Advanced Materials Research Vols. 295-297

Abstract: In energy conservation design for buildings, interior thermal insulation structure, which is made of glazed hollow beads mortar, works with exterior one of building envelope. By this way, integrated thermal insulation structure made of GHB mortar is constructed. The paper describes its structure, construction technique and energy-saving calculation, which can provide theoretical and practice basis for the further application of this thermal insulation structure.

Abstract: Metal oxynitride (V_xON, Cr_xON) thin film has been fabricated by reactive dc sputtering method and annealing process. Its electrochemical properties are investigated in a M_xON/Li cell. The reversible specific capacities are around 830 mAh g^-1 for V_xON and 730 mAh g^-1 for Cr_xON. By using selected-area electron diffraction and X-ray photoelectron spectroscopy measurements, New electrochemical reaction mechanism is uncovered, which should be responsible for its good electrochemical performance.

Abstract: The Optical Microscope and Scanning Electron Microscope were used to analyze the causes of Nonconformity in ultrasonic flaw detection for three steel plates. The metallographic and energy spectrum analysis show that the main reasons were inclusions, porosity and cracks respectively, which were caused by the slag inclusion, center porosity and center segregation of the billets. Improving the quality of the steel water and optimizing continuous casting process could reduce the defects, and increase the percent qualified in ultrasonic flaw detection.

Abstract: Superhydrophobic surface was prepared by hydrothermal method on copper substrate via immersing the clean pure copper substrate into the mixed solution of H₂O₂ and C₂H₅OH, and then the substrate was heated at 100°C for 1.5 h, followed by modifying with stearic acid. The product was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The wettability of the products was also investigated. It was found that the as-prepared surface had a high water contact angle of about 153°. SEM images of the film showed that many irregular micro-nano sheets distributed on the surface in a random pattern. The special porous architecture, with the low surface energy leads to the surface superhydrophobicity.

Abstract: The effect of solution treatment at 420°C on the microstructures and mechanical properties of the Mg-6Al-Zn+xSn (x=0.5, 1, 2 and 3.5 mass %) alloys have been investigated. The results showed that the Mg₂Sn phase was present in both the cast and the heat-treated alloys. The Mg₂Sn particles tended to be spherodized during the solution treatment. Amount of Sn increased the tensile strength of the alloys.

Abstract: Differential scanning calorimetry (DSC) was used to study the thermal behaviour of abaca fibre reinforced high impact polystyrene (HIPS) composites. Thermal analysis is based upon the detection of changes in the heat content (enthalpy) and the glass transition temperature (Tg) of optimum condition of abaca fibre reinforced HIPS composites. In this research, glass transitions temperature (Tg) of neat HIPS occurred below the Tg of optimum condition of composites as the temperature of an amorphous state. The endothermic peak of composites was in to range 430-435°C including neat HIPS and it observed that enthalpy of abaca fibre reinforced HIPS composites yielded below the neat HIPS 748.79 J/g.

Abstract: Longitudinal crack on HRB335 hot-rolled ribbed bar surface in cold bending test in HISCO was ever a problem that caused great economic losses. To find the main reason, continuous cast product macro-acid etching test，metallographic examination，scanning electron microscope and EDAX are carried out. It is regarded that the defect is mainly caused by serious subsurface blowholes and internal cracks in the cast product，which can run through the surface in the later hot working process and are oxidized. As a result, the inner surface of these defects can not be welded-on in the rolling process and the cracks happen finally. Related measures are suggested to eliminate the defect.

Abstract: Cement asphalt mortar (CA mortar) is a highly flowable grouting material used in the slab track structure. Temperature significantly influences the workable time of CA mortar. The workable time of CA mortar is controlled by the adsorption of asphalt droplets in the emulsion on cement grains. In the present study, the absorption behaviours under different temperatures were investigated to reveal the influences of temperature on workable properties of CA mortar. A laser particle size analyzer was employed to characterize the particle size variation in the cement and asphalt emulsion (CAE) system. The results indicated that the particle size increased more prominently at elevated temperature; The viscosity of the CAE system was measured by a rotational viscometer, results indicated that variation pattern of viscosity correlated well with that of the particle size in the CAE system and the increase of particle size was partially accountable for the increase of viscosity and impairing the flowability of CA mortar; the workable properties of CA mortar were also investigated, results showed that the slump flow increased and the workable time decreased with the increase of temperature. The addition of non-ionic emulsifier could retard the adsorption behaviour between cement and asphalt and prolong the workable time of CA mortar.

Abstract: The hydration heat of aluminate cement containing magnesium aluminate spinel (MA-spinel) and Commercial Lafarge cement are studied. The results show that five stages exist in the hydration processes of both cements, e.g. pre-induction, induction, acceleration, deceleration and stabilization stage. The N values of the two cements are both lower than 1 in acceleration stage, on the contary higher than 1 in stabilization stage. As a result, the hydration is mainly controlled by nucleation reaction and diffusion process in acceleration stage and stabilization stage respectively. The hydration heat of aluminate cement containing MA-spinel is lower than Lafarge cement. Accordingly, the hydration rate of aluminate cement containing MA-spinel is slower than that of Lafarge cement.

Abstract: A TiC whisker toughening Al₂O₃ composite ceramic tool material was developed by an in situ carbothermal reduction synthesis technology. The influence of different synthesis temperatures (1480°C and 1700°C) and holding times (90min, 60min and 30min) on the mechanical properties of the composite was investigated. The results showed that either the lower synthesis temperature (1480°C) or the higher synthesis temperature (1700°C) was necessary to the improvement on the fracture toughness of the composite. However, when an Al₂O₃-TiO₂ eutectic system was formed during the higher temperature synthesis process, grain coarsening of the Al₂O₃ matrix became much serious, which resulted in obvious decrease in the flexure strength of the composite. Therefore, the carbothermal reduction synthesis process should be divided into two parts including the lower temperature synthesis process for increasing the yield of the TiC whisker and the subsequent higher temperature synthesis process for increasing the carbon content in the TiC whisker, and and the lower temperature synthesis process should be held for enough time (e.g. 60min) to avoid an incomplete carbothermal reduction of TiO₂.