Mixture Of Alumina Research Articles

Life cycle assessment comparison between zircon and alumina sand applied to ceramic tiles

The goal of the study is to assess and compare the use of opacifier (whitener) materials zircon sand and alumina applied in ceramic tiles production. This study provides a comparison using a cradle-to-gate life cycle assessment (LCA) approach, giving an overview of the differences from an environmental perspective between these materials in body mixtures to obtain tiles with a high degree of whiteness. This ISO compliant study is backed by an independent critical review panel and presents the first European-representative LCA comparison between zircon and alumina, using primary data from industry. A super white (with CIELab coordinate L*>85) ceramic tile can be produced using zircon or alumina as opacifier, with different mixtures. For zircon data, a previous ISO reviewed LCA and its associated paper has been used. This data comes from Zircon Industry Association members. For alumina, the eco-profile of alumina and bauxite developed by the European Aluminium has been used and is available in the “Environmental Profile Report for the European Aluminium Industry”. This study considers the use phase of the compared materials as whiteners. Milling phase data was collected from specific producers and tile mixture preparation data was taken from wider industrial bodies. Sensitivity and scenario analysis were used to understand the main differences between mixtures and influences between materials. Comparing the use of zircon sand with alumina in different ceramic mixtures, the primary result is that tiles using zircon had lower environmental burdens for almost all the analysed impact potentials. The alumina mixtures investigated show about 20% higher Global Warming Potential (GWP), Eutrophication Potential (EP), Acidification Potential (AP), Photochemical Ozone Creation Potential (POCP), Abiotic Depletion Element and Fossil Potential (ADPe/f) and Primary Energy Demand (PED). The Ozone Depletion Potential (ODP) is the only potential impact that is similar for zircon mixtures and alumina mixtures. The milling process is not negligible for all the impact categories considered in this study. The results of the study show that main differences between zircon and alumina mixtures are closely tied to the environmental performance of regional grid electricity generation. This study quantifies and compares the environmental impacts associated with the production of super-white ceramic tile mixture with two different whiteners: zircon and alumina. With this study, ceramic tile producers are given a tool to guide their choices in opacifier material selection, using a rational, scientific and peer-reviewed methodology, ensuring objective comparison between two materials.

A DSC- and X-ray Diffraction Study of Mixtures of Aluminum with 50 wt % of Aluminum Hydrate after Plastic Deformation under High Pressure

A DSC- and X-ray Diffraction Study of Mixtures of Aluminum with 50 wt % of Aluminum Hydrate after Plastic Deformation under High Pressure

Phase changes during the drying of calcium aluminate cement bond castables – the influence of curing and drying conditions

This study presents the influence of different curing temperatures and the availability of unbound H2O on the phase changes during the drying process of a simplified calcium aluminate cement bond castable. A mixture of CAC and alumina was hydrated for 48 h at 5, 23 and 40 °C, which represents different working conditions during casting. After the curing process, these samples were heated up to 180 °C, and in some of them, the remaining unbound H2O had been removed by vacuum drying beforehand. The quantitative phase composition was determined by QXRD. Thermogravimetric analysis and gravimetric measurements were also used to characterize the differently cured samples. While the mineral phases in the samples cured at 40 °C were barely affected by the heating process in the investigated temperature range, the initial conditions before the drying of the samples cured at 5 and 23 °C strongly affected the final phase composition.

Protective properties of diffused chrome-calorizing coatings with TiN and Ti2AlN barrier layers on VT6 alloy

The results of the research of phase and chemical composition, structure and micro hardness of diffusion coatings, obtained by chrome-calorizing of VT6 structural titanium alloy, are presented. Chrome-calorizing was carried out at a temperature of 1050 °C for 4 h in powder mixtures of chromium, aluminum, inert additive and activator. As a result of saturation, multilayered coatings with the participation of nitrides TiN, Ti2AlN and intermetallic Al3 (Ti, Cr), Al2Ti, AlTi3 are formed. The micro hardness of TiN, Ti2AlN surface layers is 16.0–14.0 GPa, which increases the wear resistance of the VT6 alloy by 3.7 times. Moreover, it has been established that the presence of Ti2AlN and Al3 (Ti, Cr) phases increase the heat resistance of the VT6 alloy in the air atmosphere to a temperature of 700 °C.

