Addition Of Al2O3 Research Articles

Functional Design to Protect TZM Alloy Against Oxidation

One of the most important disadvantages of molybdenum (Mo) and Mo-based alloys is low oxidation resistance at elevated temperatures. TZM is a well-known Mo-based alloy having a composition containing small quantities of titanium, zirconium and carbon. These additional elements provide superior properties to TZM; however, low oxidation resistance still prevents use of this alloy over 650 °C without protection. In the present work, ceramic-based layers were formed on the surface of TZM by spark plasma sintering method. B4C–Si and Al2O3–Si powder mixtures were used to form protective layers against oxidation. Ceramic–metal (TZM)–ceramic sandwich-type samples were prepared in a single step at constant temperature of 1420 °C, pressure (40 MPa) and various holding times (5–10 min) under vacuum atmosphere. Densification behavior, phase analysis, oxidation resistance, dynamic flame test performance and hardness of the samples were investigated. Ceramic-based layers were formed successfully on the surface of TZM without any crack or spallation and bonded with different kinds of diffusion layers depending on composition. Oxidation resistance and dynamic flame test performance of TZM were improved about 70%. The highest hardness values at the surface layers were measured as 32.7 GPa and 13.8 GPa for B4C–Si and Al2O3 additions, respectively.

Pyrolysis of heavy hydrocarbons in weathered petroleum-contaminated soil enhanced with inexpensive additives at low temperatures

Pyrolysis is a promising technology for the remediation of soil contaminated with petroleum hydrocarbons. However, for weathered petroleum-contaminated soil (WPCS) with massive recalcitrant heavy hydrocarbons, pyrolysis still has the drawback of high energy consumption. To reduce energy consumption, commonly used inexpensive additives, including Fe2O3, Al2O3, K2CO3, CaO, HZSM-5, and red mud, were selected to strengthen the pyrolysis of heavy hydrocarbons in WPCS. The removal of the total petroleum hydrocarbon (TPH) content from WPCS increased as the dosage of additives increased from 1% to 5% at 400 °C for 30 min, and increased slightly or even decreased when the additive dosage was further increased to 10%. The reduction rates of the TPH content in soil treated with 5% additives of K2CO3, CaO, Fe2O3, red mud, HZSM-5, and Al2O3 increased by 26.16%, 25.65%, 25.53%, 23.93%, 23.15%, and 20.75%, respectively. Among these additives, CaO exhibited the best performance for the removal of aromatics (73.00%) and asphaltenes (72.44%), while Fe2O3 exhibited the best performance for the removal of resins (52.25%). The removal mechanisms of heavy hydrocarbons using additives during WPCS pyrolysis were proposed based on a combination of thermogravimetric analysis and the iso-conversional Flynn–Wall–Ozawa method. The reduction in the activation energy when additives were included during WPCS pyrolysis was closely related to whether the additives participated in the reaction and to the type of pyrolysis product. The soil characterization results demonstrated that the investigated additives would not severely impact further soil cultivation. The additive-assisted pyrolysis of WPCS is expected to reduce the required energy input by 34.71% compared to the traditional pyrolysis method, thus providing an energy-efficient and cost-effective method for treating petroleum-contaminated soil in future engineering applications.

Improvement in Hardness and Wear Behaviour of Iron-Based Mn-Cu-Sn Matrix for Sintered Diamond Tools by Dispersion Strengthening.

The work presents the possibility of fabricating materials for use as a matrix in sintered metallic-diamond tools with increased mechanical properties and abrasion wear resistance. In this study, the effect of micro-sized SiC, Al2O3, and ZrO2 additives on the wear behaviour of dispersion-strengthened metal-matrix composites was investigated. The development of metal-matrix composites (based on Fe–Mn–Cu–Sn–C) reinforced with micro-sized particles is a new approach to the substitution of critical raw materials commonly used for the matrix in sintered diamond-impregnated tools used for the machining of abrasive stone and concrete. The composites were prepared using spark plasma sintering (SPS). Apparent density, microstructural features, phase composition, Young’s modulus, hardness, and abrasion wear resistance were determined. An increase in the hardness and wear resistance of the dispersion-strengthened composites as compared to the base material (Fe–Mn–Cu–Sn–C) and the commercial alloy Co-20% WC provides metallic-diamond tools with high-performance properties.

