Materials Science Forum Vols. 675-677

Abstract: As an active admixture, super fine steel slag powder can be mixed into concrete to produce high performance concrete. The microstructures between cement paste mixed with steel slag powder and plain cement paste are experimentally studied. The SEM of the microstructures shows that microstructure of cement paste are changed by active mineral admixture, the internal structure of the cement paste are improved. Drying shrinkage of cement mortar with different steel slag kinds and different dosage of admixtures are measured. Experiments results show the effect of steel slag powder on drying shrinkage of cement mortar.

Abstract: A statistical analysis of creep rupture data for 2.25Cr-1Mo steel was performed. The scattering of creep rupture data was represented by Z-parameter method based on Manson-Haferd method. With the application of Z-parameter, reliability design for allowable stress of creep rupture strength was carried out according to design life. The higher the value of confidence level, the lower the allowable stress. In comparison with safety factor method and minimum rupture strength method, it can be seen that reliability design based on Z-parameter is more agree with experimental data than other methods. Reliability design provides more precise results by considering the real distribution of creep rupture property and provides more flexible choice for design due to the need of safety and economy.

Abstract: This paper studies on the characteristics of strength and deformation of brittle rock under different compression condition by experimental tests. A lot of experimental tests for the Xiangjiaba sandstone are carried out under different compression condition, including uniaxial compression, triaxial compression, uniaxial monocyclic compression and uniaxial loading and unloading. Base on the experimental test results of the Xiangjiaba sandstone, the strength and deformation of brittle rock are analyzed, and some comparative analysis for the mechanics characteristics of brittle rock are carried out. The compute results show that, the peak strength of brittle rock is increased with the confining stress, and close to a linear relationship. Its also show that, the peak strength is not increased under the monocyclic compression, neither for the loading and unloading condition.

Abstract: Molecularly imprinted polymers (MIPs) have been demonstrated to be a promising class of biomimetic materials that can be tailored to meet specific end use recognition requirements. Molecular imprinting is achieved by the interaction, either covalent or non-covalent between complementary groups in a template molecule and functional monomer units through polymerization. MIPs have been widely employed for divers applications such as chiral separation, chemical sensing, catalysis, drug screening, chromatographic separations and solid phase extraction. During respiration and metabolism, human body produce free radicals as by products, which can damage genetic material, lipids and proteins leading to several fatal diseases such as Cancer, Cardio-vascular disease, Alzheimer’s disease, Immune dysfunction etc. Antioxidants define a family of natural or synthetic nutrients in food, which acts as free radical scavengers. They are present in complex matrix such as herbs, fruit pulp in small concentration, either combined or in free form. Although several techniques have been developed for their detection, (e.g. HPLC, Thin layer chromatography, Capillary gas chromatography, Supercritical fluid chromatography), to achieve highly specific and sensitive analysis, high affinity, stable and specific recognition agents are needed. In this review, special attention is paid to the MIPs based analytical methods for antioxidants, focusing on solid phase extraction, chromatographic and non chromatographic separations and sensing approaches as well as on novel approaches for the discovery of new imprinted materials for antioxidants.

Abstract: Surface treatment of hard nitride film with high-intensity pulsed ion beam (HIPIB) was investigated in the present research. On considering the high energy density and short pulse duration of HIPIB source, a one-dimension physical model was built according to the structure feature of film-base sample. It was found that the irradiation of HIPIB lead to a very fast thermal recycle of heating rate 1011K/s and cooling rate up to 1010K/s. The highest temperature located at the surface of film irradiated. When using the HIPIB parameters of accelerating voltage 350kV, pulse duration 70ns and current density 60A/cm2, the surface layer of film would be melt with depth of about 0.35mm, that was verified by the experimental result along with the grain refinement effect due to the fast solidification process.

