Nano-sized Reinforcements Research Articles

Influence of TiO2 nanoparticles addition on the microstructural and mechanical properties of Sn0.7Cu nano-composite solder

Abstract Composites of SC solder reinforced with 0, 0.25, 0.5 and 1 wt.% of TiO2 nanoparticles were fabricated using a mechanical technique. With increased addition of TiO2 nanoparticles, the SC nano-composite solder was found to have a slightly lower melting temperature. The addition of TiO2 nanoparticles can also effectively refine the microstructure as so β-Sn and Cu6Sn5, and increase the percentage of eutectic area. The mechanical properties (microhardness, 0.2% YS and UTS) increase with the increasing presence of reinforcement, far exceeding the strength of the eutectic SC solder. The yield strength improvement was attributed to (i) the Hall–Petch effect due to β-Sn grain size refinement. (ii) Orowan strengthening, (iii) generation of geometrically necessary dislocations to accommodate CTE mismatch between the matrix and the second phase (Cu6Sn5 and TiO2), and (iv) the load-bearing effects due to the presence of nano-sized reinforcements.

Processing, microstructure and tensile properties of nano-sized Al2O3 particle reinforced aluminum matrix composites

Nano-sized ceramic particle reinforced aluminum matrix composites fabricated using conventional stir casting technique usually present poor distribution of nanoparticles within the matrix and high porosity. In this study, nano-Al2O3/2024 composites were prepared by solid–liquid mixed casting combined with ultrasonic treatment. The obtained composite exhibited fine grain microstructure, reasonable Al2O3 nanoparticles distribution in the matrix, and low porosity. Solid–liquid mixed casting technique was effective in inhibiting the agglomeration of nanoparticles in the matrix. The application of ultrasonic vibration on the composite melt during the solidification not only refined the grain microstructure of the matrix, but also improved the distribution of nano-sized reinforcement. Compared with the matrix, the ultimate tensile strength and yield strength of 1wt.% nano-Al2O3/2024 composite were enhanced by 37% and 81%, respectively. The better tensile properties were attributed to the uniform distribution of reinforcement and grain refinement of aluminum matrix.

Nano-Sized Silica Reinforcement of Epoxidized Natural Rubber Prepared in Latex State

Modified nanosilicas have been prepared by grafting an organosiliane precursor, 3-methacryloxypropyl trimethoxysilane (MPS), onto silica surface. The grafted silane content was determined by thermogravimetric analysis (TGA). Subsequently, the modified nanosilica was used to reinforce epoxidized natural rubber (ENR). The effects of surface modification and filler content on morphological and mechanical properties of ENR nanocomposites were investigated.

Effect of Milling and B4C Nanoparticles on the Mechanical Properties of Nanostructured Aluminum Composite Produced by Mechanical Milling and Hot Extrusion

Mechanical milling was used to synthesize Al nanostructured powder in a planetary ball-mill under argon atmosphere up to 20 h. The same process was conducted for Al-4 wt. % B4C nanocomposite powders to explore the role of nanosize reinforcements on mechanical milling stages. The results show that the addition of boron carbide particles accelerate the milling process, leading to a faster work hardening rate and fracture of aluminum matrix. Tensile of a nanostructured matrix of Al prepared via hot extrusion were investigated before and after incorporation of B4C nanoparticles. The results revealed a, higher yield strength and tensile strength for nanostructured Al matrix in contrast to the commercial coarse grained Al matrix. The same trend was also found to be valid for the nanocomposite samples with respect to the base matrix.

Consolidation behavior of mechanically alloyed aluminum based nanocomposites reinforced with nanoscale Y2O3/Al2O3 particles

Abstract The compaction, sintering, microstructural and micro hardness behavior of nanocomposite powders were examined using pre-mixed (elemental) Al6063, Al6063/1.5Al2O3 Al6063/1.5Y2O3 and Al6063/0.75Al2O3/0.75Y2O3 powders. Micro-crystalline (MC) and ultrafine-grained (UFG) Al6063 nanocomposites were prepared from elemental powders by blending (0 h) and mechanical alloying (40 h). The effects of nano-size reinforcement, milling time (0 and 40 h), sintering temperature and sintering time on the relative density and micro hardness of the consolidated nanocomposite powders were examined. The compressibility behavior of nanocomposite powders in terms of particle rearrangement and plastic deformation mechanisms were investigated using Panelli and Ambrozio Filho, modified Heckel and Ge equations. The sinterability analysis of the MC and UFG nanocomposites were carried out at varying sintering temperatures (773 to 873 K) and sintering time (60 to 180 min). XRD patterns were analyzed to find the phases present and to determine crystallite size, lattice strain and lattice parameter of the sintered composites with broadening of peaks. Microstructure analysis of UFG nanocomposites were examined to study the ceramic particle distribution and to confirm the absence of other phases using TEM, FESEM and SEM/EDS.

