Volume Fraction Of Powder Research Articles

Electrical conductivity of poly (L lactic acid) and poly (3-hydroxybutyrate) composites filled with galvanostatically produced copper powder

This manuscript presents experimental studies of composite materials based on poly (L lactic acid) (PLLA) and poly (3-hydroxybutyrate) (PHB) matrices filled with electrolytic copper powder, having a very high dendritic structure. Volume fractions of the copper powder used as filler in all prepared composites were varied in the range 0.5-6.0 vol.%. Samples were prepared by hot moulding injection at 170 ?C. Influence of particle size and morphology, as well as the influence of matrix type on conductivity and percolation threshold of the obtained composites were examined. Characterization included: electrical conductivity measurements using AC impedance spectroscopy (IS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier-transform Infrared spectroscopy (FTIR). Presence of three-dimensional conductive pathways was confirmed. The obtained percolation thresholds of 2.83 vol.% for PLLA and 3.13 vol.% for PHB composites were measured, which is about three times lower than the ones stated in the literature for similar composites. This property is ascribed to different morphologies of the filler used in the present investigation.

Study on Mechanical Alloying of TiB<sub>2</sub> Particulate Reinforced Titanium Matrix Composites

TiB2 particulate reinforced titanium matrix composites were prepared by mechanical alloying and spark plasma sintering. Volume fraction of TiB2 powders in the composites are 5%, 10%, 15%. The effect of milling time and the volume fraction of reinforcement on microstructure and properties of the composites were studied. The results show that with increasing milling time, the size of powder particles decreases, quantity of them increases, and microstructure of the sintered samples becomes finer and more uniform. When milling time reaches 30h, the trend of powder agglomeration increases, the downward trend of the particle size becomes slowly. With the milling time, the density of titanium matrix composites is on the rise. The density of 10vol%TiB2 particulate reinforced titanium matrix composites can reach 4.799 g/cm3, with 30h milling time and sintering at 900°C. The density and hardness of the composites increase with increasing the volume fraction of TiB2. When the volume fraction of TiB2 is 15%, after milling 10h and sintered at 800°C, the density and hardness of the composites can reach 4.713g/cm3 and HV851.58.

PENGARUH KANDUNGAN PARTIKEL SERBUK GENTENG SOKKA TERHADAP KEKUATAN TARIK DAN KEKUATAN IMPAK PADA KOMPOSIT BERMATRIKS EPOXY

Abstract — Composites consist of two or more separate materials combined in a macroscopic structure. This is different from alloy which is the structural unit is formed microscopiccally. At this research, the composite reinforcement was made of sokka Kebumen powder tile using epoxy formatrix. The percentage variations of volume fraction are 0%, 10%, 20%, 30%, and 40% with a mesh size of 180-200 mesh. This study aims to determine the tensile strength, impact strength, and SEM. The method used during the manufacturing process of composite was vacum molding. The tensile strength test showed the highest value was at 10% volume fraction with 49,946 MPa. The lowest value was at 40% volume fraction with 27,618 MPa. The impact strength test showed the highest value was at 10% volume fraction with 0,03925 J/mm2. The lowest value was at 40% volume fraction with 0,03375 J/mm2. The higher the percentage volume fraction of sokka tile powder, the lower the tensile strength and the impact strength of the composites have. The SEM test showed that there was still pull out at the side. Keywords : sokka tile powder, epoxy, volume fraction, composite .

Study on the Ingredient Proportions and After-Treatment of Laser Sintering Walnut Shell Composites.

