Al2O3 TiO2 Research Articles

Perspective of multiple slips on 3D flow of Al2O3–TiO2–CuO/H2O ternary nanofluid past an extending surface due to non-linear thermal radiation

A mathematical model is constructed under the slip flow of a Newtonian fluid based on certain assumptions. Such a mathematical model of ternary nanofluid flow is handled by invoking similarity solutions for governing equations. The obtained system of nonlinear equations is solved numerically by utilizing the fourth-fifth order Runge–Kutta-Fehlberg method. The consequences of distinguished parameters on fluid flow are analyzed in detail through the plotted graphic visuals. Physical quantities such as Nusselt number and skin-fraction coefficient are considered numerically by tables. The results indicated that the mixed convection parameter favors the flow whereas the x-direction velocity slip reduces the velocity. Furthermore, it is observed that the temperature of the nanofluid is increased for the higher values of radiation. The presence of a heat source enhances the temperature and that of a heat sink diminishes the temperature. It is found that the heat conduction capability is more in ternary nanofluid than the hybrid and monophase nanofluids.

Composition, weathering, and provenance of beach sands adjacent to volcanic rocks in the northern Gulf of Guinea, SW Cameroon

The southern coastal portion of the Tertiary Cameroon Volcanic Line (CVL), in the Gulf of Guinea, is bordered by Pan-African granitoids, metamorphic rocks, and Cretaceous sedimentary successions, which are prone to contribute sediments to the nearby Limbe beach. To better constrain the weathering intensity and provenance of the beach sediments, the mineralogy and chemical composition of these sediments were analyzed. The low values of SiO2/Al2O3 ratios and Zircon-Tourmaline-Rutile (ZTR) index, coupled with high Index of Compositional Variability (ICV) indicate compositionally immature sediments. This is further supported by the presence of rock forming minerals such as olivine, pyroxene, and amphibole. The Th/Sc versus Zr/Sc binary and Al2O3–TiO2–Zr ternary diagrams suggest that the studied sediments have not experienced recycling. The Chemical Index of Alteration (CIA), Plagioclase Index of Alteration (PIA), the A–CN–K and (A-K)-C-N triangular diagrams indicate that the Limbe beach sediments were undergone moderate to intense weathering. Several provenance discrimination diagrams based on Al2O3, TiO2, Zr, TiO2, La/Sc, and Th/Co, and the ternary plot of V–Ni–Th*10, and the comparison of chondrite normalized rare earth elements (REE) patterns of the studied sediments with potential source rocks suggest that the source area is composed of mafic rocks of CVL. This indicates that the granitic, metamorphic, and sedimentary rocks close to the volcanic structure do not significantly contribute to the sedimentation of the studied beach. In addition, the results of this study indicate that longshore currents do not influence the chemical composition of the sediments.

Liquid Immiscibility and Thermodynamic Assessment of the Al2O3\u2013TiO2\u2013SiO2 System

Phase equilibria in the TiO2–SiO2 system have been studied experimentally using DTA and SEM/EDX. The thermodynamic parameters for the TiO2–SiO2 system have been assessed considering new experimental data of the present work and from the literature. Moreover, the miscibility of the liquid in the Al2O3–TiO2–SiO2 system has been studied at 2013 K in air and shrinkage of the miscibility gap at 3.8 mol% Al2O3 has been demonstrated. The experimental data obtained in the present work and literature as well as the thermodynamic databases for the binary Al2O3–TiO2, TiO2–SiO2, and Al2O3–SiO2 systems have been used to derive the thermodynamic description of the Al2O3–TiO2–SiO2 system using the CALPHAD approach. Solid phases have been modeled using the compound energy formalism. The liquid phase has been described by the two-sublattice partially ionic liquid model. A set of self-consistent parameters have been proposed, which resulted in a reasonably good agreement between the calculated and experimental data on the phase equilibria, liquid immiscibility, and thermodynamic properties in the Al2O3–TiO2–SiO2 system.

