Effects of rare earth on microstructures and properties of Ni-W-P-CeO_2-SiO_2 nano-composite coatings

Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on common carbon steel surface by pulse electrodeposition of nickel, tungsten, phosphorus, rare earth （nano-CeO2） and silicon carbide （nano-SiO2） particles. The effects of nano-CeO2 concentrations in electrolyte on microstructures and properties of nano-composite coatings were studied. The samples were characterized with chemical compositions, elements distributions, microhardness and microstructures. The results indicated that when nano-CeO2 concentration was controlled at 10 g/L, the nano-composite coatings possessed higher microhardness and compact microstmctures with clear outline of spherical matrix metal crystallites, fine crystallite sizes and uniform distribution of elements W, P, Ce and Si within the Ni-W-P matrix metal. Increasing the nano-CeO2 particles concentrations from 4 to 10 g/L led to refinement in grain structure and improvement of microstructures, while when increased to 14 g/L, the crystallite sizes began to increase again and there were a lot of small boss with nodulation shape appearing on the nano-composite coatings surface.

Wear and corrosion resistance and electroplating characteristics of electrodeposited Cr-SiC nano-composite coatings

Cr-SiC nanocomposite coatings with various contents of SiC nanoparticles were prepared by electrodeposition in optimized Cr plating bath containing different concentrations of SiC nanoparticles. Direct current electrocodeposition technique was used to deposit chromium layers with and without SiC nanoparticles on mild carbon steel. The effects of current density, stirring rate and concentration of nanoparticles in the plating bath were investigated. Scanning electron microscopy was used to study surface morphology. Energy dispersive analysis technique was used to verify the presence of SiC nanoparticles in the coated layers. The corrosion behaviors of coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy methods in 0.05 mol/L HCl, 1 mol/L NaOH and 3.5% NaCl （mass fraction）, respectively. Microhardness measurements and pin-on- disc tribometer technique were used to investigate the wear behavior of the coatings.

Formations of AZ91/Al_(2)O_(3) nano-composite layer by friction stir processing

Composite layers containing~0.8%vol Al_(2)O_(3) nanoparticles were produced on AZ91 magnesium alloy by friction stir processing(FSP).The treated layers were characterized using optical and scanning electron microscopes,as well as microhardness and wear testing units.It was noticed that,by reducing the rotational speed and increasing the travel speed,the grain size of the treated layer reduces and its hardness increases.In addition,the presence of nano Al_(2)O_(3) reduces the grain sizes of the layers further and increases their hardness.Furthermore,FSP of AZ91 with Al_(2)O_(3) particles improved the wear resistance significantly and changed the wear mechanism from oxidation and adhesive mode in the as-received AZ91 to oxidation and abrasive in the FSPed specimens.Finally,the rotational speed of 800 rpm and the travel speed of 40 mm/min were the optimum parameters for achieving a suitable composite layer with the highest hardness and wear resistance among the treated layers.

Synthesis and study of MPNS/SMA nano-composite tanning agent

The radical polymerization of maleic anhydride（MA）,styrene（ST）with the vinyl groups introduced onto the surface of the nano-sized silica via solution polymerization method was developed.The methacryloxypropyl nano-sized silica（MPNS）was used as macromonomer and polymerized with maleic anhydride and styrene by initiating with BPO in toluene.The structure and properties of MPNS/SMA nano-composite were characterized by FT-IR spectra and TEM.Meanwhile,it was applied as tanning agent compared with the traditional styrene-maleic anhydride copolymer in leather.It was found that the applied leather had better quality characteristics with the addition of the nano-sized silica.