Modeling and Optimization of Gas-Solid Fluidization of Binary Mixtures using Box-Behnken Experimental Design

The influence of different factors on the fluidization of a binary mixture of red mud and aluminum was investigated. A new model was developed for predicting pressure drop through the solid bed using experimental data of other work. Statistical analysis based on response surface methodology has been used to develop correlations for bed pressure drop with three independent factors, minimum fluidization velocity (Umf), red mud to aluminum ratio (R/A), and static head (Hs). The design of experiments offers a best alternative to study the effect of factors and their response with the minimum number of experiments. The hydrodynamic characteristics of fluidization, bed pressure drop, superficial gas velocity (Umf), red mud to aluminum ratio (R/A), and initial static bed height (Hs) were modeled and optimized. ANOVA has been used to analyze the system parameters on bed pressure drop. A model of bed pressure drop was found to have a correlation coefficient of 0.98. The measured values of bed pressure drop from RSM were found to match the experimental values very well.

Study of CCLW, Alumina and the Mixture of Alumina- and CCLW-Reinforced Aluminum-Based Composite Material with and Without Mechanical Alloying

Study of CCLW, Alumina and the Mixture of Alumina- and CCLW-Reinforced Aluminum-Based Composite Material with and Without Mechanical Alloying

Additive manufacturing of ceramic alumina/calcium phosphate structures by DLP 3D printing

Producing micro and macroporous 3D structures that mimic the bone architecture of a specific anatomic region, namely the rounded trabeculae in trabecular bone, is a considerable challenge, to which additive manufacturing can make a fundamental contribution. The main objective of the work was to explore the Digital Light Processing (DLP) technique in obtaining customized parts, from a ceramic suspension composed of two different materials, specifically alumina and hydroxyapatite (HA), with a trabecular bone architecture, using Computer Assisted Design (CAD) modelling techniques and additive manufacturing. Hydroxyapatite (HA) was added to the alumina matrix to improve the biocompatibility and bioactivity of the composites after sintering. After optimizing all printing parameters and the suspensions rheological properties, samples in alumina and alumina-hydroxyapatite with the desired architecture were obtained. The influence of the incorporation of hydroxyapatite in the alumina formulations was also analyzed, with increasing hydroxyapatite contents: 5, 10, and 15 wt%. The rheological behaviour of the suspensions was studied in a plate-to-plate system. The physical-chemical and mechanical characterization of produced samples were carried out by X-ray diffraction, Scanning electron microscopy, and compressive tests. The suspensions prepared with two different materials showed adequate viscosity to achieve a good spread and homogeneous layers in the 3D printing process. In the produced samples, the occurrence of a hibonite phase (CaAl12O19), resulting from the reaction between alumina and hydroxyapatite during the sintering step, increased the compressive strength of the samples. The high temperature needed for sintering alumina led to the conversation of HA into TCP. The achieved mechanical strength results from the porosity level and the thickness of the struts of the printed architecture. DLP showed to be a precision printing technology of low cost that can be used to fabricate parts in the industry from a suspension composed of a mixture of alumina and HA powders, which is very useful in the bone repair field and not previously reported.

Electrostatic Self-Assembled Composite Abrasives for Chemical Mechanical Polishing of A-Plane Sapphire

