Effect Of Al2O3 Research Articles

Effect of Al<sub>2</sub>O<sub>3</sub> on Viscosity and Refining Ability of High Basicity Slag for Heat-resistant Austenitic Stainless Steel

To optimize Al2O3 content in high basicity CaO-SiO2-Al2O3-8%MgO-8%CaF2 slag (%CaO/%SiO2=6) used for the refining of heat-resistant austenitic stainless steel, the effect of Al2O3 on the viscosity and refining ability of the slag was systematically investigated, and the relevant mechanism was clarified based on the analyses of solid phase precipitation behaviour and ionic unit structure transformation. The results demonstrated that the slag viscosity dramatically decreased and marginally varied in the Al2O3 ranges of 10%–20% and 20%–30%, respectively. At 1833–1873 K, both the slag viscosity and the activation energy reached the lowest values at 25% Al2O3. Al2O3 addition not only significantly inhibited the precipitation of CaO phase but also enhanced the polymerization degrees of aluminate and silicate networks. Furtherly, the inhibiting of Al2O3 on the solid phase precipitation dominated the viscosity reduction at 10%–25% Al2O3, while the enhancing of Al2O3 on the polymerization degree of networks led to the viscosity increase with further increasing Al2O3 to 30%. Finally, we optimized the reasonable high basicity slag containing 25% Al2O3 for Sanicro 25 steel due to the lowest viscosity and optimum refining ability of this slag.

Analysis of scale and frame interface effects on the solidification properties of solar salt in mesopores

The intermittency and instability of solar irradiation can be effectively overcome by using medium- and high-temperature composite phase change materials (PCMs) for latent heat storage. Studies using metals and organics as phase change materials show that the phase change behavior of mesoporous composite phase change materials is affected by the constraint effect, and its thermophysical parameters (such as phase change point and phase change latent heat) are significantly different from those of macro volume. However, at present, research on molten salt phase change materials, which are widely used in the field of medium- and high-temperature research, is insufficient. Molecular dynamics simulations combined with experimental methods were used to analyze the changes in the freezing point, supercooling degree and enthalpy of solidification of solar salt in mesoporous composite phase change materials, which were based on the self-diffusion coefficient and the potential energy-temperature curve. The results show that a larger mesoporous size leads to a higher freezing point of the solar salt. At the same scale, with the increase in Al2O3 content in the framework, the freezing point of the solar salt first decreases and then increases. The supercooling degree of solar salt decreases with increasing scale. When the mass content of Al2O3 in the framework is in the range of 25 wt%-40 wt%, the supercooling degree of solar salt increases gradually; in contrast, it decreases in the range of 40 wt%-50 wt%, and finally, it increases again in the range of 50 wt%-75 wt%. The latent heat of phase transition increases with increasing scale. With the increase in Al2O3 content in the framework, the latent heat of phase transformation first decreases, then increases, and finally stabilizes. Al2O3 and SiO2 in the interface of the frame can promote heterogeneous nucleation and provide a substrate for the nucleation of molten solar salt. They also reduce the degree of supercooling. It is found that the effect of Al2O3 on nucleation is more significant.

Effect of Al2O3 on Nanostructure and Ion Transport Properties of PVA/PEG/SSA Polymer Electrolyte Membrane.

