Hybrid Powder Research Articles

Effect of Embedding Cu-Graphene Hybrid Powder into 2-Phase In-Cu Solders on Its Suitability as Metallic Thermal Interface Material

The effect of embedding Cu-graphene hybrid powder, namely “graphene nano-sheet Cu” (GNS-Cu) powder, into In-40 vol.% Cu solder alloy on the electrical and mechanical properties of In-Cu solder is investigated. GNS-Cu hybrid powders were prepared by mixing reduced graphene oxide powders and CuSO4·5H2O, followed by reduction of the mixture with hydrazine. Subsequently, In-Cu solders with GNS-Cu powders were prepared using a 2-step process, comprising liquid phase sintering (LPS) of In and Cu powders followed by accumulative roll bonding (ARB). During ARB, the GNS-Cu powders were embedded as distinct layers into In-Cu composite solders. Electrical conductivity of the GNS-Cu embedded solders increased by > 20% as compared to pure In-Cu solders processed through the same combination of LPS–ARB steps. The yield strength of In-Cu solder increased by only 10% with the addition of GNS-Cu powders and thus retained the moderate strength often associated with pure In-Cu composite solders. Moreover, the thermal conductivity of GNS-Cu-embedded solders was estimated theoretically to increase by > 60%. These promising findings suggest that GNS-Cu-embedded In-Cu solders can be suitable for next-generation metallic thermal interface material and package-level interconnect applications.

Magnesium-β-Tricalcium Phosphate Composites as a Potential Orthopedic Implant: A Mechanical/Damping/Immersion Perspective

The design and development of novel magnesium-based materials with suitable alloying elements and bio-ceramic reinforcements can act as a possible solution to the ever-increasing demand of high performance bioresorbable orthopedic implant. In the current study, Mg-β-tricalcium phosphate composites are synthesized using the hybrid powder metallurgy technique, followed by hot extrusion. The influence of addition of (0.5, 1, and 1.5) vol % β-tricalcium phosphate on the mechanical, damping, and immersion characteristics of pure magnesium are studied. The addition of β-tricalcium phosphate enhanced the yield strength, ultimate compressive strength, and compressive fracture strain of pure magnesium by about ~34%, ~53%, and ~22%, respectively. Also, Mg 1.5 vol % β-tricalcium phosphate composite exhibited a ~113% enhancement in the damping characteristics when compared to pure magnesium. A superior ~70% reduction in the grain size was observed by the addition of 1.5 vol % β-tricalcium phosphate particles to pure Mg. The response of Mg-β-tricalcium phosphate composites is studied under the influence of chloride environment using Hanks’ balanced salt solution. The dynamic passivation was realized faster for the composite samples as compared to pure Mg, which resulted in decreased corrosion rates with the addition of β-tricalcium phosphate particles to pure Mg.

Electromagnetic interference shielding and absorption properties of Ti3SiC2/nano Cu/epoxy resin coating

In this study, we prepared Ti3SiC2/nano Cu powders by a facile electroless plating method. XRD confirmed the successful preparation of the Ti3SiC2/nano Cu powders and SEM images showed their morphology. Then a weight ratio of 60 wt% hybrid powders with various amount of Cu were composited with epoxy resin to fabricate Ti3SiC2/nano Cu/epoxy resin absorbing coating. Electromagnetic interference (EMI) shielding and absorption properties of the coatings were investigated. As the content of nano Cu increases from 0 to 30 wt%, EMI effectiveness rises from 14 dB to 27 dB. The real and imaginary part of complex permittivity also increase with the rising Cu content. An effective absorption bandwidth is obtained in the frequency range of 9.6–12.4 GHz for the coating containing 20 wt% nano Cu with a thickness of 1.8 mm. The minimum reflection loss value is −37 dB at 11.37 GHz. The encouraging results make a contribution to exploration of absorbing coating with light weight, wide absorption bandwidth, thin thickness and high absorption efficiency.