Microstructure and mechanism of in-situ Al_2O_(3(p))/Al nano-composites synthesized by sonochemistry melt reaction

The Al2O3（p）/Al nano-composites were fabricated from Al-K2ZrF6-Na2B4O7 system by sonochemistry in situ reaction. The fabrication mechanisms, including high intensity ultrasonic influence on microstructures and reinforcement particles-aluminum matrix interface, were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The XRD results show that the component of the as-prepared composites is Al2O3 reinforcement. The SEM analysis results indicate that Al2O3 particles are uniformly distributed in the aluminum matrix. The TEM results show that the morphologies of Al2O3 particles present in nearly sphere-shape, the sizes are in the range of 20-100 nm, and the interfaces are net and no interfacial outgrowth is observed. Analysis with secondary development Image-J software shows that Al2O3 recoveries are firstly improved and then decreased with increasing ultrasonic power. When the power is 0.4 kW, the distribution is the best, and a maximum number of particles are obtained. The reaction mechanisms were investigated.

Synthesis of TiO_2/ZnSn(OH)_6 Hollow Nano-composite via a Simultaneous Crystallization-etching Route as Photocatalyst

We report the synthesis of TiO2/ZnSn（OH）6 as a novel nano-composite material via a simultaneous crystallization-etching route with cubic nano-ZnSn（OH）6 and TiF4 as the precursors. The structure, composition and morphology of the composite were characterized by XRD, EDS, FETEM and FESEM, which showed the prepared TiO2/ZnSn（OH）6 had a unique morphology of hollow cubic nano-ZnSn（OH）6 attached with rutile TiO2 nanoparticles. The results of photocatalytic activity measurement indicated the photocatalytic activity of the prepared composite was better than that of nano-ZnSn（OH）6. This study may be helpful for the design and fabrication of functional comoosite materials.

Effect of milling energy on preparation of Cu-Cr/CNT hybrid nano-composite by mechanical alloying

Production of Cu-Cr/carbon nanotube （CNT） hybrid nano-composite by wet and dry milling processes at three different levels of milling energy was investigated in order to study the effect of milling energy in two different media on dispersion of CNTs, and preparation of the nano-composite. The structural evolution and solid solution formation were evaluated by X-ray diffraction technique. The microstructure was characterized by scanning electron microscopy and transmission electron microscopy. Also, the mechanical properties were measured by microhardness test. The mean crystallite size was in the range of 20-63 nm depending on milling medium and energy. CNTs dispersion is a function of milling energy. According to FESEM images and microhardness results, it can be concluded that wet milling is more applicable in dispersing CNTs homogeneously in comparison to dry milling. It was also found that wet milling at higher milling energies can be a beneficial method of producing the homogeneous hybrid nano-composite with the least damages introducing on CNTs because of the higher microhardness which can be attributed to better dispersion of less damaged CNTs. Compared with crystallite size changes, CNTs dispersion and damages were considerably more effective on hardness.

Corrosion behavior of AZ31-WC nano-composites

In this study,the effects of WC nano-particles amount and surface roughness on corrosion behavior of magnesium metal matrix nanocomposites in 3.5%NaCl solution are examined with the help of electrochemical test.Varying wt%of WC nano-particles(0.5,1,1.5 and 2)are used to fabricate metal matrix nano-composites through ultrasonic vibration assisted stir casting method.Basic characterizations of fabricated composites are performed by using scanning electron microscopy(SEM)and energy dispersive x-ray analysis(EDAX).SEM images show that nano-particles are well distributed throughout the magnesium matrix while EDAX results confirm the presence of WC particles in nano-composites.Micro-hardness result shows increasing trend with increasing weight percentage of WC.Mg nano-composite containing 0.5 wt%WC nano-particles is found to be the most corrosion resistive one followed by base alloy,Mg-2 wt%WC,Mg-1.5 wt%WC and Mg-1 wt%WC.Additionally,corrosion behavior of Mg-2WC with different surface quality is examined and it is observed that sample with lowest surface roughness shows better corrosion resistance.In the end,corrosion mechanisms are assessed with the help of SEM and EDAX study of corroded surfaces.

