, Fe2O3, and SiO2 phases in the spent alumina catalyst and grinding sludge ball-milled powder encourages its utilization as reinforcement material (in the form of Cr) for the development of MMCs. The stir-casting technique has been used to develop the aluminum-based MMC with waste spent alumina catalyst, chrome-containing leather waste, and grinding sludge. Further, results revealed that the matrix material mechanical properties compressive strength, tensile strength, and hardness were significantly increased by 12.93%, 5.34%, and 31.81% after adding spent alumina catalyst, Cr, and grinding sludge with the weight percentage (wt.%) of 4.5%, 1.5%, and 4.5%, respectively, but the toughness was reduced. The microstructural investigation indicated the uniform distribution of reinforcing elements spent alumina catalyst (4.5 wt.%), GS (4.5%), and Cr (1.5%) in the aluminum matrix material. Further, the influence of given reinforcement elements on the thermal expansion and corrosion weight loss properties of aluminum alloy matrix material has also been investigated.

A Concurrent Enhancement of Both In‐Plane and Through‐Plane Thermal Conductivity of Injection Molded Polycarbonate/Boron Nitride/Alumina Composites by Constructing a Dense Filler Packing Structure

AbstractIn this work, a facile strategy is proposed to concurrently enhance both in‐plane and through‐plane thermal conductivity of injection molded polycarbonate (PC)‐based composites by constructing a dense filler packing structure with planar boron nitride (BN) and spherical alumina (Al2O3) particles. The state of orientation of BN platelets is altered with the presence of Al2O3, which is favorable for improving both in‐plane and through‐plane thermal conductivity of subsequent moldings. Rheological analysis showed that the formation of intact thermal conductive pathways is crucial to the overall enhancement of thermal conductivity. Both in‐plane and through‐plane thermal conductivity of PC/BN(20 wt%)/Al2O3(40 wt%) composites reached as high as 1.52 and 1.09 W mK−1, which are 485% and 474% higher than that of pure PC counterparts, respectively. Furthermore, the prepared samples demonstrated excellent electrical insulation and dielectric properties which show potential application in electronic and automotive industries.

Dissolution of cathode–electrolyte interphase deposited on LiNi0.5Mn1.5O4 for lithium-ion batteries

Adopting high-voltage positive electrodes is essential for realizing advanced lithium-ion batteries with high energy and power density. However, the operating potentials of electrodes are beyond the electrochemical stability window of commercial electrolytes, leading to a low coulombic efficiency and poor cycle life. Although the decomposition products of an electrolyte form a cathode–electrolyte interphase (CEI), which helps passivate the electrode surface and suppress further decomposition of the electrolyte in subsequent cycles, the CEI is associated with passivation failure, the mechanisms of which have rarely been investigated. This work demonstrates the local dissolution of CEI and the detrimental effects of dissolution on the electrochemical performance of a high-voltage spinel electrode. The corrosive acidic species, namely HF, is generated during electrolyte oxidation and damages the CEI by leaching inorganic components such as LiF and LixPOyFz. However, in the presence of Al2O3, which is an HF scavenger, the CEI is maintained relatively stable, and the coulombic efficiency is improved significantly. The results highlight the HF effect on the partial dissolution of the CEI and the additional role of Al2O3 in assisting CEI deposition.

Experimental Study on Influence of Al2O3, CaO and SiO2 on Preparation of Zinc Ferrite

Gossan ore of sulfide zinc deposit contains abundant zinc, iron, and other metal elements, which is a significant resource with complex components and can be utilized. In this study, a new technology of preparing zinc ferrite from zinc sulfide deposit gossan was proposed. The effects of Al2O3, CaO, and SiO2 in gossan on the formation of zinc ferrite were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and specific surface area and pore size analysis (BET). The results show that the presence of Al2O3 and CaO could hinder the formation of zinc ferrite, while silica had no effect on the formation of zinc ferrite. Under the conditions of the molar ratio of ZnO and Fe2O3 to Al2O3, CaO, and SiO2 of 1:1:1, an activation time of 60 min, and a roasting temperature of 750 °C for 120 min, the products, which had good crystallinity, smooth particle surface, and uniform particle size could be obtained. In addition, compared to the roasted products with Al2O3 and CaO, the specific surface area, pore volume, and pore size of the products with SiO2 were the largest.