Influence of Al2O3 particles on the tribological properties of CoCrAlYTa coating produced by laser-induction hybrid cladding

The influence of Al2O3 addition on the microstructure, mechanical and tribological properties of CoCrAlYTa coating produced by laser-induction hybrid cladding was systematically investigated. The results show that the coatings exhibit high metallurgy quality with no obvious defects, and mainly consist of γ, β and TaC phases. In the cladding process, a part of O element exists in the TaC and increases with the increased Al2O3 content, while the other exists in the form of Y2O3 due to low Gibbs free energy. As the Al2O3 content increases, the volume fraction of β phase (Vβ) changes from 23.82 vol% to 67.72 vol%, and leading to the microhardness of coating increased from 515.15 HV to 610.17 HV. Meanwhile, the wear rate of coating increases with the Vβ in a relationship of y = −5.97x+110.65, due to a fact that the wear mechanism changes from adhesive wear to microcutting.

Microstructural, mechanical and wear behavior of electroless assisted silver coated Al2O3–Cu nanocomposites

Electro-less deposition synthesized Al2O3 nanoparticles coated Ag with different weight percent (0, 2.5, 5, 7.5 and 10) were mixed with pure Cu powder to manufacture Cu–Al2O3 nanocomposite through powder metallurgy route. The effect of Al2O3 coated Ag nanoparticles weight fraction on the Microstructure, mechanical and wear behaviors of Cu–Al2O3 nanocomposite were investigated. The results showed that coating of Al2O3 nanoparticles with Ag helped for achieving excellent dispersion of Al2O3 nanoparticles at high weight percent. The EDX mapping images demonstrated that the Al2O3 reinforcement particles were homogeneously distributed into the Cu matrix for Cu–10%Al2O3 nanocomposite. Microstructural analysis showed that the addition of Al2O3 coated Ag nanoparticles improved density of the produced composites. The compressive strength was improved by increasing Al2O3 content up to 10% reaching 33% improvement in the strength compared to pure Cu. Moreover, the hardness of the produced nanocomposite increased from 63.9 to 165 HV as Al2O3 content increases from 0 to 10 wt.%. Additionally, the wear analysis showed that the wear resistance of the nanocomposites improved with the increment of nanoparticle content. This improvement was due to the presence of Al2O3 coated Ag nanoparticles, which increased the dislocation density and reduced the crystallite size of Cu structure. The increased dislocation density reduced the dislocation movement, which improved the hardness and compressive strength, and thus improve the wear rates.

Additive manufacturing of alumina-silica reinforced Ti6Al4V for articulating surfaces of load-bearing implants

In this study, functional gradation via layer-wise additive manufacturing was coupled with Al2O3 and SiO2 ceramics' advantages to creating a composite of Ti6Al4V (Ti64) with improved hardness and wear resistance. It was hypothesized that with Al2O3 and SiO2 into Ti64, wear-resistance and hardness would increase compared to the base Ti64 alloy. It was also hypothesized that if the structure could be created, an additional laser pass (LP) over the structure's top surface would further increase the hardness. Successfully fabricated composite structures were found to have varying phases of TiSi2 and Ti5Si3. Refined α-Ti grains were present in the composite region. The interface between the composite and pure Ti64 regions was crack-free, indicating a metallurgically sound bond. Dendritic microstructures were observed with the addition of LP on the composite top surface. Hardness was increased from 323.8 ± 9.6 HV in Ti64 substrate to 434.7 ± 7.3 HV, and 677.1 ± 29.7 HV in 3D Printed Ti64 and the composite sample, respectively. An LP increased hardness further to 938.8 ± 57.5 HV, a 186% increase in hardness than the original Ti64 alloy. Wear resistance was also increased with the addition of Al2O3 and SiO2 by ~90%, indicating the potential processing variations placed on this material system to produce structures with site-specific functionality for biomedical applications, particularly in articulating surfaces of load-bearing implants.

