Al2O3 Ceramic Particles Research Articles

Tribological characterization of heat-treated Ni-P and Ni-P-Al2O3 composite coatings by reciprocating sliding tests

Linear reciprocating-ball-on-flat sliding wear tests were performed to evaluate the tribological performance of electroless Ni-P and Ni-P-Al2O3 composite coatings in the as-deposited and thermal-treated conditions for reinforcement contents of 8.3 and 18.2 vol% alumina particles. The tests were performed under dry conditions at loads of 5, 10 and 15 N to samples annealed in the range 100–600 °C. The effect of alumina content on the heat treatment response was studied and related with the microstructure and wear behavior. Analysis of variance (ANOVA) was used to study the effect of process parameters on the wear rate. A Taguchi L27 orthogonal array design was applied to evaluate the influence of annealing temperature, amount of reinforcement, load and sliding distance on wear rate. It was found that all the coatings decreased the wear rate of the steel substrates in more than one order of magnitude. The composite coatings are hardened by the presence of the Al2O3 ceramic particles that act as a barrier to the plastic deformation of the Ni-P matrix. With temperature, a more homogeneous texture and densification of deposits was observed, and the appearance of hard Ni-P precipitates was detected, which decreased slightly the coefficient of friction of the ternary deposits. The best behavior was observed on heat treated samples at temperature of 400 °C which corresponds to the temperature at which crystallization of hard precipitates (Ni3P) occurred. Above that temperature, the hardness and wear resistance were decreased by the growth of the phosphides and thickening of nickel grain due to overaging of the matrix. The Taguchi method confirmed an optimal combination of parameters 18.2 vol% Al2O3, 400 °C, 10 N load and 500 m sliding distance for minimum wear rate. From ANOVA analysis, annealing temperature and amount of reinforcement were identified as the highly contributing parameters over the wear behavior of electroless coatings. It was observed plastic deformation of the matrix but smother scars in the composite coatings as well as the presence of tribochemical layers. The inherent variability in wear performance under linear reciprocating sliding is correlated to the wear mechanisms involved, abrasive wear and adhesion wear. In fact, a tribochemical mixed-layer is formed, which involves a complex mechanism with wear debris from both surfaces, oxidation, comminution and formation of new sublayers.

The effect of La2O3 addition on intermetallic-free aluminium matrix composites reinforced with TiC and Al2O3 ceramic particles

Abstract In this work, intermetallic-free aluminium matrix composites reinforced with TiC and Al2O3 ceramic particles were successfully prepared via an in situ reaction of Al-Ti-C-CuO-La2O3 during self-propagating high-temperature synthesis. The effect of adding the rare earth metal oxide La2O3 was studied by using differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, optical microscopy and Brinell hardness tests. The results showed that La2O3 could promote the wettability of the C and Al melt in the Al-Ti-C-CuO system. The final products of the in situ reaction for the 2.5Al-1Ti-1.2C-0.5CuO-0.005La2O3 system were TiC particles and Al2O3 particles, and the system was free of intermetallic compounds. The prepared aluminium matrix composites were greatly refined with an average grain size of 20.6 μm. The intermetallic-free aluminium matrix composites reinforced with TiC and Al2O3 particles showed up to two times higher Brinell hardness value than the matrix 6063 aluminium alloy.

Improvement of dispersion stability and 3D-printing characteristics of ceramics in photopolymers by controlling the coating thickness of silane coupling agents

For stereolithography (SLA) 3D printing applications, Al2O3 ceramic particles with a different coating thickness of silane coupling agent (VTES, vinyltriethoxysilane) were prepared by hydrolysis and condensation reactions. Then, VTES-coated Al2O3 ceramic particles were dispersed in commercial photopolymers (3DK-A83B) based on inter-penetrating network (IPN) phenomena. The morphology and average coating thickness of VTES-coated Al2O3 ceramic particles were observed by field-emission transmission electron microscopy (FE-TEM), and the particle size of VTES-coated Al2O3 ceramic particles was investigated by a laser scattering particle size distribution analyzer. The dispersion stability of the VTES-coated Al2O3/3DK-A83B composite solution with different VTES coating thicknesses and ceramic contents was investigated by Turbiscan and relaxation nuclear magnetic resonance (NMR), while the optimum coating conditions for VTES were also observed. In the case of Al2O3 ceramic particles with a similar VTES coating thickness, the dispersion stability was similar, even when the ceramic content increased. The cross-sectional images of 3D-printed objects were observed by field-emission scanning electron microscopy (FE-SEM), and about 48% of volume shrinkage of the 3D-printed objects was calculated after sintering.