Effect of nanotube content on mechanical properties of basalt fibre reinforced polyamide 6

In this study, 30 mass-% basalt fibre and 0·5–2 mass-% multiwall carbon nanotube (MWCNT) reinforced polyamide 6 hybrid systems were prepared by extrusion and injection moulding. The effect of nanotube content on the mechanical properties was investigated by tensile and flexural tests. The results showed that the combination of macroscopic and nanosized reinforcements improved the mechanical properties significantly, and synergetic effects can also be observed. Good dispersion of the MWCNT was proven by transmission and scanning electron microscopy.

Preparation and investigation of Al–4 wt % B4C nanocomposite powders using mechanical milling

Boron carbide nanoparticles were produced using commercially available boron carbide powder (0·8 μm). Mechanical milling was used to synthesize Al nanostructured powder in a planetary ball-mill under argon atmosphere up to 20 h. The same process was applied for Al–4 wt % B4C nanocomposite powders to explore the role of nanosize reinforcements on mechanical milling stages. Scanning electron microscopy (SEM) analysis as well as apparent density measurements were used to optimize the milling time needed for completion of the mechanical milling process. The results show that the addition of boron carbide particles accelerate the milling process, leading to a faster work hardening rate and fracture of aluminum matrix. FE-SEM images show that distribution of boron carbide particles in aluminum matrix reaches a full homogeneity when steady state takes place. The better distribution of reinforcement throughout the matrix would increase hardness of the powder. To study the compressibility of milled powder, modified heckel equation was used to consider the pressure effect on yield strength as well as reinforcing role of B4C particles. For better distribution of reinforcement throughout the matrix, r, modified heckel equation was used to consider the pressure effect on yield strength as well as reinforcing role of B4C particles.

Nano-silicon carbide reinforced aluminium produced by high-energy milling and hot consolidation

Abstract High-energy milling was studied for the ex situ strengthening of aluminium with silicon carbide (SiC) nanopowders. Heptane was used as a milling agent for both planetary- and attritor ball milling. Considering the different milling techniques and the differences in the resulting powders, effective dispersion of the nano SiC was achieved. Composite samples compacted by hot pressing showed an increase in hardness (HV 20 = 220) and a decrease in Al crystallite size from 220 to 55 nm with the nano-SiC content increasing from 1 up to 20 vol.%. The ultimate tensile strength was measured for extruded samples which resulted in 205 MPa (17% elongation) for 1 vol.% of nano-SiC and a strength of 420 MPa (4% elongation) for 10 vol.% of nano-SiC reinforcement. The mechanical properties were compared with what was predicted by the Hall–Petch relationship.

Wear characteristics of polyamide nanocomposite spur gears

Polymer nanocomposites have received considerable research attention in the past decade due to its remarkable improvement in tensile, fatigue, and tribological characteristics. This article reports the wear characteristics of pristine polyamide 6 and polyamide 6 nanocomposite (PA6NC) spur gears. The nanocomposite was made by melt intercalation method and injection moulded into gears. Molecular level interaction of nano-size reinforcement enhances the mechanical properties of polymer nanocomposite. The performance of gears at different torque levels were studied using a power absorption type gear test rig. The gear tooth surface temperature affects the wear rate and service life. The enhanced mechanical properties of PA6NC results in reduced frictional and hysteresis heat generation associated with less wear and increased life.

Effect of Nano Sized Reinforcement in PZT Based Composites

PZT-PVdF composites with 0–3 connectivity were prepared through solution casting technique. The effect of particle size (>106 μm, 106–63 μm, >63–25 μm, 80 nm, 60 nm and 40 nm) on piezoelectric coefficient (d33) of the composites was studied. The amount of crystallinity and piezoelectric coefficient of the composites were obtained from DSC and piezometer, respectively. The PZT particles distribution in the polymer matrix was analyzed using SEM studies. The amount of crystallinity was found to decrease with decrease in particle size, which in turn decreases the piezoelectric coefficient. The investigation reveals that the dispersed reinforcement influences the crystallization kinetics of PVdF polymer chain, thereby promoting localized amorphous regions, which decreases the piezoelectric coefficient.

