Advanced Materials Research Vols. 798-799

Abstract: The thyristor has been widely used in many fields since it has been invented, and has promoted the development of the DC transmission technology rapidly. The increasing temperature of its junction may cause serious hazards. Because of this, a variety of methods that can obtain the junction temperature has been summarized in this paper, such as the indirect measurement method, the direct measurement method, the equivalent thermal impedance network method and the numerical calculation method, etc. Summaries have been made in different occasions which these methods were applied. It also compared the advantages and disadvantages of each method and pointed out the developing trends and researching directions in the future.

Abstract: The microstructures of a series of high Zn magnesium alloys Mg-(7-11) Zn-(2-6) Al alloys were clarified, and effects of Zn and Al concentration about the ZA system alloys on the microstructure and properties were also investigated. For Mg-(7-11)Zn-4Al alloys with the Zn content increase, improved creep resistance is obtained due to block τ-Mg₃₂(Al, Zn)₄₉ phase, with severe reduction in ultimate strength and ductility, and the best creep property is obtained with 11wt.% Zn concentration. However, a bit increasing Al content of Mg-9Zn-(2-6)Al alloys contributes to the improvement in the ambient and elevated-temperature yield strength, but seriously deteriorates the creep properties for the formation of lamellar φ-Al₂Mg₅Zn₂ eutectics or Mg₅₁Zn₂₀ phase.

Abstract: Recently, there were many accident of small dam break of reservoir in China, which reflects a problem in construction and management of small reservoir. By studying over 306 reservoirs which have been reinforced, the main problems to the safety operation of reservoir were concluded. The main 17 problems and 10 questions were discussed in this paper and the answers and suggestions are also made.

Abstract: The mechanism of TFE-P copolymer peroxide vulcanization in the presence of N, N - meta-phenylene-bis-maleimide (MPBM) was investigated by MDR Rheometer and DSC method. The results show that β-chain-scission reactions are present in TFE-P copolymer peroxide vulcanization, and the rate of β-chain-scission increase in high temperature. MPBM could improve the crosslinking efficiency and crosslinking rate. The mechanism is that TFE-P copolymer-MPBM radicals could form effective crosslinking and decrease the quantity of TFE-P copolymer radicals that would arise β-chain-scission reactions.

Abstract: The homopolymer of 6-vinyl bisferrocenylpropane and copolymer of 6-vinyl bisferrocenylpropane and 6,6'-divinyl bisferrocenylpropane were obtained from ferrocene and acetone via a series of reactions. The monomers and polymers were characterized by elemental analyses, IR spectra and ^IHNMR. The thermal stabilities of the polymers were studied through DTA-TG. The results show that the solubility of the copolymer of 6-vinyl bisferrocenylpropane and 6,6'-divinyl bisferrocenylpropane is very poor and its thermal stability is obviously higher than the homopolymer of 6-vinyl bisferrocenylpropane. The reason for it is that the monomer of 6,6'-divinyl bisferrocenylpropane has two vinyl groups, so the grafting degree of the corresponding polymer is much larger than the homopolymer of 6-vinyl bisferrocenylpropane.

Abstract: An ecofriendly advanced oxidative system was studied for the degradation of phenol. This system was composed of a self-made coordinated Fe complex and hydrogen peroxide. Factors influencing the degradation were explored. Suitable technology conditions were given as: hydrogen peroxide 2.2*10^-4mol/L, catalyst 2.5*10^-7mol/L, pH 11.5, room temperature and time 60 minute. Under this condition, phenol degradation ratio can be achieved to 99.93%.

Abstract: NiO and SDC Powders were Prepared by Sol-Gel Method and then Calcined at 400、600 and 800°C. Nio-SDC Anode Materials were Synthesized by Solid State Reaction According to the Mass Ratio of Nio:SDC=65:35 Ratio . XRD Measurement Showed that Powders Consist of Two Phases, the Cubic Nio and Fluorite Structure Ceria . the Grain Size was Shown to Increase with Increasing Temperature. the Cermet with Ni-SDC Powders Calcined at 400°C Showed the Highest Electric Conductivity and a Lower Degree of Polarization.The Electrical Conductivity was 4155Scm^-1 and Overpotential was 0.12V at 600°C.

Abstract: The nano manganese oxides were prepared with the hydrothermal method by adding surface-active agent. The influence of the type and addition amount of surface-active agent on the preparation of nano manganese oxides was studied. The products were characterized with XRD. Experimental results show that MnOOH is obtained at 180°C with the addition of N,N,N-trimethyl-1-dodecanaminium bromide, and Mn₃O₄ is obtained at 180 °C with OP Emulsifier or Tween-80 added. Different addition amount of surface-active agent would have diverse effects on the purity of products.

Abstract: Recent studies indicated that Mg-(7-11)Zn-4Al (the composition of the alloys in the present paper are given in weight percentage.) based alloys exhibited good creep resistance and additions of trace alkaline elements to the alloys further improved the mechanical properties at elevated temperatures. In order to optimize the zinc concentration and reveal the effect of small amount of alkaline element additions to Mg-Zn-Al ternary alloys on their microstructure and elevated temperature creep resistance, five alloys with compositions of Mg-7Zn-4Al, Mg-9Zn-4Al, Mg-11Zn-4Al, Mg-11Zn-4Al-0.2Ca and Mg-11Zn-4Al-0.6Ca, respectively, were prepared in the present investigation and the microstructure and creep properties of these alloys were studied.

Abstract: Currently, environmental contamination by polybrominated diphenyl ethers (PBDEs) in the world is of important concern and requires the effective remediation technologies. The degradation of decabromodiphenyl ether (BDE-209) in the supercritical n-hexane by zerovalent iron was studied in this work. The results showed that BDE-209 can be rapidly reduced into nona-, octa-, hepta-and lower brominated polybrominated diphenyl ethers (PBDEs) under the supercritical reaction conditions. Among n-hexane, methanol, tetrahydrofuran and mixed n-hexane+ tetrahydrofuran solvents, the conversion of BDE-209 in tetrahydrofuran was the highest. BDE-209 conversion increased with increased reaction temperature and pressure. Under the reaction condition: temperature: 523K; pressure: 3.2Mpa; reaction time: 10min; reaction system: 200ml 50mg BDE-209/L n-hexane; atmosphere: N₂ and catalyst load: 2g/L, the conversion of BDE-209 was as high as 88.9%.