Abstract: This study evaluates the thermal and oxidative stability of a specific polymer composite. A TGA/FTIR combined technique was employed to characterize this polymer/graphite fiber composite. The polymer composite sample was pyrolyzed in nitrogen, air and 2% oxygen atmosphere, respectively, in a Perkin-Elmer thermo-gravimetric analyzer. The use of a gas-cell Fourier transform IR spectrometer downstream from the TGA allowed for the identification of the evolved gas products, the thermal oxidative stability (TOS) of this composite was compared to its thermal stability; also, comparison of the TOSs in different atmospheres is presented. In addition, the effects of specimen geometry in terms of sample thickness and surface area to volume ratio (A/V) were investigated and are discussed by relating gas diffusion into the specimen to its relative stability.

Abstract: Whisker pull-out, which indicates that the interfacial bond strength of whiskers/cement is not high enough, is dominant in the microstructure of whisker-reinforced cement fractured surfaces. The weak interfacial bond of whiskers in cement matrix severely restrained the further improvement of properties. Superfine slag powder was used to modify and improve the strength and bond behavior of whisker-reinforced cement. Crystal structures, microcosmic appearances and characterizations of Slag Micro powder and the composite were studied by X-ray diffraction (XRD), and scan electron microscope (SEM/EDS), etc. Effect and mechanisms of different Slag powder content on the micro-structure and macro-properties of cement composite were investigated. The results show that Slag Micropowder can modify and improve the microstructure, interfacial and mechanical properties of whisker-reinforced cement.

Abstract: Ag/AgCl electrode was made from anodized Ag wire and the influence of anodization current density on stability of Ag/AgCl electrode was studied in this paper. Potential response of Ag/AgCl electrode was tested in synthetic concrete pore solutions with different concentrations of chloride ions and influences of sulfate, calcium, potassium and sodium ion on the potential response of Ag/AgCl electrode were also measured. The results show that Ag/AgCl electrode has the best potential stability when it is prepared with 0.4 mA/m2 of current density for 2 hours and there is no measurable potential difference among 20 electrodes prepared with such anodizing condition. The potential of Ag/AgCl electrode develops to a constant value in less than 60 seconds and maintains stable during the test period when immersed into synthetic concrete pore solution with different amount of chlorides. Ag/AgCl electrode shows a good linear potential response to a wide range of chloride concentrations from 0.005 to 1.0 M. Sulfate, calcium and sodium ions show inconsiderable influences on the potential of Ag/AgCl electrode. Therefore, it is suggested that Ag/AgCl electrodes can be used as chloride sensors in concrete exposed to different environments.

Abstract: This study reported on Taguchi-Fuzzy logic model with statistical experiments to characterize the tungsten carbide/cobalt (WC-Co) deposited quality properties of the high-velocity oxygen-fuel (HVOF) process. The eight control factors were designed in a factorial orthogonal array experiment, and the effects of control parameters on the integrated surface properties were critically evaluated in the Taguchi designed experiments. A fuzzy logic system with knowledge bases in the inference engine was used to explore the relationships between variables and responses in the modified structures. In addition, the structure and properties of HVOF sprayed WC-Co coating were reported. Furthermore, a confirmation experiment of the optimal process was conducted. It was clear that HVOF sprayed WC-Co coating estimations are greatly improved through the Taguchi-Fuzzy logic operation, and these findings achieved the desired values in the modified properties.

Abstract: This paper describes the results of an experimental investigation on the drop off impact test on a range of sandwich panels. The magnesium alloy sandwich panels were fabricated with rolled sheets at different thickness by pressing and bonding method. Out-plane compression test was employed to obtain its basic deformation-force behavior. The impact experiments were carried out in which a steel cylinder was dropped off at various height levels, ranging from 0.5m to 1.5 cm to impact the panel. A high speed camera was employed to take pictures at 20 thousand frames per second and the low-velocity impact response on the sandwich panels is recorded with a dynamic force senor under the panel simultaneously. The shock response with time and the impact absorption energy were analyzed and compared. The results of this study proved that the magnesium alloy honeycomb sandwich panels have good impact energy absorption performance.