Advanced Materials Research Vols. 79-82

Abstract: Ceramics, Composite Material, GFRP, Clay, Recycling, Bending strength Abstract In this study, as the effective recycling technique for the waste GFRP, the process for the producing the porous glass fiber reinforced ceramics by firing the mixture of the clay and the crushed waste GFRP was proposed. The proposed recycling technique for the waste GFRP enables to produce various ceramics parts by effectively reusing the glass fibers included in the waste GFRP as well as to dispose injurious GFRP radically. By changing the mixing ratio of the waste GFRP and clay, and by firing the mixture at some temperatures, several kinds of ceramics specimens (tiles) were produced. The microstructure of each specimen was observed using the SEM and the microscope, and then water absorption and the bending strength of the specimens were examined in detail by comparison with those of specimens without the glass fiber. From those results, it was confirmed that the high-strength porous glass fiber reinforced ceramics could be produced by our proposed process.

Abstract: The Al-Mg-B polycrystalline bodies were prepared using vacuum hot-pressing sinter method by pure Al, Mg and B powders. Process parameters and constitution variation were investigated to obtain compact Al-Mg-B sintered body with high mechanical properties. Al-13%Mg-72.7%B(weight ratio) sintered body prepared under 1600°C, 30MPa for 1 hour in vacuum was proved to be optimum, which bending strength was 156MPa and Vickers hardness was 2220. X-ray diffraction (XRD), Micron Probe Micro-analyzer (EPMA) were employed to analyse the ultimate phases. The results showed that the matrix phases were metal borides including AlB12, MgB6 and AlMgB14, while Al2O3 and MgAl2O4 phases existed which connected or filled in the matrix grains to promote the compactness degree, where oxygen introduced from impurities in raw materials. A portion of Mg in AlMgB14 combined with oxygen during heating to 1600°C which helped to form MgAl2O4 and AlB12 in the end.

Abstract: With the emergence of large-size complex structures, conventional discrete sensors can’t meet the requirement of structure health monitoring because they can only sense the strain in a single direction. In this paper, based on sensing and covering properties of carbon fiber smart material (CFSM), an idea of a sensitive layer placed on the structure surface was proposed. By setting finite electrodes on the edge of the sensitive layer, the stress field of tested structure is transformed to electric field which is apt to be tested, and with resistivity tomography technology (ERT), field(global) monitoring on civil engineering structure can be realized. To avoid impact resulting from measuring errors caused by misc factors in experiment, CFSM ERT system was utilized in virtual experiments. Virtual Experiments were conducted on ANSYS finite element software aided by its excellent abilities in coupled field analysis. The virtual experiments included two cases: circular plate simply supported at its perimeter under single loading of different values in the center, and circular plate simply supported at its perimeter under multipoint loading in different positions. In the virtual experiments current incentive in adjacent electrodes and voltage measurement in other adjacent electrodes were implemented, and the measured voltage data was transmitted to the ERT system to obtain the contour plot of resistivity distribution. It indicates that for the single loaded CFSM virtual experiment with tensile strain, its resistivity is increased with the load increase. Compared with 1st and 2nd principal strain distribution in structure tested area, resistivity distribution will qualitatively reflect force field of structure. In multipoint loaded CFSM virtual experiment with compress strain, resistivity descends. Compared with 3rd and 2nd principal strain distribution in structure tested area, low resistivity area just locates at area of biggest strain. Based on virtual experiment, efficiency of CFSM ERT system is demonstrated, greatly supporting the consequent practical application.

Abstract: The composite materials TiN/3Y-TZP, 3Y-TZP doped by TiN with different contents and particle sizes, were fabricated through the same hot-pressing techniques. Compared with 3Y-TZP, the low temperature degradation resistance of TiN/3Y-TZP aged at the temperature from 170°C to 350°C in air for 50 h was investigated in virtue of XRD and SEM in the experiment. For TiN/3Y-TZP and 3Y-TZP, the maximum aging rate all occurs at 220°C. The addition of TiN can availably improve the low temperature degradation resistance of 3Y-TZP at different aging temperatures, but cannot change the relationship between the aging rate and the aging temperature. For TiN/3Y-TZP, the matrix particle size is the key factor responsible for its low temperature degradation resistance.

