Al2O3 Particle Size Research Articles

The cruciality of particle size and shape on fracture mechanism of aluminum matrix composites

Metal matrix composites are generally believed to achieve better performance with spherical reinforcements than irregular ones. In this work, through experiments and computational simulations, we have demonstrated that spherical reinforcements do not necessarily enhance the tensile ductility of composites. There exists a critical size for spherical particles. Using an Al2O3-Al2024 composite as an example, we found that when the size of spherical Al2O3 particles is less than 3 µm, they are not fractured during deformation, resulting in enhanced ductility. We elucidated the competitive mechanism between particle and matrix fracture under various reinforcement sizes and volume fractions, and constructed a deformation map that can be utilized to determine fracture mechanisms. This work clarifies the micro-mechanical mechanisms of reinforcements on material fracture behavior, providing guidance for the design and fabrication of strong and ductile metal matrix composites.

Preparation of ultra-high permeability dual-layer Al2O3 hollow fiber supports for zeolite membrane fabrication

Four-channel dual-layer Al2O3 hollow fiber with ultra-high permeability and mechanical strength was prepared by co-extrusion and co-sintering technique for the first time and used as support for NaA zeolite membranes fabrication. The macroporous inner layer of the Al2O3 hollow fiber, composed by large Al2O3 particle, gives supports the high permeability and mechanical strength, while the thin out layer, composed by small particles, provides an even and smooth surface for zeolite membrane growth. By using SiO2 as the sintering aid, the sintering temperature of the inner layer was reduced and match with that of the outer layer. The effects of SiO2 adding amount, sintering temperature, Al2O3 particle size and their content on the structure and properties of the prepared hollow fiber were investigated systematically. At a sintering temperature of 1520 °C, a dual-layer hollow fiber with surface pore size of 0.38 μm and fracture load of 24.52 N, exhibits pure water flux as high as 22.23 m3 m 2 h−1 bar−1. The NaA membrane prepared on this support achieved a flux of 14.14 kg m−2 h−1 and a separation factor >10,000 in pervaporation separation of EtOH/H2O solution (90 wt%, 75 °C). This work provides an efficient and low-cost way to prepare ceramic hollow fiber support for high-performance zeolite membrane fabrication.

Effect of particle size and concentration of Al2O3 on the corrosion behavior of silane-Al2O3/MWCNT double-layer coating: towards protecting the AZ91 magnesium alloy

Effect of particle size and concentration of Al2O3 on the corrosion behavior of silane-Al2O3/MWCNT double-layer coating: towards protecting the AZ91 magnesium alloy

Computational damage analysis of metal matrix composites to identify optimum particle characteristics in indentation process

This paper presents an integrated numerical model that investigates the effects of Al2O3 particle volume fraction, distribution, size, shape, and clustering on the deformation, damage, and failure behaviors of particle-reinforced metal matrix composites. Additionally, the effects of the cohesive strength of the matrix-particle interface and the initial void volume fraction on these behaviors are investigated. In this study, random microstructure-based finite element modeling approach is used. The Gurson-Tvergaard-Needleman model is used to capture the plastic deformation and ductile cracking of the matrix, whereas the Johnson–Holmquist II model is used to model particle fracture. The matrix-particle interface decohesion is modeled using the surface-based cohesive zone method. A two-dimensional nonlinear finite element model augmented with Python-generated code is developed in ABAQUS/Explicit to analyze the damage mechanisms in AA6061-T6/Al2O3 particle-reinforced metal matrix composites. The results show that Al2O3 particle enhance the ability of particle-reinforced metal matrix composites to resist deformation. However, this enhancement is dependent on the indentation location, particulate characteristics, and the applied load. An increase in the particle volume fraction increases the risk of particle fracture, particularly when particles are close to the material surface. Circular particles are the optimal choice for the reinforcement of particle-reinforced metal matrix composites. The predictions are in good agreement with the experimental data, particularly in terms of Rockwell hardness and deformation characteristics.