Sapphire substrates with different orientations have wide applications due to their excellent physical, chemical and optical properties. However, the chemical mechanical polishing of sapphire is challenging due to its chemical inertness, extreme hardness and brittleness. Herein, chemical mechanical polishing of A- and C-plane sapphire was systematically studied using α-Al2O3 and silica abrasives and polishing mechanism was analyzed by X-ray photoemission spectroscopy (XPS) and nanoindentation meter. The high MRR selectivity for C-plane sapphire in α-Al2O3 slurry is the synergy of selective hydration of C-plane and stronger crystal structure of A-plane. The low MRR selectivity for C-plane sapphire in silica slurry can be attributed to the formation of Al2SiO5 on both planes which reduced the impact of strong mechanical effect of α-Al2O3 abrasives. To improve the MRR of A-plane sapphire, a new nanocomposite particle with alumina as the core and silica as the soft shell was prepared by an electrostatic self-assembly method. The new composite abrasives combined the mechanical effect of α-Al2O3 abrasives and chemical effect of silica abrasives and demonstrated substantially higher MRR for A-plane sapphire than pure alumina abrasives, pure silica abrasives and physical mixture of alumina+silica abrasives.

Thermal and Thermomechanical Properties of Refractory Forsterite-Spinel Ceramics

This article examines the utilization of fly ash in comparison with alumina as raw materials and sources of aluminium oxide for synthesis of forsterite-spinel refractory ceramics. Raw materials were milled, mixed in different ratios into two sets of mixtures and sintered at 1500°C for 2 hours. Sintered samples were characterized by X-ray diffraction analysis and scanning electron microscopy. Samples were also subjected to determination of porosity, water absorption and bulk density. Thermal and thermomechanical properties were determined by thermal analyses, refractoriness, refractoriness under load, thermal shock resistance and thermal dilatometric analysis with determination of thermal expansion coefficient. Mixtures with 10 wt.% and 20 wt.% of fly ash had the most promising results compared to alumina mixtures. Thermal shock resistance and modulus of rupture were improving with increasing content of aluminium oxide in the mixture.

CREATION OF ELECTRIC CONDUCTIVE COATINGS USING GAS-DYNAMIC SPRAYING

The article presents the results of research on the processes of creating conductive coatings based on copper and aluminum in order to determine the interaction of components on each other during cold gas-dynamic spraying (CGDS) and substantiate the method of introducing an additional component to obtain the desired composite coating. In particular, under conditions when the copper sputtering coefficient is almost zero (at a working air temperature of 300 °C), it is the search for the experimental dependence of the sputtering coefficient on the percentage of copper and aluminum powders in the sprayed mixture, determining their residual content in the coating and then calculating based on these data, the sputtering coefficients of copper and aluminum. The CGDS method obtained samples with composite coatings from mixtures of aluminum and copper powders at different initial mass concentrations of aluminum (from 0 to 100%, in increments of 10%) Other things being equal (air pressure 0,6 MPa, air heating temperature 300 ° C) . The spraying ratio of the mixture and the residual content of the components in the obtained composite coatings were measured. Data on the residual content of the components in the coating allows you to select the composition of the source powder required to obtain a given content of components in the coating. The dependences of the sputtering coefficients of copper and aluminum on the mass content of aluminum in the sprayed mixture are found. At an initial concentration of aluminum less than 66%. the coefficient of copper sputtering is higher than the coefficient of sputtering of aluminum. Both increase monotonically with increasing aluminum concentration until it reaches 61%. At high concentrations of aluminum (more than 66%) the spray coefficients of copper, aluminum and their mixtures coincide. The obtained data on the residual content of the components in the coating allows you to select the composition of the source powder required to obtain a given content of components in the coating. For example, the maximum residual copper content (~ 95%) can be obtained by adding to the source powder 30-40% aluminum. The obtained results confirm the interaction of the components on each other and justify the method of introducing an additional component to obtain a composite coating containing a component that is difficult to spray.

Numerical study of heat transfer and friction drag in MHD viscous flow of a nanofluid subject to the curved surface