Novel Nano-composites SDC–LiNaSO_4 as Functional Layer for ITSOFC

As an ionic conductive functional layer of intermediate temperature solid oxide fuel cells(ITSOFC), samarium-doped ceria(SDC)–Li Na SO4nano-composites were synthesized by a sol–gel method and their properties were investigated. It was found that the content of Li Na SO4 strongly affected the crystal phase, defect concentration, and conductivity of the composites. When the content of Li Na SO4 was 20 wt%, the highest conductivity of the composite was found to be, respectively, 0.22, 0.26, and 0.35 S cm-1at temperatures of 550, 600, and 700 °C, which are much higher than those of SDC. The peak power density of the single cell using this composite as an interlayer was improved to, respectively, 0.23, 0.39, and 0.88 W cm-2at 500, 600, and 700 °C comparing with that of the SDC-based cell. Further, the SDC–Li Na SO4(20 wt%)-based cell also displayed better thermal stability according to the performance measurements at 560 °C for 50 h. These results reveal that SDC–Li Na SO4 composite may be a potential good candidate as interlayer for ITSOFC due to its high ionic conductivity and thermal stability.

Optical and Magnetic Properties of Fe_2O_3/SiO_2 Nano-composite Films

Fe2O3/SiO2 nano-composite films were prepared by sol-gel technique combining heat treatment in the range of 100-900 ℃. The particle size was observed by FE-SEM. Optical properties of the films were investigated by UV-visible spectra. Structural and magnetic characteristics were investigated through FT-IR and VSM. The transparency of the Fe2O3/SiO2 nano-composite films decreased with the content of the Fe2O3. Water and organic solvent in the films were evaporated with heat treatment, so the transparency of the films was enhanced under high temperature. It is also found that the saturation magnetization （Ms） of the films increases with the temperature. As the content of the Fe2O3 increases, when the content of the Fe2O3 is around 30wt%, the Ms of the films has a maximum value.

Nano-composite Particles Synthesized by a Hydrogen Arc Plasma

Nano-composite particles can be synthesized by a hydrogen arc plasma method, which possesses the advantages of high productivity, controllable size distribution and low electric energy consumption comparing with conventional gas condensation method. With this method, not only the nanoparticles of metals and alloys, but also the nano-composite particles with shell structure can be synthesized. The microstructures, compositions and the formation mechanism of the nano composite particles were studied

Determination of A.C. Conductivity of Nano-Composite Perovskite Ba_{(1- x - y)}Sr_(x)TiFe_(y)O₃Prepared by the Sol-Gel Technique

Nano-composite, perovskite Ba(1- x - y)Sr(x)TiFe(y)O3, denoted as (BSTFe) in powder form was derived via sol-gel (SG) method followed by sintering at fixed temperature 750℃ for one hour. The chemical composition, morphology and structure of the powder samples were investigated by using X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM). The XRD characterization indicates formation of a cubic crystalline phase in the pure BST. A well defined perovskite phase with nano-crystallite sizes equal to about 34 nm was achieved from XRD for B10ST3F sample, while TEM study confirmed the obtained XRD results giving the following crystallite size value about 33.75 nm for the same sample. The dielectric A.C. conductivity was evaluated as a function of temperature and frequency ranging from 42 Hz up to 1 MHz.

Forced vibration analysis of nano-composite rotating pressurized microbeam reinforced by CNTs based on MCST with temperature-variable material properties

In this study, free and forced vibration analysis of nano-composite rotating pressurized microbeam reinforced by carbon nanotubes （CNTs） under magnetic field based on modify couple stress theory （MCST） with temperature-variable material propertiesis presented. Also, the boundary conditions at two ends of nano-composite rotating pressurized microbeam reinforced by CNTs are considered as simply supported. The governing equations are obtained based on the Hamilton＇s principle and then computed these equations by using Navier＇s solution. The magnetic field is inserted in the thickness direction of the nano-composite microbeam. The effects of various parameters such as angular velocity, temperature changes, and pressure between of the inside and outside, the magnetic field, material length scale parameter, and volume fraction of nanocomposite microbeam on the natural frequency and response systemare studied. The results show that with increasing volume fraction of nano-composite microbeam, thickness, material length scale parameter, and magnetic fields, the natural frequency increases. The results of this research can be used for optimization of micro-structures and manufacturing sensors, displacement fluid, and drug delivery.

