Filler from crushed aggregate for concrete: Pore structure,specific surface,particle shape and size distribution

Characteristics of fine particles (0–125 μm diameter) from seven different crushed and natural sands from five different Norwegian rock types were determined. The results suggest that the same water absorption values, as determined by EN 1097-6 on coarser sand fractions, can be applied to the fines. The values of specific surface area measurements vary widely between different materials and between different measurement methods. BET measurements seem to be strongly affected by the mineralogical composition (presence of mica) and surface morphology (weathering) of the particles. Specific surface area calculated from the particle size distributions (PSD) is mainly dependent on the precision of the test methods in the size range below about 3–5 μm, because these small particles contain most of the surface area. Shape measurements by both Dynamic Image Analysis (DIA), which is a 2-D method, and X-ray microcomputed tomography (μCT), which is a 3-D method, have yielded similar relative length-to-thickness aspect ratios of the particles between different mineralogies, though with lower absolute values for DIA due to 2-D projection of 3-D quantities.     

Martensitic transformation, mechanical property and magnetic-field-induced strain of Ni-Mn-Ga alloy fabricated by spark plasma sintering

Martensitic transformation, mechanical property and magnetic-field-induced strain of Ni-Mn-Ga alloys obtained using the spark plasma sintering method have been investigated. The results show that the martensitic transformation of the sintered specimen is basically similar to that of conventional bulk alloys. The ductility of sintered Ni-Mn-Ga alloys is significantly enhanced compared to the specimen obtained by conventional melting technique. The highest fracture strain so far is reported. Moreover, magnetic-filed-induced strain in sintered Ni-Mn-Ga alloys has been studied for the first time.     

Effect of high undercooling on Co-Ni-Ga ferromagnetic shape memory alloys

Co₄₅Ni₂₅Ga₃₀ ferromagnetic shape memory alloys were treated by glass fluxing combined with superheating cycling. The effect of high undercooling on solidified microstructure and transformation temperatures was investigated. The martensite lath is obviously refined and a mass of sub-grains are produced with the increase of undercooling. Undercooling rapid solidification introduces a number of dislocations and large internal stress, which give rise to the production of sub-grains in recovery. During the following annealing process, these sub-grains can gradually recrystallize and grow up with an amount of γ′ phase precipitated. Meanwhile, transformation temperatures of undercooled alloys are greatly elevated compared with those of as cast, which results from the large internal stress, and gradually reduce with the heating time.     

蜗壳形状对高速部分流泵性能的影响

利用FLUENT6.3.21软件,选择了S-A湍流模型,对同一叶轮配两种蜗壳的高速部分流泵进行了内部流场数值模拟和性能预测,通过比较分析,提出采用矩形螺旋蜗壳能提高关死点扬程,得到较为平坦的扬程曲线,且能提高泵的效率.并通过内部流场分析,解释了引起外特性差异的原因.     

焦家金矿矿体形态的变化对运输系统的影响

通过对焦家金矿主矿体形态及位置的探采对比，指出导致中段主沿脉运输巷道向矿体下盘移动的原因，得出了深部中段设计时，主沿脉运输巷距主参考面——主断层面的最小距离为１１０ｍ的统计参考值。     

发泡聚苯乙烯防潮保温性能设计

论述了聚苯乙烯材料的防潮保温的性能、设计计算以及成型方法和特点，为建筑业合理使用材料提供了理论依据。     

土的基本掘削形态及分析

当土作为机械的被加工物考虑时，由于其物理性能和力学性能等的影响，基本形态是不同的。本文结合试验情况，探讨土的基本掘削形态、掘削刀具几何参数的影响。     

Cr12标牌失效分析

经过一系列分析、试验后得出Ｃｒ１２标牌由于钢内夹杂物的影响及组织中碳化物带状分布严重致使韧性下降，冲击崩裂。