Influence of gradation in the reinforcement particles on the interfacial microstructure and mechanical properties of functionally graded composites

In this research, Al6061 alloy-based Functionally Graded Composites (FGCs) were fabricated by hot pressing which is composed of 7 layers with different proportions of Al2O3 reinforcement particles. The addition of Al2O3 particles is gradually increasing in the other layers from top to bottom (Layer 1 - Pure Al6061 alloy, Layer 2–5 wt% Al2O3, Layer 3–10 wt% Al2O3, Layer 4–20 wt% Al2O3, Layer 5–30 wt% Al2O3, Layer 6–40 wt% Al2O3, Layer 7–50 wt% Al2O3). Moreover, three different Al2O3 particle sizes (8, 16 and 32 µm) were used to fabricate three sets of FGCs. Reciprocating wear studies were performed and the result shows that the FGC with 8 µm Al2O3 particle size shows 85.5% improved wear resistance. Further, various wear mechanisms were investigated and finally compressive strength analysis proved that the homogenous distribution of Al2O3 particles in the FGC with 16 µm Al2O3 particle size helps achieve the maximum compression stress of 476.04 MPa compared with other FGCs.

Viscoelastic and vibrational studies of nano hybrid fibre metal laminates

Employment of distinct fibres (glass/carbon etc.) in Fibre Metal Laminates (FMLs) is one way of enhancing the durable life of an FML and its performance under dynamic loads. In the present work, carbon fibre is employed in GLARE (Glass/Aluminium laminated epoxy) to enhance the vibration (natural frequency) and viscoelastic (storage modulus ( E′), loss modulus ( E″) and Tan δ) properties. Similarly, the influence of 1 wt% of Al2O3 (alumina), ZrO2 (zirconium oxide) and TiO2 (titanium oxide) nano particles are also studied in hybrid (carbon/glass) FML. The mean particle size of Al2O3 (5.1 nm), ZrO2 (25.3 nm) and TiO2 (63.2 nm) were estimated using the Scherer equation with the aid of X-ray diffractometer analysis. Hybridisation resulted in a 22%, 10% and 2% increase of natural frequencies from mode 1 to mode 3 and 36.3%, 15% and 13.2% of E′, E″ and Tanδ, respectively, when compared to GLARE (glass fibre reinforced aluminium laminated epoxy). TiO2-reinforced hybrid FML shows the highest natural frequencies among all nanohybrid FMLs. The results summarise that natural frequencies and viscoelastic properties of nanohybrid FMLs are sensitive to the type of fibre, nano particle reinforcement and its size. A stereo microscope and a scanning electron microscope (SEM) were used to analyse the defects at the interface and the nanoparticle dispersion in the matrix, respectively. Further, a numerical model was developed to perform free vibration analysis, and it was noticed that the results were similar to experimental values.

A clarification on local microstructural inhomogeneity in friction stir additively manufactured functionally graded composite materials

A microstructure gradient functionally graded composite structure (MG-FGC) with Al2O3particle reinforcement within the additive layers of different grades (7475-T761, 5083-O, and 6061-T6) of aluminium alloys is successfully fabricated. It has been observed that the properties are spatially varied within the additive layers of the fabricated MG-FGC. The presence of the different sizes of the reinforcement Al2O3particles further causes the local deformation and microstructural inhomogeneity. The electron backscattered diffraction (EBSD) results show evidence of recrystallization followed by grain coarsening at the large-size particle/matrix interface, while smaller Al2O3particles are surrounded by the smaller equiaxed grain structure. This shows that the size and morphology of the Al2O3 particles affect the microstructural development. Therefore, understanding the physics related to the microstructural evolution affected by the size/morphology of Al2O3particles needs to be clarified.