The basic objective of this article is to highlight the impact of Joule heating, thermal radiation, and viscous dissipation on heat transfer rate and friction drag in the flow of viscous nanofluid subject to the curved stretching sheet. Moreover, the effects of magnetic field and two-heating process termed as prescribed surface temperature and prescribed heat flux is considered on the surface. The nanofluid is addressed as a mixture of alumina ( A l 2 O 3 ) nanoparticle and ethylene glycol ( C 2 H 6 O 2 ) base fluid. Initially, certain dimensionless variables have been addressed to modify the governing partial differential equation (PDEs) and the associated boundary condition into non-dimensional ordinary differential equations (ODEs) coupled with boundary conditions. Subsequently, the resulting equations are solved numerically by implementing bvp4c package in MATLAB. Multiple graphical results for heat transfer rate, friction drag, velocity, and temperature are obtained under the influence of several flow parameters like radiation parameter, Eckert number, curvature parameter, stretching parameter, Hartmann number, and volume fraction of nanoparticles. Moreover, several interesting results for the flat surface ( K → ∞ ), with prescribed heat flux and surface temperature have been determined. The current radiative and dissipative flow coupled with the Joule heating process have countless applications in various industrial and engineering techniques.

Developmental alterations, teratogenic effects, and oxidative disruption induced by ibuprofen, aluminum, and their binary mixture on Danio rerio

Several studies highlighted the ubiquitous presence of ibuprofen and aluminum in the aquatic environment around the world and demonstrated their potential to induce embryotoxic and teratogenic defects on aquatic species individually. Although studies that evaluate developmental alterations induced by mixtures of these pollutants are scarce; and, since environmental contamination presented in the form of a mixture of toxicants with different chemical properties and toxicity mechanisms capable of generating interactions; the objective of this study was to evaluate the developmental defects, teratogenic alterations, and oxidative stress induced by individual forms and the mixture of ibuprofen (IBU) and aluminum (Al) on zebrafish embryos. Oocytes exposed to environmentally relevant concentrations of IBU (0.1–20 μg L-1) and Al (0.01–8 mg L-1) and one binary mixture. The LC50 and EC50 were obtained to calculate the teratogenic index (TI). The IBU LC50, EC50, and TI were 8.06 μg L-1, 2.85 μg L-1 and 2.82. In contrast, Al LC50 was 5.0 mg L-1with an EC50 of 3.58 mg L-1 and TI of 1.39. The main alterations observed for individual compounds were hatching alterations, head malformation, skeletal deformities, hypopigmentation, pericardial edema, and heart rate impairment. The mixture also showed significant delays to embryonic development.Moreover, oxidative stress biomarkers of cellular oxidation and antioxidant defenses at 72 and 96 hpf significantly increased. Results show that environmentally relevant concentrations of ibuprofen (IBU), aluminum (Al), and their mixture promote a series of developmental defects, teratogenic effects, and oxidative disruption on D. rerio embryos, and the interaction of both substances altered the response. In conclusion, morphological and biochemical tests are suitable tools for assessing the health risk of aquatic wildlife by exposure to individual and mixed pollutants in freshwater bodies.

Analysis of entropy generation in AA7072-methanol and AA7072+AA7075-methanol flow near a parabolic surface

This article presents a study of nanofluid and hybrid nanofluid near a parabolic surface under the influence of heat generation and MHD. AA7072 and AA7075 are treated as nano particles while mathanol is used as a base fluid. We incorporated aluminum alloy of AA7072 in a base fluid for nanofluid and AA7072+AA7075 in base fluid for hybrid nanofluid. AA7072 and AA7075 manipulated in this study are uniquely manufactured to possess high heat transfer features. AA7072 alloy is a combined mixture of zinc and aluminium with some metallic elements such as copper, silicon, and ferrous. Similarly AA7075 is a compounded mixture of zinc, magnesium, ferrous, and silicon. By using similarity transformations, the PDEs are transmuted into ODEs. Furthermore, the transmuted equations are than interpreted numerically in MATLAB using Bvp4c. The graphical analysis is performed for different parameters to check the behaviour of velocity and temperature profiles. Velocity field attains increasing behaviour by an accretion in volume fractionϕ1for both methanol+AA7072(nanofluid) and methanol+AA7072+AA7075(hybrid nanofluid). The velocity profile for methanol+AA7072 is higher than methanol+AA7072+AA7075. By increasing magnetic field parameter M, the velocity componentf′(ψ)proceeds diminish trend for both methanol+AA7072 and methanol+AA7072+AA7075. But velocity field for methanol+AA7072 is moderate than methanol+AA7072+AA7075. The influence of heat generation parameterγshows rising trend in temperature profile for both fluids. But heat generation parameterγis more effective for hybrid nanofluid. Moreover, an entropy generation rate is also evaluated.

