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The valorization of CO2 as a biofuel, transforming it through methanation as part of the power-to-gas (P2G) process, will allow the reduction of the net emissions of this gas to the atmosphere. Catalysts with 13 wt.% of nickel (Ni) loading incorporated into alumina and graphene derivatives were used, and the effect of the support on the activity was examined at temperatures between 498 and 773 K and 10 bar of pressure. Among the graphene-based catalysts (13Ni/AGO, 13Ni/BGO, 13Ni/rGO, 13Ni-Ol/GO, 13Ni/Ol-GO, and 13Ni/Ol-GO Met), the highest methane yield was found for 13Ni/rGO (78% at 810 K), being the only system comparable to the catalyst supported on alumina 13Ni/Al2O3 (89.5% at 745 K). The incorporation of 14 wt.% of lanthanum (La) into the most promising supports, rGO and alumina, led to nickel-support interactions that enhanced the catalytic activity of 13Ni/Al2O3 (89.5% at lower temperature, 727 K) but was not effective for 13Ni/rGO. The resistance against deactivation by H2S poisoning was also studied for these catalysts, and a fast deactivation was observed. In addition, activity recovery was impossible despite the regeneration treatment carried out over catalysts. The resistance against deactivation by H2S poisoning was also studied for these catalysts, observing that both suffered a rapid/immediate deactivation and which in addition/unfortunately was impossible to solve despite the regeneration treatment carried out over catalysts. [ABSTRACT FROM AUTHOR]

A series of highly reusable heterogeneous catalysts (10-40 wt.% SiMo12/Al2O3), consisting of molybdosilicic acid (SiMo12) impregnated on alumina (Al2O3) support was synthesized by the wetness impregnation method. The physicochemical properties of synthesized catalyst were studied using FT-IR, XRD, SEM, EDX, TEM, BET and TG-DTA analysis techniques. The study proves that the synthesized SiMo12 catalyst efficiently incorporated on the surface of Al2O3. The catalytic activity of prepared catalyst was investigated for the synthesis of pyranopyrazole(6-amino-4-phenyl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5carbonitrile) via cyclocondensation reaction of aldehydes, malononitrile, hydrazine hydrate and ethyl-acetoacetate under solvent-free conditions. Among different catalysts, 30% SiMo12 supported on to Al2O3 showed the highest catalytic activity. High yield, shorter reaction time, operational simplicity, solvent-free conditions and reusability of the catalyst are the distinct features of this protocol. An economic, sustainable, and straightforward environmentally friendly synthesis of pyranopyrazole derivatives in presence of catalytic amount of SiMo12/Al2O3 under solvent-free condition. Excellent yields, and environmentally sustainability are the main advantages of the present method. [ABSTRACT FROM AUTHOR]

This review article presents the current status of various micromachining techniques used to create microfeatures in alumina ceramic. Alumina has emerged as an advanced substrate in various radio-frequency communication and automotive packaging applications due to its superior electrical resistivity, lower dielectric loss, higher wear resistance, and dimensional stability at high temperatures. However, creating complex-shaped microfeatures in alumina is challenging due to its hard and brittle nature. Traditional contact-based methods fail to create microsized shapes in alumina; thus, the researchers are exploring novel machining methods, like abrasive, thermal, chemical, and hybrid micromachining processes. This review article comprehensively summarizes various micromachining methods used to create microfeatures in alumina ceramics. The mechanism, unique features, pros/cons, novelty, and applications of ultrasonic machining, laser ablation, electrochemical discharge machining, abrasive-jet machining, etc., are presented. The associated processing challenges in various alumina micromachining and the potential remedies to produce high-quality alumina microparts for microelectronics applications are discussed. [ABSTRACT FROM AUTHOR]

Refractory and heat-resistant materials with a coarse-grained and large-porous structure were obtained using silica glass suspensions with mullite, spinel, alumina, and quartz fillers. The influence of sintering temperature on the phase composition, structure, porosity, and density of the materials were studied. Although the strength of the ceramics was found to increase in the temperature range 1300 – 1400°C, it decreases at 1500 – 1600°C due to the crystallization of the silica glass. Composites in the silica glass-alumina system were found to have the most stable strength characteristics. [ABSTRACT FROM AUTHOR]

Owing to the native character of the coefficient of thermal expansion (CTE) mismatch between Al2O3 and 304 stainless steel, obtaining high strength for Al2O3/304 stainless steel joints remains challenging. In this study, the residual stress of an Al2O3/304 stainless steel brazed joint was relieved using the Ag‐Cu‐Ti + boron nitride (BN) composite filler. The results indicated that the elements between the filler and base metals on both sides were mutually diffused. Moreover, reaction layers formed at the interface, connecting the Al2O3 ceramic and 304 stainless steel. The microstructure of the joint was as follows: Al2O3/Cu3Ti3O + TiCu/Ag (s, s) + Cu (s, s) + TiN + TiB2 + TiCu/Cu0.8Fe0.2Ti/TiFe2/Fe‐Cr/304 stainless steel. When the.1 wt% BN was added, the average strength of the joint reached 151 ± 10 MPa, 15% higher than the average strength of the joint only using Ag‐Cu‐Ti filler (131 ± 9 MPa). The improvement in the shear strength and reduction in the residual stress was attributed to the formation of TiN and TiB2, reducing the CTE difference and refining the microstructure. [ABSTRACT FROM AUTHOR]

Sintering phenomena, densification, and grain growth are crucial for proper control of the microstructure for good mechanical strength. Here, materials and processing parameters, the addition of La2O3, and two‐step sintering (TSS) were combined to lead to higher strength in the porous alumina prepared by freeze‐casting. Based on grain growth and densification behaviors with the La2O3 doping, a beneficial thermal profile was designed for the TSS. As a result, higher relative density levels and smaller grain size were obtained compared with the results with conventional sintering (CS): 38.56% and 0.82 µm at 1500°C by CS; 40.78% and 1.78 µm at 1600°C by CS; 41.43% and 0.87 µm by TSS. The microstructural benefits provided ∼1.4 times higher compressive strength (5.46 MPa) from TSS than from the CS sample (3.92 MPa), highlighting the synergetic effect of La2O3 doping and the TSS strategy. [ABSTRACT FROM AUTHOR]