To alleviate resource shortage, reduce the cost of materials consumption and the pollution of agricultural and forestry waste, walnut shell composites (WSPC) consisting of walnut shell as additive and copolyester hot melt adhesive (Co-PES) as binder was developed as the feedstock of selective laser sintering (SLS). WSPC parts with different ingredient proportions were fabricated by SLS and processed through after-treatment technology. The density, mechanical properties and surface quality of WSPC parts before and after post processing were analyzed via formula method, mechanical test and scanning electron microscopy (SEM), respectively. Results show that, when the volume fraction of the walnut shell powder in the WSPC reaches the maximum (40%), sintered WSPC parts have the smallest warping deformation and the highest dimension precision, although the surface quality, density, and mechanical properties are low. However, performing permeating resin as the after-treatment technology could considerably increase the tensile, bending and impact strength by 496%, 464%, and 516%, respectively.

MICROSTRUCTURE AND MECHANICAL BEHAVIOR OF AMORPHOUS Al–Cu–Ti METAL FOAMS SYNTHESIZED BY SPARK PLASMA SINTERING

Amorphous Al–Cu–Ti metal foams were prepared by spark plasma sintering (SPS) process with the diameter of 10[Formula: see text]mm. The SPS process was conducted at the pressure of 200 and 300[Formula: see text]MPa with the temperature of 653–723[Formula: see text]K, respectively. NaCl was used as the space-holder, forming almost separated pores with the porosity of 65 vol%. The microstructure and mechanical behavior of the amorphous Al–Cu–Ti metal foams were systematically investigated. The results show that the crystallinity increased at elevated temperatures. The effect of pressure and holding time on the crystallization was almost negligible. The intermetallic compounds, i.e. Al–Ti, Al–Cu and Al–Cu–Ti were identified from X-ray diffraction (XRD) patterns. It was found that weak adhesion and brittle intermetallic compounds reduced the mechanical properties, while lower volume fraction and smaller size of NaCl powders improved the mechanical properties.

Preparation of epoxy chicken eggshell composite as thermal insulation

Epoxy/ES composites have been prepared. X-ray diffraction (XRD) was used to study the microstructure of this composite; the results showed that the composites, epoxy/3% ES and epoxy/4% ES, have a crystalline structure. Effects of volume fraction of natural filler as chicken eggshell (ES) powder on thermal stability, glass transition, and thermal conductivity of epoxy resin have been studied. The epoxy with (4% ES) powder volume fraction of loading shows a good result for composite thermal insulation compared with other volume fractions.

Influence of Terfenol-D Powder Volume Fraction in Epoxy Matirx Composites on their Magnetomechanical Properies

Abstract In this paper the investigations of magnetostriction as well as DC magnetic properties for composites doped with Terfenol-D particles are presented. All investigations were performed for the materials with 35%, 46% and 70% volume fraction of the Terfenol-D particles surrounded by epoxy matrix. Moreover, the bulk Terfenol-D alloy was tested. The obtained results show that the magnetization of the composite materials increases with increasing the volume fraction of Terfenol-D particles. Similar dependence as for magnetization was observed for the magnetostriction measurements. Although the magnetostriction of composite material is smaller than for solid Terfenol-D it is still tens of times bigger than in case of traditional magnetostrictive materials. Obtained results gives opportunity to use these materials for variety applications such as actuators and sensors.

Effects of material and processing conditions on powder-binder separation using the Taguchi method

The effects of material and processing conditions—powder size, injection temperature, initial powder volume fraction, and shear rate—on powder-binder separation in powder injection molding were investigated. A minimum set of experiments were performed based on the Taguchi method. The non-Newtonian viscosity model was employed to describe the rheological behavior of the feedstock. The critical solid loadings for the different powder sizes were determined by torque rheometry experiments. All other parameters for the viscosity model for the different powder sizes were obtained by capillary rheometry and linear fitting. The powder volume fractions along the radial direction of the polished surface were measured by image processing, based on the intensity difference between the powder and binder. The powder distribution profile was determined by a mean residual method. Powder-binder separation under the different processing and material conditions were quantitatively calculated by the definition of Variation. Finally, the effects of powder size, injection temperature, initial powder volume fraction, and shear rate were analyzed by the Taguchi method. Furthermore, the results of the Taguchi analysis were verified by additional experiments.

