Advanced Materials Research Vol. 509

Abstract: A simulation method was used to study the effects of physical parameters, including the contact angle between molten metal and material of orifice, surface tension and viscosity on particle formation of POEM. Droplets can be stably obtained only when the contact angel is at least 90° or larger, as well as the surface tension is adequate. Within a wide range, viscosity has little effect on droplet formation; as the viscosity increases, necking time is postponed and vibration time is shortened.

Abstract: Corrosion under insulation (CUI) is a localized corrosion occurring at the interface of a metal surface and the insulation on the metal surface. In order to explore the mechanism of CUI, some tests were conducted on 20 # carbon steel under insulation dripping different testing solution at 80°C in an experimental simulation device for CUI. Corrosion behaviors were analyzed by weight loss methods and other methods. The results showed that CUI rate of 20# carbon steel increased with NaCl concentration. The addition of sulfur and the decrease of pH promoted corrosion. The pits and small cracks were found on the corroded metal and the bonding between products and matrix was strong.

Abstract: The homogeneous rare-earth catalytic system was used to initiate the polymerization of isoprene, and a novel IR was synthesized with high molecular weight and narrow molecular weight distribution. According to the self-developed rare-earth IR properties, a study on IR and IR/NR blend was made. Microstructure and molecular characteristics of JiHua rare-earth IR were identified by IR spectra, 13C NMR and GPC, and the effect of JiHua rare-earth IR on the vulcanization characteristics and dynamic properties in IR/NR blend was investigated and compared with IR (SKI-3) synthesized with titanium catalyst system and rare-earth isoprene rubber (SKI-5) made in Russia. The results showed that JiHua rare-earth IR to be developed independently was a novel synthetic rubber with excellent comprehensive performance, and it can be used independently and partly substitute natural rubber to make tire. In the IR/NR blend, Not only vulcanization characteristics and the safety in operation for NR was greatly improved, But also dynamic properties of vulcanizates such as dynamic cutting resistance, abrasion resistance, wet-skid resistance and aging resistance were improved to different degrees. These properties reach or surpass the level of the foreign similar products like Russia SKI-3 and Russia SKI-5.

Abstract: The microstructures and mechanical properties of the Ni-22Cr-14W-2Mo superalloys with various La contents have been investigated. The results indicate that the grain diameters of the alloys with different La additions are similar to that of the alloy without La. It has also been found that the Vickers Hardness of the alloys increases with the increasing of the La content form 0.000% to 0.087%. The tensile properties of the alloys can be improved by La additions, whereas the σ_0.2 proof strength and the elongations of the alloys first increase and then decrease with the increasing of the La content form 0.000% to 0.087%. The alloy with 0.026% La shows the best tensile properties. This result ascribes to the different types of the La-riched phases and the different sizes of them. The La-Ni intermetallic phases with large size precipitating in the alloys have deleterious effects on the improvement of the mechanical properties, if the La content is too high.

Abstract: Nanostructured ZnO films are hydrophobic. The effects of oxygen plasma treatment on the wetting properties of the ZnO film surfaces were studied. The oxygen plasma treatment makes the nanostructured ZnO films superhydrophilic and helps to enhance the absorption of the dye molecules on the nanostructured film.

Abstract: A new method to evaluate the critical cooling rate, Rc of Fe-based metallic glass alloy was proposed and discussed. [(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4 alloy particles were prepared with narrow size distribution and high sphericity by Pulsated Orifice Ejection Method in Ar, He and 50%Ar+50%He mixed atmosphere, respectively. Phase transition of a particle from amorphous to amorphous-crystalline and fully crystalline occurred with the increase of particle diameter. Rc of the formation of fully amorphous phase was estimated to be in the range of 700-1100 K/s, lower than that measured by time-temperature transformation diagram of bulk metallic alloy. No change of Rc occurred in Ar, He or 50%Ar+50%He mixed atmosphere, which proved it an effective method to evaluate the critical cooling rate of Fe-based metallic glass alloy.

Abstract: A series of yellow-emitting phosphors based on a silicate host matrix, Ca3-xSi2O7: xEu2+, were prepared by solid-state reaction method. The structure and photoluminescent properties of the phosphors were investigated. The XRD results show that the Eu2+ substitution of Ca2+ does not change the structure of Ca3Si2O7 host. The SEM images display that phosphors aggregate obviously and the shape of the phosphor particle is irregular. The EDX results reveal that the phosphors consist of Ca, Si, O, and Eu elements. The Ca3-xSi2O7: xEu2+ phosphors can be excited at wavelength of 300-490 nm, which is suitable for the emission band of near ultraviolet or blue light-emitting-diode (LED) chips. The phosphors exhibit a broad emission region from 520 to 650 nm and the emission peak centered at 568 nm. The phosphor for has the strongest excitation and emission intensity, and the energy transfer style between Eu2+ ions is quadrupole-quadrupole interaction for higher concentration Eu2+ doped Ca3Si2O7 phosphor. The Ca3-xSi2O7: xEu2+ phosphors can be used as candidates for white LEDs.

Abstract: Mooney viscosity, cure characteristics, tensile properties, tear strength, rolling resistance property, abrasion resistance ,dynamic cutting property and other properties of the homogeneous rare earth IR/NR blend were investigated, and compare to Russian SKI-3/NR blend, SKI-5/NR blend and NR. The results showed homogeneous rare earth IR/NR blend has similar or even better properties compare to SKI-3/NR blend, SKI-5/NR blend and NR. The tire products made by these rubbers have similar performance. The tires passed the China National Quality Supervision and Inspection Center of rubber tire certification, which met the requirements of all-steel TBR tire. The homogeneous rare earth IR prepared by Petro China Jilin Petrochemical Company could part instead of NR using in all-steel TBR tire.

Abstract: Plasma surface alloying technology was applied to introduce Ni element into Ti6Al4V to improve its tribological property. The microstructure, composition, phase constituent and hardness of the alloyed layer were examined. Wear mechanisms were discussed on the basis of wear scar observations. The tribological performance of the alloyed layer was investigated by ball-on-disk sliding tests in different environments. The results showed that the Ti-Ni alloyed layer was about 12μm in thickness and the content of Ni element reached to 28% on the surface. The surface hardness of the layer was 677HV, nearly twice as the untreated Ti6Al4V. The wear resistance of the modified Ti6Al4V substrate was improved obviously in different environments.