Structural, thermal and electrical properties of Li2O–Al2O3–GeO2–P2O5 glasses

Glassy electrolytes in Li2O–Al2O3–GeO2–P2O5 system with varying Al2O3 content have been obtained by melt quenching. Their thermal properties and crystallization kinetics were investigated by DSC at various scanning rates (3, 5, 10 and 15 °C/min). The phase composition of the samples was studied by XRD. The impact of Al2O3 addition on the Ec, molecular structure and transport properties of lithium germanophosphate glasses was investigated. The structure of the glasses was studied by IR spectroscopy. It was established the phosphate part of the glass structure undergoes modification. The conductivity of the undoped glass was found to be one order of magnitude lower compared to that of the Al-doped solid electrolytes.

Investigation of Survival/Hazard Rate of Natural Ester Treated with Al2O3 Nanoparticle for Power Transformer Liquid Dielectric

Increasing usage of petroleum-based insulating oils in electrical apparatus has led to increase in pollution and, at the same time, the oils adversely affect the life of electrical apparatus. This increases the demand of Mineral Oil (MO), which is on the verge of extinction and leads to conducting tests on natural esters. This work discusses dielectric endurance of Marula Oil (MRO), a natural ester modified using Conductive Nano Particle (CNP) to replace petroleum-based dielectric oils for power transformer applications. The Al2O3 is a CNP that has a melting point of 2072 °C and a low charge relaxation time that allows time to quench free electrons during electrical discharge. Al2O3 is blended with the MRO and Mineral Oil (MO) in different concentrations. The measured dielectric properties are transformed into mathematical equations using the Lagrange interpolation polynomial functions and compared with the predicted values either using Gaussian or Fourier distribution functions. Addition of Al2O3 indicates that 0.75 g/L in MRO has an 80% survival rate and 20% hazard rate compared to MO which has 50% survival rate and 50% hazard rate. Considering the measured or interpolated values and the predicted values, they are used to identify the MRO and MO’s optimum concentration produces better results. The test result confirms the enhancement of the breakdown voltage up to 64%, kinematic viscosity is lowered by up to 40% at 110 °C, and flash/fire points of MRO after Al2O3 treatment enhanced to 14% and 23%. Hence the endurance of Al2O3 in MRO proves to be effective against electrical, physical and thermal stress.

Mechanical Behaviour of Nano-material (Al2O3) Stabilized Soft Soil

Rapid urbanization and requirement of infrastructure, stable construction sites are not available. Therefore, there is a dire need for improvement of marginal soils to be used as a construction material. However, weak soils comprise of saturated clays, fine silts, and loose sand, which are susceptible to failure and pose problems of stability. Therefore, this research aims to study the strength and microstructural behavior of soft soils treated with nano-alumina (Al2O3) additive. In this study, Al2O3 of different percentages (0.5, 1.0, 1.5, and 2.0%) by dry weight of soil was added to a clayey soil and subjected to compaction and unconfined compression strength tests. The compaction tests showed that nano-Al2O3 (< 2.0%) stabilized soils exhibit higher unit weight and lower water content compared to untreated soils. This may be attributed due to the fact that nano-materials possess higher unit weight compared to untreated soils and these materials occupy the pore spaces in-between the soil grains, which reduce soil porosity and increase the shear strength. The unconfined compressive strength test on cured treated soil specimens showed a significant increase in shear strength on the addition of nano-alumina. The scanning electron microscopic analysis on untreated and treated soil specimens showed that untreated soil samples exhibit a compact array of clay grains and nano-material treated soil display closely packed and condensed fine structure, which authenticates an increase in shear strength. Thus, with the addition of Al2O3, there has been a significant improvement in the engineering properties of soft soils.