Corundum and transition alumina powders are commonly produced through the Bayer process—that is, by digestion of bauxite in a sodium hydroxide solution, followed by gibbsite precipitation, which contains significant amounts of Na+ ions. During the de‐hydroxylation of gibbsite, Na+ is associated with retardation of the structural phase transformations between transition alumina and corundum (α‐Al2O3) phases, although the exact role of Na is unclear. The influence of Na+ ions on the phase transformation of γ‐Al2O3 to α‐alumina was investigated by varying the concentration of NaOH in aqueous γ‐Al2O3 suspensions. The phase transformation behavior of γ‐Al2O3 was monitored through thermal analysis, X‐ray diffraction, scanning electron microscope, X‐ray photoelectron spectrometer (XPS), and transmission electron microscope. As the Na concentration in γ‐alumina suspensions increased, the amount of α‐Al2O3 decreased in samples that were heat treated at 1200°C for 2 h. XPS analysis indicated that washing transition alumina powders with NH4OH solutions had decreased the surface concentration of Na+ and facilitated the phase transformation to α‐Al2O3. [ABSTRACT FROM AUTHOR]

Symmetrical as well as asymmetrical statistical models play a prominent role in describing and predicting the real-world phenomena of nature. Among other fields, these models are very useful for modeling data in the sector of civil engineering. Due to the applicability of the statistical models in civil engineering and other related sectors, this paper offers a statistical methodology to improve the distributional flexibility of traditional models. The suggested method/approach is called the extended-X family of distributions. The proposed method has the ability to generate symmetrical and asymmetrical probability distributions. Based on the extended-X family approach, an updated version of the Weibull model, namely, the extended Weibull model, is studied. The proposed model is very flexible and has the ability to capture the symmetrical and asymmetrical shapes of its density function. For the extended-X method, the estimation of parameters, a simulation study, and some mathematical properties are derived. Finally, the practical illustration/usefulness of the suggested model is shown by analyzing two data sets taken from the field of engineering. Both data sets represent the fracture toughness of alumina (Al2O3). [ABSTRACT FROM AUTHOR]

This article presents the findings of a study on oxide reduction utilizing a novel reducing plasma torch, employing greenhouse gases such as CO2 and CH4 as plasma gases. The primary aim of this investigation is to establish the viability of this approach. The innovative plasma torch was employed to reduce various oxides, including aluminum oxide, iron oxide, and titanium oxide, as well as a mixed oxide composition, employing a CO2/CH4 molar ratio of 1:1 within a spouted bed reactor. Following plasma treatment, X-ray diffraction (XRD) analysis was conducted to examine the metallic phases, notably titanium, iron, and aluminum. SEM–EDS observations were carried out to assess microstructural changes and identify elemental compositions pre- and post-plasma treatment. The results demonstrate that within the conical section of the reactor, titanium oxide experiences partial reduction, resulting in limited titanium production, while aluminum oxide and iron oxides (magnetite and hematite) undergo reduction to yield aluminum and iron, respectively. Thermodynamic calculations, performed using Factsage software version 8.3, were utilized to predict stable-phase formations following plasma treatment for each material. [ABSTRACT FROM AUTHOR]

The main groups of catalytic materials used in the conversion of methanol to dimethyl ether (the MTD process) were presented with respect to their advantages, disadvantages, and the methods of their modifications, resulting in catalysts with improved activity, selectivity, and stability. In particular, the effects of strength, surface concentration, and the type of acid sites, the porous structure and morphology of the catalytic materials, the role of catalyst activators, and others, were considered. The prosed mechanisms of the MTD process over various types of catalysts are presented. Moreover, the advantages of membrane reactors for the MTD process are presented and analysed. The perspectives in the development of effective catalysts for the dehydration of methanol to dimethyl ether are presented and discussed. [ABSTRACT FROM AUTHOR]

Alumina inorganic molecularly imprinted polymer (MIP) modified multi-walled carbon nanotubes (MWCNTs) on a glassy carbon electrode (MWCNTs-Al2O3-MIP/GCE) was firstly designed and fabricated by one-step electro deposition technique for the detection of uric acid (UA) in sweat. The UA templates were embedded within the inorganic MIP by co-deposition with Al2O3. Through the evaluation of morphology and structure by Field Emission Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM), it was verified that the specific recognition sites can be fabricated in the electrodeposited Al2O3 molecular imprinted layer. Due to the high selectivity of molecular imprinting holes, the MWCNTs-Al2O3-MIP/GCE electrode demonstrated an impressive imprinting factor of approximately 2.338 compared to the non-molecularly imprinted glassy carbon electrode (MWCNTs-Al2O3-NIP/GCE) toward uric acid detection. Moreover, it exhibited a remarkable limit of detection (LOD) of 50 nM for UA with wide detection range from 50 nM to 600 μM. The MWCNTs-Al2O3-MIP/GCE electrode also showed strong interference resistance against common substances found in sweat. These results highlight the excellent interference resistance and selectivity of MWCNTs-Al2O3-MIP/GCE sensor, positioning it as a novel sensing platform for non-invasive uric acid detection in human sweat. [ABSTRACT FROM AUTHOR]

The aerosol deposition process, involving the impact of solid particles on a substrate at high velocities, is an attractive method for the manufacture of ceramic coatings at room temperature. For process optimisation, it is crucial to select a powder having the appropriate physical characteristics and evaluate the particle flow behaviour during the deposition process. In this study, a powder modification process using high-energy milling and spray drying to improve the applicability of precursor powders was developed and evaluated both numerically and experimentally. A modified aerosol deposition system incorporating a brush-type aerosol generator was employed to maintain the continuity of the aerosol supply and improve the stability of the particle concentration. The deposition efficiency was nearly tripled when using spray-dried granules (0.68%) instead of the as-received powders (0.26%). From tribological measurements, the strongest interfacial bonding was also confirmed for coatings prepared with alumina granules. [ABSTRACT FROM AUTHOR]