Synthesis and characterization of belite clinker by sustainable utilization of alumina sludge and natural fluorite (CaF2)

Certain reservations regarding the high energy costs needed for Portland cement production and eco-friendliness of the cement synthesis process are pointed out. Belite clinker synthesis offers an effective alternative approach capable of addressing these reservations by producing cements at reduced temperatures/CO2 emission. The present study suggests a new method to synthesize belite clinkers at even lower temperatures by incorporating the natural fluorite (CaF2) into a mixture of limestone and alumina sludge originated from the water purification plants. The obtained clinkers and their respective cements are characterized by free lime contents, X-ray fluorescence, X-ray diffraction, scanning electron microscopy, refusal, Blaine fineness and mechanical resistance analyses. The obtained results reveal that the synthesized belite cement possesses mechanical strength similar to that of ordinary belite cement. In addition, the introduction of CaF2 into the clinkers not only lowers their preparation temperatures but also facilitates the formation of crystalline phases which eventually leads to inproved hydraulic properties of the cement.

Analysis of Machining Operation using Vegetable Oil and Nano Fluids

The influence of the hybrid additives of alumina and titanium oxide on varied lubricant characteristics as a cut fluid in steel turning. In varied volumetric concentrations, the hybrid nano lubricant has to evolve. The mixture of alumina and titanium oxide improved its tribology. The new nano-lubricant reduces the wear and nodal temperature of the tool's flank substantially. The application of hybrid nano-particles rather than nano-particles is among the most significant jobs in improving the heat transfer of fluids. We saw several sorts of pairs used to cut fluid and their effects on machining (turning).A potential MQL approach can be tested to limit the excessive use of traditional cutting fluid. The minimum amount of any cutting fluid in this approach is sprayed into the cutting zone at high pressure to improve its penetration into the machining area. Using MQL enhances surface quality and the life of the tool. MQL is a feasible alternative to wet machining. In their perspective. Therefore, both production costs and environmental dangers may be minimized through MQL..

Metallurgy and Mechanism of Underwater Wet Cutting Using Oxidizing and Exothermic Flux-Cored Wires.

This paper considers the metallurgical processes of dissociation, ionization, oxidation, deoxidation, and dissolution of oxides during underwater wet cutting. A multiphase mechanism of underwater wet cutting consisting of working and idle cycles of the electrical process in a pulsating vapor gas bubble is proposed. A model of arc penetration into metal due to metal oxidation and stabilization of the arc by the inner walls of a narrow kerf is proposed. For underwater cutting of 10 KhSND, 304L steel, CuAl5, and AlMg4.5Mn0.7 alloy, we provide a principle of modeling the phase composition of the gas mixture based on high oxygen concentration, improving ionization, enthalpy, heat capacity, and thermal conductivity of plasma through the use of a mixture of KNO3, FeCO3 and aluminum. The method of improving the thermophysical properties and ionization of plasma due to the exothermic effect when introducing Fe3O4, MoO2, WO2 oxides and Al, Mg, Ti deoxidizers is proposed. Although a negative effect of refractory slag was revealed, it could be removed by using the method of reducing surface tension through the ionic dissolution of refractory oxides in Na3AlF6 cryolite. In underwater cutting of 10 KhSND and 304L, the steel welding current was 344–402 A with a voltage of 36–39 V; in cutting of CuAl5 and AlMg4.5Mn0.7 alloy, the welding current was 360–406; 240 A, with a voltage of 35–37; 38 V, respectively, with the optimal composition of flux-cored wire: 50–60% FeCO3 and KNO3, 20–30% aluminum, 20% Na3AlF6. Application of flux-cored wires of the KNO3-FeCO3-Na3AlF6-Al system allowed stable cutting of 10KhSND, AISI 304L steels, and CuAl5 bronze with kerf width up to 2.5–4.7 mm.