Abstract: How to moderate ship the damages caused by the underwater explosion (UNDEX) is of great interest to the modern ship designers. A new type of rubber sandwich with periodic honeycomb core was developed to mitigate the ship shock due to UNDEX. A ship with or without the rubber coat was tested under “near combat conditions” by igniting a 8 kg charge of TNT underwater at varying standoff distances from the ship. The effects of the shocks to ship systems were observed and the responses of the ship were monitored and recorded for each shot. The pressures in the water around the ship were also recorded to explore the fluid-structure interaction and UNDEX shock wave reflection with different targets. Acceleration and strain records indicate that the rubber coat is capable of moderating the high-frequency response excited by shock wave efficiently. Pressure records show that the core crushing and water cavitation promote superior energy absorption that yields an increased resistance to UNDEX.

Abstract: The preparation of MgCl2/AC composite and its adsorption behavior of azo dye from aqueous solution were investigated. The pore size of the new kinds of adsorbent increased with increasing the dosage of MgCl2 solution, while specific surface area decreased. The removal rate of Weak Acid Red 2R from aqueous solution on the MgCl2/AC composite was 93.4 % at the optimum conditions of the preparation: activated carbon with 2 M MgCl2 solution at 110°C for 2 h.

Abstract: Wastes such as saw dust (Pinus Radiata) and milk bottles (High Density Polyethylene - HDPE) are available in abundance. HDPE bars and composite bars, consisting of different volume percentages (50%, 60% and 70%) of saw dust and recovered HDPE, were extruded using a co-rotating, conical, twin screw extruder with a slit-profile die and an innovative sizing-cooling box. The extruded bars were evaluated on their surface finish, shape conformance and materials distribution across the cross-section. Mechanical testing of the extruded bars was carried out using appropriate ASTM standards after they met the required quality ratings.

Abstract: The microstructures and magnetic properties of nickel ferrite synthesized by coprecipitation and sol–gel methods are comparatively studied. The coprecipitation-derived samples have Fe/Ni ratios differing from their raw materials because of the precipitation washing process. The stoichiometric metal cations (Fe/Ni=2.0) in the xerogel facilitated the nucleation and growth of nickel ferrite nanocrystallites at lower calcination temperature in sol–gel method. The samples consist of nickel ferrite nanocrystallites, and have superparamagnetic properties at room temperature.

Abstract: In this paper Polyglycol (PG) was used as ‘soft’ template to induce the polymerization of aniline in aqueous ethanol and hence control both the nucleation and growth of polyaniline (PANI) nanofibers. The products were characterized by Transmission electro microscope (TEM) and X-ray diffraction (XRD) techniques. TEM photos showed that the diameter of PANI nanofibers synthesized in pure water is 100nm while that of PANI nanofibers synthesized in aqueous ethanol is 50nm. It revealed that the volume fraction of ethanol showed really important effect on the morphological parameters of the PANI nanofibers. The X-ray diffraction patterns of the PANI nanofibers showed high crystallinity. Moreover, the resulting PANI nanofibers exhibited an unusual electromagnetic loss at the microwave frequency (f = 8.2~12.4 GHz) . Compared with 1.79, the highest electrical loss, tanδe, of the microparticles PANI at 8.47 GHz and 0.72, the highest magnetic loss, tanδm at 10.93 GHz, it was noted that the highest electrical loss, tanδe, of PANI nanofibers reached 3.26 at 10.4 GHz, and the highest magnetic loss, tanδm, was 2.85 at 9.35 GHz. It might arise from order arrangement of polaron as charge carrier caused by nanofibers morphology and can be used for the potential application as microwave absorbing materials.

Abstract: A simple ultrasonic method was developed to synthesize rod-like SnS nanocrystals, using tin chloride and thioacetamide as starting materials, ethanolamine and water as solvents. The as-obtained nanostructures were characterized by X-ray diffraction (XRD) study, energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Ultraviolet-visible spectrophotometry (UV). From the XRD pattern, the reflection peaks of the as-obtained samples can be indexed to the orthorhombic structure with lattice constants a = 3.99, b = 4.34, c = 11.20 Å , which are very consistent with the values in the standard card of SnS phase (JCPDS No. 39-0354). No characteristic peak was observed for other impurities such as SnO2 and SnS2, implying the formation of single-phase tin monosulfide. The quantification calculation shows the ratio of Sn/S to be 51.30/48.70 via the EDS analysis. These data clearly indicate that the as-prepared rod-like nanostructures are exactly SnS. TEM results show that, the SnS nanorods have length about 100nm and width less than 30nm. The direct and indirect band gaps of the SnS nanorods are determined to be 1.53 eV and 1.34 eV, respectively. The band gaps of the as-obtained SnS nanorods showed blue shifts due to the quantum size effects. The ultrasonic condition is believed to be critical for the formation of SnS with pure phase. For it provides the energy to form rod-like nanostructures and helps preventing the hydrolysis of Sn2+ to form tin oxides and hydrates. Also, it prevents oxidation of the final products.