A Study on the Rheological and Mechanical Properties of Photo-Curable Ceramic/Polymer Composites with Different Silane Coupling Agents for SLA 3D Printing Technology.

Silane coupling agents (SCAs) with different organofunctional groups were coated on the surfaces of Al2O3 ceramic particles through hydrolysis and condensation reactions, and the SCA-coated Al2O3 ceramic particles were dispersed in a commercial photopolymer based on interpenetrating networks (IPNs). The organofunctional groups that have high radical reactivity and are more effective in UV curing systems are usually functional groups based on acryl, such as acryloxy groups, methacrloxy groups, and acrylamide groups, and these silane coupling agents seem to improve interfacial adhesion and dispersion stability. The coating morphology and the coating thickness distribution of SCA-coated Al2O3 ceramic particles according to the different organofunctional groups were observed by FE-TEM. The initial dispersibility and dispersion stability of the SCA-coated Al2O3/High-temp composite solutions were investigated by relaxation NMR and Turbiscan. The rheological properties of the composite solutions were investigated by viscoelastic analysis and the mechanical properties of 3D-printed objects were observed with a nanoindenter.

The effect of Milling time, Milling Speed and Ball to Powder Weight Ratio on the Physical Properties of Submicron Al2O3 Ceramic Particles Fabricated by Mechanical milling Method

The effect of Milling time, Milling Speed and Ball to Powder Weight Ratio on the Physical Properties of Submicron Al2O3 Ceramic Particles Fabricated by Mechanical milling Method

Interface transition layer interaction mechanism for ZTAP/HCCI composites

Abstract ZrO2-toughened Al2O3 (ZTA, 40%) ceramic particles reinforced by high chromium cast iron (HCCI) matrix composites were fabricated by casting infiltration. The interaction between the ZTA ceramic particles and the matrix by the interface transition layer (ITL) was investigated. From the perspective of interfacial bonding, the ceramic particles and HCCI experienced metallurgical bonding by the ITL. Electron probe microanalysis results demonstrated that Cr, Fe, and Mn diffused from the matrix to the ITL. Transmission electron microscopy revealed that the main phases in the transition layer were glassy. The wear resistance of the composites with the transition layer was better than those without, as indicated by the three-body abrasive wear tester.

Effect of particle morphology of Ni on the mechanical behavior of AZ91E-Ni coated nano Al2O3 composites

The properties of any composite always depend on the bonding between the matrix and reinforcement phases. One way of improving the wettability of reinforcement in a matrix is to apply a layer of coating on reinforcing particles. The present study aims at developing Ni coating on nano Al2O3 ceramic particles and dispersing them in AZ91E magnesium matrix material. The electroless plating method has been employed to coat the particles and semi solid stir casting technique was adopted to prepare the composites. Several weight fractions of dispersed phase are considered to analyze the behavior of the fabricated composites. Field emission scanning electron microscopy (FESEM) and x-ray diffraction analysis has been carried out to investigate the distribution of particles and phase characteristics of the proposed material. The physical and mechanical behavior of the material was examined through density measurements, hardness, elastic modulus, ductility and tensile strength calculations. The metal coating on reinforcement aids to promote metal–metal bonding interface reactions which result in improved properties of the composite. Tensile fractography was carried out under FESEM and presented.

Composite gel polymer electrolyte with ceramic particles for LiNi1/3Mn1/3Co1/3O2-Li4Ti5O12 lithium ion batteries

In this study, a composite polymer matrix for gel polymer electrolyte (GPE) is prepared by the electrospinning process, combining poly(vinylidene fluoride-co-hexafluoropropylene) and nano-sized Al2O3 ceramic particles. The composite matrix is impregnated with a liquid electrolyte to prepare the GPE-Al2O3 composite and its properties are compared with those of pure GPE. The GPE-Al2O3 composite improves the interfacial resistance, ion coordination and the electrochemical stability of the GPE. The electrochemical performances are analyzed by applying the GPEs to LiNi1/3Mn1/3Co1/3O2 (NMC) and Li4Ti5O12 (LTO) cells. The GPE-Al2O3 composite exhibits a higher discharge capacity than the GPE at 0.1 C-rate and excellent performance in both the LTO and the NMC half-cells under cyclic conditions. The GPE-Al2O3 composite shows good compatibility and high electrochemical property on LTO/NMC full-cell.

