Through adding different additional water use, the compressive strength, splitting tensile strength and fluidity of recycled concrete of three aggregate combination forms were studied by experiment respectively. The experimental results show that with the increase of adding additional water use, the compressive strength and splitting tensile strength of recycled coarse aggregate concrete decrease, but that of recycled fine aggregate concrete and recycled all aggregate concrete increase firstly then decrease. When additional water use is added more 15% or 20% than that of basic ordinary concrete, the recycled coarse aggregate concrete and fine one can get pretty good fluidity. When it is added more 30%, the recycled all aggregate concrete has fluidity that is just satisfied.
The high sintering temperature of Al2O3 is the main reason of the high cost of the common ceramic membrane supports. To decrease the sintering temperature, kaolin and talc were chosen as sintering aid because the reaction between kaolin, talc and Al2O3 generates cordierite. The Al2O3-cordierite porous ceramic samples were sintered in the range of 1450~1510°C. The microstructure and the bending strength of the samples were characterized. The results show that the content of kaolin is no more than 8%, the bending strength of the porous ceramic sintered at 1460°C and 1510°C are 77MPa and 153MPa, respectively. The further increases of the kaolin content result in the decrease of the bending strength and the porosity. The needle-like cordierite locates in the neck of Al2O3 grains. The reaction between kaolin and Al2O3 contributes to increasing the sintering velocity. The ceramic support using cordierite as sintering aid has the acid/alkali corrosion resistance in some degree.
Green compact containing Yellow River sand and several additives was prepared by slip casting and the as-made compact was used to synthesize SiAlON multiphase ceramics by carbothermal reduction nitridation. The processing parameters of slip casting including the type and concentration of dispersant, solid loading, ball milling time, pH value and particle size distribution were optimized by orthogonal experiments. The results indicated that the raw materials could disperse uniformly in the suspension under the use of the mixed dispersant of skip liquid (SL, PT) and sodium carboxymethylcellulose (CMC). The green body with high bulk density of 1.86 g·cm-3 was obtained. After sintered in flowing N2, the compact could transform to SiAlON multiphase ceramics.
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