Authors: Sung Wi Koh, Hyung Jin Kim, Jae Dong Kim, Byung Tak Kim, Sun Oug Hwang, Woo Seok Choi
Abstract: In the present study, the influences of load on the abrasive wear properties of
silica-filled epoxy resin composites were investigated at ambient temperature. The friction
coefficient, wear rate and specific wear rate against SiC abrasive paper were determined
experimentally. The sliding wear tests of the materials demonstrated that the friction coefficient and
the wear rate of silica filled epoxy composites were lower than those of the pure epoxy. The
cumulative wear volume tended to increase nonlinearly with increase of sliding distance and
depended on diameter of the silica particle for all these composites. The friction coefficient and
wear rate were raised substantially with an increase in applied load.
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Authors: Shunkichi Ueno, Li Ming Lin, Hideo Nakajima
Abstract: A porous alumina with cylindrical pores was fabricated by unidirectional solidification
under hydrogen gas flow (0.1 MPa) using alumina feed rods doped with silica, calcia or sodium oxide.
The additives in the feed rods strongly affect the formation of porous structure during the
solidification. The porosity increases with increasing silica content. The increase of porosity is
enhanced by further addition of sodium oxide. The addition of calcia to the feed rod is effective on the
homogenization of pore distribution. The porous alumina with 1mol%CaO and 20mol%SiO2
additives showed 50% porosity and homogeneous pores distribution.
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Authors: Li Guo Ma, Yun Sheng Zhang
Abstract: The hydration heat evolution process is studied on the pure cement paste, the cement- fly ash binary system and the cement- silica fume binary system with water binder ratio(w/b) of 0.53, 0.35 and 0.23 by using isothermal calorimeter(TAM Air). The fly ash replacement in the cement-fly ash binary system is 10%, 30% and 50% respectively. The silica fume replacement in cement-silica fume binary system is 4%, 8% and 12% respectively. The experiments results indicate that w/b had great impact on the hydration heat evolution and the hydration heat decrease with the decrease in w/b. The addition of fly ash greatly decrease the exothermic rate and total hydration heat. The addition of silica fume shortens dormant period and increases the peak exothermic rate, but reduces the total hydration heat.
4001
Authors: Yue Ping Xu, Xiao Ming Yu, Yang Ji, Ning Zhang, Yang Hong, Hua Zhe Yang
Abstract: Hydrochloric acid was directly adopted as water phase and catalyst to prepare the silica shell, hexane and Span 80 were respectively adopted as oil phase and emulsifier to prepare water-in-oil (W/O) emulsion. TEOS was adopted as the silica source, then the silica shell can be obtained through the sol-gel route at the interface of emulsion. The SiO2 inorganic medical capsule was obtained, and the morphology of samples experience from irregular to regular with the increase of both water phase and stirring rate. Stability of emulsion can greatly affect the morphology of capsule. Control of ratio of water phase to oil phase is vital to the formation of SiO2 inorganic medical capsule. Furthermore, schematic transformation model of emulsion droplet under different conditions was proposed.
356
Authors: Nan Chun Chen, Cheng Ju Zhao, Wei Wang, Meng Ying Li
Abstract: This paper describes the synthesis and surface characterization of a new silica white prepared from a high Si:Al fine powder by using the sulfuric acid precipitation method. In the beginning, water and alkali are added to the sieved high Si:Al fine powder. The mixed liquid is then heated until it is boiling and left alone at the same temperature for 2.5 hours before it is filtrated. Applying liquid NaCl (20%) to the filtrated solution before it is heated to 80°C. Applying certain amount of surfactant and H2SO4 (20%) while maintaining the temperature at 80°C for 3 hours before it is washed, precipitated, filtrated, and dried to produce the final product of silica white. Examinations with XRD and IR show that the silica white is amorphous silicon. It has a PH value of 7-7.5 determined by aqueous suspension method, a white index of 96% and above, a volume average particle diameter of 4.6 - 7.1 µm, a specific surface area of 95.5-103.1 m2/g, an oil absorption rate of 4.34-4.87 ml/g, and a LOI (loss on ignition) of 5.12% at 1000°C. The synthesized silica white has a satisfying uniformity of particle sizes, meeting standard of HG/T 3061-1999.
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