Effect of Al2O3 Ceramic Particles on Corrosion Behaviour and Tribological Properties of Nickel Composite Coatings

The paper presents a study on corrosion behaviour and tribological properties of nickel composite coatings deposited by electrochemical method on aluminium alloy from 2xxx series (AlCu4MgSi). The nickel composite coatings were produced in a Watts bath of the following chemical composition: NiSO4·7H2O 150 g/l, NiCl2·6H2O 30 g/l, H3BO3 30 g/l with the addition of saccharin in an amount of 2 g/l. As hard ceramic dispersed particles embedded in the coating, alumina (Al2O3) was used in an amount of 12,5; 25; 50 and 75 g/l. Coatings were produced using cathodic current density of 6 A/dm2, bath temperature of 60°C, pH 4, and the time 60 minutes. The electroplating bath was stirred with a mechanical stirrer (350 rpm). The results obtained were compared with a nickel coating deposited without the ceramic particles. It was found that the presence of Al2O3 increases the wear resistance of composite coatings, but does not significantly improve the corrosion properties.

The effect of TiC/Al2O3 composite ceramic reinforcement on tribological behavior of laser cladding Ni60 alloys coatings

Abstract The composite coating reinforced with TiC and Al2O3 ceramic particles were fabricated on the Cr12MoV steel by laser cladding. The cross-section, microstructure, phase, microhardness and wear resistance of the composite coating were investigated by the optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Vickers microhardness tester and dry sliding wear testing machine, respectively. An obvious crack occurs in the coating when the content of the ceramic reinforcement is 15%. Composite coatings have good metallurgical bonding with the substrate when the content of the ceramic is less 15%. The phases of the composite coatings are composed of solid solutions (Ni–Cr–Fe and γ-(Fe,Ni)), chromic carbides (Cr3C2 and Cr2C), ferric carbide (Fe3C) and ceramics (TiC and Al2O3). The composite ceramics that Ti-rich alloy compound was coating unfused Al2O3 and TiC ceramics respectively were generated in the coating. A part of Ti element and C element, dissolved from the original TiC ceramic, precipitate from the matrix to form new TiC ceramic. These kinds of composite ceramic particles significantly improved the wear resistance of the coating via enhancing the bonding strength between the ceramic particles and the matrix.

Physiopathologie du syndrome des jambes sans repos

Two methods were used to obtain amorphous aluminium alloy powder: gas atomization and melt spinning. The sprayed powder contained only a small amount of the amorphous phase and therefore bulk composites were prepared by hot pressing of aluminium powder with the 10% addition of ball milled melt spun ribbons of the Al84Ni6V5Zr5 alloy (numbers indicate at.%). The properties were compared with those of a composite containing a 10% addition of Al2O3 ceramic particles. Additionally, a composite based on 2618A Al alloy was prepared with the addition of the Al84Ni6V5Zr5 powder from the ribbons used as the strengthening phase. X-ray studies confirmed the presence of the amorphous phase with a small amount of aluminium solid solution in the melt spun ribbons. Differential Scanning Calorimetry (DSC) studies showed the start of the crystallization process of the amorphous ribbons at 437 °C. The composite samples were obtained in the process of uniaxial hot pressing in a vacuum at 380 °C, below the crystallization temperature of the amorphous phase. A uniform distribution of both metallic and ceramic strengthening phases was observed in the composites. The hardness of all the prepared composites was comparable and amounted to approximately 50 HV for those with the Al matrix and 120 HV for the ones with the 2618A alloy matrix. The composites showed a higher yield stress than the hot pressed aluminium or 2618A alloy. Scanning Electron Microscopy (SEM) studies after compression tests revealed that the propagation of cracks in the composites strengthened with the amorphous phase shows a different character than these with ceramic particles. In the composite strengthened with the Al2O3 particles cracks have the tendency to propagate at the interfaces of Al/ceramic particles more often than at the amorphous/Al interfaces.