Influence of SiO_2 Particles on Microstructures and Properties of Ni-W-P-CeO_2-SiO_2 Nano-Composite Coatings

Ni-W-P-CeO2-SiO2 nano-composite coatings were prepared on the carbon steel surface by pulse co-deposition of nickel, tungsten, phosphorus, nano-CeO2 and nano-SiO2 particles. The influence of nano-SiO2 particles concentrations in electrolyte on microstructures and properties of the nano-composite coatings were researched, and the characteristics were assessed by chemical compositions, element distribution, deposition rate, microhardness and microstructures. The results indicate that when nano-SiO2 particles concentrations in electrolyte are controlled at 20 g·L-1, the deposition rate with 27.07 μm·h-1 and the microhardness with 666 Hv of the nano-composite coatings are highest, element line scanning and area scanning analyses show that the average contents of elements W, P, Si and Ce in the nano-composite coatings are close, displaying that the distribution of every element within the nano-composite coatings is even. An increase in nano-SiO2 particles concentrations in electrolyte (when lower than 20 g·L-1) leads to refinement in grain structure of nano-composite coatings, but when it improved to 30 g·L-1, the crystallite sizes increase again and in the meantime there are a lot of small boss with nodulation shape appearing on the surface of nano-composite coatings.

Effect of temperature and strain rate on compressive response of extruded magnesium nano-composite

The hot deformation behaviour of extruded magnesium-zinc oxide nano composite has been studied using hot compression test.The test was conducted in the temperature range of 250-400℃ and in the strain rate range of 0.01 to 1.5 s^(−1).The processing map was obtained using the power dissipation efficiency with the functions of temperature and strain rate.The workability and instability domains were observed in the processing map for a nano composite.The optical microscopy(OM),scanning electron microscopy(SEM)and transmission electron microscopy(TEM)images were used to confirm the formation of dynamic recrystallization(DRX),dynamic recovery(DRY)and instability regions.The workability region of the composite was identified at a working temperature of 400℃ and the strain rate of 0.01 s^(−1) from the processing map.The instability regions were observed at higher strain rates(>0.1 s^(−1))and temperatures(250-400℃).

Preparation and Properties of TiO_2/Montmorillonite Nano-Composite with Different TiO_2

The hydrated-titanium-oxide/montmorillonite composite samples were prepared using a hydrolysation- intercalation composite method by controlling the amount of TiOSO4·2H2O. The TiO2/montmorillonite composite samples were got after calculated at 700℃ and 1100 ℃. The results show that: when the value of Ti/montmorillonite is 12.5 mmol/g, the c axis of hydrated-titanium-oxide/ montmorillonite composite sample began to disorder, moreover, the crystal size of anatase is just 13.4nm in the TiO2/montmorillonite composite sample calculated at 700 ℃, and after calculated at 1100 ℃, the crystal size of anatase is 55.8 nm, and the relative content of anatase reaches the highest (55.7%). Compared with pure TiO2 nano-particle sample, TiO2/montmorillonite composite sample has a higher phase transition temperature from anatase phase to rutile phase and smaller crystal size of TiO2. Montmorillonite structure layer has a significant blocking effect on TiO2 phase transformation and grain growth, and the blocking effect reaches saturation when the value of Ti/montmorillonite is 12.5 mmol/g.

Hydrogen Adsorption Study upon Ni/AI203 Nano-composite Synthesized by MOCVD Technique

The hydrogen adsorption （storage） studies upon Ni/A1203 nano-composite prepared by metal organic chemical vapor deposition technique （MOCVD） exploiting single source molec ular precursor （SSP） approach were carried out. The Ni/A1203 nano-composite is prepared in cold walled MOCVD reactor by the decomposition of SSP, [H2AI（OtBu）]2, on a substrate holding Ni（acac）2 powder. The SSP is a reducing agent which reduces Ni＋2 to Ni0 and works as source for Al203 matrix in which the Ni0 is dispersed. The resulting Ni/A1203 nano-composite is characterized by XRD, SEM, TEM, and EDX. The hydrogen adsorption （storage） studies are performed using home-made Sievert＇s type apparatus. The hydrogen storage studies reveal that approximately 2.9% （mass ratio） hydrogen can be stored in the Ni/A1203 nano-composite. The results show that Ni/A1203 nano-composite can be a po- tential candidate for hydrogen storage which can be used for onboard fuel purposes.

