Advanced Materials Research Vols. 391-392

Abstract: The development of bulletproof materials indicates the military and scientific strength of a country in the fields of modern national defenses and military affairs. With the advancement and development of scientific technologies in the world of human being, the bulletproof materials experienced the changes from the ordinary natural plants or simple metal substances to the synthetic composite materials with high intensity. In this work, we emphasized the applications of some advanced composite materials and their study in bulletproof fields.

Abstract: A manufacturing process of new type carburized bainitic hollow steel by “hot-penetrating and hot-rolling” method is described in this paper. A good surface quality and hot working performance can be achieved by using hot-penetrating and hot-rolling method fabricated new type bainitic hollow steel. The mechanical properties ofnew type carburized bainitic hollow steel can satisfy the properties of Cr-Ni type carbonized steel requirements, so the hollow steel can be used as drill steel material. The carburized test of new type bainitic hollow steel showed that the new steel is organized by the bainitic, ferrite and austenite; the layer of cementite is organized by the high carbon martensite and austenite. The drill rod with the new type carburized bainitic hollow steel is with good carburization properties. After carburizing air (wind) cold, the surface hardness of the dill rod will satisfy HRC> 5~7, with good air cooling harden ability and harden ability, so the new type carburized bainitic hollow steelis good at practical application.

Abstract: The graphene/poly(vinyl alcohol) nancomposites with enhanced filler-matrix interfacial interaction were fabricated via water-blending partially reduced graphene oxide (PRGO) and poly(vinyl alcohol)(PVA). The nanocomposites were characterized by X-ray Diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), Scanning Electron Microscopy(SEM), thermogravimetry(TG). The results showed that the graphene nanosheets were homogeniously dispersed in the PVA matrix and enhanced interfacial adhesion was greatly enhanced due to new covalent linkage and hydrogen-bonding between graphene and PVA backbone. The mechanical and thermal properties of the nanocomposites were significantly improved at low graphene loadings. An 116% increase in tensile strength and a 19°C improvement of onset thermal degradation temperature were achieved by the addition of only 0.8 wt% graphene.

Abstract: Through laboratory experiments, viscosity stability of high concentration polymer solution was studied. Viscoelasticity of high concentration polymer was measured by HAAKE RS-150 Rheometer. The flow tests of high concentration polymer solution were carried out by utilizing artificial homogeneity cores, while the influence of injection time on displacement characteristics of high concentration polymer were studied on artificial heterogeneous cores. The results showed that high concentration polymer solution had a good stability within 15 days, but decreased significantly after 30 days. Both viscosity and elasticity of high concentration polymer are higher than the lower ones’. Because the high viscoelasticity of high concentration polymer made the flow resistance increase, resistance coefficient and residual resistance coefficient were very high. Therefore viscoelasticity of high concentration polymer could make a large improvement on chemical flooding recovery.

Abstract: Nano-crystals with hollow structure were synthesized by microemulsion method. XRD(X-rays Diffraction), EDS(Energy Dispersive Spectrometer) and TEM(Transmission Electron Micrograph) techniques were used to characterize the structure, composition and morphology of nano-crystals. Results of XRD and ED(Electron Diffraction) revealed that nano-crystals were the mixture of CdSe and CdSeO₃. TEM images shows nanotube and bamboo-like nanotube, CdSe nano-particles are observed in bamboo-like nanotubes. Reports on nanotubes and bamboo-like nanotubes by microemulsion method are little. In this experiment nanotubes and bamboo-like nanotubes are successfully prepared. In this experiment just through one step nano-crystals with hollow structure are obtained, which greatly simplify the experiment process to removing core.

Abstract: We have carried out detailed investigations into the light absorption in single Si (core)/SiO₂ (shell) coaxial nanowires (NWs) within the framework of the Lorenz-Mie light scattering theory. We have found that the light absorption in single coaxial NWs can be significantly enhanced as compared to in Si NWs, due to SiO₂ shells. We have also found that the photocurrent can be enhanced up to ~56% for the coaxial NW of the core radius of 150 nm by tuning the shell thickness.

Abstract: Grain size distribution in the sinter is an important index sign to measure the quality of sinter. In this paper, according to the fractal theory and the contrast experiment of sinter, the fractal characteristic of grain size distribution of sinter with low SiO₂ is discussed. The relation between the fractal dimension and content of SiO₂ is proposed. Combine with the SEM graphs of the sinter with low SiO₂, the relation between the fractal dimension and microstructure of sinter with low SiO₂ is also analyzed. Pass to the quantificational description of the grain size distribution of sinter with low SiO₂, to predict and optimize the grain size constitution of sinter, and offer a new idea, a new way for the further thorough research of sinter ore.

Abstract: Effects of different pore size nano-mesoporous molecular sieves fillers, i. e. MCM-41, SBA-15, together with organic-montmorillonite (OMMT), mixture of OMMT/MCM-41 or OMMT/SBA-15 (m (OMMT): m (MCM-41)/m (SBA-15) =1:1) and their amounts on mechanical properties of the polymethylmethacrylate (PMMA) composites were investigated. When the amount of OMMT/SBA-15 mixture was 0.5 %, tensile strength of the nano-composite reached maximum values of 46.3 MPa. When OMMT/SBA-15 mixture addition amount w (filler) was 1.2 %, impact strength of the nano-composite reached maximum values of 14 KJ/m2. In comparison with PMMA without any filler, the tensile strength and impact strength of nano-composite were increased by 8.4 % and 48 %, respectively.

Abstract: In order to improve compatibility between PP/PS blends, different types of fillers were prepared by melt compounding techniques. The effects of the MCM-41 and PP-g-MAH on the mechanical and crystallization properties of PP/PS composites were investigated. The results of mechanical tests showed that the co-incorporation of MCM-41 filler and PP-g-MAH gave rise to much better tensile and impact strength than adding of MCM-41 and PP-g-MAH respectively due to different interfacial structure between the fillers and the matrix. DMA attested that the good adhesion between PP/PS blend was obtained by adding MCM-41 and PP-g-MAH fillers.

Abstract: A new kind of thermally conductive composites reinforced by glass fibers with boron nitride (BN) as thermally conductive filler was prepared in heat press molding. Thermal conductivity of the composites was found to increase with increasing in filler content. But impact strength and flexural strength reach the top point, 385.05KJ/m² and 912.6481MPa, with content of 50wt% and 20wt% respectively. The thermal conductivity of 0.8385 W/mK was obtained at 50wt% filler content. Experimental dates show that mixed matrix of epoxy (EP) and polyimide (PI) displays high thermal stability and can improve thermal stability compared to pure epoxy obviously at 50wt% PI content. Additionally, the obtained composites possess high surface resistivity and volume resistivity, which are suitable for substrate materials.