Chromite geochemistry of the Jinchuan Ni-Cu sulfide-bearing ultramafic intrusion (NW China) and its petrogenetic implications

Chromite, as an early-fractionation phase, has good potential to trace the petrogenesis and tectonic setting of mafic-ultramafic cumulate rocks. The Jinchuan ultramafic intrusion in NW China contains one of the world’s largest magmatic Ni-Cu sulfide deposits. Many studies have been carried out on this intrusion, however, the geochemical features of chromite and its related petrogenetic implications are still poorly constrained. In this study, the geochemistry of chromite enclosed in olivine from the Jinchuan intrusion is investigated. The chromite grains have large variations in Fe# (100*Fe3+/(Fe3++Al + Cr) = 1.3–47.0), Cr# (100*Cr/(Cr + Al) = 44.9–92.4), and Mg# (100*Mg/(Mg + Fe2+) = 4.7–25.7). They are depleted in Ni (142–1704 ppm) and Co (214–538 ppm) and enriched in Ti (3507–66298 ppm), accompanied by highly variable contents of Zn (1186–10726 ppm) and Mn (1362–4579 ppm). In the MORB-normalized patterns, chromite grains within the most primitive olivine are characterized by positive anomalies of Ti, V, Zn, and Mn and negative anomalies of Ni, similar to those in the Hawaiian tholeiitic basalts and typical layered intrusions. Variable correlations among the major, minor, and trace elements indicate that all these elements, except for Zn and Mn, may have been governed by multistage magmatic processes with little overprint from postmagmatic hydrothermal alteration. The strong Ni and Co depletions in chromite indicate prior removal of sulfide liquids at depth. The wide range of Ti in chromite may have been caused by the fO2 change during magma fractionation. The variable contents of Zn and Mn, by contrast, may be related to postcumulus processes. Furthermore, the relatively high TiO2 but low Al2O3 contents of the primitive chromite are comparable with those of mantle plume-related cumulate rocks. This feature, coupled with the MORB-normalized patterns in chromite, implies that the Jinchuan intrusion is similar to typical tholeiitic layered intrusions genetically related to a mantle plume.

Forecast of Crystallizing Phases and Description of the Chemical Interaction in the Al2O3–TiO2–MgO System

Forecast of Crystallizing Phases and Description of the Chemical Interaction in the Al2O3–TiO2–MgO System

Synthesis by the Method of Pyrolysis and Electrophysical Properties of Ceramics Based on the K2O–TiO2–Al2O3 System

Synthesis by the Method of Pyrolysis and Electrophysical Properties of Ceramics Based on the K2O–TiO2–Al2O3 System

Features of Creating Nanostructured TiO2–Al2O3 Layers for Superdense Storage Media with an Addressing System Based on Crossbars

Features of Creating Nanostructured TiO2–Al2O3 Layers for Superdense Storage Media with an Addressing System Based on Crossbars

Optimization of Coating Process from Cermet Powders by Plasma Spraying in Air

The paper presents studies on the optimization of the process of applying coatings from cermet powders with different solid phase contents by plasma spraying in air to restore and harden parts of machines and mechanisms operating under adverse conditions. Such conditions are usually created in heavily loaded tribojoints when the mechanisms operate at a low speed of relative movement of surfaces during friction. At the same time, the destruction of the working surfaces is mainly due to the process of microcontact setting and subsequent detachment of the formed particles at their contact points. The application of special protective coatings with the required properties is possible with the manufacture of high-quality starting powder materials and optimization of the technology for their application. Such powders and powder compositions can be obtained by the method of agglomeration of a fine powder mixture with its subsequent high-temperature sintering. To identify the hardening mechanism of composite coatings made of cermet by gas-thermal spraying, important stages are the optimization of the deposition process parameters and the study of the properties of plasma coatings obtained in this case. When optimizing the technological parameters of plasma spraying of coatings, the utilization rate of the sprayed powder material has been taken into account as the main indicator of the process efficiency, the structure of the obtained layers, and the morphology of individual particles deposited on the polished surface. The paper provides data on the structural elements of sprayed materials for wear-resistant coatings obtained by plasma spraying at optimal conditions. Taking into account the processes that occur during the wear of tribological conjugations, the data indicate the existing prerequisites for the wear resistance of the studied composite coatings made of metal ceramics. Special wear-resistant coatings made of materials with a soft matrix hardened by solid inclusions Al2O3–TiO2–Ni–Cr–Al–Y are widely used in various industries. Based on the detailed analysis of the features of cermet plasma coatings, it can be stated that such powder compositions (complex oxides-metal component) are often used as wear-resistant plasma coatings. The research results can be taken into account in cases of application of wear-resistant plasma coatings made of metal-ceramics and compositions based on them, containing solid phases in the form of oxides, as well as the manufacture of a whole range of parts operating under conditions of intense wear.