Binary or multi-component phase mixtures are of particular technical importance. Despite the wide field of application of Al 2 O 3 and ZrO 2 composites, the literature reveals contradictions about the liquidus region. Containerless processing avoids typical problems of conventional techniques like melt contamination or lack of suitable container materials. Composition ranging from 0–80 mol% ZrO 2 were melted and solidified in an aero acoustic levitator. A high-speed camera recorded the crystallization, allowing a direct correlation with the observed microstructures. Due to homogeneous nucleation, all samples exhibited significant undercooling before crystallization. The nucleation temperature of the different compositions roughly followed the slope of the liquidus line. Undercooling, solidification kinetics, and local reheating played a considerable role in microstructure formation. A lamellae eutectic microstructure was created over a large compositional range from 36–48 mol% ZrO 2. On the hypoeutectic side, the effect was attributed to solidification within the coupled zone. However, hypereutectic samples also exhibit a zirconia-rich eutectic as well. We assume impaired ZrO 2 nucleation or growth favors alumina precipitation from the melt. Aero acoustic levitation proved to be an excellent technique for studying complex high melting oxide systems, enabling a better understanding of their crystallization process. [ABSTRACT FROM AUTHOR]

Strontium zirconate (SrZrO 3) is a technical ceramic with potential for refractory applications due to its chemical stability at high temperatures, high melting temperature, and favourable thermal expansion coefficient. Practical use of SrZrO 3 is limited by poor mechanical strength relative to ceramics such as alumina (Al 2 O 3). Sintering of SrZrO 3 with a hydratable Al 2 O 3 binder is investigated as a method for improving mechanical performance. Density, phase composition, thermomechanical properties, and chemical stability in contact with alloys up to 1350 °C are considered. Results are compared with SrZrO 3 samples formed using a traditional polyvinyl alcohol (PVA) binder. SrZrO 3 reacts with alumina during sintering to form SrAl 2 O 4 and ZrO 2. Compared to the PVA binder, the alumina binder drastically reduced porosity in the ceramic, while increasing the indirect tensile strength and fracture toughness. No significant detriment to thermal expansion or chemical stability was found, offering potential for high-temperature applications particularly as a dense crucible material. [ABSTRACT FROM AUTHOR]

Herein, graphene/alumina (GR/Al 2 O 3) ceramic metacomposites with negative permittivity were prepared by hot press sintering to investigate the inherent connection between negative permittivity and external temperature. An electrical percolation phenomenon was observed in the composites with the increasing GR content. The permittivity changed from positive to negative, which was motivated from the formation of continuous three-dimensional GR networks in the composites. The negative permittivity was attributable to low-frequency plasma state of the freed electrons in the GR networks. In addition, the negative permittivity behavior was temperature-dependent in the composites with high GR contents. The higher external temperatures led to the larger absolute values of negative permittivity, and yet the negative permittivity varied very little by applying various temperature, compared to changing the additive amount of GR. As the external temperature elevated, the variation amplitude of negative permittivity enlarged in the composites with higher GR contents. [ABSTRACT FROM AUTHOR]

An alumina rich Al 2 O 3 –ZrO 2 –TiO 2 compound was used for the preparation of self-supporting parts via the rod flame spraying technology. The as-sprayed material was compared to self-supporting parts, fabricated from commercially available alumina rods. For both materials, the flexural strength, the fracture resistance, and the behaviour under subcritical loading was evaluated and compared, either before as well as after cold thermal shock. While the flexural strength and the subcritical damaging of both materials were basically affected through thermal shock in a similar manner, the Al 2 O 3 –ZrO 2 –TiO 2 compound showed an outstanding behaviour in terms of its fracture resistance, which was only barely reduced after thermal shock quenching. [ABSTRACT FROM AUTHOR]

This article explores the use of alumina as an activator for copper catalysts in the hydroboration of alkynes. Hydroboration of alkynes is important in the synthesis of vinylboronic acids and esters. The traditional method using dialkoxyboranes has limitations, so transition-metal-catalyzed hydroborations have gained popularity. Alumina simplifies the experimental procedure and allows for hydroboration in air and aqueous media. The article presents the results of different reaction conditions and demonstrates successful hydroboration of various substrates. It also discusses the use of alumina as a base surrogate in Cu-catalyzed hydroboration and provides technical information and procedures for synthesis and characterization of compounds. [Extracted from the article]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to prepare the well-dispersed modified chitosan–alumina (CA) with size less than 50 nm by the facile synthesis method to evaluate the adsorption of hydroquinone and arsenic (V) ions in the aqueous solutions. Derived gamma-alumina from boehmite was coated and modified by chitosan and sodium dodecyl sulfate (SDS) and salicylic acid, respectively. The characterization of nanocomposites was studied by XRD, FTIR, FESEM, EDX TEM and BET analysis. The chitosan and SDS phases were detected in the structure of the adsorbent as confirmed by XRD achievements. A quadratic polynomial model was developed to describe the effect of the operating parameters including pH, temperature and initial concentration on the adsorption capacity of the prepared sample while the experimental data were designed by a response surface method (RSM). The maximum adsorption capacity for the best adsorbent named CSAS3 was measured to be 86.95 and 95.24 mg/g for HQ and As (V) ions by employing linear Langmuir equation, respectively. The kinetic study indicated that the experimental data were in an appropriate matching with the linearized pseudo-quadratic kinetic equation (R2 = 0.999). The results showed the successful removal of hydroquinone and arsenic ions form the aqueous after 5 consecutive cycles. [ABSTRACT FROM AUTHOR]

