Advanced Materials Research Vols. 418-420

Abstract: The research on water vapor transmission (WVT) has an important function on analyzing moisture transport through building materials. According to ASTM Standards, there are two traditional methods (Dry cup and Wet cup) to test WVT of porous materials for practical application, without considering the influence of relative humidity and air flow. In this paper, multilayer method is used to test WVT of porous materials, without the influence of air flow on the whole testing process. Multilayer test method is the new way and there is little experience on how to conduct the whole process, how to obtain the accurate data and make the whole process reasonable is the big issue. Through several cases are worked on and analyzed, then renew desiccant every two hour which is depending on the type of porous materials, is the best way to make the whole testing system reaching to steady state for special building materials. At last, this paper shows that the new way is more reasonable and has higher accuracy than traditional method to get WVT.

Abstract: Fluorinated amorphous carbon (a-C:F) films have long attracted much consideration due to their low surface energy, hydrophobicity, low refractive index, good electrical and thermal insulation and good thermal stability, and so on. To repair of some polymer films that have good flexibility and low permeability, F₂₃₁₄ resin was used as main film-forming material of coating in this paper. The solubility parameter of F₂₃₁₄ was estimated by group contribution method, which is 20.548 J^1/2•cm^-3/2. And proper solvents were selected on the basis of the solubility parameter. FEVE resin was selected as one of the components of coating, because of its good adhesion and compatibility. The adhesion of the F₂₃₁₄ coating was improved, and penetration resistance performance of F₂₃₁₄ coating was enhanced to 300(mg•mm)/(m²•h).

Abstract: The superconducting Tl_0.8Bi_0.2Sr₂Ca_0.8Y_0.2Cu₂O₇ powder prepared from chemical route was mixed with varying amounts of nano-sized MgO powders (x=0 to 0.50 wt. %) to form bulk superconducting composites. XRD results show that the addition of 0.15 wt.% nano-MgO is accompanied by an increase in 1212-phase and the disappearance of SrCO₃ impurity. SEM investigations revealed more regular-shaped and smaller grains microstructure for MgO added samples in contrast to MgO-free sample which revealed irregular shaped grains. EDS showed homogenous distribution of Mg for all MgO-added samples with the exception of x=0.50 where agglomeration of MgO particles were observed. However, MgO added samples exhibit lower zero-resistance critical temperature, T_{c zero} than the MgO-free sample.

Abstract: A large number of high-speed soot particles would be produced after fossil fuels' (oil or coal) combustion in the boiler. These high-speed particles not only directly attack the heating surface of boiler tubes (damaging the tubes mechanically), but also condensate on the wall, causing even more serious chemical corrosion. The discussion has deeply studied the occurrence sites, reaction mechanism, influence factors as well as identification and prevention methods of oil-ash corrosion, coal-ash corrosion, so it would have a positive guiding significance for reducing (or preventing) the flue-gas side corrosion.

Abstract: The performances of Ce-doped Lu₃Al₅O₁₂ (LuAG:Ce) and LaBr₃ (LaBr₃:Ce) scintillators were compared for γ-ray detection using photomultiplier tube ( XP5500B PMT) readout. For 662 keV γ-rays (137Cs source), an energy resolution of 3.5% obtained for LaBr₃:Ce is much better than that of 6.7% obtained for LuAG:Ce, while the estimated photofraction of 28.0% for LuAG:Ce is higher than that of 16.2% for LaBr₃:Ce. The light yield non-proportionality and energy resolution versus γ-ray energy were measured and the intrinsic resolution of the crystals was calculated. The coincidence timing resolution, obtained in this work for 511 keV annihilation quanta, was 583 ps and 204 ps, respectively, for LuAG:Ce –BaF₂ and LaBr₃:Ce – BaF₂ detectors.

Abstract: By analyzing the crucial structure of digital microphone , it has character of welding and bonding technology, in order to increase reliability of PCB connecting , especially reliability of PCB for IC bonding with chip connecting , ENEPIG PCB is leaded in , and achieve the high reliability connecting . And according to the demand of bonding technology , bonding temperature, bonding machine pressure, bonding power and bonding time are elected , a series of bonding experiments have been done , obtain some related experiment data of bonding point and analyze the data , obtained the plating thickness parameter of matching with ENEPIG PCB .

Abstract: A particle reinforced hardface coating was prepared by vacuum cladding process. Firstly, titanium carbide composite powders were prepared by self-propagating high-temperature synthesis (SHS). The hardface coating was then formed on plain carbon steel substrate with the TiC composite powders and high chromium iron-based alloy powders by vacuum sintering. The microstructure of the coating was observed and then the wear resistance was studied. The results show that TiC composite particles uniformly distribute in the coating. The coating and the steel substrate are chemical bonded with each other. When the size of TiC particles is unchanged, with the increase of quality fraction of the TiC particles, the hardness increased gradually and the wear resistance of composite coating under different conditions changed. The unit area weigh loss increased following by the load increasing, and the unit area weigh loss is the most under Alkaline condition. And the unit area weight loss increased following by the increase of the abrasive and the reaction time.

Abstract: The effects of the concentrations of NiSO₄•6H₂O, NaH₂PO₂•H₂O and complexing agents in bath, temperature, pH, SiC concentration etc. on deposition rate of electroless Ni-P plating were systematically studied. The appropriate deposition rate of electroless Ni-P plating (17μm h^-1) was obtained at the optimal conditions. The deposition reaction dynamics of electroless Ni-P plating on AZ91D magnesium alloy was discussed and the corresponding kinetic model was also determined based on the corresponding experimental results.

Abstract: Natural gas compressor is the absolutely necessary link of natural gas storage and transportation technology. The safety operation of the exhaust steel tube directly influences the ability of natural gas gathering and transportation system. In this paper, the accident of the exhaust steel tube explosion of natural gas compressor was carried out to study the reasons of the failure using methods of macroscopic analysis, size measurement and SEM et al and proposed the safety countermeasures. The results show that the failure of exhaust steel tube related to the wicked service conditions, rough machining, the fatigue crack initiation and propagation. The sulfide stress corrosion (SSCC) and the longitudinal processing damage accelerate the fatigue crack propagation rate.

Abstract: The research on water vapor isothermal sorption of porous building materials have an important function on controlling and solving hygrothermal problems, such as durability, thermal insulation, mold growth and indoor air quality, when building materials are in hygrothermal environment, especially in the high humidity environment. The isothermal sorption is used to describe the maximum moisture sorption capacity, if moisture content exceeds the limitation, probably there will be liquid water appearance, which lead to the risk of mold growth, decreasing durability and increasing thermal conductivity, and so on. The classic testing method of isothermal sorption could be found in ASTM Standards C 1498-01. In this paper, the eco-stucco, eco-fiber batt and eco-fiber board is tested using traditional method. Meanwhile, pore size distribution and capillary condensation is analyzed which is challenge for the design basis of hygrothermal character for the building envelope.