Experimental Study on the Partial Discharge Characteristics of Palm Oil and Coconut Oil Based Al2O3 Nanofluids in the Presence of Sodium Dodecyl Sulfate.

This experimental study aims to examine the partial discharge (PD) properties of palm oil and coconut oil (CO) based aluminum oxide (Al2O3) nanofluids with and without surfactants. The type of surfactant used in this study was sodium dodecyl sulfate (SDS). The volume concentrations range of Al2O3 dispersed in oil samples was varied from 0.001% to 0.05%. The ratio of surfactants to nanoparticles was set to 1:2. In total, two different types of refined, bleached and deodorized palm oil (RBDPO) and one type of CO were measured for PD. Mineral oil (MO) was also examined for comparison purpose. PDIV measurements for all samples were carried out based on rising voltage method whereby a needle-sphere electrode configuration with a gap distance of 50 mm was chosen in this study. Al2O3 improves the PDIVs of RBDPO, CO and MO whereby the highest improvements of PDIVs are 34%, 39.3% and 27%. The PD amplitude and repetition rate of RBDPO improve by 38% and 81% while for CO, it can increase up to 65% and 80% respectively. The improvement of PD amplitude and repetition rate for MO are 18% and 95%, regardless with and without SDS. Without SDS, the presence of Al2O3 could cause 26%, 75% and 65% reductions of the average emission of light signals for RBDPOA, RBDPOB and CO with the improvement of PD characteristics but both events do not correlate at the same volume concentration of Al2O3. On the other hand, the average emission of light signal levels of the oils increases with the introduction of SDS. The emission of light signal in MO does not correlate with the PD characteristics improvement either with or without SDS.

Assessment of the chemical degradation of PFPE lubricants and greases for space applications: implications for long-term on-ground storage

Liquid lubricants and greases used in space applications are generally susceptible to degradation or aging. Depending on the specific material combination and storage conditions, aging effects are also relevant for long-term storage (LTS). An overview on both physical and chemical aging processes for liquid lubricants and greases is given and processes which are seen as relevant for LTS and may impact the long-term performance of these materials are identified. Individual degradation processes as well as causes and potential risks are discussed, providing complementary data for two liquid perfluoropolyether (PFPE) lubricants (Fomblin Z25 and Brayco 815Z) and a PFPE grease (MAPLUB PF 100-b), focussing on thermo-oxidative and catalytic degradation. For these lubricants, monitoring of degradation effects is done indirectly by their mass loss at different temperatures and in the presence of a catalyst over a total duration of 1000 h. An increased mass loss during accelerated thermo-oxidative aging at temperatures above 200 °C is observed, with overlapping effects of thickener degradation for the investigated grease. Noticeable catalytic degradation effects are further seen for accelerated thermo-oxidative aging in the presence of Al2O3 above 200 °C.

A critical review on the utilization of SAC and eggshell in the development of aluminium based composite material

Spent alumina catalyst (SAC) and Eggshell (ES) are the waste material produced from oil refinery industries and food industries respectively. These wastes generate lots of soil pollution along the industrial areas. However, presence of Al2O3 in SAC and CaCO3 in ES showed these wastes as good partial replacement of ceramic particles as reinforcement with the aluminium alloy. In the present study, probability of SAC and ES as reinforcement with the aluminium alloy has been discussed. Exhaust literature review showed that SAC and ES can be utilized in the development of aluminium based composite material.