Experimental investigation of laser-assisted powder bed fusion of Fe-Cu powder mixture

Powder bed fusion is an additive manufacturing method which allows production of complex parts, in a shorter time compared to the conventional fabrication methods. During the last 60 years, Fe–Cu powders were widely used because of their anti-friction behavior and superior mechanical properties. Therefore, Fe–Cu powder has been selected as the basic material for the powder bed fusion process. In the present study, laser-assisted powder bed fusion of Fe–Cu powder mixture has been studied experimentally. Nd:YAG laser with a maximum power of 75 W has been used to melt the powder. The effects of volume fraction of the Cu powder in the mixture and applied energy density on thickness, surface concavity and geometrical accuracy of manufactured parts have been investigated. Results show that higher values of energy density lead to lower geometrical accuracy, higher thickness and surface concavity.

Filling of Microarray Fabricated by Micro Powder Injection Molding

Flow analysis during injection molding is crucial for dimensional control in micro powder injection molding. Numerical simulation of injection molding of ZrO2 microarray based on in-house feedstock was conducted. A powder-binder two fluid model was developed to analyze temperature, viscosity and powder volume fraction of the feedstock for micro pillars of different dimensions with diameters of 0.2, 0.5 and 1 mm, respectively. In general the binder temperature decreased with size reduction of the micro cavity caved on the silicon wafer and increased with mold temperature. The micro pillars of φ0.2 mm exhibited the highest viscosity, which indicated difficulty for filling during injection molding. An increase in mold temperature facilitated the decrease of the feedstock viscosity, which improved the filling of the micro cavities. Powder-binder segregation became evident as the size of the micro cavities reduced to 0.2 mm.

The strain sensitivity of copper powder reinforced concrete

Earthquakes, material deteriorations and other environmental factors challenge the structural safety. In order to protect the lives, structural health monitoring is crucial. The metal foil strain gages have low durability, low sensitivity and can get point wise measurements which are disadvantages. In this study six different concrete mixtures were designed; one without any copper powder, the rest five having different copper powder volume fractions. Three cube samples from each mixture were cast and cured. Simultaneous measurement of electrical resistance and strain were conducted during the compression tests. A strong linear relationship between strain and electrical resistance change was obtained for copper powder reinforced concrete. The results are contribution to the development of “Smart Concrete” which can sense its strain and damage.

Effect of Glass Powder on Some Mechanical Properties of Polymer Matrix Composite Material

This research deals with the study of the effect of adding glass powder of grain size (35μm) with different volume fraction (10%, 20%) to the blend of unsaturated polyester and polyurethane using hand lay-up method, after preparing the matrix from weight fraction (90%) of Unsaturated polyester and (10%) of polyurethane. The results have shown that the addition of particles to the polymer blends lead a great extent in mechanical properties, since testing bending, Shore D hardness and impact strength. It has shown that the values of young modulus, impact strength and hardness were increased with increasing of volume fraction of glass powder. Fracture surface of the samples were examined by using optical microscope with magnification (40 X) and the results showed that the nature of fracture is seems brittle fracture for all samples.

Thermophysical behavior of thermal sprayed yttria stabilized zirconia based composite coatings

The effective thermal conductivity of a composite coating depends on intrinsic thermal conductivity of the constituent phases, its characteristics (size, shape) and volume fraction of porosities. The present study concerns studying the effect of CoNiCrAlY and Al2O3 content on the coefficient of thermal expansion and thermal conductivity of the YSZ (YSZ-CoNiCrAlY and YSZ-Al2O3) based composite coatings developed by thermal spray deposition technique. The coefficient of thermal expansion and thermal conductivity of the composite coatings were measured by push rod dilatometer and laser flash techniques, respectively, from room temperature to 1000 °C. Variation in density, porosity, coefficient of thermal expansion, and thermal conductivity was observed in the composite coatings with the addition of different volume fraction of CoNiCrAlY and Al2O3 powders in YSZ-CoNiCrAlY and YSZ-Al2O3 composites, respectively. Comparison between the theoretical and experimental thermal conductivities showed a mismatch varying from 4% to 58% for YSZ-CoNiCrAlY composite coatings and from 58% to 80% for YSZ-Al2O3 composite coatings. Model based analyses were used to understand the mechanism of thermal conductivity reduction in the composite coatings. It was concluded that the morphology of porosities varied with composition.