This study explores the impact of non-stoichiometric aluminum oxide (AlxOy) coatings applied via thermal atomic layer deposition (ALD) on carbon fiber fabrics (CFFs), emphasizing volume per cycle, FESEM analyses, color transitions, and thermal stability enhancements. Using trimethylaluminum and water at 100 °C, AlxOy was deposited across a range of 1000 to 5000 ALD cycles, with film thicknesses extending up to 500 nm. This notable increase in the volume of material deposited per cycle was observed for the 3D CFFs, highlighting ALD's capability to coat complex structures effectively. FESEM analyses revealed the morphological evolution of CFF surfaces post-coating, showing a transition from individual grains to a dense, continuous layer as ALD cycles increased. This morphological transformation led to significant color shifts from green to red to blue, attributed to structural coloration effects arising from variations in film thickness and surface morphology. Thermogravimetric analyses (TGA and dTG) indicated that the AlxOy coatings enhanced the thermal stability of CFFs, with a postponement in degradation onset observed in samples subjected to more ALD cycles. In essence, this research highlights the nuanced relationship between ALD processing parameters and their collective influence on both the aesthetic and functional properties of CFFs. This study illustrates ALD's potential in customizing CFFs for applications requiring specific color and thermal resilience, balancing the discussion between the surface morphological changes and their implications for color and thermal behavior. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Yttrium-stabilized zirconia (YSZ) and alumina are the most commonly used dental esthetic crown materials. This study aimed to provide detailed information on the comparison between yttrium-stabilized zirconia (YSZ) and alumina, the two materials most often used for esthetic crowns in dentistry. Methodology: The ground-state energy of the materials was calculated using the Cambridge Serial Total Energy Package (CASTEP) code, which employs a first-principles method based on density functional theory (DFT). The electronic exchange–correlation energy was evaluated using the generalized gradient approximation (GGA) within the Perdew (Burke) Ernzerhof scheme. Results: Optimization of the geometries and investigation of the optical properties, dynamic stability, band structures, refractive indices, and mechanical properties of these materials contribute to a holistic understanding of these materials. Geometric optimization of YSZ provides important insights into its dynamic stability based on observations of its crystal structure and polyhedral geometry, which show stable configurations. Alumina exhibits a distinctive charge, kinetic, and potential (CKP) geometry, which contributes to its interesting structural framework and molecular-level stability. The optical properties of alumina were evaluated using pseudo-atomic computations, demonstrating its responsiveness to external stimuli. The refractive indices, reflectance, and dielectric functions indicate that the transmission of light by alumina depends on numerous factors that are essential for the optical performance of alumina as a material for esthetic crowns. The band structures of both the materials were explored, and the band gap of alumina was determined to be 5.853 eV. In addition, the band structure describes electronic transitions that influence the conductivity and optical properties of a material. The stability of alumina can be deduced from its bandgap, an essential property that determines its use as a dental material. Refractive indices are vital optical properties of esthetic crown materials. Therefore, the ability to understand their refractive-index graphs explains their transparency and color distortion through how the material responds to light..The regulated absorption characteristics exhibited by YSZ render it a highly attractive option for the development of esthetic crowns, as it guarantees minimal color distortion. Conclusion: The acceptability of materials for esthetic crowns is strongly determined by mechanical properties such as elastic stiffness constants, Young's modulus, and shear modulus. YSZ is a highly durable material for dental applications, owing to its superior mechanical strength. [ABSTRACT FROM AUTHOR]

The adsorption of ethanol and ammonia changes the basic properties of alumina, and new basic sites are created. Ethanol reacts with surface Al-OH groups, forming ethoxy group Al-O-C2H5. The substitution of Al-OH by Al-O-C2H5 increases the negative charge of neighbouring oxygen atoms, and they became sufficiently basic to react with adsorbed CO2 forming carbonate species CO32−. These carbonates were found to be monodentate and bidentate species. Preadsorption of ammonia also increases the basicity of alumina, but the mechanism is different than for ethanol adsorption. Adsorbed ammonia interacts with surface Lewis acid sites being three-coordinated aluminium atoms. This interaction is accompanied by an electron transfer from ammonia molecules to surface sites, and increases the basicity of the neighbouring oxygens, which can react with the absorbed CO2. The carbonate species formed are polydentate ones. [ABSTRACT FROM AUTHOR]

Novel fuels for internal combustion engines are being tested due to increased energy demand and the presence of pollutants. Alternative energies can be produced from biowaste, plants and their seeds, which have become a crucial source. IC engines powered by petroleum have a significant impact on the environment, resulting in various environmental issues. Hence, incorporating an alternative fuel into an engine may require modifications to achieve comparable performance to traditional fuels. The performance of mahua biodiesel and diesel blends, including alumina nano additive, was examined in a single-cylinder compression ignition engine. The performance of mahua biodiesel and its diesel blends, with the addition of alumina nanoparticles, was evaluated in a single-cylinder compression ignition engine. The engine was tested using different fuels. The performance and emissions of mahua biodiesel blend with concentrations of 20%, 40% and 100% were assessed under different load conditions. The performance of a biodiesel blend consisting of 20% mahua biodiesel and 80% diesel (B20) was favourable compared to other biodiesel blends, showing minimal tailpipe emissions. A blend of biodiesel, comprising 80% diesel and 20% mahua biodiesel, was prepared with the addition of nano alumina at concentrations of 25 and 50 ppm. The biodiesel blend, containing 50 ppm of alumina nanoparticles, exhibits improved thermal efficiency and reduced emissions due to better fuel atomization caused by the presence of nanoparticles. The Brake Thermal Efficiency (BTE) and Brake Specific Fuel Consumption (BSFC) of biodiesel blended with 50 ppm alumina nanoparticles increased by 2.85% and decreased by 14% respectively, compared to regular diesel fuel. The use of mahua biodiesel blended with regular biodiesel led to a significant reduction in HC and CO emissions by 20% and 14% respectively. Nano-blended mahua biodiesel proves to be a superior substitute energy source for unaltered compression ignition engines. [ABSTRACT FROM AUTHOR]

Iron oxide-modified 1Pd0.5Fe and 1Pd10Fe catalysts with a target content of 1 wt % Pd and 0.5 or 10 wt % Fe have been synthesized by the wet impregnation of Al2O3 with iron and palladium nitrates. The catalysts have been compared with each other and with a monometallic 1Pd catalyst in diclofenac (DCF) hydrodechlorination (HDC) in dilute aqueous solutions at 30°C in batch and flow reactors after high-temperature (320°C) and mild reduction (30°C), the latter being run in a batch or flow reactor. X-ray photoelectron spectroscopy (XPS) has revealed that, after reduction at 320°C, the catalysts contain mostly Pd0, Fe2+, and Fe3+. The Fe2+/Fe3+ ratio on the surface increases with a decrease in the iron content. The reduction of Pd2+ to Pd0 can occur even at 30°C; however, on the 1Pd0.5Fe surface, it is significantly less effective than that on 1Pd10Fe. According to XPS, temperature-programmed reduction, and diffuse reflectance infrared Fourier transform spectroscopy of adsorbed CO, modification with iron oxides leads to an increase in the palladium content on the surface compared with that on 1Pd, contributes to the formation of new Pd–O–Fe sites, and affects the reducibility of palladium. These effects enhance with an increase in the iron content. The iron-modified catalysts reduced at 320°C exhibit similar activity and stability in DCF conversion in flow and batch systems. The 1Pd10Fe catalyst, unlike 1Pd0.5Fe, is highly efficient and stable even after mild reduction at 30°C. Under flow conditions, it provides a DCF conversion comparable to that provided by 1Pd and a selectivity in the DCF HDC reaction that is higher than that provided by 1Pd, which is also active in hydrogenation. [ABSTRACT FROM AUTHOR]

