Advanced Materials Research Vols. 834-836

Abstract: We prepared the novel coralloid hierarchical structure of α-FeOOH composed of rod-shaped nanosheets by wet method using ammonia and ferrous sulfate. Through observation by Field emission scanning electron microscope (FESEM), the morphology and structure of α-FeOOH in the process of growth was presented. And the formation mechanism of this coralloid crystal α-FeOOH was studied, in order to provide important theoretical support for the preparation of high quality iron oxide yellow products.

Abstract: The single crystalline In₂S₃ nanosheets with highly efficient photocatalytic activity have been controllably synthesized via a facile hydrothermal process without adding any surfactant. The morphologies of the nanosheets were characterized by SEM and TEM. The results show the diameter of the nanosheets ranges from 100nm to 400nm. The photocatalytic decomposition of methyl orange on the catalyst shows it has much higher photoactivity than that of nanoTiO₂ which means it may be more capable to be used as photocatalyst in decomposition of organic pollutants.

Abstract: Hydrothermal method was used to prepare Ce doped ZnO. Effects of doping ratio, reaction time, reaction temperature, filling degree on the flower-like morphology of ZnO were studied. And the phase, morphology and size of the products were characterized by XRD and SEM. The vector network analyzer was used to characterize the products electromagnetic performance. The results show that, Ce is successfully doped into the lattice of ZnO. The products maintain perfect flower-like structure when Ce:ZnO (molar ratio) is 0.5%. However, the flower-like morphology is damaged more and more obviously with the doped concentration increasing. The crystal growth rate accelerates with reaction temperature increasing. Microwave absorbing properties of ZnO can be improved greatly by doping Ce. The reflection loss is more than 10dB when the frequency between 9.8 GHz and 11.6GHz.

Abstract: The research of the nano-mechanical properties on mono-crystalline silicon by nanoindention technology is reported in this paper . Using the calculation method given by Oliver and Pharr, the hardness and the elastic modulus of mono-crystalline silicon are gained from the load-penetration depth curve. The simulation on mono-crystalline silicon in the plastic phase is carried out by ABAQUS. Based on the bilinear constitutive law and approximate relationship between the hardness and the yield strength, the obtained load-penetration depth curve through the finite element method is compared with the materials actual load-penetration depth curve and good correlation is achieved.

Abstract: Ti (C,N)/ZrO₂/WC nanocomposite cermet die materials were fabricated by vacuum hot pressing process, the materials have better comprehensive mechanical properties. The friction and wear properties of Ti (C,N)-based nanocomposite cermet die materials were studied, and the worn surfaces microstructure were observed and analysed by SEM and XRD. The experimental results showed that when the rotate speed was higher, the coefficient of friction of the developed cermet die material, which is 0.3-0.4, was lower than that without the addition of nanoZrO₂ and micrometer WC. The main wear mechanisms were abrasive wear, oxidation wear and adhesive wear.

Abstract: TiO₂ nano film with different nano structure were prepared on the surfaces of titanium TA1 and titanium alloy TC4 via electrochemical anodization. The surface morphology was observed with SEM, and it is found that TiO₂ films prepared on TA1 surface have porous structures, while the TiO₂ films synthesized on TC4 surface look like nano rod. The contact angle(CA) test results show that the TiO₂ nano film prepared on TA1 is hydrophilicity and the CA is about 19°,the film on the TC4 is super hydrophilicity and its CA is smaller than 2°. After combined with fluorinated silane the self-assembled film synthesized on the surfaces and they are superhy- drophobic and the Contact angle is 150° and 158° respectively. It is concluded that both nano- structures and fluoroalkysilanes with low surface energy have play an important role in the wettability with the contact angle is more than 150°. The surface only have nano roughness without the low energy does not show superhydrophobicity.

Abstract: In this paper, the process parameters of graphene during fabrication and transfer are investigated. Cu is utilized as the substrate and chemical vapor deposition are used to obtain graphene. The results show that, the surface condition of the Cu substrate tends to be worse than as-received after a relatively higher temperature (1035°C) annealing and growth process, which lead to bad graphene quality. In addition, pre-treatment of Cu substrate by acetic acid is helpful to reduce the nucleation sites. Reflow process before PMMA etching is an effective method to eliminate the wrinkles formed during transfer. High-quality graphene for optoelectronic applications were obtained based on the optimized fabrication and transfer process.

Abstract: We fabricated mono-dispersed β-quartz GeO₂ by microemulsion synthesis at room temperature. The obtained particles were 300 nm sized GeO₂ walnut and hollow waxberry shaped GeO₂ which were consisted of nanosphere with average size of 20 nm. The evolution of high pressure studies were devoted in a diamond anvil (DAC) cell by Angle Dispersed X-ray Diffraction (ADXD) at room temperature. A phase transformation of β-GeO₂ to amorphous GeO₂ was detected in walnut GeO₂, while the waxberry GeO₂ was found to transform to monoclinic phase directly. It is strongly suggested that size effect played a key role in the high-pressure transformation from the amorphous and monoclinic phase. By fitting the compression data to the BirchMurnaghan equation of state, the bulk moduli of the walnut and waxberry shaped β-GeO₂ particles were determined to be 33±5, and 38±4 GPa with B₀ = 3, respectively.

Abstract: In the paper, we prepared superhydrophobic surfaces on copper foils via a facile solution-immersing method. The influence of experiment conditions, such as solution concentration, immersing time and temperature, on the surface structure is investigated in detail. When the concentration of stearic acid-ethanol solution, the immersing time and the temperature are 2 g/L, 120 min and 40°,respectively, the resulting copper surface possesses great superhydrophobicity with a water contact angle of up to 159° and a sliding angle of only 3°.