Tunable friction performance of magneto-rheological elastomer induced by external magnetic field

In order to investigate the magnetic-induced friction properties of magneto-rheological elastomers, isotropic and anisotropic magneto-rheological elastomers are fabricated, tribological testing setup is built, and the friction experiment is carried out. The experimental results show that the isotropic magneto-rheological elastomer has a decreasing friction coefficient with magnetic field applied, which is also affected by particle volume fraction. The influence of magnetic field on friction coefficient of the anisotropic magneto-rheological elastomers is not monotonic. The experimental results also show that the friction coefficient of magneto-rheological elastomers decreases with the increase in load for both isotropic and anisotropic magneto-rheological elastomers in most circumstances. The volume fraction of carbonyl iron powders being around 10% is the best for magneto-rheological elastomers in tuning friction. The tunable range of friction could be as high as 25% under a magnetic field of 0.25 T. Images of the magneto-rheological elastomer interfaces show that the surface roughness is reduced by about 20.7% when a magnetic field of 0.5 T is applied. The aggregation phenomenon is observed on the surface of the magneto-rheological elastomer under a magnetic field. On the basis of three-dimensional surface topography, a preliminary model for the aggregation of micro asperities on the surface of the magneto-rheological elastomer is built to interpret the influence of the magnetic field on the tribological properties of magneto-rheological elastomers.

Study on the thermal and mechanical properties of novel neutron shielding composite laminates at elevated temperature

Neutron shielding fibre metal laminates (NSFMLs) containing 10–50wt% of boron carbide (B4C) powder were fabricated using hot molding process, and the effects of experimental temperature on the thermal and mechanical properties of composite laminates were investigated in this work. Thermal stability of composite laminates was conducted with thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC), and their mechanical properties were also measured. The testing results indicated that good interfacial adhesion between different layers, uniform distribution of B4C particles and carbon fibres tightly surrounded by polyimide (PI) resin were crucial to the mechanical properties of composite laminates. TGA-DSC results illustrated the scarcely mass loss of composite laminates below 300°C, yet began to decompose when it exceeded over 390°C. Moreover, tensile strength of the NSFMLs degraded with the increasing of experimental temperature and the volume fraction of B4C powder. Double bear shear (DBS) testing results showed that the NSFMLs with 30wt% of B4C powder had the maximum interlaminar shear value, while the primary delamination zone occurred at the interface between two layered carbon fibre reinforced prepregs (CFRPs). The composite laminates still maintained the good interlaminar shear strength even at 300°C.

Self-healing efficiency of ferrite-filled asphalt mixture after microwave irradiation

Asphalt-based composites have the ability to heal themselves. Under certain conditions, strength and stiffness modulus can be restored so that the fatigue life can be extended. However, without the aid of external influences (energy supply or material supplement), the self-healing ability of asphalt mixture is quite limited. In this paper, the efficiency of self-healing of asphalt mixture with Ni-Zn ferrite powders was analyzed based on the concept of microwave heating. The recovery rate of stiffness modulus and the fatigue life extension ratio were adopted to evaluate the self-healing efficiency of asphalt mixture. Different influence factors, such as heating temperature, healing time and damage level, were analyzed in this study. The analysis results proved that Ni-Zn ferrite powders can promote the self-healing ability of asphalt mixture significantly. It is found that when the asphalt mixture is filled with 80% ferrite powders (volume fraction of mineral powders), under the condition of healing for 3h after heating to 55°C by microwave, the fatigue life extension ratio of 50% damaged ferrite-filled asphalt mixture can reach 1.33.