Improving Surface Quality of Resin Impregnated Paper Used for Laminated Flooring Overlaid

This study aimed to improve the quality properties of impregnated papers used as a coating material in wood-based composites, especially for high-density fiberboard (HDF) floorings, using the Taguchi method and parameter design. Three factors were evaluated in determining the interactions as they are considered the most important in affecting the product quality characteristics such as particle size of Al2O3, surface modification agent and melamine raw material. Experiments were conducted in three replications using the L18 (21 × 32) orthogonal array. Color and gloss measurements were evaluated together with the sensory analysis method, which takes into account the number of the spots in the sample as quality characteristics. The best values obtained as a result of statistical analysis were A2 for the melamine raw material, 30 to 60 μm for the particle size and N-methyl-3-(trimethoxysilyl) propylamine for the surface modifier agent. Whether the experimental factors have a meaningful effect on the quality characteristics was also tested separately by analysis of variance. Only 58 % of the effect of the evaluated factors on the outcome could be expressed with the linear model (R2adj = 0.5785).

Effect of spherical alumina crystalline phase content and particle size distribution polydispersity on the properties of silicone rubber composites

High loading of thermally conductive fillers for enhancing thermal conductivity (TC) conflicts with proper rheological viscosity in excellent thermal interface materials (TIMs), which remains a significant challenge. The physical properties (crystalline phase, particle size and distribution, etc.) of thermally conductive filler are the base of the high load in the polymer. In this paper, the α-phase content of spherical aluminum (S–Al2O3) increases after calcination, leading to the viscosity of composites increasing sharply but was only slightly improved for the TC. The polydispersity of the S–Al2O3 particle size distribution was regulated to fill the silicone rubber under the premise of controlling the same average particle size, crystalline phase content and filling amount. Results indicated the viscosity of the sample with a polydispersity value of 0.74 was 41.21 Pa s at a shear rate of 10 s−1 at 66 vol%, which was 87.7% lower than that of the sample with a polydispersity value of 0.48. And the viscosity difference became more prominent with the increasing filling amount. However, the difference in TC between several groups of samples with different polydispersity is insignificant at 60–67 vol%, which provides practical, theoretical guidance for achieving controllable viscosity and developing low-viscosity TIMs in the processing process.

YÜKSEK ENERJİLİ ÖĞÜTME İLE ÜRETİLEN Al2O3 TAKVİYELİ CU KOMPOZİTLERDE PARÇACIK BOYUTUNUN ETKİSİ

Production of copper (Cu) composites with a reinforced Cu matrix using mechanical alloying with Aluminum oxide (Al2O3) particles of different sizes was achieved using high-energy ball milling procedure. The initial materials consisted of inert gas-atomized spherical electrolytic Cu powders containing 0.5 wt. % commercial Al2O3 powders, with particle sizes ranging from 10 µm to 1 µm. Cu powders with different particle sizes of Al2O3 were high-energy ball milled at 500 rpm for 3 hours to attain a consistent distribution of Al2O3 throughout in the Cu matrix. The powders that were high-energy ball milled were then subjected to cold-pressing at 500 MPa and isothermally sintered for 1.5 hours at 880°C in an Ar atmosphere. The fabricated copper composite materials were characterized using X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDXS), density and macrohardness tests. The wear properties and mechanism were investigated through tribological pin-on-disc experiments, which revealed that the reinforcing effect was more significant when finely dispersed Al2O3 particles were combined into the Cu matrix compared to coarse Al2O3 particles.

Comparison of the wear behavior and surface properties of zirconia and resin-based CAD/CAM restorative materials after different sandblasting procedures