Modification of the junction parameters via Al doping in Ag/CdS:Al thin-film Schottky diodes for microwave sensors

In this article, it is investigated the effect of Al doping in the junction parameters of Ag/CdS:Al thin-film Schottky diodes and their electrical response to microwave irradiation. Nanocrystalline CdS:Al thin-films with thicknesses between 109 and 173 nm were prepared by chemical bath deposition and, subsequently, Ag thin-films with an average thickness of 102 nm were grown on the CdS:Al using dc sputtering. The structural, chemical, morphological and optical properties of CdS:Al and Ag films were characterized by x-ray diffraction (XRD), scanning electron microscope, atomic force microscope, energy-dispersive x-ray spectroscopy and UV-Vis spectrophotometer, respectively. Current-voltage (I − V) characteristics of Ag/CdS:Al diodes, with different Al content, were obtained at room temperature in dark conditions. XRD studies shows that CdS:Al and Ag thin-films have an hexagonal and cubic structure, respectively. Crystallite sizes decreases with Al content for CdS:Al films and were found to be in the 15–40 nm range. A decrease in the intensity of the XRD main peak of CdS:Al films is observed, caused by the inclusion of amorphous Al2O3 on the CdS film. It was found that band gap of CdS:Al films increases with increasing Al content, from 2.28 eV to 2.40 eV. Based on the I − V characteristics of the diodes, their barrier height ϕ 0, ideality factor n, and series resistance R s were calculated, and it was found that these values are modified by increasing Al content in CdS films, in the ranges: ϕ 0: 0.7037–0.8426 eV; n: 3.485–4.213; R s : 0.54–9.86 MΩ. Besides, it was stated that Al doping changes the average surface roughness and the energies of the charge neutrality levels of CdS:Al films. The effects of physical properties of the films on the junction parameters of the diodes were also discussed. Finally, I − V characteristics of the Ag/CdS:Al diodes were studied under X-band microwave irradiation at room temperature in dark conditions. For a specific Al doping value, the current density across the diode during irradiation was found to be lower (0.87–11.6 mA cm−2) than unirradiated diode (1.14–15.6 mA cm−2), when the bias voltage was higher than certain value (3 V), due to an increasing temperature of the diode and the presence of Al2O3 on the CdS:Al film. This last result could be useful in a potential X-band thin-film microwave sensor.

Experimental Study of the Individual Effects of Al2O3, CaO and MgO on Gas/Slag/Matte/Spinel Equilibria in Cu-Fe-O-S-Si-Al-Ca-Mg System at 1473 K (1200 °C) and p(SO2) = 0.25 atm

The individual effects of Al2O3, CaO and MgO on gas/slag/matte/spinel equilibria in the Cu-Fe-O-S-Si-(Al, Ca, Mg) system at 1473 K (1200 °C) and p(SO2) = 0.25 atm. have been experimentally measured for a range of oxygen partial pressures and matte compositions. The experimental methodology has included the high temperature equilibration of individual samples on a spinel primary phase substrate under controlled gas atmospheres (CO/CO2/SO2/Ar), followed by rapid quenching of the equilibrium condensed phases and direct measurement of the phase compositions using electron probe x-ray microanalysis. The experimental results show that the presence of Al2O3, CaO and MgO reduce the iron, sulphur and copper concentrations in the slag phase. Present study is undertaken as part of an integrated approach involving thermodynamic modelling and experimental measurements. The experimental data are compared with predictions obtained using the current thermodynamic database for the Cu-Fe-O-S-Si-(Al, Ca, Mg) system in order to further improve thermodynamic parameters.

Investigations for Wear Characteristics of Aluminium-Based Metal Matrix Composite Prepared by Hybrid Reinforcement

In this study, an attempt has been made to investigate the wear characteristics of aluminium (Al) 6063 alloy reinforced with Al2O3/SiC/Al2O3 + SiC particles of double particle size (DPS) and triple particle size (TPS). The hybrid Al-metal matrix composites (MMC’s) were prepared by using a synergistic combination of fused deposition modeling and V-process assisted stir casting and wear performance was examined on pin-on disc tester. The outcome of this study reveals that DPS-based Al-MMC’s with hybrid reinforcement of Al2O3 and SiC exhibit better wear characteristic. In this case study, overall 6% improvement in wear resistance was observed at proposed parametric settings. The results have been supported by photomicrographs, which confirmed the presence of Al2O3 and SiC contributing towards the improved wear property of the hybrid Al-MMC’s.