Ferrosilicate glass ceramics based on wastes from ore concentration

We showed in this work that there is a possibility of recycling the wastes derived from iron ore concentration by using glass technology. The compositions of new glass ceramics with high technological and decorative properties were developed. The influence of Al2O3, MgO and Na2O additives to the waste from ore benefication on the parameters of the synthesized glass and its crystallization products was studied. The optimal temperatures of synthesis, annealing and crystallization of glass samples in the systems (Fe2O3–FeO)–SiO2–Al2O3–Na2O and (Fe2O3–FeO)–SiO2–Al2O3–MgO were shown to be 1450100С, 500–6000С and 700–8000C, respectively. It was established that the redox conditions of crystallization of glasses in the system (FeO–Fe2O3)–SiO2–Al2O3–Na2O strongly affect the nature of the iron-containing phases that are formed: oxidative conditions favors the formation of hematite (Fe2O3) and aegirinite (Na2OFe2O34SiO2), whereas reducing conditions contributes to the formation of wustite (FeO) and fayalite (2FeOSiO2). In the system (FeO–Fe2O3)–SiO2–Al2O3–MgO under both oxidative and reducing conditions of crystallization, the same crystalline phases appear: olivine (2(Mg,Fe)OSiO2), hercin (FeOAl2O3) and iron metasilicate (FeOSiO2). It was shown that the crystallization of samples under reducing conditions allows producing materials with higher microhardness. The surface layer of glasses and glass ceramics exhibited less microhardness than their deep layers.

THERMAL ANALYSIS OF NICKEL ALLOY/AL2O3/TIO2 HYBRID METAL MATRIX COMPOSITE IN AUTOMOTIVE ENGINE EXHAUST VALVE USING FEA METHOD

The current research aims to develop a hybrid metal matrix composition that focuses on the nickel alloy and its thermal properties. The different temperature ranges are used to analyze the function of MMCs such as thermal conductivity and coefficient of thermal expansion. This paper addresses the thermal properties obtained from a series of Al2O3 and TiO2 reinforced nickel alloy (ASTM A494 M), with dispersed particle sizes ranging from 40-45 microns of Al2O3 and 1-5 microns of TiO2. The quantity of the Al2O3 addition varies from 3-12 weight % and 9 weight % of TiO2 unvarying in the stages of three weight percentages. The microstructural investigation states that, because of the stir casting on the vortex, the distribution of reinforcements is uniform with a strong bond. With the increase in Al2O3 and TiO2 content in HMMCs, a thermal property is found to diminish significantly. The results indicate that the reinforcements have a major effect on the thermal expansion coefficient as well as on the thermal conductivity of the hybrid composites being produced. Various types of microstructural have been performed using electron microscopy scanning and EDAX. The limited examination of the exhaust valve of the I C engine shows that the nickel combination composites can be utilized as a substitute for the present valve material (Ni-Cr alloy steel). All tests acted in this investigation meet ASTM specifications.

Effect of Al2O3 Addition on Magnetoelectric Properties of Ni0.5Zn0.5Fe2O4/Ba0.8Sr0.2TiO3 Composite Ceramics

Effect of Al2O3 Addition on Magnetoelectric Properties of Ni0.5Zn0.5Fe2O4/Ba0.8Sr0.2TiO3 Composite Ceramics

Collective effect of ternary nano fuel blends on the diesel engine performance and emissions characteristics

The present study aims to evaluate the emission and performance characteristics of a CI engine using biodiesel blends with three different nanoparticles. Biodiesel was prepared from palm oil using transesterification process. Biodiesel yield has been optimized using response surface methodology, which develops an interaction among the independent operating parameters reaction temperature methanol to oil ratio, and catalyst concentration, where they are changed as follows: 50–65 °C, 5:1–12:1, and 0.25–1.75, respectively. Nano fuel blends were prepared by dispersing CNT, TiO2 and Al2O3 nanoparticles into the B30 blend. The stability of these nanoparticles was improved by adding sodium dodecyl sulfate (SDS) as a surfactant, and the stability was characterized by ultraviolet–visible spectrometry. These nanoparticles were mingled with palm methyl ester at a proportion of 100 ppm using an ultrasonication water bath. The engine performance and emission characteristics were determined at varying engine speed and a full load condition. At all engine speeds, B30 with Al2O3 ternary fuel blend exhibits a promising reduction in brake specific fuel consumption (BSFC) of 5.98%. A significant improvement of 9.83%, 3.91% and 1.37% in brake thermal efficiency (BTE) has been observed for Al2O3, CNT, and TiO2 additives as compared to B10 blend, respectively. B30 with TiO2 ternary blend shows a sharp reduction of 27.89% and 30.68% in the CO and HC emissions respectively, and 10.37% decrease in NOx level with the addition of CNT as a fuel additive in the ternary fuel blend. Palm biodiesel blended with nanoparticle additives enhanced both engine performance and emission characteristics.