Characterization Investigations of a Al-5 wt.% Si/2 wt% (NbB<sub>2</sub>, NbC) Hybrid Composite Fabricated via Mechanically Alloying and Sequentially Milling (Mechanical Alloying + Cryomilling)

In this study, microstructural and mechanical properties of a Al-5 wt.% Si/2 wt% (NbB2, NbC) composite synthesized by sequentially milling (mechanical alloying (MA) and/or cryogenic milling (CM)) were investigated. Nb2O5, B2O3 and C powder blends were milled using high energy milling for 5 h and annealed at 1400 oC for 12 h to produce NbB2-NbC hybrid powders. The NbB2-NbC hybrid powders were mixed with the matrix Al-5 wt.% Si powders to constitute the Al-5 wt.% Si/2 wt.% (NbB2-NbC) powders blends which were mechanically alloyed (MA'd) for 4 h using SpexTM Mixer/Mill, cryo-milled for 10 min in a SpexTM 6870 Freezer/Mill and finally MA’d for 1h in SpexTM Mixer/Mill again. As-blended, MA’d and cryomilled powders were compacted in a hydraulic press with a uniaxial pressure of 450 MPa. Compacted samples were sintered at 570°C for 2 h under Ar gas atmosphere. Microstructural characterizations of the as-blended/MA'd powders and the sintered composites were performed using X-ray diffractometry (XRD) and scanning electron microscopy (SEM) techniques. Density and microhardness measurements and sliding wear tests were performed on the sintered composite samples. Sequentially milled and sintered Al-5 wt.% Si-2 wt.% (NbB2-NbC) samples had the highest mean microhardness value (2.29 ± 24.98 GPa) and the lowest wear volume loss (0.038 mm3).

Sol-gel preparation of self-cleaning SiO2-TiO2/SiO2-TiO2 double-layer antireflective coating for solar glass

Self-cleaning SiO2-TiO2/SiO2-TiO2 double-layer antireflective (AR) coating is prepared by sol-gel process. SiO2 sol is prepared by using tetraethyl orthosilicate (TEOS) as precursor and ammonia as catalyst, while TiO2 sol was prepared by using tetrabutyl orthotitanate (TBOT) as precursor and hydrochloric acid as catalyst. The effect of TiO2 content on refractive index, abrasion-resistance and photo-catalytic activity of SiO2-TiO2 hybrid thin films or powders is systematically investigated. It is found that the refractive index of SiO2-TiO2 hybrid thin films increases gradually from 1.18 to 1.53 as the weight ratio of TiO2 to SiO2 increased from 0 to 1.0. The SiO2-TiO2 hybrid thin film and powder possesses good abrasion-resistance and photo-catalytic activity, respectively, as the weight ratio of TiO2 to SiO2 is 0.4. The degradation degree of Rhodamine B by SiO2-TiO2 hybrid powder is 88.3%. Finally, SiO2-TiO2/SiO2-TiO2 double-layer AR coating with high transmittance, abrasion-resistance and self-cleaning property is realized.

Spray dried TiO2/WO3 heterostructure for photocatalytic applications with residual activity in the dark

Synthesizing titanium dioxide with energy storage ability represents a paradigm-shift for photocatalytic applications. We prepared titania tungstated photocatalysts (TiO2/WO3) by sol–gel and crash precipitation methods followed by spray drying to produce a micro-sized hybrid material. X-ray diffraction confirmed the tetrahedral and monoclinic crystalline structure of TiO2 and WO3 in the hybrid material calcined at 600 °C. Spray drying a suspension of titanium hydroxide alone creates spherical 20 μm TiO2 particles, whereas a suspension of ammonium paratungstate dissolved in hydrochloric acid produces 7 μm median size needle like WO3 particles. According to SEM-EDX images, spray drying both semiconductors together produces a homogeneously distributed mixture of the powders. The TW0.075 (titanium dioxide/tungsten oxide having 0.075 molar ratio of tungsten precursor) hybrid powder, with a surface area of 221 m2/g, 2.88 eV band gap energy, and 21.5% of anatase [001] facets (Raman analysis), decreased the electron-hole recombination with 1594 ns of carrier lifetime (PL-TRPL analysis). TW0.075 outperforms the rest of the samples in the UV degradation of the model pollutant methylene blue (MB), converting 90% MB in 100 min (30 min dark + 40 min light + 30 min dark), thus demonstrating energy storage ability in the absence of UV irradiation. Hydroxyl radicals (OH) and superoxide anions (O2−) are the species mainly involved in the pollutant degradation. We propose the transfer pathways mechanism of the photogenerated charge carriers in the hybrid samples.

