Advanced Materials Research Vols. 989-994

Abstract: Formation of chip is a typical severe plastic deformation progress in machining which is only single deformation stage. The rake angle of tool is governing parameter to create large strain imposed in the chip. Effect of rake angle and deformation times on effective strain, mean strain, strain variety and strain rate imposed in the chip are researched respectively. The result of simulation have shown that the chip with large strain and better uniform of strain along the longitudinal section of chip can be produced with negative rake angle at some lower cutting velocity by multi-deformations in large strain machining.

Abstract: Single-frequency microchip lasers have been widely used in differential absorption radars, pulse coherent Doppler radars, pumping optical parametric oscillators, and etc. So theoretical analysis and experimental researches on the LD-pumped 2.09 μm microchip laser have important realistic meaning. According to quasi-three-level Cr, Tm, Ho: YAG(CTH:YAG) laser crystal working characteristics, the theoretical expression and relationship curve between the output optical power and 785nm LD-pumped power are obtained by theoretical calculating based on the pumping rate equation. The CTH:YAG crystal with 4mm diameter and 1 mm thickness is used to do experimental test. The corresponding three kinds of particle concentration are 0.85%, 5.9% and 0.36% respectively. When the crystal temperature is controlled at 10 °C, microchip laser beam output characteristic curve is obtained under different pump spots. The results show that when the pump spot diameter is 75um the maximum single-frequency output power is 32mW and when the pump beam is 100um the maximum single-frequency output power is 30mW. The corresponding optical to optical conversion slope efficiencies are 6.8% and 6% respectively.

Abstract: Near space airship increasingly becomes a research hotspot with its inclusive potential military and civilian values. It is necessary to consider single and multiple-coupling space environment effects on evaluating envelope tearing damage mechanisms. The basic characteristics of the space environment and the complexity of tear damage mechanism are introduced, and this presentation also summarizes the research status of the tear damage mechanical mechanism and damage properties under the influence of the multiple space environment factors of high-performance airship envelope. Besides, the main existing problems and prospect in tear damage characterization under real working condition are discussed. The study provides some technical support for high-performance and protecting tearing damage design on airship envelope.

Abstract: PZT672/epoxy 1-3 piezoelectric composites were fabricated by the cut-filling method. The parameters of PZT672/epoxy 1-3 piezoelectric composites varying with different PZT volume fractions have been measured and compared with theoretical values. The results show a good match between theoretical values and measurements. The authors conclude the regular of the properties of composites varying with PZT volume fraction.

Abstract: Ce³⁺/Tb³⁺/Sm³⁺ co-doped phosphate glasses were prepared by melt quenching method. The full colors including blue, green and reddish orange emitting were observed simultaneously in the photoluminescent spectra of the glasses at 377 nm excitation, and the combination of these three emitting allows the realization of white light emitting. The CIE chromaticity coordinate (x=0.339, y=0.331) of the emission from the glass is close to the standard white-light illumination (0.333, 0.333). Moreover, the tunable luminescent color and chromaticity parameters could be realized by varying the content of Tb₄O₇ dopant in the glass composition, which is promising fluorescent materials for white light emitting diodes applications.

Abstract: The porous graphene oxide (GO) gels were prepared using the process of aqueous gel precursor freezing, solvent exchange, and ethanol drying technology. The GO sheets were consolidated by PVA and the obtained GO-PVA gel was reduced by glucose to prepare graphene nanosheet-SA (RGO-PVA) gel. GO-PVA and RGO-PVA gels exhibited the ultra-light densities of 10.52 and 11.24 mg/cm³, respectively. GO-PVA and RGO-PVA can effectively adsorb the liquids. The less the polarity of the liquid was, the more the adsorption for both GO-PVA and RGO-PVA gels was. The equilibrium and the dynamic adsorption of methylene blue dye were also investigated. The maximum adsorption capacities of dye were 571.4mg/g for GO-PVA and 81.0 mg/g for RGO-PVA at 30 oC.

Abstract: A review of recent research on mechanical performance of high strength structural steel (HSSS) in the level of both materials and members is presented, including the static material performance, toughness and mechanical property under cyclic loadings of HSSS, buckling and hysteretic behavior of high strength steel columns (HSSC), the ductility and resistance of bolted connection with high strength steel slices etc. Previous research work shows that the application of high strength steel (HSS) is limited in seismic zone .Finally, two design methods of using HSS in seismic zone are proposed based on current seismic design philosophy.

Abstract: A series of Eu³⁺, Dy³⁺ actived Ca_1-xBa_xSnO₃ phosphors were synthesized by coprecipitation method. The structure, morphology and fluorescence property of phosphors were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectroscopy. SEM results showed that the as-prepared phosphors are smooth and uniform with the cubic morphology. The incorporation of a small amount of Ba to CaBaSnO₃ improved the emission characteristics. Fluorescence spectrum showed the emission intensity is the best with the incorporation of Ba²⁺ (x = 0.3), when calcination temperature is 900°C.

Abstract: The dislocation density of GaN thick films has been measured by high-resolution X-ray diffraction. The results show that both the edge dislocations and the screw dislocation reduce with increasing the GaN thickness. And the edge dislocations have a larger fraction of the total dislocation densities, and the densities for the edge dislocation with increasing thickness reduce less in contrast with those for the screw dislocation.

Abstract: LED as the fourth generation light source has been extensively studied. In order to get a high-performance White Light Emitting Diode (WLED) green phosphor, YPO₄:Ce³⁺,Tb³⁺ was prepared by co-precipitation. It was excited at 380nm. The structure, morphology, fluorescence property and colorimetry of the phosphors were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometer. Final results show the optimal concentration ratio are 1:0.05:0.01. The crystal grain of luminescent material is 200 nm. When the bath temperature is 80°C and calcined at 1000°C for 3h, the luminescence performance of the luminescent material is excellent.