Effects of Graphene on a Resin Transfer Molding Process Using Bisphenol A Based Epoxy Resin

Resin transfer molding is a popular process to fabricate polymer composites reinforced with a large amount of glass or carbon fibers. In general, fiber reinforcements are put in a mold, and a liquid resin such as epoxy resin is injected into the mold after preheating. For successful production of polymer composites via a resin transfer molding process, the filling and curing stages of the liquid resin as well as the mold design should be optimized. Recently, polymer composites reinforced with nanoparticles are attracting attention of researchers in academia and industries because efficient reinforcement can be achieved by small loading of nanoparticles such as carbon nanotubes and exfoliated clays. In this work, as an effort to develop light weight automotive parts, graphenes were investigated as a nano size reinforcement of epoxy resin for resin transfer molding. Graphenes were prepared from graphites by microwave irradiation. Addition of graphenes to bisphenol A based epoxy resins such as YD-128 from Kukdo Chemical results in an increase in viscosity and shear thinning behavior, affecting the filling process. The curing of epoxy resins is also affected by graphenes. In order to develop a model for simulation of the filling and curing of epoxy resins containing different amounts of graphenes in the resin transfer molding, FLUENT and MATLAB have been used in this study, which are a finite element based computational fluid dynamics analysis tool and a general purpose numerical analysis tool, respectively. The effects of graphenes on the mold filling pattern and curing profile are discussed for the resin transfer molding of bisphenol A based epoxy resins.

Role of nano-size reinforcement and milling on the synthesis of nano-crystalline aluminium alloy composites by mechanical alloying

High-energy wet ball milling was successfully employed to synthesize nano-crystalline Al 6063 alloy powders reinforced with 1.3 vol.%Al 2O 3, 1.3 vol.%Y 2O 3 and 0.65 vol.%Al 2O 3/0.65 vol.%Y 2O 3 at nano-size level. In the present study, the crystallite size of the matrix powder particle was affected by the addition of different types of nanoceramic particles separately and in combination keeping total volume percentages of such addition as constant. The nano-composite powders were characterized by SEM, FESEM, HRTEM, XRD, particle size analyzer, EDAX and DTA. Using Williamson–Hall equation, crystallite size and lattice strain of various aluminium composite powders were estimated with broadening of XRD peaks. XRD results showed that the crystallite size of aluminium reached 53 and 37 nm, respectively, after 40 h milling in case of pure Al 6063 and Al 6063/0.65 vol.%Al 2O 3/0.65 vol.%Y 2O 3 nano-composite powder with uniform particle size distribution. HRTEM observation confirmed the nano-crystalline nature of Al 6063/0.65 vol.%Al 2O 3/0.65 vol.%Y 2O 3 milled powder.

High temperature mechanical spectroscopy of fine-grained ceramics

Abstract Mechanical loss measurements were performed at high temperature in fine-grained ceramics, such as zirconia and alumina. At high temperature, the mechanical loss increases exponentially with temperature, which accounts for material creep. The results are analyzed with a model of grain-boundary sliding lubricated by an intergranular glassy phase. When the amount of the intergranular glassy phase is higher, the mechanical loss level is globally higher and so is the creep rate. On the other hand, doping fine-grained ceramics with nano-sized reinforcements such as multiwall carbon nanotubes results in a decrease in the high-temperature mechanical loss. In this case grain-boundary sliding is more difficult and as a consequence better creep resistance is observed.

Using Microwave-Assisted Powder Metallurgy Route and Nano-size Reinforcements to Develop High-Strength Solder Composites

In the present study, Sn-0.7Cu and Sn-3.5Ag lead-free solders used in the electronics packaging industry were reinforced with different volume percentages of nano-size alumina and tin oxide particulates, respectively, to synthesize two new sets of nanocomposites. These composites were developed using microwave-assisted powder metallurgy route followed by extrusion. The effects of addition of particulates on the physical, microstructural, and mechanical properties of the nanocomposites were investigated. Mechanical properties (microhardness, 0.2% YS, and UTS) for both composite systems increase with the presence of particulates. The best tensile strength was realized for composite solders reinforced with 1.5 vol.% alumina and 0.7 vol.% tin oxide particulates, which far exceeds the strength of eutectic Sn-Pb solder. The morphology of pores was observed to be one of the most dominating factors affecting the strength of materials.

Influence of Ultrasonic Processing on Nano-Sized Particle Dispersion in Magnesium Matrix Nanocomposites

The parameters of ultrasonic processing have important effects on the distribution and dispersion of nano-sized particles in magnesium matrix nanocomposite (MMNC) fabrication. In order to learn more about the above effects and produce guidelines for the fabrication of MMNC, the acoustic cavitation and streaming effects produced by high intensive ultrasonic method with different frequency and power were experimented with water, glycerol, soybean oil and oil-water mixture respectively. The results showed that the acoustic cavitation and streaming were influenced by ultrasonic frequency and power as well as the depth of waveguide dipped into melts. The ultrasonic processing of the MMNC melts with 20kHz and 1.4kW greatly improved the dispersion and distribution of nano-sized reinforcement particles in MMNC.