Enhanced electrochromic performance of WO3 hybrids using polymer plasma hybridization process

A series of electrochromic hybrid materials were synthesized with in-situ polymerization of aniline, 2-fluoroaniline and N-methylaniline onto tungsten trioxide (WO3) powders using a rotating capacitively coupled radio frequency (rf) plasma process. The materials were characterized by means of scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction analysis (XRD). Thin films of tungsten trioxide/polyaniline (WO3/PANI), tungsten trioxide/poly(2-fluoroaniline) (WO3/PFANI) and tungsten trioxide/poly(n-methylaniline) (WO3/PMANI) hybrid powders were obtained by e-beam technique onto flexible conducting polyethylene terephthalate electrodes for electrochromic works. The optical and electrochromic properties of WO3 hybrids-based ECDs were investigated by optical and electrochemical measurements. It is observed that electrochromic performance of hybrid films has changed as depending on electron acceptor or donor properties of substituent group onto PANI chain. The results of flexible electrochromic devices (ECDs) indicated that WO3/PMANI hybrid-based ECD has a high optical contrast of 49% at 750nm, reversible coloration with efficiency of 361cm2/C and fast switching times (bleaching time: 1.41s, coloration time: 0.67s).

Synthesis and Characterization Investigations of Laboratory-Synthesized VB-VB<sub>2</sub>-V<sub>3</sub>B<sub>4</sub> Reinforced Al-7wt.% Si Composites via Mechanical Alloying and Pressureless Sintering

In this study, the effect of mechanical alloying (MA) on the microstructural, mechanical and physical properties of vanadium boride particulate reinforced Al-7 wt. % Si matrix composites were investigated. VB-VB2-V3B4 containing vanadium boride hybrid powders were mechanochemically synthesized for 5 h from the V2O5-B2O3-Mg powder blends and leached with hydrochloric acid (HCl) for purification. Laboratory-synthesized VB-VB2-V3B4 powders were incorporated into the Al-7wt. % Si matrix powders with the amount of 2 wt.% via MA for 4h in a SpexTM Mixer/Mill using hardened steel vial/balls with a ball-to-powder weight ratio of 7/1. After the MA process, phase analysis (X-ray diffraction), particle size analysis (laser particle size measurement), surface area analysis (Brunauer-Emmett-Teller measurement) and microstructural characterization (scanning electron microscope (SEM) micrograph) and thermal analysis (differential scanning calorimetry (DSC)) of the non-milled/milled Al-7 wt.% Si-2wt.% (VB-VB2-V3B4) powders were conducted. As-blended and MA’d powders were compacted at a uniaxial hydraulic press to obtain cylindrical compacts with a diameter of 12 mm under a pressure of 400 MPa. Green bodies were sintered at 570°C for 2 h under Ar gas flowing conditions. Microstructural characterizations of the sintered samples were carried out using XRD and optical microscope (OM). Physical and mechanical properties of the composites were investigated in terms of density (Archimedes method), Vickers microhardness and wear rate. The microhardness and wear rate of the 4h of MA’d and sintered sample respectively increased to 0.865±0.256 GPa and 0.0036 mm3/N.m as compared with those of as-blended and sintered sample.

Diatom frustules decorated with zinc oxide nanoparticles for enhanced optical properties

Zinc oxide (ZnO) nanoparticles were synthesized on diatomite (DE) surface by a low temperature sol gel technique, starting from zinc acetate dihydrate (Zn(CH3COO)2 · 2H2O) solution in water/ethyl alcohol, in presence of triethanolamine (TEA) with functions of Zn2+ chelating agent, catalyst and mediator of nanoparticle growth on DE surface. Microstructural features were investigated by field emission scanning electron microscopy and x-ray diffraction. ZnO crystalline nanoparticles, well distributed both on the surface and into the porous architecture of diatomite, were obtained just after the synthesis carried out at 80 °C without the need of calcination treatments. The optical properties of ZnO/DE hybrid powders were measured for the first time by means of photoacoustic spectroscopy (PAS). A new method to retrieve both the optical absorption and scattering coefficients from PAS is here discussed for powder aggregates. The fingerprint of the zinc oxide nanoparticles has been highlighted in the Mie scattering resonance in the UV–Vis range, and in the enhancement of the optical absorption with respect to diatomite.