Objective: To evaluate the effects of different sandblasting procedures on the wear and surface properties of zirconia and resin-based CAD/CAM restorative materials and to evaluate the relationships among materials and procedures. Materials and Methods: A total of 160 specimens of 2 mm thickness were prepared from Cerasmart, Vita-Enamic, Tetric-CAD, and Katana-Zirconia CAD/CAM materials. Each material was divided into four groups. Group-1: Control; Group-2: 29 μm Al2O3; Group-3: 30 μm CoJet; and Group-4: 50 μm Al2O3. Sandblasting procedures were applied from a distance of 10 mm for 15 s at 2 bar pressure. The volume loss resulting from sandblasting was calculated. The samples were then scanned with a Nanovea-PS50 non-contact profilometer. The Ra, Rz, and Sa values were recorded. The data were analyzed with the Shapiro-Wilk test and two-way ANOVA. Results: Group-4 showed the highest Ra and Rz values in all materials. The highest Sa and volume differences values were observed for Cerasmart, Vita-Enamic, and Tetric-CAD in Group-4; similar values were obtained for Katana-Zirconia. When the materials were compared, Cerasmart exhibited the highest volume differences, Ra, Rz, and Sa values in Group-4, while Katana-Zirconia demonstrated the lowest. Conclusions: Sandblasting procedure and material type showed a significant impact on the wear and surface properties. The abrasive effect increased with the increasing Al2O3 particle sizes for resin-matrix materials. Sandblasting with 50 μm Al2O3 exhibited the lowest wear and surface roughness values for Katana-Zirconia and the highest for Cerasmart.

Effect of the substrate surface and coating powder hardness on the formation of a cold sprayed composite layer

Abstract In this study, the powder hardness and substrate surface hardness on the coating formation in the cold spray process was investigated. The AA6082 aluminum alloy hardened by the shot-peening process was used as the base material. Two different metallic powders and a ceramic particle powder were used as powder materials with different hardness. Thus, the powder particles from different materials were sprayed onto the surface under the same spraying process conditions. In order to obtain a workpiece surface with different hardness values, shot-peening treatment was applied to the substrate material at different treatment times. According to the microstructural examination, the harder metallic coating powder has accumulated more and the lower hardness metallic coating powder has accumulated less when the substrate material hardness increases. Al2O3 particles in the layer formed were distributed close to homogeneous. Furthermore, the size of Al2O3 particles near the contact surface has become much finer especially in the long-term shot peened samples due to their higher hardness. From the indentation experiments, the elastic behavior and recovery amount of the composite coating layer increased due to the increase of the substrate surface hardness, and the stress distributions were performed less after the load was removed.

Nano alumina effect on ionic conductivity of (X)KNO3 – (1-X)Ba(NO3)2

In this research, the dc ionic conductivity of (X)KNO3–(1-X) Ba(NO3)2 systems has been investigated by varying the particle size of diffused nano alumina. Crystals of Ba(NO3)2 and KNO3 were synthesized by slow evaporation method. DSC,DTA and XRD analysis of the diffused systems indicate no new phase has been evolved after the addition of alumina. An increase in ionic conductivity has been observed upto a threshold mole percent in the diffused system with various particle size of Al2O3. Around 2 3 order magnitude difference in conductivity value is also recorded in the diffused samples as compared to unmodified system. The enhancement of ionic conductivity has also been explained on the basis of generation of vacancies and development of space charge region in the system. we have aimed at enhancing the conductivity of this host by studying the influence of γ-Al2O3 with different particle sizes viz. 1 µm, 0.3 µm, 0.06 µm. An attempt has been made to identify the conductivity enhancement mechanism operating in this system.

Improving Thermal Conductivity of Injection Molded Polycarbonate/Boron Nitride Composites by Incorporating Spherical Alumina Particles: The Influence of Alumina Particle Size.

In this work, the influences of alumina (Al2O3) particle size and loading concentration on the properties of injection molded polycarbonate (PC)/boron nitride (BN)/Al2O3 composites were systematically studied. Results indicated that both in-plane and through-plane thermal conductivity of the ternary composites were significantly improved with the addition of spherical Al2O3 particles. In addition, the thermal conductivity of polymer composites increased significantly with increasing Al2O3 concentration and particle size, which were related to the following factors: (1) the presence of spherical Al2O3 particles altered the orientation state of flaky BN fillers that were in close proximity to Al2O3 particles (as confirmed by SEM observations and XRD analysis), which was believed crucial to improving the through-plane thermal conductivity of injection molded samples; (2) the presence of Al2O3 particles increased the filler packing density by bridging the uniformly distributed BN fillers within PC substrate, thereby leading to a significant enhancement of thermal conductivity. The in-plane and through-plane thermal conductivity of PC/50 μm-Al2O3 40 wt%/BN 20 wt% composites reached as high as 2.95 and 1.78 W/mK, which were 1183% and 710% higher than those of pure PC, respectively. The prepared polymer composites exhibited reasonable mechanical performance, and excellent electrical insulation properties and processability, which showed potential applications in advanced engineering fields that require both thermal conduction and electrical insulation properties.