Aluminium based composites strengthened with metallic amorphous phase or ceramic (Al2O3) particles

Two methods were used to obtain amorphous aluminium alloy powder: gas atomization and melt spinning. The sprayed powder contained only a small amount of the amorphous phase and therefore bulk composites were prepared by hot pressing of aluminium powder with the 10% addition of ball milled melt spun ribbons of the Al84Ni6V5Zr5 alloy (numbers indicate at.%). The properties were compared with those of a composite containing a 10% addition of Al2O3 ceramic particles. Additionally, a composite based on 2618A Al alloy was prepared with the addition of the Al84Ni6V5Zr5 powder from the ribbons used as the strengthening phase. X-ray studies confirmed the presence of the amorphous phase with asmall amount of aluminium solid solution in the melt spun ribbons. Differential Scanning Calorimetry (DSC) studies showed the start of the crystallization process of the amorphous ribbons at 437°C. The composite samples were obtained in the process of uniaxial hot pressing in a vacuum at 380°C, below the crystallization temperature of the amorphous phase. A uniform distribution of both metallic and ceramic strengthening phases was observed in the composites. The hardness of all the prepared composites was comparable and amounted to approximately 50 HV for those with the Al matrix and 120 HV for the ones with the 2618A alloy matrix. The composites showed a higher yield stress than the hot pressed aluminium or 2618A alloy. Scanning Electron Microscopy (SEM) studies after compression tests revealed that the propagation of cracks in the composites strengthened with the amorphous phase shows a different character than these with ceramic particles. In the composite strengthened with the Al2O3 particles cracks have the tendency to propagate at the interfaces of Al/ceramic particles more often than at the amorphous/Al interfaces.

Effects of alumina (Al2O3) addition on the cell structure and mechanical properties of 6061 foams

Abstract

Preparation and microstructure of in-situ (ZrB2+Al2O3+Al3Zr)p/A356 composite synthesized by melt direct reaction

(ZrB2+Al2O3+Al3Zr)/A356 composites were synthesized by melt direct reaction from A356-(K2ZrF6+KBF4+Na2B4O7) system. The phase compositions and the microstructures of the as-prepared composites were investigated by XRD, SEM and TEM. The results show that the reinforcements are composed of ZrB2 and Al2O3 ceramic phase particles and Al3Zr intermetallic particles. The ZrB2 particulates are easy to join together to form some particle clusters and distribute along the α(Al) grain boundary. The morphologies of the ZrB2 particulates are in hexagon-shape with the size of about 50 nm. The TEM investigation results of Al3Zr indicate that Al3Zr grows in the form of facet with the length-diameter ratio of about 20. The morphologies of Al2O3 particles are in rectangular-shape and ellipsoidal-shape, with the size of about 0.1 μm. In addition, the interfaces of the matrix and particles are net and no interfacial outgrowth is observed.

Mechanical properties and microstructure of Al2O3/TiAl in situ composites doped with Cr and V2O5

Al2O3/TiAl in situ composites doped with Cr and V2O5 were successfully prepared from Ti, Al, TiO2, Cr and V2O5 by hot pressing. The effect of in situ formed Al2O3 content on the phase composition, microstructure and mechanical properties of Al2O3/TiAl composites were investigated. The results show that the as-synthesized composites mainly consisted of ?-TiAl/?2-Ti3Al matrix and dispersive Al2O3 reinforcing phases. The in situ formed fine Al2O3 ceramic particles mainly disperse on the grain boundaries of TiAl, resulting in refinement of TiAl matrix, which improves the mechanical properties of the Al2O3/TiAl in situ composite. The composite with 7.54 at.% Al2O3 possesses the maximum flexural strength and fracture toughness of 335.38 MPa and 5.39 MPa m1/2, respectively. The strengthening mechanism was also discussed in detail.