From morphology of attrited copper/MWCNT hybrid fillers to thermal and mechanical characteristics of their respective polymer‐matrix composites: An analytical and experimental study

ABSTRACTSynergistic effect of copper and multiwalled carbon nanotube on thermal and mechanical properties of high‐density polyethylene (HDPE)‐matrix composite was evaluated. Attrition mill was employed to prepare the hybrid powder. Reinforcing the polymer‐matrix was carried out using different contents of simultaneously (Sim) and separately (Sep) milled powders as hybrid fillers. X‐ray diffraction and microscopy results show different trends of particle size for Sep and Sim affected by both milling time and volume fraction ratio. Thermal characterization indicates that conductivity was enhanced by 90% and thermal expansion was reduced to 53% of neat HDPE. Young's modulus and tensile strength were improved by 7.8 and 1.22 times of neat HDPE, respectively. Also, characteristics of Sim‐reinforced composites exhibited better correlated relation with milling time compared with erratic behavior of Sep. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45397.

Development of CIP/graphite composite additives for electromagnetic wave absorption applications

In this study, the electromagnetic (EM) wave absorption ability of carbonyl iron powder (CIP)/graphite composites produced by ball milling were studied in a range of 28.5 GHz to examine the effects of the morphology and volume fraction of graphite on EM wave absorption ability. The results indicated that a ball milling technique was effective in exfoliating the graphite and covering it with CIP, thereby markedly increasing the specific surface area of the hybrid powder. The increase in the surface area and hybridization with dielectric loss materials (i.e., graphite) improved EM absorbing properties of CIP in the range of S and X bands. Specifically, the CIP/graphite composite containing 3 wt% graphite exhibited electromagnetic wave absorption of −13 dB at 7 GHz, −21 dB at 5.8 GHz, and −29 dB at 4.3 GHz after 1 h, 8 h, and 16 h of milling, respectively.

Enhanced fracture toughness of Al and Bi co-doped Mg2Si by metal nanoparticle decoration

We herein report the effects of metal nanoinclusions (Cu, Al, and Sn) embedded at grain boundaries on the thermoelectric transport and mechanical properties of Mg2Si-based compounds. Hybrid powders of microscale Al and Bi co-doped Mg2Si (Mg1.96Al0.04Si0.97Bi0.03) and nanoscale metal particles were synthesized by a nanometal decoration technique and their nanocomposites were fabricated by a spark plasma sintering process. In compacted polycrystalline bulks, homogeneous dispersion of metal nanoparticles (~150 nm) was readily achieved at grain boundaries. The thermoelectric performance of the nanocomposites deteriorated mainly because of the reduced mobility owing to intensified electron scattering at the phase boundaries between the Mg2Si matrix and metal nanoinclusions, while the fracture toughness (~1.10 MPa m1/2, 35% improvement) was significantly enhanced on introducing Al nanoparticles.

Thermally stable superhydrophobic polymethylhydrosiloxane nanohybrids with liquid marble-like structure

We prepared novel hybrid materials by in situ self-hydroxylation and condensation of polymethylsiloxane (PMHS) with multi-walled carbon nanotubes (MWCNTs). The hybrid material showed superhydrophobic and non-stick properties, mesoporous structure, and liquid marble-like non-stick water droplet behavior. Moreover, we found that the in situ addition of MWCNTs to the PMHS would increase the thermal stability of the hybrid material. Thermal stability of the hybrid is enhanced by increasing the percentage of MWCNTs to the PMHS. The superhydrophobic hybrid powder covered non-stick water droplet showed anti-icing behavior for long time. The hybrids also showed oils sorption behavior and easy reusable property. The obtained results suggest that the thermally stable superhydrophobic hybrid mesoporous materials with anti-icing, oils sorption properties can be easily synthesized and used for various applications.

Electromagnetic and Microwave Absorption Properties of Hybrid FeCrAl/Ti3SiC2 Composite in X-Band

Hybrid magnetic–dielectric absorbers for electromagnetic applications consisting of FeCrAl and Ti3SiC2 powders have been fabricated by a ball-milling process and their electromagnetic characteristics and microwave absorption performance investigated in the frequency range from 8.2 GHz to 12.4 GHz. The dielectric loss increased with increasing Ti3SiC2 content, while the magnetic loss decreased. The electromagnetic parameters of the hybrid FeCrAl/Ti3SiC2 powders could be adjusted by adding various contents of Ti3SiC2. The hybrid powder with 20 wt.% Ti3SiC2 and 80 wt.% FeCrAl presented the most favorable microwave absorption performance. For the sample with thickness of 2.6 mm, effective absorption (<−10 dB) was obtained in the frequency range from 8.4 GHz to 12.1 GHz with a minimum value of −43.6 dB at 9.7 GHz. These results indicate that hybrid FeCrAl/Ti3SiC2 powders with appropriate weight ratio present better absorption performance than FeCrAl powder alone. This study makes a significant contribution to exploration of microwave absorption materials with low density, thin thickness, broad absorption bandwidth, and strong absorptivity.