High-temperature mechanical loss and creep behavior of fine-grained zirconia-containing nano-sized reinforcements

Polycrystalline zirconia (3Y-TZP grade) specimens unreinforced and reinforced with multiwalled carbon nanotubes (MWCNTs) or silicon carbide whiskers (SiCws) were processed by powder metallurgy and studied by mechanical spectroscopy. The high-temperature mechanical-loss spectrum of pure 3Y-TZP presents mainly an exponential background. Doping 3Y-TZP with nano-sized reinforcements such as MWCNT or SiCw results in a decrease in the high-temperature background with respect to pure zirconia. It has been shown that these spectrum modifications by doping are associated with a better resistance to creep.

Nanoparticulate reinforced metal matrix nanocomposites – a review

Particulate reinforced metal matrix composites (MMCs) are widely used in many industries. With the development of nanotechnologies, the particulates scales down to the nano-level to enhance MMCs. MMCs with nano-sized reinforcements are termed as metal matrix nanocomposite (MMNCs). MMNCs have shown promising properties. Many researchers are using different methods to fabricate MMNCs. In this paper, some commonly used methods used to fabricate MMNCs are introduced including: powder metallurgy, casting, rapid solidification and in-situ fabrication. The enhancing mechanism of MMNCs is discussed. The properties obtained by different methods are illustrated. Some unsolved problems are also listed.

Rigid, Fused-ring Molecules as Nano-reinforcements for Engineering Polymers

Rigid, fused-ring molecules were investigated as nano-sized reinforcements for engineering polymers. Because of the high specific surface area associated with their small size, it was expected that they would provide greater enhancement of modulus than equally stiff reinforcements of millimeter and micron dimensions. The expected enhancement was not realized, a result attributed to the bulky alkyl substituents on the rings, placed there to make the fused-ring molecules soluble and dispersible at the molecular level in engineering polymers. It was concluded that the free volume introduced to the nanocomposites by these substituents counteracted the stiffening effect of the fused-ring structure in the molecules. The results point out the inherent trade-off with fused-ring molecules as reinforcements; the types of substituents required to make the molecules dispersible in a polymer matrix are also those that reduce its modulus.

Creep property of composite solders reinforced by nano-sized particles

In the present work the creep properties of Sn37Pb and Sn0.7Cu based composite solders with nano-sized metallic Cu, Ag and nano-sized oxide Al2O3, TiO2 reinforcement particles have been studied. First, a series of volume percentages of reinforcements were selected for optimizing the content of particles. Then, the composite solder with optimum volume fraction of the reinforcement particles, corresponding to maximum creep rupture life, is selected for investigating the effect of applied stress level and test temperature on creep rupture life of the composite solder joints. In the creep rupture life test, small single-lap tensile-shear joints were adopted. The results indicate that all the composite solders have improved creep resistance, comparing to the eutectic Sn37Pb solder and the Sn0.7Cu lead-free solder. The creep rupture life of the composite solder joints is first increased with the increase in the volume fraction of reinforcement in the composite solders. Then, the creep rupture life is decreased, as the reinforcement content exceeds a certain value. The creep rupture life of the solder joints is decreased with the increase of applied stress and testing temperature. Moreover, the reinforced efficiency of nano-sized Ag particles is the best in all the tested nano-sized reinforcements for the Sn37Pb based and Sn0.7Cu based composite solders, when the particles contents are in their own optimum content.

Fabrication and Characterization of High Temperature Resin/Carbon Nanofiber Composites

Multifunctional composites present a route to structural weight reduction. Nanoparticles such as carbon nanofibers (CNF) provide a compromise as a lower cost nanosize reinforcement that yields a desirable combination of properties. Blends of PETI-330 and CNFs were prepared and characterized to investigate the potential of CNF composites as a high-performance structural medium. Dry mixing techniques were employed and the effect of CNF loading level on melt viscosity was determined. The resulting powders were characterized for degree of mixing, thermal and rheological properties. Based on the characterization results, samples containing 30 and 40 wt.% CNF were scaled up to approximately 300 g and used to fabricate moldings 10.2 cm ′ 15.2 cm ′ 0.32 cm thick. The moldings were fabricated by injecting the mixtures at 260-280°C into a stainless steel tool followed by curing for 1 h at 371°C. The tool was designed to impart high shear during the injection process in an attempt to achieve some alignment of CNFs in the flow direction. Moldings were obtained that were subsequently characterized for thermal, mechanical and electrical properties. The degree of dispersion and alignment of CNFs were investigated using high-resolution scanning electron microscopy. The preparation and preliminary characterization of PETI-330/CNF composites are discussed.