Locally found Egyptian dolomite, commercial zirconia, and alumina were used to fabricate calcium zirconate-based refractory with improved thermal shock damage resistance. CaZrO3/MgO (CZM) and CaZrO3/MgAl2O4 (CZS) green compacts were obtained by mixing dolomite, commercial zirconia, and alumina with molar ratios of 1:1.23:0 and 1:1.23:0.59, respectively, and then ball milled for 1 h and uniaxially pressed at 150 MPa. The obtained green compacts were sintered at 1200, 1300, 1500, and 1650 °C for 2 h with a heating rate of 5 °C/min. The phase composition, microstructure, densification parameters, and thermal shock damage resistance of the prepared refractory were investigated. The results showed that CaZrO3 was present as the predominant phase and c-ZrO2 as a secondary phase due to the solubility of calcium and magnesium ions in the zirconia lattice structure. CZM1500 and CZS1500 showed a bulk density of 4.05 and 3.8 g/cm3 respectively. Thermal shock damage resistance of CZM samples was greatly improved with the in situ spinel synthesis where CZS1500 was able to withstand 16 cycles before fracturing compared to 10 cycles recorded for CZM1500. [ABSTRACT FROM AUTHOR]

Bauxite is the basic raw material of aluminium used to extract alumina in Bayer's process. With the huge demand and the rapid development of the global alumina industry, bauxite consumption is rising and has reached more than 160 million tonnes per year. With such a high demand for aluminium, it is becoming more difficult to meet the consumption due to the gradual global decline of high-grade bauxite resources. In the current market scenario, treating bauxites containing more than 5% reactive silica (SiO2) is generally considered uneconomic due to excessive soda consumption in Bayer's process. The present study is conducted to examine the influence of the wet beneficiation process in the pre-treatment of low-grade and high-grade bauxite ores and a comparative analysis of the results obtained regarding alumina recovery and silica reduction. For this study, High-Grade (HG) and Low-Grade (LG) bauxite ore samples were collected from different bauxite mines of the East Coast region and subjected to wet beneficiation. Comparative chemical analysis of the before and after beneficiation samples revealed the wet beneficiation process to be significantly effective in the pre-treatment of LG bauxite samples with an average increment of 10.84% in the alumina content and 18.38% average reduction in silica after wet beneficiation. [ABSTRACT FROM AUTHOR]

This contribution discusses the impact of sintering temperatures on dielectric properties of 3D-printed alumina (Al2O3) in the W-band, by evaluating high quality factor (-Q) resonators integrated in a 2D photonic crystal structure. By varying the sintering temperature of the lithography-based ceramic manufactured (LCM) samples, the microstructure of the material can be defined, which has a direct impact on the dielectric permittivity and material losses. Using a highly accurate photonic crystal structure, with a dimensional variation below 2% from print to print, an accurate extraction and evaluation of the dielectric material properties could be achieved. The relative permittivity of the alumina was tuned from 4.4 at 1250°C to 9.2 at 1650°C, whereas the observed change in dielectric losseswas moderate. Themaximum in observed dielectric loss for samples sintered at the lowest evaluated temperature, only yields an average value of 30 x 10-4. This demonstrates the versatility of the LCMtechnology for mm- and sub-mm-wave applications and its possibilities for material tuneability. [ABSTRACT FROM AUTHOR]

Alumina is one of the crucial and extensively utilized refractory components. As the refractory wear due to dissolution at elevated temperatures during operation is a major threat to refractory lifespan, quantifying dissolution is important for developing cost-effective and resource-efficient refractories. This study investigated the dissolution of alumina particles in two silicate and one calcium aluminate slags at 1 450, 1 500, and 1 550 °C using high-temperature confocal laser scanning microscopy (HT-CLSM). Dissolution was quantified in terms of diffusivity, with all influencing factors, including Stefan flow and bath movement, incorporated into the determination process. The trends observed in total dissolution time and diffusivity in three slags at three experimental temperatures could not be explained solely on the basis of slag basicity. Two parameters, considering the influencing factors, were introduced to explain these trends. Furthermore, the linear trend observed in Arrhenius plots of diffusivities supports the diffusivity results. Additionally, good agreement between the diffusivities of alumina in one silicate slag obtained via CLSM and rotating finger test investigations verified the reliability of the results. [ABSTRACT FROM AUTHOR]

SiO2-Al2O3 composite aerogel (SAA) has shown a wide range of application in aerospace, chemical metallurgy, furnace insulation and other fields due to the characteristics of low bulk density, high specific surface area, low thermal conductivity and high temperature resistance. Ambient pressure drying has the advantages of low preparation cost, easy industrial mass production and so on, so it has a good practical application prospect. In this work, the preparation methods of SAA were introduced, with emphasis on the research status of precursors, surface modifiers and fiber reinforcements in the preparation of SAA by ambient pressure drying. Finally, the development direction of SAA prepared by ambient pressure drying was prospected. [ABSTRACT FROM AUTHOR]

Ceramic‐based polymer composites are commonly utilized as thermal management materials due to their high thermal conductivity and electrical insulation properties. One efficient method to enhance the thermal conductivity of these composites is by constructing a three‐dimensional thermal conductive network within the polymer matrix. In this study, alumina was coated onto the surface of polyurethane (PU) foam, followed by high‐temperature removal of the PU foam and sintering of the alumina sheets to obtain a continuous alumina framework. Epoxy resin was then infiltrated into this alumina framework to fabricate highly thermally conductive EP/f‐Al2O3 composites. The EP/f‐Al2O3 composite achieved a thermal conductivity of 2.44 W m−1 K−1 when the filler content of 26.8 vol%, representing a 400% improvement compared to EP/Al2O3 composite with randomly dispersed fillers, and a remarkable 1180% enhancement compared to epoxy resin. Infrared thermal imaging also confirmed the excellent heat dissipation capability of the EP/f‐Al2O3 composites. Overall, this research presents an effective method for producing highly thermally conductive and electrically insulating composites that can be used in electronic thermal management applications. Highlights: Fabrication of porous Al2O3 frameworks/epoxy composites.Porous Al2O3 frameworks were fabricated by polyurethane foam template.The obtained EP/f‐Al2O3 composite exhibited excellent thermal conductivity. [ABSTRACT FROM AUTHOR]