Enhancement of exchange coupling interaction of NdFeB/MnBi hybrid magnets

MnBi ribbons were fabricated by melt - spinning with subsequent annealing. The MnBi ribbons were ground and mixed with NdFeB commercial Magnequench powders (MQA). The hybrid powder mixtures were subjected thrice to the annealing and ball-milling route. The hybrid magnets (100 - x)NdFeB/xMnBi, x=0, 30, 40, 50 and 100wt% were in-mold aligned in an 18kOe magnetic field and warm compacted at 290°C by 2000psi uniaxial pressure for 10min. An enhancement of the exchange coupling of NdFeB/MnBi hybrid magnets was obtained by optimizing the magnets’ microstructures via annealing and ball-milling processes. The magnetic properties of prepared NdFeB/MnBi hybrid magnets were studied and discussed in details.

Hydration of Concrete Containing Hybrid Recycled Demolition Powders

AbstractIf not properly managed, the hybrid powders produced during recycling mixed construction and demolition (C&D) materials will present a serious hazard to the environment and human health. Re...

Photocatalytic Water Splitting for O₂ Production under Visible Light Irradiation Using NdVO₄-V₂O₅ Hybrid Powders.

The study investigated photocatalytic water splitting for O2 production under visible light irradiation using neodymium vanadium oxide (NdVO4) and vanadium oxide (V2O5) hybrid powders. The results in a sacrificial agent of 0.01 M AgNO3 solution were obtained, and the highest photocatalytic O2 evolution was 2.63 μmol/h, when the hybrid powders were prepared by mixing Nd and V at a volume ratio of 1:3 at a calcination temperature of 350 °C for 1 h. The hybrid powders were synthesized by neodymium nitrate and ammonium metavanadate using the glycothermal method in ethylene glycol at 120 °C for 1 h. The hybrid powders consisted of two shapes, NdVO4 nanoparticles and the cylindrical V2O5 particles, and they possessed the ability for photocatalytic oxygen (O2) evolution during irradiation with visible light. The band gaps and structures of the hybrid powders were analyzed using UV-visible spectroscopy and transmission electron microscopy.

On demand rapid patterning of colored amorphous molybdenum oxide using a focused laser beam

We report a facile method to achieve rapid conversion and patterning of a carbon nanotube (CNT)–molybdenum sulfide (MoSx) hybrid powder into a blue material via a focused laser beam.

A gigantically increased ratio of electrical to thermal conductivity and synergistically enhanced thermoelectric properties in interface-controlled TiO2-RGO nanocomposites.

We report synergistically enhanced thermoelectric properties through the independently controlled charge and thermal transport properties in a TiO2-reduced graphene oxide (RGO) nanocomposite. By the consolidation of TiO2-RGO hybrid powder using spark plasma sintering, we prepared an interface-controlled TiO2-RGO nanocomposite where its grain boundaries are covered with the RGO network. Both the enhancement in electrical conductivity and the reduction in thermal conductivity were simultaneously achieved thanks to the beneficial effects of the RGO network, and detailed mechanisms are discussed. This led to the gigantic increase in the ratio of electrical to thermal conductivity by six orders of magnitude and also the synergistic enhancement in the thermoelectric figure of merit by two orders. Our results present a strategy for the realization of 'phonon-glass electron-crystals' through interface control using graphene in graphene hybrid thermoelectric materials.

In-situ addition of graphene oxide for improving the thermal stability of superhydrophobic hybrid materials

Superhydrophobic mesoporous hybrid materials were synthesised by the in-situ self-hydroxylation and condensation of polymethylhydrosiloxane in ethanol and sodium hydroxide solutions in the presence of a cetyl trimethylammonium bromide (CTAB) as a surfactant and graphene oxide (GO). The samples were analysed by a range of characterisation techniques, such as Fourier-transform infrared and Raman spectroscopy, 29Si cross polarisation magic angle spinning nuclear magnetic resonance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, surface area analysis, high resolution scanning electron microscopy, and high resolution transmission electron microscopy. The superhydrophobic hybrid powder was used for the detection and separation of chloroform in water from water/chloroform mixtures.