Advanced Materials Research Vol. 910

Abstract: A metamaterial is an artificially structured material which attains its properties from the unit structure rather than the constituent materials. Here, artificially designed silver dendritic structure was used as basic cells to fabricate metamaterials working at IR frequency range, silver dendritic structure was prepared in the mixture of F127 and PEG, then assembled on glass substrate by self-assembly process and further fabricated into sandwich-like metamaterials with Indium-Tin-Oxides (ITO) glass. Micro-morphology of the dendrites array was examined by scanning electron microscopy. These complex-structured metamaterials exhibit pass-bands at IR frequencies, and show slab focusing effect subsequently.

Abstract: The Co₃O₄ nanoparticles were obtained from the precursor precipitated by CoCl₂ and NaHCO₃ via precipitation method, and were characterized by IR, XRD. The firing system of precursor was detected by TG-DSC, and the effects of temperature on grain size were investigated.

Abstract: In this paper, the NiCu alloy coatings were electroplated on the 304 stainless steel coupon. The XRD was used to identify the phase structure of the as-prepared products. The SEM and EDS were used to observe the surface morphology of the as-prepared coatings and the atomic composition of the as-prepared coatings, respectively. The influences of the temperature on the as-plated NiCu coatings are systematically researched. It was found that the lower of the temperature, the more compact of the coatings. With the increasing of the temperatures, the content of the nickel decrease and that of the copper increase. When the temperature is lower than 35 °C the contents of nickel and copper do not vary apparently. When the temperature is larger than 40 °C, there are significant increases of the copper content while apparent decreases of the nickel content.

Abstract: In this paper, the NiCu alloy coatings were electroplated on the 304 stainless steel coupon. The XRD was used to identify the phase structure of the as-prepared products. The SEM and EDS were used to observe the surface morphology of the as-prepared coatings and the atomic composition of the as-prepared coatings, respectively. The influences of the pH value on the as-plated NiCu coatings are systematically researched. It was found that the weak acid environment was beneficial to the deposition of nickel copper alloy. With the increasing of the pH value, the content of the copper decrease and that of nickel increase.

Abstract: A kind of alcohol-soluble acrylate adhesive was synthesized by solution-polymerization. The influences of monomer ratio of soft to hard, function monomer and initiator content were studied on adhesive performance. The optimal conditions: ethanol as solvent, MA : MMA : AA : VAc = 4.5 : 4 : 1.5 : 2 : 0.8, and BPO is 0.8% of total mass, the temperature is 73 °C for 3.5 h. The properties of adhesive were determined.

Abstract: A new technique to prepare macroporous hydroxyapatite (HA) scaffolds was introduced. Porous HA ceramics were prepared by sol-gel method from chitin dissolved in dimethylacetylamide (DMAc) / lithium chloride (LiCl) solvent, three dimensional stacking with HA gel fibers and pore agent. The blocks dried were heated to optimum sintering temperature of 1280°C. The porous HA ceramics reinforced by homogeneous fibers, with interconnected pores and high porosity and pore-diameter were obtained, whilst improving mechanical strength. Sintered ceramics were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analysis confirmed that the crystal structure remained HA. SEM showed the samples presented a highly interconnected porous reticulate structure with average pore size ranging from 340μm to 450μm. The porosity was varied from 61% to 83%. The maximum compressive strength of HA ceramic was 3.4MPa.The mechanical strength of samples was improved with addition of homogeneous fibers.

Abstract: A duplex-layered phosphate conversion coating was obtained on AZ31Mg alloy through a phosphate bath with citric. Morphology, composition and corrosion behavior of the coating immersed into 3.5% NaCl solution for various time were investigated using scanning electron microscopy (SEM), X-ray diffractometer (XRD) and electrochemical method. The results show that the coating is completely degraded after immersed in NaCl solution for 48h. The corrosion mediums mainly peel coating through the cracks among particles. The phosphate coating is damaged and falls out primarily, then the intermediate layer is degraded, and the substrate happens to dissolve with increasing of immersion time.

Abstract: Graphene nanoplatelets (GNP) were prepared by ball milling, and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). PMMA/GNP composites were produced by a melt process. The flammability of PMMA/GNP composite was evaluated by the cone calorimeter (Cone) and thermal degradation of the composite by thermogravimetric analyses (TGA). Cone data indicate that the incorporation of 1% GNP leads to a 12% reduction in the peak heat release rate compared to pure PMMA. The TG results show that the addition of small amount of GNP (1%) can improve thermal stability of PMMA.

Abstract: Laboratory results from sandstone Brazilian splitting tests and uniaxial compression tests based on acoustic emission (AE) monitoring indicated that the acoustic emission parameters analysis method can be applied to analyse the characteristics of acoustic emission and to classify the crack modes in rock materials. It concluded that more than 99 per cent of the whole cracking signals in Brazilian tests were classified as tensile mode, and no shear cracks occurred. And more than 65 per cent of the AE signals in uniaxial tests were tensile-shear crack mode, along with about 30 percent of tensile mode and 5 percent of shear mode, and shear cracks only occurred in the unstable crack extension stages; tensile-shear cracks are the main crack modes in the crack stable extension stage.