Abstract Complex alumina parts were printed using vat photopolymerization (VPP), which is a stereolithography‐based additive manufacturing (AM) technique used to shape ceramic preforms, or green parts. The critical flaw size was determined using classical fracture mechanics techniques. The strength and fracture toughness were measured and compared to flaws detected in x‐ray computed tomography (XCT or CT) distributions as well as the fracture surfaces. The strength was lower compared traditionally made alumina, and that is due to layering effects, slurry defects, and printing defects. The critical flaw size from fracture mechanics was 206 µm. XCT has high enough resolution to detect the critical flaw size and much smaller features, where the average flaw size observed in CT scans was around 80–100 µm. The fracture surfaces indicate that flaws causing failure are larger than that of the critical flaw size (∼300 µm), but fracture surfaces do not show definitive features compared to traditionally made ceramics. Since XCT can observe flaws smaller than the critical flaw size, this method can be used as a screening technique.

The encapsulation of phase change materials (PCMs) into additive manufactured porous supports is attracting great interest for developing thermal energy storage (TES) materials with improved energy performance. Here, highly porous (86 %) self-supported 3D activated carbon/alumina supports are fabricated by direct ink writing (DIW) and, then, infiltrated with solar salt, a highly corrosive PCM with a melting temperature around 220 °C commonly employed in concentrated solar power plants. This novel, robust, chemically compatible, and lightweight infiltrated 3DTES exhibits good thermal energy storage efficiency (70 %) and thermal stability, high energy storage density (381 J g−1), and avoids the liquid leakage of the molten salt. Besides, the 3D activated carbon/alumina support promotes a better ability to absorb solar energy (79 %) and enhances the thermal conductivity of the solar salt (up to 64 %). These results validate the use of DIW for manufacturing innovative TES with an enhanced energy storage behaviour.

This in vitro study examines the electrochemical responses and surface degradation of alumina and feldspar dental ceramic materials in acidic environments using cyclic polarization and electrochemical impedance spectroscopy (EIS). Alumina and feldspar demonstrate balanced responses in both Fusayama Artificial Saliva and acidic solutions, indicating effective passivation. SEM/EDX analyses after 168-h immersion reveal significant elemental variations, suggesting complex surface phenomena and chemical reactions leading to oxide layer formation. Alumina exhibits increased Si, O, Al, Na, K, and C counts, while feldspar shows increased Si, O, Al, Na with reduced C and Ca levels, indicating complex reactions. Immersion induces notable elemental composition modifications, with alumina showing remarkable corrosion resistance and feldspar undergoing selective dissolution. This study provides insights into the electrochemical and surface degradation of these materials, emphasizing long-term stability and the need for continuous monitoring of protective layer dynamics in future research on corrosion-resistant dental biomaterials.

Coolant-facing alloys in a tokamak will face harsh environments due to the synergistic effect of flowing coolant, dynamic mechanical loading, ionising radiation, and tritium embrittlement. Reduced activation ferritic/martensitic (RAF/M) EUROFER-97 is the primary candidate as the structural alloy for the breeder blanket to be used in DEMO reactor. Under fusion-like conditions, coatings are required to improve both its corrosion properties and act as a tritium permeation barrier (TPB) layer. In this study, Al-base self-passivating coatings have been investigated as possible solution to provide protection against corrosion and act as TPB layer. The aim of this study was to assess the adhesion properties between different self-passivating Al-base coatings as electroplated and chemical vapour deposited (CVD) coatings on a RAF/M EUROFER-97 under strain. These studies showed the high ductility of pure electroplated Al-coatings, whereas both CVD coatings cracked under the applied strain.

In this work, hot-pressing of alumina in contact with hexagonal boron nitride or doped with boron carbide was conducted at 1500 °C for 30 min. After hot-pressing, abnormal grain growth induced by boron diffusion from these substances into alumina was detected, as clearly demonstrated with SEM, EDS, EBSD, and Raman spectroscopy. Grain boundary complexion transformations, solute drag, or another mechanism relating to interface-controlled grain boundary mobility are presumed to be the fundamental mechanism responsible for abnormal grain growth observed in this work.

Aluminium industry stands out as a significant source of CO2 emissions, due partially to the high energy demand of the alumina extraction stage. Accordingly, this study explores the implementation of direct resistive heating of mid-temperature processes in alumina production as an alternative to decrease CO2 emissions. Additionally, two different strategies are evaluated to decarbonize alumina industry: the generation of renewable electricity through solar photovoltaic panels and the integration of a CO2 capture plant based on calcium looping technology. This work comprehends the modelling and sizing of these plants and the assessment of their economic performance through the calculation of their Net Present Value and their respective payback periods. The integration of both strategies into an alumina refinery model reveals that electrification of low and mid-temperature processes yields a 15 % reduction in CO2 direct emissions, whereas calcium looping demonstrates the potential to capture 97 % of emissions with a 7 % energy penalty. Also, economic assessments indicate substantial potential for improvement through in-site electricity generation via solar photovoltaic panels, exhibiting a payback time of 4.5 years. Conversely, the feasibility of a calcium-looping plant is hindered by high capital expenses, necessitating a longer payback period of 19–24 years. Sensitivity analyses underscore the suitability of in-site renewable electricity generation, whereas carbon emission taxes emerge as crucial in incentivizing carbon-neutral processes, with thresholds around 95–125 €/tonne of CO2. Despite potential deviations from real industrial settings, this study provides evidence for environmentally friendly strategies in alumina production that demonstrate limited adverse effects on economic performance.

Dimethylaluminum isopropoxide (DMAI) is attracting attention as an alternative precursor for atomic layer deposition (ALD) of aluminum oxide (Al2O3). However, the surface chemical reaction mechanisms of DMAI during ALD regarding its dimeric structure under vacuum deposition process conditions has yet to be clear. In this work, the adsorption mechanism of dimeric and monomeric DMAI on a fully hydroxylated Al2O3 surface is studied using machine-learning potential (MLP) calculations. The initial adsorption of DMAI appears facile and would result in the coexistence of both methyl and isopropoxy ligands on the surface. The reactivity of DMAI is smaller than that of TMA, owing to the propensity of DMAI to adopt a dimeric form. Especially when the substrate is partially covered by other adsorbate species, the large molecular size and low reactivity of dimeric DMAI considerably hinder its reactivity toward surface adsorption. Current results are in good correspondence with the previous experimental results, where lower growth per cycle (GPC) and higher selectivity in area-selective ALD (AS-ALD) could be observed by using DMAI than compared to those of TMA processes.