Preparation and Properties of Al<sub>2</sub>O<sub>3</sub> Ceramic Reinforced Mo-Based Composites by Al(NO<sub>3</sub>)<sub>3</sub> Precursor

To enhance the wear resistance of molybdenum alloys, Mo-based composites reinforced by Al2O3 ceramic particles were developed. Using Al(NO3)3 aqueous solution and MoO3 as raw materials, the Molybdenum powders mixed with Al2O3 particles were prepared by liquid-solid incorporation, drying, pyrolysis of Al(NO3)3 and deoxidation of MoO3 by H2. And then the Mo-based composites with 3-10vol.% Alumina were prepared by compaction and sintering at 1840°C. The morphology of the Molybdenum powder and microstructure of the composites were analyzed by SEM and XRD. The micro-hardness, density and wear property of composites were researched. The results showed that α-Al2O3 ceramic particles and Molybdenum matrix compose the composites. With the increase of Alumina content, the molybdenum powders become fine and rule, the grains of composites become fine, the microhardness of Molybdenum matrix increases, and the density first increases and then decreases. The friction coefficient of composite is scarcely affected by the alumina content. While the wear weight of the composite decrease with the increase of Alumina content. There are obvious plow furrow and abrasive dust on the worn surface, showing the abrasive wear characterization.

Fabrication In Situ TiB2–TiC–Al2O3 Multiple Ceramic Particles Reinforced Fe-Based Composite Coatings by Gas Tungsten Arc Welding

A Fe-based composite coating reinforced by multiple TiB2–TiC–Al2O3 ceramic particles was developed by gas tungsten arc welding (GTAW) melting process. Mixture of aluminum (Al), boron carbide (B4C), and titanium dioxide (TiO2) powders was used as precursors, and as a consequence TiB2–TiC–Al2O3 multiple ceramic particles were in situ synthesized during GTAW melting process. Microstructural investigations showed that TiB2 particles exhibit a blocky morphology, TiC particles are of flower-like shape, and the Al2O3 particles exist as small black dots and located in the core of reinforced particles. The hardness and wear resistance of the coatings increased drastically in comparison with that of the substrate.

Fabrication of AA6061/Al2O3 nano ceramic particle reinforced composite coating by using friction stir processing

Nano ceramic particle reinforced composite coatings were created by incorporating Al2O3 ceramic particles into the surface of AA6061-T6 alloy plate with multiple pass friction stir processing (FSP). Optical microscopy and Micro-Vickers hardness tests were employed to investigate the influence of axial force and the number of FSP pass on the distribution of the ceramic particles and the hardness of the generated nano ceramic particle reinforced composite coating. Results show that the composite coating is as deep as the length of the pin probe. No distinct interface was developed between the coating and the base metal. The composite region becomes greater as the axial force and the number of FSP pass increased. At the same time, the distribution of the ceramic particles became more homogeneous. Nano particles in the coating have no significant effect on the macro-hardness of AA6061-T6 aluminum alloy even in the composite zone due to the softening of matrix material resulted from overaging. Spindle torque of the tool increased with increasing axial force, while it became less variable and smaller in subsequent pass compared to that in the first pass.

Thermal diffusivity of Al-Mg based metallic matrix composite reinforced with Al2O3 ceramic particles

Thermal diffusivities of Al-Mg based metallic matrix composite reinforced with ceramic particles of Al2O3 are reported in this article. The samples were produced by rheocasting and the studied operational condition in this case is the shear rate: 800, 1400 and 2000 rpm. Additionally, the AlMg base alloy was tested. Measurements of thermal diffusivity were performed at room temperature by using photoacoustic technique.

Investigation on silver electric adhesive doped with Al2O3 ceramic particles for sealing planar solid oxide fuel cell

Abstract The silver electric adhesive doped with Al2O3 ceramic particles is used as sealing material for planar solid oxide fuel cell (SOFC). The sealing temperature of this sealing material is 600 °C with the heating rate of 2 °C min−1, and the minimal leak rate ranges from 0.030 sccm cm−1 to 0.040 sccm cm−1. When doping 15 mass% Al2O3 ceramic particles into this sealing material, the thermal expansion coefficient of this material decreases from 20 ppm K−1 to 15 ppm K−1, which improves the thermal matching performance and the long-term stability of the material significantly. When using the gradient sealing method with the pure silver electric adhesive and the silver electric adhesive doped with Al2O3 ceramic particles to seal the interface of Ni-YSZ/SUS430 in the simulating cell, the minimal leak rate of 0.035 sccm cm−1 is obtained for the cell. Furthermore, the simulating cell sealed with the compound silver electric adhesive presents good heat-resistant impact ability. Therefore, this compound sealing technique is a very promising sealing method for SOFC.