Advanced Materials Research Vols. 557-559

Abstract: In this paper, initial Ti-6Al-4V seamless tube was prepared and cold rolled to a final size of 32*2, and the microstructure and mechanical properties development was investigated, and the (0002) and (10 -10) texture was measured on XRD, pole figure calculated by Microsoft of Labotex. Pass between annealing was taken for stress-relieving, heat-treatment parameter was 800°C-1hr, furnace cooling to 500°C and then air cooling to room temperature. The results show that rolling process result in effective grain refinement and mechanical properties improvement after several rolling passes. The increase number of rolling pass improves strength but reduce the elongation, annealing improve elongation, reduce strength. A trend of texture reorientation was found in this paper also, textures of materials rolled by deformation rate were compared, different deformation rate effect texture evolution has been proved.

Abstract: The thermoplastic processing and mechanical properties of starch and polyvinyl alcohol (PVA) composites were studied. Glycerol was chosen as the plasticizer and nano-silica (nano-SiO2) as the reinforcing agent of the starch/PVA composites. The results showed that the mechanical properties of the obtained starch/PVA blend were best when the glycerol content was 30% of starch and 20% of PVA, and the weight ratio of PVA and starch was 0.8 (w_PVA / w_starch = 0.8/1). After the addition of nano-SiO₂, the mechanical properties of the starch/PVA blends were improved. When the weight percent of nano-SiO₂ was 2%, the mechanical properties of the SiO₂/starch/PVA composite were most excellent. It was shown that the tensile strength was increased by 16% and the elongation increased by 72%. Moreover, it was confirmed by rheological measurements that nano-SiO₂ could interact with the composite materials, which results in the improvement of the mechanical strength of the starch/PVA composites.

Abstract: The influence of Mo addition on the microstructure and mechanical properties of the TiC-Fe cermets has been studied. The specimens with different contents of Mo (4-8 wt.%) added into the TiC-Fe cermets were fabricated by conventional powder metallurgy and vacuum sintered at temperatures of 1440 °C. The microstructure and mechanical properties such as bending strength, impact toughness, hardness, wear resistance were investigated. The micrographs with different Mo content show that the final grain size of carbide phase became smaller and the specimens became more homogeneous and compact with increasing Mo content from 4 wt.% to 8 wt.% in raw powders. The mechanical properties measured show that the bending strength, impact toughness and wear resistance are the best when the Mo content is 6 wt.%.

Abstract: The effects of polypropylene grafted with maleic anhydride (PP-g-MA) and unsturated polyester (UP) on the interfacial interaction of PP/GF composites were investigated by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and mechanical properties. The experimental results demonstrate that PP-g-MA and UP could effectively improve interfacial interaction between the PP and GF. Based on SEM, good interfacial adhesion between PP and GF in PP/UP/GF and PP/ PP-g-MA /GF composites was observed. DSC results showed that the existense of PP-g-MA or UP caused t crystallization temperature and melting temperature shift to high temperature. All results in this paper were consistent, and showed the good interaction between PP and GF, which were proved by the mechanical properties of the composites.

Abstract: The microstructure and impact toughness of in-situ Mg₂Si/Al-Si composites were studied in the different content of Sb. The results show that Sb can improve the microstructure and impact toughness of Mg₂Si/Al-Si composites. When the content of Sb is 0.4%, the morphology of primary Mg₂Si changes from dendrites to fine particles, the average size of Mg2Si particles is refined from 52μm to 25μm, and the impact toughness of the composites increases from 6.3572J/cm2 to 11.4394J/cm2. The improvement of impact toughness can be attributed to the fine-grain strengthening. However, excessive Sb is disadvantageous to the modification of the composites.

Abstract: Compatibilization between polypropylene(PP) and wood-flour was achieved by means of direct reactive extrusion of glycidyl methacrylate(GMA), PP, wood-flour, and other additives. Impact cracking surfaces of the PP/wood-flour composites(WPCs) was observed via scanning electron microscope(SEM), and mechanical properties of the WPCs were tested. The effect of comonomer styrene(St) and antioxygen triphenyl phosphite(TPP) on the reactive compatibilization was also evaluated. Experimental results indicated that the anchoring strength of interface in the composites was obviously strengthened after direct reactive extrusion. The tensile and flexural strength of the WPCs were obviously improved, but the elongation at break and notched impact strength slightly declined after reactive compatibilization by GMA and dicumyl peroxide(DCP). The addition of St and TPP improved the mechanical properties of the WPCs. At 1.5% of GMA, 0.3% of DCP, 1.5% of St and 1% of TPP in the extrusion composition of WPC, the tensile strength, flexural strength, elongation at break and notched impact strength respectively increased by 39%, 31%, 28% and 29% comparing to those of the WPC without reactive extrusion.

Abstract: A new soften curing agent for toughening epoxy resins was synthesized by m-phenylene diamine modified with epoxypropyl butyl ether. Fourier transform infrared (FT-IR) analysis showed that the longer the reaction time was, the smaller the absorption peaks of epoxy group were. The results of the mechanical properties demonstrated that the impact property of the epoxy resin cured by modified m-phenylene diamine at the moderate temperature was better than that of cured by un-modified one because of the introduction of soft ether chain.

Abstract: The effect of the gradual substitution of Ti by Al on glass forming ability and structure in the Cu₅₂Zr₄₀Ti_8-xAl_x(x=0, 2, 4, 6, 8) alloys was studied by using XRD, DSC and SEM. Furthermor, the nanocrystallization behavior of the amorphous alloys also was studied by annealing method. The result indicates that the glass-forming ability and thermal stability is decreased with the increasing of the content of Al. On the other hand, the nano crystals with diameter of 50 - 100 nm were all observed when the five amorphous samples were annealed at 650 K for 1h.

Abstract: High manganese matrix composite, reinforced by TiC particles, was synthesized in situ by means of conventional powder metallurgy route. The microstructure was investigated by means of Scanning electron microscopy. Pin-on-disc dry sliding wear tests had been carried out to study the wear behavior of TiC-reinforced high manganese steel matrix composites. The results show that TiC carbides are distributed uniformly in the composite. The abrasive wear resistance of the composites is higher than that of the unreinforced high manganese steel.

Abstract: A core-shell structure material, carbon fiber/ZnO was prepared by a surface modification precipitation process in aqueous solution. The structure, absorptive properties and photoluminescence properties of the composites were investigated. Results showed that the energy bandgap of samples calculated from the absorptive spectra was about 3.30eV. The green emission peak of the samples was ascribed to the oxygen vacancies.