Processing of Ni-WC-8Co MMC casting through microwave melting

ABSTRACTThe melting and casting of nickel-based powder metal matrix composites (MMCs) through microwave energy is carried out in the present work. The nickel powder was mixed with 5% and 10% volume fraction of the WC-8Co reinforcement powder and processed in a microwave oven at 2.45 GHz and 900 W. The developed castings revealed complete melting of the nickel powder within 25 minutes of microwave exposure. The processing mechanism of MMC castings through microwave is explained and the developed castings were subjected to the microstructure and mechanical characterizations. The results of XRD analysis revealed the formation of some hard intermetallics such as NiSi and Cr23C6. The back-scattered scanning electron microscopy images of castings microstructures revealed the formation of nearly equiaxed grains of the matrix. It was observed that WC particles within the matrix were in agglomerated patterns, which were randomly dispersed. The presence of hard phases of WC reinforcement and formed intermetallic carbides enhanced the microhardness (788 ± 52 HV) of the developed composites.

Development of Porous Ti-6Al-4V Dental Implant by Metal Injection Molding with Palm Stearin Binder System

The dental restorations by the usage of implants have been one of the most favourable treatment. However, the existing dense dental implant causes overloading towards the human bone that triggers ‘stress shielding effect’ and also implant loosening. This paper focused on the development of highly porous Ti-6Al-4V dental implant by metal injection molding with palm stearin binder system with an addition of sodium chloride as space holder which has been established in the fabrication of porous Ti-6Al-4V. The evaluated compositions consist of the powder volume fraction of 63vol% and 65vol%. SEM analysis shows that highly porous Ti-6Al-4V dental implant were obtained. The average density is 3.325g/cm3 for 63vol% sample and 3.915g/cm3 for 65vol% sample. While for the Vickers hardness are 113.68HV and 162.8HV for 63vol% and 65vol% respectively.

Effect of Temperature on Deformation Behavior of Sintered Porous AA2024 During Semisolid Compression

Semisolid processing as a promising manufacturing route has recently gained wide use for dense materials. Nevertheless, very few investigations on porous materials or powders were reported and the effect of temperature on deformation behavior of porous materials or powders remains unclear. Sintered porous AA2024 specimens with initial relative density of 83% were compressed at a semisolid state. The liquid volume fraction of gas-atomized AA2024 powders at a semisolid state was determined by the Thermo-calc prediction, the differential scanning calorimetry (DSC) experiment, and metallographic analysis. The results show that the DSC experiment is the best suitable method in this study. As temperature increases, two opposite effects simultaneously act on the microstructure: More powders of samples after compression are broken up, making grains finer, whereas the surface energy decreases, making grains more spherical and coarser. The relative density increases with the increasing temperature because more powders crush and more liquid flows. Thus, the deformation resistance of sintered porous materials decreases, which makes true stress decrease with the increasing temperature. Therefore, the effect of temperature on deformation behavior of sintered porous materials at a semisolid state is attributed to the liquid fraction, which significantly affects the breakup of solid skeleton or powders and the flowing of liquid.

Experimental investigation on incipient mass flow rate of micro aluminum powder at high pressure

Experiments on powder entrainment have been carried out to study the influence of different variable parameters on incipient mass flow rate. A semi-empirical model was established by taking into account many affecting parameters, including: initial total pressure, particle mean size, throttling orifice area and powder volume fraction. This model could be used to predict the incipient mass flow rate with particle mean sizes from 10μm to 100μm. By comparing the relative error between the semi-empirical model and previous model, the results show that the semi-empirical model has higher prediction accuracy than previous model.In the progress of particle entrainment, there exists three stages: flow-out stage with gas (stage I), flow-out stage with large amounts of particles (stage II), and flow-out stage with small amount of particles (stage III). The result of stage I shows that there exists a pickup delay for particles, which is good for the ignition sequence matching research of powder engine.