Ediacaran‐Cambrian intra‐oceanic arc volcanic rocks in southern West Junggar, NW China: New constraints on the initial subduction of the Junggar‐Balkhash Ocean and migration of arc magmatism

As numerous blocks of the Ediacaran‐Cambrian supra‐subduction zone ophiolites, seamounts, subduction‐related metamorphic rocks, and arc granitoids have been identified in the ophiolitic mélanges in the contiguous West Junggar (China) and Balkhash (Kazakhstan) area, the initial subduction of the Junggar‐Balkhash Ocean, a major branch of the southern Palaeo‐Asian Ocean is emerging as an interesting topic. In this study, we present new data from diabase and basalt xenoliths in an Ediacaran‐Early Cambrian quartz‐monzonite block within the Tangbale ophiolitic mélange and an isolated dacitic tufflava block within the Saleinuohai ophiolitic mélange in southern West Junggar, NW China, as another line of evidence for the Ediacaran initial subduction of the Junggar‐Balkhash Ocean and the Cambrian migration of arc magmatism in West Junggar. The diabase and dacitic tufflava yield concordant zircon U–Pb ages of 568 and 530 Ma, respectively. The diabase and basalt exhibit high Al2O3 (17.38–17.75 wt%) and low TiO2 (0.69–0.90 wt%), with Mg# = 47–55, whereas the dacitic tufflava is characterized by high Na2O (7.87–8.43 wt%), with Mg# = 46–49. All the samples display similar LREE and large‐ion lithophile element (LILE) enrichment and Nb, Ta, Ti, and varying Zr and Hf depletion, indicating that they were formed in an intra‐oceanic arc setting. An integration of the new and published data shows that the subduction of the Junggar‐Balkhash Ocean was initiated in the Late Ediacaran at least, followed by slab rollback and retreat of subduction zone, which would be responsible for the northward migration of arc magmatism.

Investigation of heated fins geometries on the heat transfer of a channel filled by hybrid nanofluids under the electric field

In this study, Galerkin Finite Element Method or GFEM is used for modeling the heat transfer in a channel filled by hybrid nanofluids under the electric field. Three voltages of 1, 3 and 5V are supplied to the inlet boundary condition and four types of hybrid nanofluid were used (TiO2–CuO, TiO2–Al2O3, Al2O3–CuO and Al2O3–Cu) to improve the average Nusselt number. 11 different cases also were proposed to examine the effect of fins geometries on the heat transfer by Central composite design (CCD). Number of fins (4–8), length of fins (10–20 cm) and thickness of fins (2–4 cm) are the considered variables and levels. Results indicated that TiO2–Al2O3 with ϕ=0.05 had the greatest Nusselt number among the other experienced cases. Also, increasing the nanoparticles concentrations by 0.01 could improve the Nusselt number up to 5.19%. Furthermore, Results showed that increasing the supplied voltage for electric field from 1V to 5V can improve the heat transfer process in the channel.

Origin of the post-collisional carboniferous granitoids associated with the Azhahada Cu-Bi deposit in Inner Mongolia, Northeast China and implications for regional metallogeny