Experimental investigation of rheological properties and formation damage of water-based drilling fluids in the presence of Al2O3, Fe3O4, and TiO2 nanoparticles

The successful drilling of the oil and gas wells almost relies upon the drilling fluid properties. Maintaining wellbore stability, transportation, and releasing cuttings at the surface, and controlling formation pressure are the essential functions of the drilling fluid. Improving the rheological properties of the drilling fluid results in an increase in transport power and also provides better stability. One of the new methods to improve different properties of the drilling mud is the application of nanoparticles. Nanoparticles induce favorable effects on the rheological properties of the fluid. Improvement of mud properties yields in better cleaning of the well, the stability of the wellbore, higher drilling bit efficiency, and, consequently, a lower cost in the long run. Therefore, the present study investigates the effect of adding three different nanoparticles including aluminum oxide, iron oxide, and titanium oxide to the drilling fluid in several experiments by measuring rheological properties (plastic viscosity, yield point, filtration rate, gel strength) and also formation damage and permeability reduction. The number of experiments was determined by the experiment design method. The results of the experiments implied that in nanofluids with the weight of 70 pcf, rheological properties were relatively improved in most of the nanofluids samples concentrations. Samples containing iron oxide exhibited a decreasing filtration rate compare to base drilling fluid that indicates increasing stability in the fluid environment. The gel strength (GS) of titanium oxide and aluminum oxide samples has increased appropriately, which shows improvement in attractive forces in the fluid. For the case of the 80 pcf nanofluid, iron oxide indicates appropriate rheological properties and decreasing of filtration rate that all of them represent nanoparticle caused an increasing and improving the stability of fluid. But titanium oxide and aluminum oxide couldn't show significant effects. This phenomenon can be described by the lack of a uniform and thorough mixing of nanoparticles in the drilling fluid under field conditions. Besides, results obtained from the formation damage test equipment demonstrated the 54% reduction in initial permeability of the iron oxide nanoparticle that is the lowest damage between another nanofluid.

Investigating the effect of nanofluids of aluminum oxide and titanium dioxide on the heat transfer of the engine cooling coil by considering the boiling phenomenon

AbstractAutomotive industries are constantly seeking to produce more powerful and efficient engines. One of the factors affecting engine efficiency is the engine's temperature. Several research studies have been done to control and reduce engine temperature. The generated heat due to combustion of fuel in the engine should be cooled down to avoid engine heat up. In the present study, the cooling circuit of a real‐scale internal combustion engine is simulated using GT‐suite software along with a proposed model. Also, in this study, a model for simulating boiling and the effect of employing nanofluids as a coolant is presented. Initially, the performance of the proposed model is examined in a channel. The results show that the proposed model increases accuracy by about 20% compared with the default GT‐suit model, which ignores boiling. The simulation results show that the presence of Al2O3 and TiO2 nanofluids up to 2 vol% reduces the engine wall temperature by 7% and 6.7%, respectively.

Biphenyl liquid crystal epoxy containing flexible chain: Synthesis and thermal properties

AbstractA biphenyl type liquid crystal epoxy (LCE) monomer 4,4′‐di(2,3‐epoxyhexyloxy)biphenyl (LCBP4) containing flexible chain was synthesized and the curing behavior was investigated using 4,4′‐diaminodiphenylmethane (DDM) as the curing agent. The effect of curing condition on the formation of the liquid crystalline phase was examined. The cured samples show good mechanical properties and thermal stabilities. Moreover, the relationship between thermal conductivity and structure of liquid crystalline domain was also discussed. The samples show high thermal conductivity up to 0.28–0.31 W/(m*K), which is 1.5 times as high as that of conventional epoxy systems. In addition, thermal conductive filler, Al2O3, was introduced into LCBP4/DDM to obtain higher thermal conductive composites. When the content of Al2O3 was 80 wt%, the thermal conductivity of the composite reached to 1.86 W/(m*K), while that of diglycidyl ether of bisphenol A (Bis‐A) epoxy resin/DDM/Al2O3 was 1.15 W/(m*K). Compared with Bis‐A epoxy resin, the formation of liquid crystal domains in the cured LCE resin enhanced the thermal conductivity synergistically with the presence of Al2O3. Furthermore, the introduction of Al2O3 also slightly increased the thermal stabilities of the cured LCE.