Abstract In this study, we produced, through hot pressing (HP) and spark plasma sintering (SPS) techniques, Al2O3-NbC composites for applications in machining processes. We report an experimental investigation of sintered composites’ structural, thermal, morphological, physical, and mechanical properties. The results confirm that the Al2O3-NbC composite sintered by both techniques presents a heterogeneous microstructure with distinct grain sizes and irregular geometries. Another stimulating factor is the increase of 25.86% in Vickers hardness, 14.89% in Young’s modulus, and 16.52% in mechanical strength of the composite sintered by SPS about the composite sintered by HP. Thus, our results can be used to address material properties targeting the needs of specific technological applications.

More efficient electronic systems need more temperature-stable substrate materials and more flexible production possibilities. Ceramics such as alumina can be used for 2D and 3D base bodies, since they provide better thermal properties than their polymeric counterparts and can be additively manufactured utilizing e.g. Fused Filament Fabrication. Proper functionalization can be achieved by applying methods of printed electronics. Here, adhesion of the functional ink to a substrate is a crucial issue and especially challenging on ceramic substrates. This contribution reached a noteworthy increase in this matter, using a modified silver-based ink with piezojet-printing, while preserving very low electrical resistance after convection sintering. Adhesion is determined by pull-off testing, based on ISO 4624. By the approach shown in this work, printed ceramics could become a more viable choice for use in functional electronic systems.

This article investigates the development and potential applications of low-melting point lead-free glasses. Their importance is due to strong market demands to comply with the strict international regulations against the use of lead. In this work, a preliminary study of the existing interactions of a low-melting-temperature glass belonging to the P2O5–CaO–Na2O system when it is deposited on different ceramic substrates, both traditional (porcelain stoneware) and technical (alumina and zirconia), has been carried out. The ionic diffusion through the studied interfaces, the phases present, the composition of the glassy phase and the surface morphology of the coating have been studied by Field Emission Scanning Electron Microscopy (FESEM), with coupled EDX microanalysis. The chemical resistance of the different glassy coatings obtained is also evaluated. The results showed that these new lead-free low-melting-temperature glassy coatings are chemically and mechanically compatible, and promising candidates for applications and markets in a broad range of fields. Resumen: Este artículo investiga el desarrollo y aplicaciones potenciales de los vidrios sin plomo de bajo punto de fusión. La importancia de estos materiales se debe a las fuertes demandas del mercado por las estrictas normativas internacionales contrarias a la utilización del plomo. En este trabajo se ha realizado un estudio preliminar de las interacciones existentes de un vidrio de baja temperatura de fusión, perteneciente al sistema P2O5-CaO-Na2O, cuando se deposita sobre diferentes sustratos cerámicos tanto tradicionales (gres porcelánico) como técnicos (alúmina y circona). Mediante un estudio por microscopía electrónica de barrido con emisión de campo (FESEM) con microanálisis EDX acoplado, se han evaluado la difusión iónica a través de las interfases estudiadas, las fases presentes, la composición de la fase vítrea y la morfología superficial del recubrimiento. Además, se ha evaluado la resistencia química de los recubrimientos vítreos obtenidos. Los resultados muestran que son química y mecánicamente compatibles con las cerámicas tradicionales y técnicas. Estos resultados convierten a estos vidrios sin plomo y de baja temperatura de fusión en prometedores candidatos para un amplio rango de aplicaciones y mercados.

Starch consolidation casting (SCC) technique was successfully employed to produce both porous alumina and graded porous alumina ceramics. The solid content in the alumina suspension was maintained at 40 vol.%, with potato starch varying from 5 to 15%. Structures of the porous alumina (monolithic) samples obtained by SCC and uniaxial pressing were compared. In addition, the influence of the SCC consolidation temperature and the starch content were evaluated in the monolithic samples, while the consolidation temperature and the number of layers numbers were evaluated in the graded samples. The lower SCC consolidation temperature resulted in lower linear shrinkage and a slight increase in total porosity due to the increased pore size. The compressive strength values for the monolithic samples ranged from 60 to 200MPa, which can be considered high when compared to previous works. The graded samples exhibited porosity variations across layers and interfaces were free of cracks and imperfections. Linear shrinkage was the same for the adopted consolidation temperature and the porosity was slightly higher for the 3-layer samples. They achieved strength of 60MPa with fracture mode parallel to the applied load.

To increase the impulse mechanical strength of alumina, the pore structure of alumina was modified by surface coating. It was found that the impulse mechanical strength of alumina samples coated with aluminum chloride increases from 35 MPa to 51 MPa and the mechanical strength of alumina samples coated with aluminum-based complex increases from 21 MPa to 46 MPa at the calcination temperature range of 100 ℃ to 1100 ℃ by the DL-3 typed impulse mechanical strength test device, while the mechanical strength of uncoated alumina samples increases from 17 MPa to 39 MPa. According to scanning electron microscopy and X-ray diffraction, the surface coating of aluminum chloride has little influence on the crystal type of alumina materials after high temperature calcination. At the same time, it can effectively fill the matrix pore of alumina materials, increase the density of the support, and improve the mechanical strength of alumina materials. In addition, compared with the alumina sample coated with aluminum complex, the alumina material coated with aluminum chloride possesses larger surface area and smaller pore size after high temperature calcination. More importantly, the surface of the alumina sample coated with aluminum chloride formed a rough shape after high temperature calcination, which was beneficial to the loading and dispersion of the active metals.