Flexible Cu1.5Mn1.5O4 combined with Co3O4 and Al2O3 conductive ceramic film as a cathode current collecting layer for solid oxide fuel cells

Novel flexible conductive ceramic films consisting of Cu1.5Mn1.5O4, Co3O4 and Al2O3 are developed for the cathode current collecting layer (CCCL) in solid oxide fuel cell (SOFC) stacks. These ceramic films are prepared by a water-based tape-casting method and sintered in situ at the operation temperature of intermediate temperature (IT)-SOFCs. The effects of addition amounts of Co3O4 and Al2O3 on the electrical conductivity of the CCCL and area specific resistance (ASR) of (La0.75Sr0.25)0.95MnO3-δ (LSM) cathode/the CCCL/SUS430 interconnect sandwich are studied. The results indicate that adding 3 wt.% of Co3O4 as sintering aids in Cu1.5Mn1.5O4 precursor powder can promote its sintering and thus reduce its contact resistance with neighboring components. Further combining Al2O3 as the binder with Cu1.5Mn1.5O4-3 wt.% Co3O4, though electrical conductivity of obtained materials decreases with the amount of Al2O3 addition increasing, the minimum ASR of 24.4 mΩ cm2 at 800 °C and a stable ASR of around 27 mΩ cm2 at 750 °C are achieved on LSM cathode/Cu1.5Mn1.5O4-3 wt.% Co3O4-10 wt.% Al2O3 CCCL/SUS430 interconnect sandwich. The developed flexible CCCL shows pronounced low contact resistance and high stability. Moreover, it can be easily cut and sintered in situ in SOFC stack, which is promising for the practical application in SOFC stacks.

Investigation the effect addition of nano Al2O3 on microstructure of Yttria tetragonal Zirconia polycrystalline ceramic

Purpose: This research aimed to prepare tetragonal zirconia polycrystals powder by coprecipitation method and study effects of addition of different amounts of nano Al2O3 (1, 2 and 4) wt.% on its microstructure and mechanical properties of (5Y-TZP) composite. Design/methodology/approach: The powder was uniaxial pressed at a pressure of 150 MPa and held for 60 s, and sintered at the 1500°C, held for two hours and then cooling down at 5°C/min to room temperature. Microhardness and fracture toughness tests were utilized to evaluate the mechanical properties of yttria tetragonal zirconia polycrystal composite. The microstructure has been observed using field emission scanning electron microscopy(FESEM). Findings: The results showed an addition of nano Al2O3 has a great influence on hardness and microstructure, the increase in Vicker's microhardness of composite samples with the increase in the nano Al2O3 wt.% and microstructure were characterized with homogeneous zirconia distribution, grain growth destruction with the increasing percentage of nano Al2O3. The most important influence is the enhancing of the densification process as the porosity decreased. The highest hardness and maximum fracture toughness were recorded at 4 wt.% nano Al2O3. Research limitations/implications: Ceramic matrix composites are developed to overcome the brittleness of ZrO2 and the low toughness of alumina by formation, a large difference of elastic behavior between matrix and particles(dispersion phase )which disturbs the stress field as a dislocation comes near a particle. Practical implications: Zirconia has mechanical properties similar to those of stainless steel. Yttria-stabilized tetragonal Zirconia (Y-TZP) is growing used in dentistry due to its good mechanical properties such as hardness and fracture toughness. Thus, controlling of microstructure by adding nanoalumina plays an important role in enhancing these properties. Originality/value: Study the adding bitty percentage from nano alumina on microstructure and mechanical properties of (5Y-TZP) ceramic.