Study on Ni composite coating on Al6061 substrate material with different nano particle reinforcement by electrodeposition process

The Ni composite coating has found wide industrial applications due to their anti-wear and better functional properties. The coatings generated by the electrodeposition process are popular for its economical and flexibility in its operating conditions. The incorporation of hard micro and submicron particles in the conventional coating is providing a new window for the researchers. At the same time the use of Al6061 material in automobile industries is phenomenal for its low weight high strength ratio. In the present work, the Ni coatings with different nano particles at different particle concentration are studied. The microhardness and wear properties are evaluated for different combinations of the composite coating. Further work is carried out in order to optimize the wear parameters in respect to study the influence of normal load, sliding speed, and sliding distance on the composite coating. The lower wear rate and higher microhardness is observed for the composite coating of Ni-Al2O3 compared to rest of Ni-xx coating. The presence of Al2O3,TiO2 particles restrict movement of dislocation though the weaker ZrO2 particles undergo plastic deformation with deep grooves. The debris formed between the pin sample and disc acts as the third body for abrasive nature of wear which accelerated the wear with higher load.

Synthesis and Characterization of Biodiesel from Khaya senegalensis Seed Oil using Heterogeneous Catalyst

Biodiesel was produced by transesterifying Khaya senegalensis oil with methanol in the presence of Al2O3 as catalyst. Molar ratio of 15:1 (methanol to oil) was followed to shift the reaction to product side for more yield of fatty acid methyl esters (FAME) and the use of a heterogeneous catalyst enabled the reaction to proceed faster. The oil and biodiesel were characterized following ASTM standards. The free fatty acid, acid value, viscosity, specific gravity, moisture content, saponification value, pour point, cloud point were examined in this research and the result obtained show that Khaya senegalensis Seed Oil is a good for biodiesel production. The biodiesel obtained was separated from glycerol, washed with distilled water and dried. Samples of oil and biodiesel were scan within mid-infrared region of 4000 cm-1 – 400 cm-1 with fourier transform infrared spectrometer by agilent technologies. The spectra obtained were interpreted and analyzed with the aid of structure correlation chart. The results revealed that the biodiesel contained fatty acid methyl esters (FAME). The FTIR spectrum for the biodiesel revealed the functional groups with characteristics bands, C=O, -(CH2)n-, C-O, C=C and C-H in the spectrum.

Optical study of Y3-xGdxAl5O12:Ce crystals grown from the melt

Y3-xGdxAl5O12:Ce (x = 0.6, 1.2, 1.8 in the melt) single crystals were grown from the melt by the Czochralski technique. XRD results shown that crystalline samples contain main garnet Y3-xGdxAl5O12 and additional Al2O3 and GdAlO3 phases. The maximal content of Gd3+ in the main garnet phase was determined at about of 40 at%. The presence of Al2O3 and GdAlO3 phases is explained by the thermal decomposition of Gd3Al5O12. The red-shift of Ce3+ emission with increasing of Gd3+ concentration in Y3-xGdxAl5O12:Ce was found. The latter is in a good agreement with data presented for Y3-xGdxAl5O12:Ce ceramics and powder phosphors.An additional 330–360 nm double-peaked emission observed in Y3-xGdxAl5O12:Ce crystals has been assigned to the 5d→4f radiative transitions of Ce3+ ions in GdAlO3 perovskite phase.In the view of potential application for white light-emitting diodes (WLEDs) light conversion characteristics tests of the Y3-xGdxAl5O12:Ce crystals were performed. The best parameters were obtained for Y1.2Gd1.8Al5O12:Ce sample.

Effect of Al2O3 reinforcement and precipitates on corrosion behaviour of 2618 and 6061 aluminium MMCs

ABSTRACTThe corrosion resistance features of two different Metal Matrix Composites based on 6061 and 2618 aluminium alloys reinforced by 20% Al2O3 particles by stir casting process, were studied in 3.5% NaCl and compared. The composites and their respective base alloys were characterised in terms of microstructure by optical and scanning electron microscopy and in terms of corrosion resistance by polarisation curves and electrochemical impedance. Results show how the presence of Al2O3 has different effects depending on matrix composition. In 6061 MMC, Al2O3 promotes the formation of Mg2Si which has a cathodic behaviour altering the pitting susceptibility of the composite. In 2618 MMC, the high content of Cu induces a strong uniform attack. The subsequent increase in the Open Circuit Potential caused a pitting attack.