Plasma actuators have demonstrated great potential for active flow control applications, including boundary layer control, flow separation delay, turbulence control, and aircraft noise reduction. In particular, the material used as a dielectric barrier is crucial for the proper operation of the device. Currently, the variety of dielectrics reported in the literature is still quite restricted to polymers including Kapton, Teflon, poly(methyl methacrylate) (PMMA), Cirlex, polyisobutylene (PIB) rubber, or polystyrene. Nevertheless, several studies have highlighted the fragilities of polymeric dielectric layers when actuators operate at significantly high-voltage and -frequency levels or for long periods. In the current study, we propose the use of alumina-based ceramic composites as alternative materials for plasma actuator dielectric layers. The alumina composite samples were fabricated and characterized in terms of microstructure, electrical parameters, and plasma-induced flow velocity and compared with a conventional Kapton-based actuator. It was concluded that alumina-based dielectrics are suitable materials for plasma actuator applications, being able to generate plasma-induced flow velocities of approximately 4.5 m/s. In addition, it was verified that alumina-based ceramic actuators can provide similar fluid mechanical efficiencies to Kapton actuators. Furthermore, the ceramic dielectrics present additional characteristics, such as high-temperature resistance, which are not encompassed by conventional Kapton actuators, which makes them suitable for high-temperature applications such as turbine blade film cooling enhancement and plasma-assisted combustion. The high porosity of the ceramic results in lower plasma-induced flow velocity and lower fluid mechanical efficiency, but by minimizing the porosity, the fluid mechanical efficiency is increased.

The selection of abrasive material and parameters of the Air-Abrasion device for a particular application is a crucial detail. However, there are no standard recommendations or manuals for choosing these details; the operator must depend on his experience and knowledge of the procedure to select the best possible material and set of parameters. This short review attempts to identify some of the effects that the selection of material and parameters could have on the performance of the Air-Abrasion procedure for a particular application. The material and parameter data are collected from various studies and categorized according to the most popular materials in use right now. These studies are then analyzed to arrive at some inferences on the performance of Air-Abrasion materials and parameters. This review arrives at a few conclusions on the effectiveness of a material and parameter set, and that there is potential for developments in the area of standardizing parameter selection; also, there is scope for further studies on Bio-Active Glass as an alternative to the materials currently used in Air-Abrasion.

The separator is one of the core inner components of the lithium-ion battery, and its performance directly affects the electrochemical properties, life, and safety performance of the battery. In this research, the physical and electrochemical properties of polyethylene (PE), polypropylene (PP) / PE/PP multilayer, (PP), and aluminum oxide ceramic-coated PE (PE–Al2O3) separators were analyzed and compared in detail. Among the separators, the PE–Al2O3 separator exhibited better performance pertaining to puncture strength, thermal stability, wettability, and ionic conductivity. However, its tensile strength is slightly lower than that of the PP/PE/PP separator. The surface of the PE, PP, and PP/PE/PP separators exhibited a large number of submicron pores. Alumina particles were uniformly distributed on the surface of the PE–Al2O3 separator, and a large number of clear pores were presented between the alumina particles. The PP/PE/PP separator exhibited the best tensile properties among the separators in the mechanical direction; the tensile strength of the PP/PE/PP separator was 247.53 MPa, which is higher than that of the PE–Al2O3 (197.58 MPa), PP (119.06 MPa), and PE (147.69 MPa) separators. Meanwhile, the puncture strength of the PE separator was the lowest among the separators at 144.26 N·mm−1 whereas that of the PE–Al2O3 separator was the highest at 426.91 N·mm−1, which was attributed to the high hardness of alumina particles. The melting temperature of the PE–Al2O3 separator was 140.9 ℃, which is lower than that of the PP and PP/PE/PP separators but higher than that of the PE separator. Further, it exhibited no heat shrinkage with heat treatment at 140 ℃ for 1 h. Accordingly, the PE–Al2O3 separator exhibited the best thermal stability compared to the PP, PP/PE/PP, and PE separators. The unique hydrophilic properties of alumina particles improved the wettability between the separator and electrolyte; the wetting angle between the PE–Al2O3 separator and the electrolyte was 12.3°, which was considerably smaller than that for the PP (35.9°), PE (38.3°), and PP/PE/PP (35.3°) separators. The electrolyte wettability of the PE–Al2O3 separator effectively reduced the transmission resistance of lithium ions between the anode and cathode, enabling the separator to exhibit an excellent ionic conductivity (0.719 mS·cm−1). After 100 cycles at 1 C, the capacity retention rate of the PE Al2O3 separator was 91.19%, which was considerably better than the other three types of separators. To summarize, this study reveals that the PE–Al2O3 separator has the best application prospect in high power, long-term stability, and high-safety lithium-ion batteries.

Abstract We created AA2024–AA1050 and AA2024–AA1050/0.005 vol.% Al2O3 nanocomposites by six accumulative roll bonding (ARB) process cycles. We used AA2024 and AA1050 sheets with a thickness of 0.7 mm and plate-shaped alumina nanoparticles to create a composite. The two AA1050 and one AA2024 sheets (among the two AA1050 sheets) were ARB-ed up to six cycles with and without adding alumina nanoparticles. Also, a sample of the AA1050 without composite making was ARB-ed up to six cycles. We aged some composites after the ARB process in the furnace at 110, 150, and 190 °C. This project performed SEM, TEM, and EDS-MAP analyses, tensile strength, microhardness, and Pin-on-Disc tests to study the ARB-ed sheets. The results of the tensile tests showed that the tensile strength of AA2024–AA1050 created by the six cycles ARB process was two times more than primary AA1050. Also, the wear resistance of this composite was 74% more than six cycles ARB-ed the AA1050. Using 0.005 vol.% alumina nanoparticles in AA2024–AA1050 composite improved its wear resistance by 30%. In the following, the aging process caused an improvement in tensile strength and total elongation of AA2024–AA1050/Al2O3 nanocomposites.

Alumina is widely used in the automotive, electrical component and aircraft industries due to its low thermal conductivity and high hardness. However, alumina is notoriously difficult to machine due to its extreme hardness. According to some researchers, laser machining offers a cost-effective machining technique for alumina. Even though many works on laser machining of alumina have been published, most have focused on thin alumina plates. This study determined the effect of a CO2 laser machining method on hole quality in terms of the heat-affected zone (HAZ) and taper angle for 3 mm alumina thickness. Design of Experiment (DOE) was performed to identify the effect of laser power and frequency on the output findings. The HAZ and the taper angle were measured using a Scanning Electron Microscopy image. Based on the ANOVA analysis, HAZ and taper angles were influenced by the laser power input. The HAZ thickness increased as laser power and frequency decreased, but the taper angle decreased as frequency decreased. Low laser power (50 W) resulted in a small inlet diameter (0.236 mm), while high laser power (150 W) resulted in a larger inlet diameter (0.272 mm). Multi-response optimization analysis for both HAZ and taper angle showed that 149 W and 2956 Hz frequency were the optimum process parameters which yielded the best output conditions.