A Novel Treatment: Effects of Nano-Sized and Micro-Sized Al2O3 on Steel Surface for the Shear Strength of Epoxy-Steel Single-Lap Joints.

Traditional steel surface treatment (e.g., sand blasting, or silane treatment) was regarded as an effective method to improve the bonding strength of steel–epoxy single-lap joints. In the present study, a new steel surface treatment method was developed. With this method, the steel surfaces were treated with suspensions of nano-sized and micro-sized Al2O3 particles in ethanol/water mixture using the dip-coating method. Both Al2O3 particle sizes were previously treated or not treated with silane. Single-lap shear tests of the steel–epoxy bonds were conducted to compare the effects of the treating methods. According to the testing results, the highest increase in the bonding strength (by 51.8%) was found for the steel coated with the suspension of silane treated nano-Al2O3 particles. Scanning electron microscopy (SEM) analysis and energy dispersive spectrometer (EDS) analysis indicates that the nano-Al2O3 particles were clearly attached to the treated steel surfaces. Moreover, the steel surface with the silane-treated nano-Al2O3 particles was found to clearly enhance the contact angle between the steel and epoxy resin. The fracture morphology analysis of the single-lap shear testing specimen shows that the bonding between the steel and adhesive changed from steel–epoxy interfacial failure to cohesive failure when the steel surfaces were treated with the nano-Al2O3 particles suspension. The developed steel surface treatment method with the suspension of nano-particles proves to be effective and reliable in enhancing the bonding strength of the steel-to-epoxy adhesives.

The 3D Printing Behavior of Photocurable Ceramic/Polymer Composite Slurries Prepared with Different Particle Sizes.

Ceramic polymer composite slurries were prepared using nano- and micro-sized Al2O3 in order to analyze rheological properties, sedimentation, and curing behavior. Slurries with different Al2O3 particle sizes were prepared with varying concentrations of photoinitiator, and subjected to different exposure times to prepare a printing object. All slurries exhibit shear-thinning behavior, and the viscosity increases with decreasing Al2O3 particle size. The 100 nm Al2O3 slurry is confirmed to be more sol-like, while the 500 nm and 2 μm Al2O3 slurries have a gel-like structure. As the Al2O3 particle size increases, a thick sedimentation layer forms due to rapid settling, but as the distance between particles increases, the UV light scattering reduces, and the curing rate increases. The exposure time range viable for printing, and the dimension conformity of the printed specimen with the design file, is improved by increasing the Al2O3 particle size. In the case of 500 nm and 2 μm Al2O3 slurries, the maximum heat flow, curing enthalpy, and conversion rate are high with respect to photoinitiator concentration, in the order of 1.0 > 0.1 > 3.0 wt.%. When the photoinitiator concentration exceeds 1 wt.%, it appears to affect the reactivity of the slurry.

Structure-property correlation and high-temperature erosion performance of Inconel625-Al2O3 plasma-sprayed bimodal composite coatings