The Azhahada quartz vein-type Cu-Bi deposit is located in the Erenhot-East Ujimqin polymetallic metallogenic belt, on the western part of the Great Xing’an Range, Inner Mongolia, northeast China. The Cu-Bi veins are hosted by volcanic and metasedimentary rocks in the Devonian Niqiuhe Formation and Carboniferous felsic intrusions (monzogranite, syenogranite, and granite). Three hydrothermal ore stages (I-III) for Cu-Bi formation at Azhahada have been identified. Chalcopyrite and bismuthinite are the dominant ore minerals and mainly occur in vein stage II (quartz–pyrite ± chalcopyrite ± bismuthinite veins). New LA-ICP-MS zircon U-Pb dating indicates the monzogranite, syenogranite, and granite emplaced between 313.9 ± 1.7 and 308.4 ± 1.5 Ma. The monzogranite, syenogranite, and granite show the same geochemical affinity with I-type granites, which are characterized by high SiO2, K2O, and Al2O3 contents, low MgO, TiO2, and P2O5 contents, negative Eu anomalies (EuN/EuN* = 0.04–0.57), and strong enrichment in Rb, K, Pb, and Nd. Moreover, these granitic intrusions have low Mg# values of 22 to 39, low (87Sr/86Sr)i ratios (0.7023 to 0.7053), εNd(t) values between −0.8 and +0.4, positive εHf(t) values of +1.6 to +10.4, suggesting that their parental magmas were most likely derived from partial melts from the lower crust involving some mantle materials in a post-collisional tectonic setting. Sulfide samples from Azhahada have 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios similar to those of granitic intrusions. The silicon isotope compositions of the quartz samples (−0.3 to −0.1‰) are highly consistent with values of the granitic intrusions (−0.4 to −0.1‰), indicating that the silicon was derived from the granitic magma. Combined our whole-rock geochemical and Sr–Nd–Hf–Pb–Si isotopic data with previous investigation of regional tectonic evolutions, we suggest that the Azhahada granitoids genetically associated with the Cu-Bi mineralization were generated by the postorogenic lithospheric extension and magmatic underplating during the Late Carboniferous. A post-collisional extensional event coupled with the rising of hot mantle derived melts triggered partial melting of the lower crust, as well as provided metals (Cu and Bi).

CO hydrogenation reaction on Fe–Co–Mn nanocatalyst: impact of support and process conditions on performance and structure

AbstractThe hydrothermal method was used in order to prepare Fe–Co–Mn nanocatalysts. The prepared specimens were evaluated for the CO hydrogenation reaction. The impact of different kinds of supports such as Al2O3, SiO2, ZSM5, TiO2, MgO, ZSM5–Al2O3, ZSM5–TiO2, Al2O3–TiO2, Al2O3–SiO2, SiO2–ZSM5 and Al2O3–MgO on the behavior and structural characteristics of the Fe–Co–Mn ternary nanocatalysts was investigated. Evaluation of these various supported samples was performed under the same process conditions. Al2O3‐supported sample showed better performance for light olefin production chosen as an optimum sample. Furthermore, the influence of a change of support type on the rate of surface reactions was studied. The impact of operating parameters was also investigated, with the conditions of T = 623 K, P = 2 bar and H2/CO = 2 determined as the optimum reaction conditions. Catalyst characteristics were defined using a variety of methods. © 2021 Society of Chemical Industry (SCI).

Experimental investigation of the effects of ethanol‐diesel mixture on the performance and emissions of the thermal barrier coated diesel engine

AbstractIn this study, the effects of thermal barrier coating (TBC) and diesel‐ethanol mixture fuel on carcinogenic and greenhouse‐causing harmful emissions from diesel engines were experimentally investigated. In the first stage, the combustion chamber parts of the single cylinder diesel engine were coated with ceramic Al2O3TiO2 material with low thermal conductivity. Plasma spray method was used as the coating method. Then, coated and uncoated engines were run on diesel fuel. In the second stage, ethanol‐diesel mixture containing 5% ethanol E5 (v/v) was used in both engines. In both stages, the engines were operated at full load and at different engine speeds and compared in terms of emissions and performance. Combustion improved as the effect of the increased in‐cylinder temperature thanks to the low heat transfer with TBC. Therefore, an increase in engine power occurred. However, when E5 fuel was used in the TBC engine, the engine power decreased slightly. In the coated engine, HC and CO emissions have been significantly reduced. NOx emission increased with the effect of the thermal barrier coating, but decreased by 18% with the addition of ethanol in the TBC engine due to lower calorific value of ethanol.

Study of the Photocatalytic Antimicrobial Activity of Nanocomposites Based on TiO2–Al2O3 under Action of LED Radiation (405 nm) on Staphylococci

Study of the Photocatalytic Antimicrobial Activity of Nanocomposites Based on TiO2–Al2O3 under Action of LED Radiation (405 nm) on Staphylococci

Modification of the MgO–Al2O3–TiO2–SiO2 Glass by Silver Diffusion for the Formation of Luminescent Molecular Clusters

Modification of the MgO–Al2O3–TiO2–SiO2 Glass by Silver Diffusion for the Formation of Luminescent Molecular Clusters

Effect of B2O3 on the Melting Temperature and Viscosity of CaO–SiO2–MgO–Al2O3–TiO2–Cr2O3 Slag

