Advanced Materials Research Vols. 306-307

Abstract: Sudden water inflow is the typical geological hazard during the construction period of underground, especially for the karst area. According to a new type of polymer chemical grout material called Malisan, plugging performance optimization tests of different grouting material had been carried out, such as ordinary cement, superfine cement and special cement of HSC, the geo time, consolidating strength, anti-erosion property and comprehensive properties of grouting harnessing had been systematically analyzed and compared. Test results showed that the new type of polymer chemical grout material has the significant characteristics of controllable gel time, high consolidating strength, anti-scour performance, water swelling and extremely strong permeability, it is more effective than conventional grouting material for grouting harnessing of seepage, water spraying and water inflow with high water pressure, in addition, it is convenient for transportation, material configuration and process operation.

Abstract: In this paper, emulsion type sizing agents for carbon fiber were prepared by epoxy resin with the aid of various emulsifiers. Effects of emulsifier comprise and content on properties of emulsion were investigated by centrifugal sedimentation analysis and zeta potential measurement. Processing characteristics of desized and sized carbon fibers were compared. Results showed that the optimal emulsion was obtained when weight ratio of polyoxyethylene nonylphenol phosphoric ammonium (NP-10A) and polyoxyethylene styrenated phenol ether (602) was 2:1, ωe/r was 12%. The sizing agent emulsion could significantly improve the processability of carbon fibers due to the increase of abrasion resistance and flexibility of carbon fibers and the decrease of fluffs and breakage.

Abstract: In this article the finite element software was used to analyse the values for compressive strength of X-cor sandwich. During the analysis, the failure criteria and materials stiffness degradation rules of failure mechanisms were proposed. The failure processes and failure modes were also clarified. In the finite element model we used the distributions of failure elements to simulate the failure processes. Meanwhile the failure mechanisms of X-cor sandwich were explained. The finite element analysis indicates that the resin regions of Z-pin tips fail firstly and the Z-pins fail secondly. The dominant failure mode is the Z-pin elastic buckling and the propagation paths of failure elements are dispersive. Through contrast the finite element values and test results are consistent well and the error range is -7.6%~9.5%. Therefore the failure criteria and stiffness degradation rules are reasonable and the model can be used to predict the compressive strength of X-cor sandwich.

Abstract: This paper explores the brazing process of SiC_p/A356 composites and aluminum alloy using semisolid metal. The two substrates were heated up to the semisolid temperature range of Zn-Al filler metal in the joint region by a resistance heating plate. In order to mix the filler metal with the base metal of both sides to be a single uniform joint, a stirrer was introduced into the weld seam. After stirring, specimens were sectioned for analysis of macro- and micro-structures along the weld region. The research shows that SiC_p/A356 composites and aluminum can be local joined with semi-solid filler metal. It can be found that part of the oxide film on the interface of the base metal was disrupted and removed through the observation by SEM. The metallurgical bonds can be formed between the filler metal and the base materials. Moreover, the oxide film of surface of aluminum alloy disrupted and removed was easier than that of surface of composites with existing of Sic particle. The joint microstructure with globular α-Al grain enclosed by rich-Zn phase can be obtained after stirring brazing.

Abstract: The eletrodeposition nano-TiO₂/Ni composite coating on AZ91PH Mg alloy was prepared using the nano-TiO₂ as the second phase particles. The corrosion resistance of the composite coating was measured by the static immerging corrosion test and the polarization curve test. The result shows that the corrosion resistance of the composite coating was better than that of Mg alloy. The corrosion resistance of the composite coating was optimal when the content of nano-TiO₂ in the plating solution was 10g/l-15g/l.

Abstract: In this paper, army-green ceramic coating has been obtained by Micro-arc Oxidation, a study of the effects of terminal voltage and colored salt concentration on the thickness, chromaticity and luminance has been made. The performance of anti-aging performance to ultraviolet light of the coatings and anodized oxide film on aluminum by electrolytic coloring was investigated. The thickness, chromaticity ,luminance of the coating were measured .The best sample was obtained at the terminal voltage of 360V and the colored salt concentration of 15g/L, the anti-aging of the army-green coatings to ultraviolet light is apparently better than that of the anodized oxide film by electrolytic coloring.

Abstract: Emulsion type sizing agent for carbon fiber was synthesized using epoxy resin (E-51) and epoxidized polybutadiene (EPB) by adding emulsifiers and other additives. Standing stabilization of sizing agents was analyzed. Meanwhile, abrasion resistance, fluffs and breakage, stiffness were used to analyze the processability of carbon fiber. The effect of sizing agents on interfacial adhesion of carbon fiber/resin composites was estimated by interlaminar shear strength (ILSS). The results showed that the sizing agent could significantly improve processability of carbon fiber due to the increase of abrasion resistance and reduce of fluffs and breakage. By adding EPB in sizing agent and adjusting the ratio to E-51, the flexibility of carbon fiber was ameliorated and the sizing agent could adapt to various resin matrices. Compared to the desized carbon fiber reinforced composite, ILSS of sized carbon fiber/epoxy resin composite was increased by 16.9%, and ILSS of sized carbon fiber/vinyl ester resin composite was enhanced by 19.1%.

Abstract: The physical and mechanical properties of alumina (Al₂O₃) ceramics by introduction of zirconia (ZrO₂) fiber were studied. ZrO₂/Al₂O₃ ceramics at different sintering temperature was investigated by porosity and water absorption measurements, flexual strength and thermal shock resistance analysis. Results showed that Al₂O3 ceramics containing 15 wt% ZrO₂ fiber with sintering temperature of 1650°C exhibited good mechanical properties and thermal shock resistance. The porosity and water absorption were 7.4% and 0.69%, respectively. The flexual strength was 613 MPa and the thermal shock times reached 29 times. Scanning electron microscope (SEM) was used to analyze the microstructure of Al₂O3 ceramics.

Abstract: This work aims to evaluate the effect of Kevlar fibers with chemical treatment on the flexural strength, compressive strength and impact resistance of cement mortar. The experimental results exhibit that Kevlar fiber with a larger percentage can increase the flexural strength and improve the impact resistance of cement mortar, and the reinforcement effect of Kevlar fiber with chemical treatment is more obvious. The surface morphology of Kevlar fiber and the fracture surface of cement mortar reinforced with Kevlar fiber were observed by SEM, and the reinforcement mechanism of the Kevlar fiber on cement mortar was discussed.

Abstract: This work aims to evaluate the effect of cotton stalk fibers with styrene acrylic emulsion treatment, slag and ordinary Portland cement on the properties of crops fiber/gypsum composites. The results show that crops fibers with surface treatment, slag and ordinary Portland cement can increase the bending strength and improve the water-proof property of crops fiber/gypsum composites obviously. The fracture surface of crops fiber/gypsum composites were observed by SEM, and the action mechanism of the crops fibers, slag and ordinary Portland cement on crops fiber/gypsum composites were discussed.