Advanced Materials Research Vols. 152-153

Abstract: We demonstrated a method of fabricating thermosetting epoxy polymer with shape memory effect modified Poly (ether ether ketone) (6F-PEEK) based on the formation of a phase-segregated morphology. The peculiarities of shape memory effects of the epoxy resin modified by 6F-PEEK were investigated. DMA result showed two glass transition temperatures in this blended material. The cured epoxy phase showing high Tg of 223oC acted as hard-segment-forming phase the and was responsible for the permanent shape. The 6F-PEEK can be used as switching phase for a thermally induced shape-memory effect. The transition temperature (Ttran) was 150oC, which was between the Tg of cured epoxy and 6F-PEEK. At the special concentrations of 6F-PEEK, the shape memory effect accompanied by a significant increase in volume was observed. The highest shape memory effect was obtained for the blended material with 25.00 wt% of 6F-PEEK. The shape retention rates and the shape recovery rates were 96-99% and 100%, respectively. The times of shape-recovery were all defined in 2 min. The mechanism of shape memory effects and the mechanical properties of the cured resin were discussed.

Abstract: A comprehensive numerical study of tensile deformation on electro-deposited Cu with nano-scale growth twins is presented using a conventional theory of mechanism-based strain gradient plasticity (CMSG). Systematic research on the size effects of growth twins in Cu polycrystalline is carried out. The roles of many material parameters which affect the size effects, such as grain sizes, Young’s modulus, twin/matrix lamellar structures aspect ratio and volume fraction, as well as the plastic strain hardening exponent, are presented.

Abstract: The forming limit diagram of clad was developed with Hill’s instability criterion and M–K analysis at the positive strain ratio. The relationships of forming limit with stain path, thickness ratio and thickness irregular coefficient were analyzed. The results show that the forming limit of clad material is between those of its component materials, and increase with the rising of stainless steel thickness ratio and the thickness irregular coefficient. The most suitable value of f0 is 0.094 and the stainless steel aluminum clad break with local interfacial cracks.

Abstract: Fly ash particles reinforced aluminum matrix composites were fabricated by powder metallurgy method. The influence of different fly ash content on hardness, the friction and wear behavior of the composites were investigated at a constant sliding velocity of 400r/min. The worn surfaces of composites were observed by scanning electron microscope, and worn mechanism of composites was discussed. The results showed that the hardness of composites increased first and then decreased with fly ash content increasing. Under the lower loads and at the lower fly ash content, the friction co-efficient is steadily lower than that of Al alloy matrix. The wear resistance of composites increased with the volume fraction of fly ash particles and the wear mechanism was characterized as abrasive wear and adhesive wear.On the other hand, the wear mechanisms in the composites have been transformed with increasing load and fly ash volume; it mainly was delamination wear and abrasive wear.

Abstract: In the present work, the resistances to corrosion of heat treated soft magnetic alloy Fe81Cr17Si1.5TiBRe and untreated one have been comparatively studied, which were tested in neutral salt spaying tester, in 50%vol. hydrochloric acid (HCl) at 100 , in humidity thermal oxidation tester, specially in simulating oilfield waters containing sulfide ion (S2-) and without S2-. Heat treatment was carried out at 1150 for 4 hours under the protection of hydrogen gas. The results show that heat-treatment affect the magnitude of grain of Fe-base soft magnetic alloy and distribution of inclusions in grain and in grain boundaries. Heat treatment enhances anti-corrosion properties, i.e. resistance to chlorine ion (Cl-) corrosion of the alloys, resistance to humidity thermal oxidation corrosion, oilfield water corrosion. The electrochemical corrosion mechanisms of the alloy in oilfield waters are not affected by heat treatment. In simulating oilfield water, the passivity property of the alloy is affected by S2- or HCO3-.

Abstract: Layered double hydroxide (LDH)-ibuprofen (IBU) host-guest materials were prepared by in situ coprecipitation method for the purpose of drug controlled release. Three hosts containing different metal cations, MgAl-, ZnAl-, and MgFe-LDH, were studied. The results showed that the types of the metal cations had great influence on the structures of the host-guest materials and thus led to different drug release properities.

Abstract: In the present paper a research has been made on the effect of aging on the microstructure and mechanical properties of AZ80 and ZK60 wrought magnesium alloys by virtue of optical microscope, electronic scanning microscope and mechanical testers. The research indicates that both the tensile strength and elongation of AZ80 alloy first increase and then decrease as the aging temperature rises, and that, at 140°C-170°C aging temperature, the alloy has good performances in both tensile strength and elongation, they both reaching their peak values at 170°C aging temperature. It has been proved in these researches that while the hardness of ZK60 alloy first increase and then decrease as the aging temperature rises and that the hardness reaches its peak value at 170°C aging temperature, the impact of toughness of the alloy is just the opposite. ZK60 alloy has good performances in both impact toughness and other properties at 140-200°C aging temperature. Constrastive researches have shown that, at the same aging temperature, ZK60 alloy has a better performance than AZ80 alloy.

Abstract: An understanding of the surface and interface states of the organic material and the underlying andoe material is meaningful for organic light-emitting devices (OLEDs). The 8-Hydroxyquinolinolatolithium (Liq) was deposited on indium-tin-oxide (ITO) coated glass by traditional vacuum evaporation.The thickness of Liq is about 120nm. The morphology, surface and interface electron states of the Liq and the underlying ITO have been investigated with the utilization of the atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) technology. AFM observation indicated that Liq grows in the shape of an asymmetrically-distributed island, with each island resembling a round hillock and different size. The Liq film is not very uniform and teemed with many pinholes and cracks.The analysis on XPS spectra of the surface of the Liq/ITO samples shows that, the core-levels of Li1s, C1s, N1s, O1s, In3d5/2, and Sn3d5/2, spectra slightly shift towards lower binding energy with the increase of the sputtering time, which may be caused by the effect of oxygen, indium and tin in ITO diffusing into Liq layer and the argon ions beam with energy. Coordination bond between Li atoms and N atoms does not exist in Liq, which is the main reason why Liq is the blue electroluminescent material. The C atoms mainly bond to C, N and O atoms, forming C-C, C-N=C and C-O bonds, respectively. And there is a speculation of the existence of contaminated C atoms in the surface of ITO, while the O atoms basically originate from quinolate rings and the absorption of O2 and H2O. At the interface N and O, In and Sn interact to some extent, which probably affects the emitting colour of Liq based OLEDs. The analysis of surface of In3d and Sn3d spectrum by XPS provides additional evidence of the existence of cracks and pinholes in Liq layer, leading to much absorption of air molecules.

Abstract: The preparation method of low-temperature resistance nitrile-butadiene rubber coat-metal sealing gasket was introduced. The type and the dosage of curing agent, reinforcing agent and other additives were considered, the optimum technological factor was determined. Use of such nitrile-butadiene rubber coat-metal sealing gasket, its low temperature resistance and oil resistance were good enough for the seals which work at -40 -160 .

Abstract: Multi-walled carbon nanotube (MWCNT)/Pb-Sn composite coatings were prepared by electrodeposition technique. Friction coefficient and wear weight losses were investigated on a double rings apparatus using carbon steel (C: 0.45%) rings as counterparts under wet friction condition. Tribological characteristics were compared among the samples as carbon nanotubes concentration was changed in the bath. The results indicate that the composite coatings had smaller friction coefficient and weight loss than that of ordinary Pb-Sn coatings under the same work conditions. In addition, the wear performance of Pb-Sn-CNTs composite coating was optimized when the CNTs concentration in bath was 2 g L-1.