Decomposition of Hydroxylammonium Nitrate Solution Over Nanoporous CuO Supported on Honeycomb.

We investigated the influence of a copper loading strategy over a honeycomb structure on the catalytic performance during the decomposition of a hydroxylammonium nitrate (HAN) aqueous solution. Copper was supported on the honeycomb surface by means of a metal coating method (MC), i.e., a method of directly coating a metal, and a metal alumina coating method (MAC), i.e., a method of coating a mixture of metal and alumina. The properties of the catalysts were analyzed by N₂ adsorption, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The Cu(16.8)/honeycomb-MC catalyst showed a lower decomposition onset temperature during the decomposition of the HAN aqueous solution compared to that over the Cu(7.0)/honeycomb- MAC catalyst, an outcome ascribed to the higher copper loading and the higher dispersion of copper in the Cu(16.8)/honeycomb-MC catalyst compared to that in the other catalyst. The Cu(16.8)/honeycomb-MC catalyst was confirmed to have both excellent activity and heat resistance during the decomposition of a HAN aqueous solution.

The effect of the stages of chemical reactions on the composition of the products formed under a dynamic thermal explosion of the mixtures of aluminium and nickel powders

The paper is the first to propose the mathematical model of the process of intermetalliс composite synthesis in the mode of dynamic thermal explosion taking into account the stages of chemical reactions, the rate of which slows down with the increase of the refractory product content. The model takes into account the mutual influence of thermal and chemical processes, as well as the condition of conjugate heat exchange with the reactor walls. Examples of composition evolution in the synthesis process are given. According to the results of the study, diagrams have been compiled for the first time to illustrate changes in the phase composition of the product depending on changes in the composition of the initial pressed material. It is shown that as a result of bulk synthesis a composite of complex composition is formed. It was found that in the studied conditions in the general case there is an inhomogeneous distribution of concentrations.

Pharmacological implications of ipriflavone against environmental metal-induced neurodegeneration and dementia in rats.

Long-term exposure to environmental neurotoxic metals is implicated in the induction of dementia and cognitive decline. The present study aims to illustrate the therapeutic role of ipriflavone asa synthetic isoflavone against environmental metal-induced cognitive impairment in rats. Dementia was induced by a mixture of aluminum, cadmium, and fluoride for 90 days followed by ipriflavone for a further 30 days. Metal-treated animals exhibited abnormal behaviors in the Morris water maze task. Neuropathological biomarkers including oxidative stress (TBARS, NO, SOD, GPX, GST, and GSH), inflammation (TNF- α, IL-6, and IL-1β), neurotransmission (AChE and MAO), and insulin resistance (insulin, insulin receptor, and insulin-degrading enzyme) were altered, which consequently elevated the level of amyloid-β42 and tau protein in the hippocampus tissues inducing neuronal injury. Ipriflavone significantly (P < 0.05) ameliorated the neurobehavioral abnormalities and the cognitive dysfunction biomarkers via antioxidant/anti-inflammatory mechanism. Moreover, ipriflavone downregulated the mRNA expression level of amyloid precursor protein and tau protein, preventing amyloid plaques and neurofibrillary tangle aggregation at P < 0.05. A molecular docking study revealed that ipriflavone has a potent binding affinity towards AChE more than donepezil and acts as a strong AChE inhibitor. Our data concluded that the therapeutic potential of ipriflavone against dementia could provide a new strategy in AD treatment.

Reduced graphene oxide as reinforcement in aluminium nanocomposites prepared by powder metallurgy

This study investigated the use of reduced graphene oxide (rGO) obtained by chemical route as a reinforcement phase in aluminium matrix nanocomposites (AMNCs) fabricated by powder metallurgy. Mechanical milling of a mixture of aluminium and rGO powders was able to form homogeneous and highly densified composites, allowing an effective interaction between matrix and reinforcement to establish. The effect of rGO content (ranging for 0.01 to 1.0 wt%) on the mechanical properties of rGO-AMNCs was investigated. Microhardness, elastic modulus and yield strength increase gradually up to 0.5 wt% with respective gains of 308%, 61% and 86%.