Hai Yan Zhang

Effect of Wood Flour on the Curing Behavior, Mechanical Properties, and Water Absorption of Natural Rubber/Wood Flour Composites

The preparation of natural rubber/wood flour (NR/WF) composites and the influence of WF content, modification, and particle size on the vulcanizing behavior, mechanical properties, and water absorption of NR/WF composites are described. Results show that the addition of WF into NR delayed the scorching time and vulcanizing time of NR. The appropriate WF contents can improve the mechanical properties of NR. However, the overloading of WF destroys the mechanical properties of NR. The addition of WF increased the water absorption of NR. The silicone couple agents that were used to modify the WF had little effect on the water absorption of NR/WF composites. Decreasing the WF particle size enhanced the water absorption of NR/WF composites because the water-absorbing surface area increased with decreasing WF particle size. The water absorption of sisal-fiber-filled NR-based composites was larger than that of the WF-filled NR-based composites. A useful equation, w=ktn , was inferred from the water absorption results to calculate the water absorption (w) of the NR/WF composites as a function of time (t), where k was a constant concerning the compounds’ character that was primarily determined by the WFs character and n was the power of time that was related to the NRs inherent character, such as cross-linking density, and primarily determined the water absorption rate.

Hydrogen Storage in Carbon Nanotubes Prepared by Using Copper Nanoparticles as Catalyst

carbon nanotubes were synthesized by pyroysis method using copper nanoparticles as catalyst. The structure, phase composition and hydrogen storage capacity were investigated by TEM, XRD spectra and Electrochemical System. The results show that the diameter of carbon nanotubes is 200-500nm, The P-C-T curve of adsorbing hydrogen of samples was measured in the pressure up to 12 MPa at room temperature. we show that a SWNT can strongly adsorb up to 8-wt% hydrogen. These results advance our fundamental understanding of dissociative adsorption of hydrogen in nanostructures and suggest new routes to better storage and catalyst materials.

Electromagnetic Characteristics and Microwave Absorption Properties of CNT Composite

The microwave permittivity and permeability of Carbon Nanotubes (CNTs)/paraffin and CNTs-Co(C)/paraffin were measured respectively and their differences were discussed in detail. Furthermore, the reflection losses for double-layer CNTs (CNTs-Co(C))/epoxy coatings, with the thickness ranged from 1.6-2 mm, were practically tested through Arc Method in 2.6-18 GHz frequence range. The results indicated that the reflection loss peak shifted towards low frequency and the peak value decreased with the coating thickening and possible mechanisms for the phenomena were given.

Study on the Effect of Ultrasonic Waves on the Low Temperature Electroless Ni-P Plating on Copper Substrate

In this paper，electroless Ni-P plating on copper substrate at 50 °C in ultrasonic field was carried out. The frequency of ultrasonic waves was 40 kHz. The effect of ultrasonic on the composition, plating rate and morphology of Ni-P deposite was investigated at the ultrasonic power of 40, 70 and 100 W. The experimental results showed Ni-P deposit could not be obtained without ultrasonic field at 50 °C. The content of nickel and the thickness of Ni-P deposit increased with the ultrasonic waves power increase. Ultrasonic irradiation power remarkably refines the nodule size of Ni-P particles. The collapse of cavities in solution seems to suppress the Z-direction growth of the nodule.

The Influence of Electroless-Silver Coated Cenosphere Powders on the Electromagnetic Shielding Interference Effectiveness and Mechanical Properties of the Silicone Rubber

Silver plating cenosphere powders were developed by electroless plating method. After being mixed with silver plating cenosphere powders and curing agent, silicone rubber composites was obtained. The surface morphology, microstructure and cross-section of Ag-coated cenosphere powders and composites were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influence of different concentration of Ag-coated cenosphere powders on the conductivity, electromagnetic shielding interference effectiveness and mechanical properties of the silicone rubber was discussed from the point of view of condition of Ag-coated cenosphere powders and silicone rubber. The results showed that the smooth and compact silver coating was deposited on the surface of cenosphere powders. The Ag-coated cenosphere powders possessed good oxidation resistance and enough strength to resist being crushed during the preparation of composites. The adhension between the silver film and cenosphere powders was good. There existed the extreme shielding effectiveness (SE) of silicone rubber composites filled with Ag-coated cenosphere powders. The electrical conductivity no longer plays an important role in enhancing the SE of composites when the SE of composites reaches the extremum. When the content of the Ag-coated cenosphere powders was 180 parts per hundred of rubber (phr), the SE values of composites were typically above 80 dB and close to the extremum across the tested frequency range from 2.6 GHz to 3.95 GHz. And the mechanical properties of composites with 180 phr were not degraded obviously.

