Papers by Keyword: Nano-Alumina

Abstract: Mechanical properties and failure behavior of 3D printed poly (lactic) acid (PLA) reinforced with varying loadings of nano-alumina (Al₂O₃) (0, 2.5, 5.0, and 10.0 wt.%) were investigated through simulation using a finite element analysis (FEA)-based software. Tensile test specimens were 3D printed via fused deposition modeling (FDM) technique and underwent actual testing. The mechanical properties determined were then used as parameters for the FEA simulation to achieve prediction accuracy. Specifically, this study utilized MSC Patran and Nastran software to simulate the tensile test on the modeled test specimen with tetrahedron mesh. The finite element model was verified by comparing the simulated values with the results of actual experimental testing. Upon calculation, the average percentage differences for the tensile strength, elastic modulus, and displacement were 5.86%, 12.07%, and 10.57%, respectively. Although percentage differences were obtained, using FEA as an initial analysis for the prediction of mechanical properties and failure behavior could serve as a solution for better design and materials optimization.

Abstract: Nowadays, multi-functional materials are strongly needed to meet the requirements of next-generation electronic devices. In this work, two different nanostructured fillers, reduced graphene oxide (RGO) and nanoalumina, were chosen to study their effect on the thermal, electrical and mechanical properties of the prepared epoxy composites at different loadings (0.5 to 2 wt%). RGO was firstly prepared and characterized by XRD, Raman spectroscopy and TEM confirming its production. The results revealed that RGO showed excellent adhesion with the polymer. Whilst, alumina aggregated and debonded from the matrix, as confirmed by SEM images. Hence, at only 2 wt%, RGO/epoxy composites exhibited the highest thermal conductivity (0.391 W/m-K), which was 1.96 times higher than the neat epoxy. Whereas, the alumina/epoxy composites showed lower increment at the same loading (0.206 W/m-K). However, at 2 wt% RGO, electrical percolation networks had been formed across the matrix (DC conductivity = 2×10^-7 S/cm). While, epoxy filled with alumina remained insulative at any loading (~ 10^-12 S/cm at 100 Hz). Besides, the tensile strength of the composites was improved by 75% and 37% when filled with 0.5 wt% RGO and alumina, respectively. These results are very useful for preparing multi-functional polymeric materials, which are critically required for packaging industries.

Abstract: This paper presents the effect of adding nanoparticles SiO₂ and Al₂O₃ in the cement with respect to mechanical, physical and structural properties. Nanoparticles were chosen for the development of nanocomposite building materials with high mechanical strength, durability and low permeability. Correspondingly, the cement used is Portland Cement CEMI42.5N. Five compositions have been prepared, a reference sample (OPC) and pastes with different nanoparticles. Nanoparticles of SiO₂ and Al₂O₃ were added in 1.5% and 3% by weight of cement and the produced samples were tested after 7, 28, 90 and 120 days of curing. All the samples, in every hydration period, were tested for compressive strength, while their open porosity was measured and their microstructure was examined by means of infrared spectroscopy. Furthermore, for certain hydration periods, the chemical and elemental composition of the samples was evaluated by means of X-ray diffraction and scanning electron microscopy. The samples were also evaluated for capillary water absorption and shrinkage, while thermal analysis was performed for specific samples. The comprehensive analysis revealed a positive effect, in terms of structural properties, of nanoparticle admixture in cementitious systems. The addition of nanoparticles influence the workability of the composites and contributes to the formation of crystallization nuclei, which in turn enhance the durability of the material. Interestingly, it was found that high concentration of nanoAl₂O₃ in the admixure, results in high mechanical properties. Highlights: Different analytical techniques were combined in order to holistically test nanomodified cement pastes. nanoalumina is systematically tested as additive in cement pastes.

Abstract: Earthen materials have been used in construction for centuries. Nowadays, a certain appeal towards natural materials rose again due to the various benefits they hold. Besides being inexpensive and approachable, earthen construction offers a clear sustainable method of modern manufacturing. Since earthen materials present high absorption and relatively low compressive strength, the main purpose of this study was to enhance these abilities of clay-based mortars using nanoadditives. To achieve the mechanical and physical invigoration of the clay matrix two different compositions were fabricated by the use of nanoclay, nanosilica and nanoalumina. The addition of nanoclay (NC) at 5%w/w of binder, indicated a lower water absorption and an increase in mechanical properties, while the use of nanosilica and nanoalumina combined at 1.5% and 1% w/w of binder respectively, outline a less stable and compact structure.

Abstract: This work investigates the effect of nanosized Al2O3 addition on the sinterability of YSZ electrolyte. (1−x)YSZ + Al2O3 ceramics with compositions x = 0 to 0.01 were prepared by the conventional mixed oxide route from a commercial powder suspension (particle size <50 nm), and sintered at 1200 to 1500°C for 2 hours in air. Densification, phase evolution, and microstructure were characterized by SEM/EDS and XRD. An improvement in sintered density was observed for the samples with 0.2 to 0.5 mol% Al2O3, though depending on the sintering temperature. Only cubic zirconia was detected as crystalline phase, although XRD features suggested chemical interactions depending upon the amount of Al2O3. The grain size of YSZ was homogeneous and no second phase segregation was detected in the tested range of incorporated nano-Al2O3 and sintering temperatures.

Abstract: Synthesis processes of nano alumina abrasive precursor using precipitation method and sol-gel method were investigated in this study. Using pressureless sintering, the nano alumina abrasive was prepared. Mechanical properties of the samples were measured by using single particle compressive strength tester. The microstructures of them were examined by using field emission scanning electron microscopy (FESEM). The results indicated that the performance and microstructure of the samples are greatly relative to the synthesis processes. Compared with samples prepared by precipitation method, the samples prepared by sol-gel method have higher compressive strength, smaller grain size and more uniform microstructure. The average grain size of the alumina abrasive was below 100nm.

Abstract: In this paper, the anticorrosive performances of fastener coatings containing PTFE and/or nano aluminum particles were investigated by using electrochemical impedance spectroscopy, scanning electron microscope. The impedance spectroscopy was interpreted by means of analysis equivalent electrical circuits. The coating capacitance of the films was monitored with the immersion time to establish the water and ions permeability of these paint films. By comparison with clear coating, PTFE and PTFE- nano aluminum pigmented coatings, the results indicated that PTFE lowers the protective properties of the waterborne epoxy film although it can provide lubricating effect. The nano aluminum powder presented the best beneficial effect and resulted in a significant increase in corrosion resistance of the PTFE- nano aluminum composite coatings. The corrosion-resistant mechanism of the effect of PTFE and nano aluminum particles in the coating is discussed.

Abstract: In the present research the thermal properties of phenolic resin 2123-P mix-modified by nano-alumina are investigated. The nano-alumina employed in the research can be classified two kinds, one is treated by 1%wt. silane coupling agent KH-550 relative to the weight of alumina, and the other is commercial alumina untreated. DTA-TG results show the thermal stability and anti-weight loss ability of the mix-modified phenolic resin 2123-P with KH-550 treated alumina are increased relative to those of the pure 2123-P and those of the mix-modified 2123-P with commercial alumina, and the results are to be proved by the constant speed friction and wear tests. It can be observed from SEM that KH-550 treated nano-alumina particles are dispersed equably in phenolic resin.