Polymer electrolyte membrane (PEM) fuel cells have the potential to reduce our energy consumption, pollutant emissions, and dependence on fossil fuels. To achieve a wide range of commercial PEMs, many efforts have been made to create novel polymer-based materials that can transport protons under anhydrous conditions. In this study, cross-linked poly(vinyl) alcohol (PVA)/poly(ethylene) glycol (PEG) membranes with varying alumina (Al2O3) content were synthesized using the solvent solution method. Wide-angle X-ray diffraction (XRD), water uptake, ion exchange capacity (IEC), and proton conductivity were then used to characterize the membranes. XRD results showed that the concentration of Al2O3 affected the degree of crystallinity of the membranes, with 0.7 wt.% Al2O3 providing the lowest crystallinity. Water uptake was discovered to be dependent not only on the Al2O3 group concentration (SSA content) but also on SSA, which influenced the hole volume size in the membranes. The ionic conductivity measurements provided that the samples were increased by SSA to a high value (0.13 S/m) at 0.7 wt.% Al2O3. Furthermore, the ionic conductivity of polymers devoid of SSA tended to increase as the Al2O3 concentration increased. The positron annihilation lifetimes revealed that as the Al2O3 concentration increased, the hole volume content of the polymer without SSA also increased. However, it was densified with SSA for the membrane. According to the findings of the study, PVA/PEG/SSA/0.7 wt.% Al2O3 might be employed as a PEM with high proton conductivity for fuel cell applications.

Effect of Al2O3 on Sound Velocity of MgSiO3 Glass at High Pressure

Silicate glass has been used as an analog for silicate melts to understand the nature of dense magmas in the Earth’s mantle. To understand the effect of Al2O3 on the sound velocity and structure of MgSiO3 glass, in this study, combined with Brillouin scattering and diamond anvil cells (DACs), the acoustic velocity of MgSiO3∙5 mol%Al2O3 (MA1) and MgSiO3∙24.5 mol%Al2O3 (MA2) glass were measured up to 20 and 42 GPa, respectively. Our studies show that the incorporation of Al2O3 could increase the sound velocity of MgSiO3 glass. Using the obtained velocities, the bulk and shear moduli (KS, G), density (ρ) and Poisson’s ratio (ν) are calculated at high pressures, and the results indicate that Al2O3 could induce the stiffness of MgSiO3 glass. However, the effect of Al2O3 content on the stiffness of MgSiO3 glass is non-linear, and MA1 and MA2 exhibit similar KS and G at high pressures. With the increase of pressure, the transverse acoustic mode (VS) of MA1 and MA2 shows abnormal changes at 17.8 GPa and 31.8 GPa, which are related to the transition of coordination number (CN) for Si-O in Al-bearing MgSiO3 glass. Compared with previous studies on sound velocity of MgSiO3 glass, the incorporation of Al2O3 delays the transition pressure of Si-O coordination to a higher pressure. Our study has profound implications for understanding the density and sound velocity of Al-bearing MgSiO3 melt in the Earth’s interior.

Effect of Al2O3 and MgO nanofiller on the mechanical behaviour of alkaline-treated jute fibre–reinforced epoxy bio-nanocomposite

Effect of Al2O3 and MgO nanofiller on the mechanical behaviour of alkaline-treated jute fibre–reinforced epoxy bio-nanocomposite

Investigation of evaluated temperature oxidation for IN-738 LC superalloy turbine blade thermally coated by AL2O3 using slurry coating process

The study aims to investigate the effect of Al2O3 and Al additions to Nickel-base superalloys as a coating layer on oxidation resistance, and structural behavior of nickel superalloys such as IN 738 LC. Nickel-base superalloys are popular as base materials for hot components in industrial gas turbines such as blades due to their superior mechanical performance and high-temperature oxidation resistance, but the combustion gases' existence generates hot oxidation at high temperatures for long durations of time, resulting in corrosion of turbine blades which lead to massive economic losses. Turbine blades used in Iraqi electrical gas power stations require costly maintenance using traditional processes regularly. These blades are made of nickel superalloys such as IN 738 LC(Inconel 738). Few scientists investigated the impact of Al2O3 or Al additions to Nickel-base superalloys as coating layer by using the slurry coating method on oxidation resistance to enhance the Nickel-base superalloy's oxidation resistance. In this study, IN 738 LC is coated with two different coating percentages, the first being (10 Al+90 Al2O3) and the second being (40 Al+60 Al2O3). Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) were performed on all samples before and after oxidation. According to the results, SEM images of the surface revealed that the layer of the surface has a relatively moderated porosity value and that some of the coating layers contain micro-cracks. The best surface roughness of specimens coated with 60 % alumina+40 % aluminum was 5.752 nm. Whereas, the surface roughness of specimens coated with 90 % alumina+10 % aluminum was 6.367 nm.Results reveal that alloys with both Al2O3 and Al additions have reported a positive synergistic effect of the Al2O3and Al additions on oxidation resistance. Moreover,the NiCrAl2O3 thermal coating has good oxidation resistance and the effective temperature of anti-oxidation is raised to 1100 °C in turn reducing the maintenance period of turbine blades