Dry Sliding Wear Behavior of Al0.4FeCrNiCox(x = 0, 0.25, 0.5, 1.0 mol) High-Entropy Alloys

This study aims to investigate the dry sliding wear behavior of Al0.4FeCrNiCox(x = 0, 0.25, 0.5, 1.0 mol) high-entropy alloys (HEAs) at room temperature by varying sliding speed and normal load. X-ray diffraction studies indicate that the BCC phase decreases and completely disappears as cobalt content increases from x = 0–1.0 mol. Correspondingly, the hardness of the proposed alloys decreases from 377.7 to 199.5 HV with the addition of cobalt content from x = 0–1.0 mol. The wear analysis indicates that the highest specific wear rate occurs in the case of Al0.4FeCrNiCox=1 HEA with varying sliding velocity and normal load, respectively. The worn surface was analyzed by using scanning electron microscopy with attached energy-dispersive X-ray spectroscopy, 3D profiling, and X-ray photoelectron spectroscopy (XPS) in order to understand the wear mechanism and oxides formed during the wear process. Results indicated that the wear occurred due to adhesion along with delamination, plastic flow, and oxidative wear. XPS results indicate that the presence of Al2O3, Fe2O3, Cr2O3, and Co3O4 oxides formed on the worn surface.

Investigation of active species in methanation reaction over cerium based loading

A series of cerium oxide based catalyst has been studied by various cerium loadings that calcined at 1000oC using wet impregnation method. The potential Ru/Mn/Ce (5:35:60) /Al2O3 catalyst calcined at 1000oC was characterized using XRD, XPS, and BET analyses. As could be observed from the XRD analysis, at Ce ratio of 55% and 65%, both revealed the presence of RuO2 with tetragonal phase and intense, sharper peaks indicating to high crystallinity and in line with lower surface area, 50.95 m2/g in BET analysis. Meanwhile, CeO2 (cubic phase) and MnO2 (tetragonal phase) were also observed for 55%, 60%, and 65%, respectively. However, the presence of Al2O3 with rhombohedral phase at 55% and 65% was revealed as an inhibitor which decreased the CO2 conversion. The presence of active species on Ru/Mn/Ce (5:35:60) /Al2O3 catalyst has been confirmed using XPS analysis with the deconvolation peaks belonged to Ce4+ with the formation of CeO2 compound and Mn4+ for MnO2. The product formed in catalytic methanation was proposed to be H2O and CH3OH from GC and HPLC analysis.

Seleno‐Michael Reaction of Stable Functionalised Alkyl Selenols: A Versatile Tool for the Synthesis of Acyclic and Cyclic Unsymmetrical Alkyl and Vinyl Selenides

AbstractSeleno‐Michael additions of stable functionalised primary alkyl selenols to activated alkenes and alkynes are described. In the presence of Al2O3, β‐hydroxy‐, β‐amino‐, and β‐mercapto selenols react smoothly with electron‐poor alkenes and alkynes to afford the corresponding unsymmetrical functionalised dialkyl‐ and alkyl−vinyl‐selenides in good yield. The very mild conditions allow a broad range of selenols and Michael acceptors to be converted into the corresponding synthetically valuable seleno‐Michael adducts, demonstrating high selectivity and excellent functional group tolerance. Hydroxy‐ and mercapto‐substituted vinyl selenides were efficiently employed for the synthesis of functionalised 1,3‐oxaselenolanes, 1,3‐thiaselenolanes, and 1,4‐thiaselenanes through intramolecular oxa‐ and thia‐Michael additions. Furthermore, a NaH‐promoted lactonization enables the synthesis of variously substituted 2‐oxo‐1,4‐oxaselenanes from hydroxy−vinyl‐selenides. Evaluation of thiol peroxidase‐like properties of novel functionalised organoselenides demonstrated that they possess a remarkable catalytic antioxidant activity.magnified image