Enhanced nonlinear optical absorption of Au/SiO_2 nano-composite thin films

Nano metal-particle dispersed glasses are the attractive candidates for nonlinear optical material applications. Au/SiO2 nano-composite thin films with 3 vol% to 65 vol% Au are prepared by inductively coupled plasma sputtering. Au particles as perfect spheres with diameters between 10 nm and 30 nm are uniformly dispersed in the SiO2 matrix. Optical absorption peaks due to the surface plasmon resonance of Au particles are observed. The absorption property is enhanced with the increase of Au content, showing a maximum value in the films with 37 vol% Au. The absorption curves of the Au/SiO2 thin films with 3 vol% to 37 vol% Au accord well with the theoretical optical absorption spectra obtained from Mie resonance theory. Increasing Au content over 37 vol% results in the partial connection of Au particles, whereby the intensity of the absorption peak is weakened and ultimately replaced by the optical absorption of the bulk. The band gap decreases with Au content increasing from 3 vol% to 37 vol % but increases as Au content further increases.

Preparation and properties of nano-composite ceramic coating by thermo chemical reaction method

Nano-composite ceramic coating was fabricated on Q235 steel through thermo chemical reaction method. Structure of the coating was analyzed and the properties were tested. The results show that a few of new ceramic phases, such as MgAI2O4, ZnAI2O4, AI2SiO5, Ni3Fe and Fe3AI, are formed on the coating during the process of solidifying at 600 ℃. The ceramic coating is dense and the high bonding strength is obtained. The average bonding strength between the coating and matrix could be 14.22 MPa. The acid resistance of the coating increase by 8.8 times, the alkali resistance by 4.1 times, the salt resistance bv 10.3 times, and the wear resistance bv 2.39 times.

Reactive DC Magnetron Sputter Deposited Titanium-Copper-Nitrogen Nano-Composite Thin Films with an Argon/Nitrogen Gas Mixture

A sintered Ti13Cus7 target was sputtered by reactive direct current （DC） magnetron sputtering with a gas mixture of argon/nitrogen for different sputtering powers. Titanium-coppernitrogen thin films were deposited on Si （111）, glass slide and potassium bromide （KBr） substrates. Phase analysis and structural properties of titanium-copper-nitrogen thin films were studied by X-ray diffraction （XRD）. The chemical bonding was characterized by Fourier transform infrared （FTIR） spectroscopy. The results from XRD show that the observed phases are nano-crystallite cubic anti rhenium oxide （anti ReO3） structures of titanium doped Cu3N （Ti：Cu3N） and nanocrystallite face centered cubic （fcc） structures of copper. Scanning electron microscopy and energy dispersive X-ray spectroscopy （SEM/EDX） were used to determine the film morphology and atomic titanium/copper ratio, respectively. The films possess continuous and agglomerated structure with an atomic titanium/copper ratio （-0.07） below that of the original target （- 0.15）. The transmittance spectra of the composite films were measured in the range of 360 nm to 1100 nm. Film thickness, refractive index and extinction coefficient were extracted from the measured transmittance using a reverse engineering method. In the visible range, the higher absorption coefficient of the films prepared at lower sputtering power indicates more nitrification in comparison to those prepared at higher sputtering power. This is consistent with the formation of larger Ti：Cu3N crystallites at lower sputtering power. The deposition rate vs. sputtering power shows an abrupt transition from metallic mode to poisoned mode. A complicated behavior of the films＇ resistivity upon sputtering power is shown.