Effects of oxide addition on structure and properties of WC–10Co cemented carbide obtained by in situ synthesized powder

AbstractCombining spray drying and in situ synthesized technology, WC–10Co cemented carbide with uniform composition was prepared by vacuum sintering. The effects of Al2O3 and additions of different rare‐earth oxides (La2O3, Y2O3 and CeO2) on the microstructure and mechanical properties of WC–10Co were investigated. As the Al2O3 content increased from .5 to 2 wt%, the hardness of the sintered sample increased, whereas the relative density and fracture toughness decreased. Compared with the addition of .5 wt% Al2O3, the WC–10Co alloy with .5 wt% rare‐earth oxides had higher hardness. In addition, compared with the alloy without an inhibitor (.80 μm), after adding .5 wt% Al2O3, La2O3, Y2O3 and CeO2, the WC grain sizes were reduced to .73, .65, .71 and .62 μm, respectively, which indicated that the addition of Al2O3 and rare‐earth oxides could refine WC grain during sintering. Among these additives, CeO2 had the best effect. With the addition of .5 wt% CeO2, the hardness and the fracture toughness increased from 1299 to 1710 HV30 and from 16.18 to 18.90 MPa m1/2, respectively.

Effects of Al2O3 and B2O3 on the structural features of iron phosphate glasses

In this paper, the structural features of the iron phosphate glasses with Al2O3 (2.5∼15 mol%) and B2O3 (5∼15 mol%) were investigated by using Fourier transform infrared spectra and Raman spectra. The results show that the glass network of the studied iron phosphate glasses with Al2O3/B2O3 mainly consists of Q1 phosphate units. Generally, with the increasing content of Al2O3 and B2O3, Q1 and Q0 phosphate units increase and Q2 units decrease for the glasses with Al2O3/B2O3 ≤10 mol%, otherwise, an adverse variation is detected. The structural network of the iron-phosphate glasses is enhanced when the substitution of Al2O3/B2O3 is not higher than 10 mol%, as proven by the changes of the thermal parameters. Moreover, the reasons on the structural variations depending on Al2O3/B2O3 are discussed in detail. The conclusions provide researchers with the roles of Al2O3 and B2O3 in structural features of iron phosphate glasses as potential hosts for specific nuclear wastes.

Effects of Al2O3 and TiO2 nanoparticles in order to reduce the energy demand in the conventional buildings by integrating the solar collectors and phase change materials

The solar source, although it can reduce energy consumption (EC) for buildings on cold days, in the summer, its presence on the envelopes intensifies EC. In this study, two techniques were used to make better use of solar energy. In the first method, phase change material (PCM) was used on the envelopes to absorb the sun's rays, thus eliminating summer radiation problems. The second way is to rely on absorbing the sun's radiation and turning it into a heat source to produce sanitary hot water (SHW). In the first method, for hot days, EC declined by 44% which is equal to a 267 kWh drop in EC. For cold days, this figure was 48% and 2419 kWh. Extending the analysis to the whole year, it was observed that EC dropped by 2686 kWh. In the second technique, EC in SHW dropped by 36.6% which means that to supply SHW, as much as 6302 kWh lower EC is required.