The Super-Capacitor Properties of Aligned Carbon Nanotubes Array Prepared by Radio Frequency Plasma-Enhanced Hot Filament Chemical Vapor Deposition

Aligned carbon nanotubes (ACNTs) array is synthesized by plasma-enhanced hot filament chemical vapor deposition of the stainless steel substrate covered by ferric nitrate. The morphology and structure of the carbon nanotubes array are characterized by Scanning Electron Microscope and Transmission Electron Microscope. Cyclic voltammetry, constant current charge-discharge technique are employed to test the electrochemical performance of the button-like super-capacitor fabricated using the ACNTs array as electrode. The specific capacitance of the ACNTs array electrode reached 160.9F/g in the potential range of -0.2~+0.8V, at a scan rate of 1mV/s in 1mol/L Na2SO4 aqueous electrolyte.

Phase Transformations and Magnetic Properties of Electroplating Ni-Co on Aluminium

In this paper, Ni-Co coatings on Al foil were prepared by electroplating to obtain Al/Ni-Co composite. Phase transformations and magnetic property of Al/Ni-Co composite heated at 823 K for 80 h were investigated. The results showed that obviously exchanged zone in Al matrix exited and the thickness was about 2.5μm. Ni diffused into the Al easilier than Co. β phase (AlNi and AlCo) and γ phase (Al (Ni, Co) solid solution) of Co-Ni-Al formed during the annealing. The Ms of was decreased significantly when Al diffused into the NiCo alloy film and formed Ni-Al and Co-Al intermetallic compounds.

The Influence of Composition on Morphology, Structure and Magnetic Properties of Ni-Co Films on Aluminum Prepared by Electroplating Method

In this paper, Ni-Co alloy films with different composition were obtained by means of electroplating method. The morphology, structure and magnetic properties of Ni-Co alloy films with different Cobalt content are evaluated. The effect of the crystal orientation on the morphology of Ni-Co deposits with different compositon was discussed. The results showed that Ni–Co alloy films with Cobalt content decrease is composed of pyramidal, spindly, mixed pyramidal and spindly, and cellular particles respectively. To the deposits with similar composition, change of morphology is related to the preferential orientation. With the increase of the Nickel content, the saturation magnetization (Ms) value of the Ni–Co alloy films increases and then decreases sharply. The coercivety (Hc) value of the Ni–Co alloy films decreases with the Nickel content increase.

Peparation and Magnetic Propriety of Carbon-Coated Iron Magnetic Nanoparticles by Starch Coating Method

We synthesized carbon-coated iron magnetic nanoparticles by a low cost method using Ferric nitrate as the iron precursor and starch as both reductive agent and carbon source under H2 atmosphere. The structure, size distribution, phase composition, magnetic properties and oxidation resistance of the particles were investigated by transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry and differential scanning calorimetry. The results show that the carbon-coated iron nanoparticles are spherical particles with a diameter of 20-40 nm. They are particles of core-shell structure with an iron core inside and an onion skin carbon layer outside, carbon layer can protect inner iron core from been oxidized, the hysteresis curves show that they are super paramagnetic materials. At the same time the annealing can change the magnetic properties of carbon coated iron nanoparticles.

Preparation and ESR Properties of Silicon Nitride Nanowires

We prepared Solid silicon nitride nanowires using carbon nanotubes as precursors., Si and SiO2 were used as raw materials,the reaction was carried out in ammonia atmosphere The structure, phase composition, ESR properties and oxidation resistance of the sample were investigated. The results showed that the sizes of the nanorods are 60–80 nm in diameter and up to several microns in length. In the products α-Si3N4 is the main component; the FTIR spectra of the silicon nitride nanowires have blue shift phenomena;The ESR properties show that the as made materials contains a large number of unpaired electrons