MDF水泥抗弯强度与大孔尺寸和孔隙率的关系

采用压汞仪、氦比重仪和ＳＴＥＭ等仪器研究了ＭＤＦ水泥抗弯强度与大孔尺寸和孔隙率的关系。实验结果表明，抗弯强度与孔隙率有良好的相关性，孔隙率降低，抗弯强度明显增高。抗弯强度与大孔尺寸没有明显的相关性，Ｋｅｎｄａｌｌ修正的Ｇｒｉｌｆｉｔｈ方程不适用于ＭＤＦ水泥。

氨基功能化大尺寸SiO_2大孔材料的制备及其吸附性能

以具有三维骨架结构的环氧树脂大孔聚合物为整体型模板,利用硅酸酯原位水解和高温烧结制备出大尺寸SiO2大孔材料。在溶剂热条件下,用3-氨丙基三乙氧基硅烷对SiO2大孔材料进行表面修饰,得到氨基功能化SiO2大孔材料(H2N-SiO2)。用SEM和FT-IR对制备的大孔材料进行了表征。以Cu2+和Pb2+为模拟污染物,研究了H2N-SiO2的吸附性能。结果表明,室温下,在pH值为6.5时能有效吸附Cu2+和Pb2+;吸附为放热自发过程;吸附过程符合准二级动力学方程;吸附等温线用Freundlich方程拟合的结果优于Langmuir方程,H2N-SiO2对Cu2+和Pb2+的理论最大吸附量分别为76.0和143mg/g;H2N-SiO2对50mg/L水溶液中Pb2+的去除率可达99.4%,重复使用3次后对Pb2+的去除率保持在87.8%。

大尺寸SiO_2大孔材料的表面改性及其吸附性能

以具有三维骨架结构的环氧树脂大孔聚合物为整体型模板,利用硅酸酯原位溶胶-凝胶过程和高温烧结法制备出大尺寸SiO2大孔材料,通过水热法用铝酸钠对材料进行表面改性,得到铝掺杂SiO2大孔材料(Al-SiO2),并用SEM、FTIR和XPS对大孔材料进行了表征.以Cu2+和Pb2+为模拟污染物,研究改性大孔材料的吸附性能.结果表明:改性大孔材料对Cu2+和Pb2+均具有良好吸附能力;Al-SiO2对Cu2+和Pb2+的最大吸附量分别为71mg.g-1和138mg.g-1,0.100 g Al-SiO2对100mL 50mg.L-1水溶液中Pb2+的去除率达到95.3%,重复使用3次后的去除率保持在89.8%.

大型中开泵泵体的加工分析和改进

大型中开泵由于外形尺寸庞大、加工精度要求高等原因,容易出现加工尺寸超差及加工效率低的问题,从而引起泵体振动超标、工作效率低及使用寿命短等质量问题。通过分析得知,造成大型中开泵泵体加工效率低和加工精度低的原因主要是泵体内大孔镗序工艺方案不合理引起的加工系统刚性不足及间接测量造成的测量误差累计放大。通过改进泵体镗序工艺和研制跨径千分尺使泵体镗序加工效率整体提高了约20%,尺寸检测合格率达100%,综合估算每台泵加工成本降低约2万元。

Microscopic analysis of saturated soft clay in Pearl River Delta

A series of researches were carried out for the soil samples in the Pearl River Delta under the action of consolidation loads,such as the quantitative analyses of the pore scale,shape and size distributions of micro-structure units,with an environmental scanning electron microscope (ESEM),a mercury intrusion analyzer and a mineral diffractometer. The experimental results show that the consolidation pressures remarkably change the pore sizes and distribution characteristics of the silt,thus changing its compressibility and permeability. This can be proved by the fact that,in the earlier stage with a consolidation pressure of p<200 kPa,the pore sizes are greater and the compressibility and permeability coefficients are larger. However,they rapidly decrease with the increase in consolidation pressure. And in the later stage with a consolidation pressure of p>200 kPa,the pore sizes are smaller and the compressibility and permeability coefficients are less. Therefore,the empirical formulas of compression coefficient and permeability coefficient vs consolidation load and average pore diameter are deduced.

Hydrogen bubble fiotation of fine minerals containing calcium

One characteristic of electro-flotation is the presence of micro bubbles that are well known for improving the flotation performance of fine particles. An electro-flotation method was studied with fine scheelite and fluorite particles sized into three different fractions. Experiments were performed in a modified Hallimond tube. We investigated the effects of gas holdup, particle size, and different mesh electrode apertures on mineral recovery. Flotation results show that two size fractions show increased flotation recovery as the gas holdup increases. For the sized scheelite and fluorite, the flotation effect is diverse for different sizes of the cathode aperture. Pictures of the bubbles taken by a high speed CCD were used to determine the hydrogen bubble size distribution generated as a function of collector, current density, and electrode size. The diameters of the hydrogen bubbles ranged from 12 to 117μm in alkaline conditions.

Triaxial compression strength for artificial frozen clay with thermal gradient

A series of triaxial compression tests for frozen clay were performed by KoDCGF （freezing with non-uniform temperature under loading after K0 consolidation） method and GFC （freezing with non-uniform temperature without experiencing Ko consolidation） method at various confining pressures and thermal gradients. The experimental results indicate that the triaxial compression strength for frozen clay in KoDCGF test increases with the increase of confining pressure, but it decreases as the confining pressure increases further in GFC test. In other words, the compression strength for frozen clay with identical confining pressure decreases with the increase in thermal gradient both in KoDCGF test and GFC test. The strength of frozen clay in KoDCGF test is dependent of pore ice strength, soil particle strength and interaction between soil skeleton and pore ice. The decrease of water content and distance between soil particles leads to the decrease of pore size and the increase of contact area between particles in KoDCGF test, which further results in a higher compression strength than that in GFC test. The compression strength for frozen clay with thermal gradient can be descried by strength for frozen clay with a uniform temperature identical to the temperature at the height of specimen where the maximum tensile stress appears.