An improved SHDOM coupled with CFD for simulating infrared radiation signatures of rocket plumes

To analyze the infrared signatures of plumes, an improved coupled infrared radiation model is proposed based on the spherical harmonic discrete coordinate method (SHDOM) and the computational fluid dynamics (CFD) technique. We simulate the temperature field, pressure field and medium composition distribution information of the plume, and apply the information of flow field as the input data to calculate real radiation properties of the plume. The absorption coefficients of different plumes are calculated by the Weight-Sum-of-Gray-Gas (WSGG) algorithm. In addition, using the statistical average scattering phase function of particle clusters, the effect of Al2O3 on the total radiation is considered, which overcomes the inaccurate description of the multiple scattering source function of particles in the traditional SHDOM and makes it suitable for solving the infrared radiation problem of plumes. Multiple scattering, emission, and absorption processes between the alumina particles and the gases are considered rigorously. The infrared radiation signatures along different detection directions of rocket plumes with various velocities and wavebands are simulated, of which the validity is verified through the signature comparison with the Standardized Infrared Radiation Model (SIRRM). Numerical results show that the effect of aluminum particle clusters on the infrared radiation characteristics of rocket plumes cannot be neglected, especially for wavebands at which the absorption of gas molecules is weak. Moreover, the contribution of aluminum particles to the total radiation is related to the zenith angle and wave band, which indicates the importance and necessity of considering the aluminum particle clusters.

Amphoteric behavior of component and microstructure feature on CaO-Al2O3-TiO2 ternary melt by molecular dynamics simulation

Amphoteric oxides, Al2O3 and TiO2, are essential compositions in metallurgical melts and have an important role in regulating slag performance. In this study, the structural characteristics of the CaO-Al2O3-TiO2 ternary melt, such as local structural order and particle coordination changes, are investigated by molecular dynamics simulation. The effects of Al2O3 and TiO2 on the microstructure of various melts and their role differences are analyzed. The results show that the amphoteric behavior of TiO2 dominate with low titanium concentration ranging from 3 mol% to 18 mol%. It promotes the change of Al2O3 from acidic to alkaline. Meanwhile, the value of (NBO/T) increases and the melt’s viscosity decreases. In addition, the amphoteric behavior of TiO2 dominate in the high titanium system, ranging from 52 mol% to 66 mol% of TiO2 concentration. It promotes the conversion of TiO2 to alkaline. Meanwhile, the melt polymerization and viscosity are enhanced. As for the ‘aluminum avoidance principle’, it only applies to low-titanium system and invalid in high-titanium system.

Effect of Al2O3 in Refining Slag on the Cleanliness and Fatigue Property of Ultra-low-carbon Automotive Steel

The influence of Al2O3 content in refining slag on the cleanliness and fatigue property of ultra-low-carbon (ULC) automotive steel were investigated based on the industrial experiments. The inclusion-adsorption capacity of the refining slag was calculated and the total [O] (T.O) content of ULC automotive steel was measured. The number density, size distribution and morphology of inclusions were analyzed and their effects on the cleanliness and fatigue property of ultra-low-carbon (ULC) automotive steel were investigated. The results showed that as the Al2O3 content in refining slag increased from 19.92% to 39.73%, the inclusion-adsorption capacity of ULC automotive steel decreased from 210.30 down to 57.12, and the fatigue life from 1.4x104 down to 0.9x104 cycles, while the T.O content of steel increased from 12 up to18 ppm and the inclusion number density from 4 up to 9 per mm2.

Effect of Al2O3 on the molten slag microstructure information by molecular dynamics simulation and experimental analysis

