Applied Mechanics and Materials Vols. 475-476

Abstract: High-quality GaN films are deposited on diamond films using an electron cyclotron resonance plasma enhanced metal organic chemical vapor deposition (ECR-PEMOCVD) under the condition of the proper Trimethyl gallium (TMGa) flux. The influence of TMGa flux on the properties of GaN films is systematically investigated by x-ray diffraction analysis (XRD) and atomic force microscopy (AFM). The results show that the high quality GaN films with small surface roughness and high c-orientation are successfully achieved at the optimized flux. The most significant improvements in morphological and structural properties of GaN films are obtained by using a proper TMGa flux

Abstract: Highly-quality GaN films were deposited on diamond substrate using an electron cyclotron resonance plasma enhanced metal organic chemical vapor deposition system (ECR-PEMOCVD) at the proper temperature. The source of gallium is Trimethyl gallium (TMGa) and N₂, and the influence of temperature on the properties of GaN films was investigated systematically by X-ray diffraction analysis (XRD), atomic force microscopy (AFM), room temperature photoluminescence (PL), respectively. The dense and uniformed GaN films with highly c-axis preferred orientation were successfully achieved on free-standing diamond substrates under optimized deposition temperature of 400 °C.

Abstract: Oxide-dispersion-strengthened (ODS) ferritic alloys are fascinating materials for future fusion power reactors due to these materials would allow a substantial increase of the operating temperature. Y-Ti bioxides strengthened Fe-Cr alloy was produced by mechanical milling (MM) followed by hot pressing (HP). Microstructure changes of the mixed powders during mechanical milling and subsequent hot pressing were structurally characterized by means of scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The observations of structure of the mixed powders after MM indicated that the powders are fractured and welded with rotation and vibration of container during mechanical milling. And the particle size decreases with increasing milling time. Nanoscale Y-Ti bioxides were formed during the HP process.

Abstract: In present study, uniformed nanozirconia is obtained via precipitation, ball milling and spray drying. The characteristics of methylene blue adsorption by nanozirconia are studied in details. The morphology of nanozirconia is examined by SEM. The influence of temperature is studied to obtain the optimal adsorption conditions. The equilibrium adsorption isotherms and the kinetic properties of the adsorption process are investigated to study the mechanism. The thermodynamic properties of methylene blue adsorption is investigated, and the thermodynamic parameters of G^θ, H^θ and S^θ are calculated. The results show nanozirconia has high adsorption ability of 43.99 mg/g to methylene blue, and the adsorption reaction is a spontaneous and physic-sorption process.

Abstract: Nuclear energy, due to having rich savings, great power, and less air pollution, gradually uses in civilian life widely. However, when this new energy is booming, some serious problems has appeared,such as radiation damage, the pollution of radioactive wastewater.etc .So how to make an effective protection and remediation to radiation injury has become a hot spot around the world. Here we will resport the relationship between a biological nanomaterials --Mollusk shell and the nuclear radiation, and we find that Mollusk shell not only can adsorb radionuclides, but also can repair the radiation injuries.This new function may contrubute to the design and synthesis of new radiation resistant materials.

Abstract: a low surface energy coating with a long chain fluorine siloxane is prepared, and the performance in anti-freezing adhesive is studied. It is determined that the optimum proportion of (Heptadecafluoro-1,1,2,2-tetradecyl) trimethoxysilane (FAS) and SiO₂ nanopowder are 1.1% and 1.6%,respectively. the times of coating bear pendulum impact is least in this proportion. the conclusion is that bionic superhydrophobic coating plays a certain guiding role on solving material surface frozen sticky problem.

Abstract: In this paper, an efficient metal oxide sorbents for the deep removal of H₂S were synthesized using equal volume impregnation (EVIM) method. Modified coconut shell charcoal was selected as support to deposite the particles of copper oxide onto the surface. And copper nitrate were selected as the active component precursors in the preparation process of sorbents. Sorption experiments were carried out at room temperature in fixed-bed reactor. The grain size and crystal form of loading metals were characterized by X-ray diffraction (XRD). We investigated the effects of modifier onto coconut shell charcoal, load rate of metal oxide and calcination temperature on the desulfurization activity of the sorbent. Results show that the best modifier for coconut shell charcoal is KOH, which is significantly better than the other modifiers. And the optimum load rate is 20%(wt), the optimum calcination temperature is 300°C. Copper oxide onto the surface of modified coconut shell charcoal proved to be monoclinic nanoparticles with grain size of 18.7nm. Sulfidation test was carried out on the condition of i) the concentration of hydrogen sulfide gas (mixed with nitrogen ) is 1024.2ppm and ii) gas velocity is 20ml/min, iii) 0.1g sample in the middle of the fixed-bed reactor (length: 450 mm, interior diameter: 5 mm) to test. The sample show excellent sulfur removal efficiency and its breakthrough time is up to 287 min on this condition.

Abstract: Using face-to-face mode, the antifriction performance of FeS nanoparticle was studied, which prepared by biotechnology as lubricant additive. The results showed that the size about 30-50nm FeS nanoparticle with amorphous state could effectively decrease the friction coefficient of base fluid and the value of friction coefficient reached minimum value when the FeS content was 1%. Moreover, the anti-friction mechanism of FeS nanoparticle was also discussed based on the SEM and EDS results.

Abstract: Nanometer materials are widely used in the modification of polymer materials such as polypropylene because of its unique performance. nanocomposite material,which expended the application field of polymer ,is a kind of new composite materials with high performance ratio and widely application prospect .This paper adopted the surface-initiated technology to coat and modify the surface of nanosilica,which solved the problem of the agglomeration and interface compatibility of the nanometer particles and improved its dispersion in the acrylic acid,then prepared SiO₂/PAA nanocomposite .The composite was characterized by infrared spectrum and transmission electron microscopy (TEM) ,etc.The research results showed that the nanocomposite prepared by in-situ polymerization technology had higher toughness ,strength and more excellent comprehensive performance.

Abstract: The relation of time of a fire suppression to the consumption (intensity of submission) carbon dioxide is investigated thus arrest value of temperature in model and speed of burn-out of a fire load.