Effect of B2O3 on the Melting Temperature and Viscosity of CaO–SiO2–MgO–Al2O3–TiO2–Cr2O3 Slag

Mechanical Modification of Nanomaterials on Fully Saturated Concrete in Groundwater Reservoir Under Long-Term Water Immersion

With the increasing number of hydraulic structures in service, many scholars have investigated the performance of saturated concrete, however, there are few studies on the influences of different contents and types of nanomaterials on the performance of fully saturated concrete. In this paper, a series of experiments on concrete with different contents of nano SiO2, nano Al2O3 and nano TiO2 are performed, such as electron mirror scanning, uniaxial compression, acoustic emission, etc., and the microstructure, mechanical properties of samples are compared and analyzed. The results show that: 1) By the addition of various kinds of nanomaterials to saturated concrete, the microstructure of saturated concrete is significantly improved, and the compactness and integrity of the slurry are improved 2) The mechanical properties of saturated concrete are significantly improved by the addition of 3 wt% nanomaterials. And the compressive strength of the saturated concrete sample containing 3 wt% nano-Al2O3 is the largest and the deformation modulus of the saturated concrete sample containing 6 wt% nano-Al2O3 is the largest. 3) Compared with dry concrete, when the concrete is saturated, the modifying effect of nanomaterials on the mechanical properties of concrete is weakened. The results of this study have important guiding significance for the study of the nano-modification and the safe operation of hydraulic structures.

Mineralogy and geochemistry of Lobé River sediments, SW Cameroon: Implications for provenance and weathering

The Lobé River (LR) watershed basement rock, Ntem Complex (NC), south Cameroon is covered by a thick lateritic soil. To better constrain the geology of the basement rock, textural, mineralogical and bulk geochemical (major, trace, and rare earth elements) analyses were undertaken on the recent stream sediments from the LR. The aims of this study were to investigate the provenance of sediments and to determine the weathering intensity of the source area. The ternary (Al2O3–TiO2–Zr) and binary (Th/Sc–Zr/Sc) diagrams suggested high sediment recycling and sorting, indicating that the bulk hydraulic energy of the LR controls the sediment texture. Despite the diagenetic processes of K-metasomatism observed on the A-CN-K plot, the (A-K)-C-N plot, Chemical Index of Alteration (CIA), and Plagioclase Index of Alteration (PIA) indicate that the studied sediments and their source areas underwent a high degree of chemical weathering. The heavy mineral suites imply heterogeneous provenance, including igneous, metamorphic and sedimentary source rocks. The ternary diagrams and Co/Th, La/Sc, Sc/Th, Cr/V, and Y/Ni elemental ratios indicate mostly felsic source rocks with lesser contribution from mafic components. The comparison of chondrite normalized REE patterns of LR sediments with potential source rocks reveals that the sediments were derived from the Precambrian basement rocks composed of tonalitic, trondhjemitic, and granodioritic suites, with remnants derived from Archean Greenstone Belt.

Flame sprayed and plasma sprayed Al2O3-TiO2 coatings

Al2O3–TiO2 coatings were received by flame sprayed of flexible cord and plasma sprayed using powder. Shown higher mechanical and tribological properties of flame sprayed coating compared plasma sprayed coating.

Ab initio based interionic interactions in calcium aluminotitanate oxide melts: structure and diffusion

Calcium aluminotitanate (CaO–Al2O3–TiO2) ternary oxides are of fundamental interest in Materials as well as Earth and environmental science, and a key system for several industrial applications. As their properties at the atomic scale are scarcely known, interionic interactions for the melts are built from a bottom up strategy consisting in fitting first only Al2O3, CaO and TiO2 single oxide compounds separately with a unified description of the oxygen charge and O–O interaction term. For this purpose, a mean-square difference minimization of the partial pair-correlation functions with respect to the ab initio reference was performed. The potentials for the ternary oxide are finally built straightforwardly by adding purely Coulomb terms for dissimilar cation–cation interactions without further fit. This general and unified approach is transferable and successfully describes the structural and diffusion properties of the three single oxides as well as the ternary melts simultaneously. A possible underlying structural mechanism at the origin of the diffusion evolution with TiO2 content is proposed based on the formation of Ti induced triply bonded oxygen.