The metallurgical properties of blast furnace slag changed when high alumina iron ore was used extensively due to the resulting changes of the molten slag microstructure. In the study, based on typical CaO–MgO–SiO2–Al2O3 slag systems with different w(Al2O3) content, molecular dynamics simulation was used to calculate the microstructural properties of particles in the high-temperature slag system, such as bond length, partial radial distribution function, coordination numbers, and diffusion coefficient. In addition, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and 27Al solid-state magic angle spinning nuclear magnetic resonance (27Al SS MAS NMR) were used to detect and analyze the samples. The comprehensive calculations and experimental results show that increasing w(Al2O3) can enhance the structural stability of each ion pair, and the strength of the structural stability is such that Si–O > Al–O > Mg–O > Ca–O. The self-diffusion coefficients are as follows: Mg2+ > Ca2+ > Al3+ > Si4+, which leads to the transformation of the [SiO4]4−(Q0), [Si2O7]6−(Q1) and [Si2O6]4−(Q2) structural units to [Si2O5]2−(Q3). The degree of polymerization of slag increased as well as the stability of the structural units. Moreover, the coordination of Al will change from the [AlO6]9−octahedral structure of six-coordinated Al to the [AlO5]7−pentahedral structure of five-coordinated Al and the [AlO4]5−tetrahedral structure of four-coordinated Al. It was also found that the content of non-bridge oxygen in the whole slag system decreased continuously, leading to the increasing degree of polymerization of slag, and the experimental results were consistent with the molecular dynamics calculation.

Effect of Al2O3 on the structural, optical and mechanical properties of B2O3- CaO-SiO2-P2O5-Na2O glass system

To study some influences of Al2O3 on the physical properties of glass system, Boro silica phosphate glass system with formula [29B2O3-25Na2O-6SiO2-2 P2O5-(38-X) CaO-XAl2O3]; 0 ≤ X ≤ 4 (mol. %) was prepared via communal melt quenching route. The nature of the samples was determined via X-ray diffraction. The presence of structure units such as BO3 and BO4 has been recorded by FTIR data. The values of the glass transition temperature were augmented with the increases of Al2O3. The optical absorption of the glass system was documented in the wavelength between 350 and 800 nm in the UV-Vis region. The experiment density, the empirical density, and molar volume have been calculated, then the influence of addition Al2O3 on the structure and optical properties was scrutinized. Young's modulus, bulk modulus, the packing density, and Poisson's ratio were studied according to the Makishima -Mackenzie model.

Plasma-enhanced N2 fixation in a dielectric barrier discharge reactor: effect of packing materials

The effect of Al2O3 and BaTiO3 packing on the plasma-enhanced NO x synthesis from air was investigated in a packed-bed dielectric barrier discharge (DBD) reactor. The discharge characteristics are significantly influenced by packing different materials into the discharge gap. Compared with the DBD without packing, the presence of Al2O3 or BaTiO3 beads in the discharge effectively enhanced the charge accumulation, average electric field, and mean electron energy, all of which contribute to the enhanced production of NO x . The lowest energy consumption of 15.9 MJ mol−1 for NO x production was achieved when placing BaTiO3 beads in the DBD, which can be attributed to the increased mean electron energy using the BaTiO3 packing, facilitating the formation of more N2 excited species in the reaction. These results suggest that choosing proper packing materials can effectively reduce the energy cost for plasma NO x synthesis using DBD.

Effects on Al2O3 and La2O3 additions on electrochemical performances of laser‐cladded WC10Co4Cr coatings

AbstractAl2O3 and La2O3‐reinforced WC10Co4Cr coatings were fabricated on Cr12MoV steel by laser cladding (LC). The microstructure and phases of obtained coatings were analyzed using a digital microscopic system (DMS) and X‐ray diffraction (XRD), respectively. The effects of Al2O3 and La2O3 mass fractions on the electrochemical corrosion performances of WC10Co4Cr coatings in 3.5% NaCl solution were investigated on an electrochemical workstation. The results show that the WC10Co4Cr with the different Al2O3 mass fractions are composed of Co4W2C, WC, Al2O3, W2C, and Fe‐Cr phases, and the La2O3‐reinforced WC10Co4Cr‐Al2O3 coatings are composed of WC, W2C, Al2O3, La2O3, LaAlO3, and Fe‐Cr phases. The corrosion current density icorrof the substrate, WC10Co4Cr‐Al2O3, and WC10Co4Cr‐Al2O3‐La2O3 coatings decreases from 2.424 × 10−5 to 6.840 × 10−7 A•cm−2; and the corresponding polarization resistance Rp and charge transfer resistance Rct increase from 1371 to 64 536 Ω•cm2 and from 1568 to 14 020 Ω•cm2, respectively. The La2O3‐reinforced WC10Co4Cr‐Al2O3 coatings have higher electrochemical corrosion resistance than the Al2O3‐reinforced WC10Co4Cr coatings, and the WC10Co4Cr‐6%Al2O3‐9%La2O3 coating presents the highest electrochemical corrosion resistance among all the experimental coatings.