In the present experimental work, Inconel-625 (IN625) was reinforced with Al2O3 (30 wt%) to develop composite coatings with plasma spraying technique on ASTM SA210 GrA1 boiler steel. Three composite coatings were developed by varying Al2O3 particle sizes in micrometric, nano, and bimodal forms. The Inconel625 + 30 wt% micrometricAl2O3, Inconel625 + 30 wt% nano-Al2O3 and Inconel625 + 15 wt% micrometric Al2O3 + 15%nano-Al2O3 combinations were considered. The developed composite coatings were analyzed for the detailed microstructure studies, microhardness, fracture toughness, and elevated temperature erosion test. The elevated temperature erosion tests for bare substrate and coatings were conducted at 900 °C by using an erosion test rig (air jet) at two impingement angles 30° and 90°. By studying the eroded surfaces through scanning electron microscopy (SEM) micrographs, the mechanism of material removal was predicted. The existence of grooves and lips at a 30° and 90° impact angle on surfaces indicate the erosion mechanism consists of ploughing and micro-cutting action in the substrate. At 30° and 90° impact angles, all composite coatings exhibited a brittle erosion mode as erosion characteristics. The micrographs of eroded surfaces indicated splat removal, cracks, and fracture as the main erosion mechanism. The outcomes of the tests revealed that the bimodal composite coatings successfully protect the underlying substrate owing to their hardness and fracture toughness which is higher than the other two coatings. The better outcome of bimodal coatings was related to refined microstructures and good interaction among nano and micrometric Al2O3 reinforcement.

A novel approach for in-situ preparation of copper/graphene composite with high hardness and high electrical conductivity

A bulk Cu/graphene-Al2O3 composite with high electrical conductivity (96.95% IACS) and high hardness (87.21 HV) was successfully fabricated through vacuum hot pressing sintering by introducing aluminum isopropoxide as the carbon source. The in-situ formed graphene with high-quality distributes along the grain boundary, the nano sized Al2O3 particles generated near the interface. Both graphene and Al2O3 nano particles greatly refine the microstructure of the Cu/graphene composite and strengthen the matrix. The cold rolled Cu/graphene-Al2O3 sheet presents high electrical conductivity and high strength. The coexistence of graphene and Al2O3 nano particles blocks the movement of grain boundaries, delays the recovery and recrystallization process of the Cu matrix and makes the composite possess excellent softening resistance. The work provides a new idea for large-scale preparation of high-performance Cu/graphene composites.

The Establishment of Thermal Conductivity Model for Linear Low-Density Polyethylene/Alumina Composites Considering the Interface Thermal Resistance.

An optimized thermal conductivity model of spherical particle-filled polymer composites considering the influence of interface layer was established based on the classic series and parallel models. ANSYS software was used to simulate the thermal transfer process. Meanwhile, linear low-density polyethylene/alumina (LLDPE/Al2O3) composites with different volume fractions and Al2O3 particle sizes were prepared with the continuous mixer, and the effects of Al2O3 particle size and volume fraction on the thermal conductivity of the composites were discussed. Finally, the test result of the thermal conductivity was analyzed and compared with ANSYS simulations and the model prediction. The results proved that the thermal conductivity model considering the influence of the interface layer could predict the thermal conductivity of LLDPE/Al2O3 composites more precisely.

Microstructural observation and mechanical properties behavior of Al2O3/Al6061 nanocomposite fabricated by stir casting process

Aluminum oxide (Al2O3) nanoparticles are capable of improving the material characteristics if reinforced to soft and low strength material. The major limitation in the utilization of Al alloy 6061 in medium to heavy stress applications such as automobile, defense, transportations, and aerospace is low hardness and strength. In order to overcome the deficiency of Al6061, nano-Al2O3 reinforced Al6061 matrix nanocomposite (AMNC) was successfully fabricated on machinated aluminum stir casting furnace. Al2O3 nanoparticles in 2,4,6 and 8 wt.% were reinforced in the Al6061 matrix and the effect on mechanical and microstructure behavior was investigated by field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), hardness, and tensile testing methods. Higher magnification FESEM micrographs revealed that reinforcement of nano-Al2O3 leads to considerable grain refinement and uniform distribution with less porosity. The mechanical properties results showed enhancement in tensile strength (by 130%), hardness (by 156%), yield stress (by 360%) with reinforcement of nano-Al2O3 over the base alloy Al6061. It was observed that the nano size of Al2O3 particles, the quantity of reinforcement, and the stir casting process were effective factors on the microstructure and mechanical properties enhancement.