Effects of ZrO2 and Al2O3 Addition on the Physical Properties of Cu-Mo-Cr Alloy by Liquid Phase Sintering

Effects of ZrO2 and Al2O3 Addition on the Physical Properties of Cu-Mo-Cr Alloy by Liquid Phase Sintering

Revealing the Structures in Short- and Middle-Order of Lanthanum-Doped Al2O3–NaPO3 Glasses by Solid State NMR Spectroscopy

Glasses in the xLa2O3-yAl2O3-(100 – x – y)NaPO3 system were synthesized by a melt quenching method, where 0 ≤ x ≤ 7.5, y = 0 and x = 5, 5 ≤ y ≤ 15. The structures were characterized by advanced multinuclei solid-state nuclear magnetic resonance spectroscopy (SSNMR) and X-ray photoelectron spectroscopy (XPS). 31P MAS NMR spectroscopy indicates that the glass Q2 structure is depolymerized by La2O3 and Al2O3, forming multiple QxAln and QyLan phosphorus species, where n, x, and y represent the number of P–O–P, P–O–Al, and P–O–La bonds, respectively. The various phosphorus species were identified by the J-coupling effect based one and two-dimensional (1D and 2D) experiments such as 2D J-resolved, 1D refocused INADEQUATE and 1D 31P{27Al} J-coupling heteronuclear multiple quantum coherence (HMQC). La is used as a mimic to simulate the local structure of the luminescent rare earth ions. 139La wideband uniform rate smooth truncation quadrupolar Carr–Purcell–Meiboom–Gill (WURST-QCPMG) spectra show that the coordination number of La is dominantly nine, and some La atoms transfer to lower coordination with the addition of Al2O3. La, Al, and Na atoms exclusively bond to phosphorus tetrahedron PO4, which is evidenced by the 31P/23Na, 31P/27Al double resonance NMR, XPS, and the calculation of charge balance. However, the Al/P and La/P connection methods are much different based on the calculation of charge balance and bond number. Finally, comprehensive and novel local structure models are developed for these rare earth-doped aluminum phosphate glasses.

Evaluating the tribological properties of aluminium based hybrid composites reinforced with Al2O3 &amp; ZrO2 nano particles

Metal matrix composites are being increasingly identified in now a days as new wear resistant material. The main purpose of this paper is to investigate the wear and hardness of the composite material Al-6061 alloy strengthened with Al2O3 and ZrO2 particulate and constructed with the help of stir casting method. The wear rate and frictional properties of the composite were conducted in pin and disk type of wear testing machine. The investigation was carried out with constant length of sliding distance and sliding velocity over different load ranges for aluminium metal matrix composite. The testing result indicated that the wear resistance increases when there is increase in the load. Additionally, an effort was made by keeping Al2O3 as constant of 2.5% along with increase in 1, 2, 3 and 4% of ZrO2. It was observed that, the strengthened aluminium metal matrix in addition of Al2O3 and ZrO2 decreases the range of damage due to friction.

Enhanced High-Temperature Strength of HfNbTaTiZrV Refractory High-Entropy Alloys by AI &lt;sub&gt;2&lt;/sub&gt;O &lt;sub&gt;3&lt;/sub&gt; Reinforcement

The HfNbTaTiZrV refractory high-entropy alloy reinforced with 4vol.% Al2O3 displays excellent phase stability and mechanical properties at elevated temperatures. A superior compressive yield strength of 2700 MPa at room temperature, 1392 MPa at 800 °C, and 693 MPa at 1000 °C has been obtained. The improved yield strength results from multiple strengthening mechanisms caused by Al2O3 addition, including interstitial strengthening, grain boundary strengthening, and dispersion strengthening. Besides, the effects of interstitial strengthening increase with the temperature and is the main strengthening mechanism at 800 °C. These findings not only promote the development of oxide-reinforced RHEAs for challenging engineering applications but also provide guidelines for the design of refractory materials with multiple strengthening mechanisms.

Effect of the ZrO2–Al2O3 solid solution on the performance of Ni/ZrO2–Al2O3 catalysts for CO2 methanation

The appropriate addition of Al2O3 to form a ZrO2-Al2O3 solid solution will weaken the Ni-ZrO2 interaction and increase the concentration of basic sites and oxygen vacancies in the catalyst, resulting in better activation of CO2.