Effect of Al2O3 and TiO2 nano-coated wick on the thermal performance of heat pipe

Effect of Al2O3 and TiO2 nano-coated wick on the thermal performance of heat pipe

Effect of Al2O3 on shear-thinning property of mould flux for high-speed thin slab continuous casting and its study on the mechanism

ABSTRACT To solve the problems of slag entrapment risk and frequent bond alarm in the field application of mould flux for high-speed thin slab continuous casting, the idea of ‘non-Newtonian fluid mould flux with shear-thinning property’ is introduced. It was found that with an increase in the Al2O3 content, the shear-thinning behaviour of the mould flux first increased and then decreased. The sample with 8.61% Al2O3 content had the strongest shear-thinning property and the lowest fluidity index, which reached 0.75. With the addition of Al2O3, the degree of polymerization of the mould flux molecules increased, and the relative strength of the Si–O–Al bond increased. It was found that the Al2O3 content has a significant influence on the IVAl complexes. The XPS results showed that Q3(1Al) was the structural unit most easily affected by shear stress, and the higher the content of Q3(1Al), the stronger the shear-thinning property of the mould flux.

Effects of Al2O3 and “Cr2O3” on phase equilibria of the system “FeO”−MgO−SiO2 at iron saturation

“FeO”, MgO and SiO2 are the major components of the nickel laterite smelting slags. Significant amounts of Al2O3 and “Cr2O3” may be present in the slag that come from laterite, coal ash and refractory. Effects of Al2O3 and “Cr2O3” on liquidus temperatures and solid solutions have been determined in the olivine and spinel primary phase fields in equilibrium with metallic iron. The results are presented in the form of MgO−‘‘FeO’’−SiO2 pseudo-ternary section at fixed 7 wt% Al2O3 and 2 wt% “Cr2O3”. A series of pseudo-binary phase diagrams have been constructed to demonstrate the application of phase diagram on smelting reduction of laterite. The liquidus temperatures and the compositions of solid solutions are compared between experimental data and FactSage thermodynamic modelling. The possible reasons for the different results have been discussed which will help FactSage to optimize the relevant databases.

Computational analysis of the melting process of Phase change material-metal foam-based latent thermal energy storage unit: The heat exchanger configuration

In the current study, the melting process of phase change material (PCM) embedded with nanoparticles and metal foams (MF) in a large scale shell-and-tube based latent thermal energy storage unit (LTES) has been numerically studied. Initially, the developed model was validated with experimental data. Then, the effect of Al2O3 (5%) nanoparticles addition and several MFs, i.e. Aluminum (Al), copper (Cu), Nickel (Ni) and Titanium (Ti), of different porosity (96–99%) on the performance of the melting process has been compared based on temperature and liquid fraction evaluations during the melting operation. The MF-PCM systems showed the best performance over the nano- and pure- PCM, with a huge reduction in the melting time. The beneficial effect of MFs for the melting process followed the order Cu > Al > Ni > Ti, which is the same order of the thermal conductivity. Increasing the metal foam porosity results in shorter melting time; however, since the surface temperature of the porous-PCM unit is almost constant for different metal foam porosities, a system with higher porosity (99%) is desirable. This study optimizes the design to enhance practical application performance and to reduce waste energy.