同质多形现象

SiC polytypes of 6H and 15R and a transition zone between the two were observed under HREM and TEM and discussed from the point view of the crystal structures; the clear evidence of Al〓C〓 nucleated in the SiC particle was provided, indicating the aluminum penetrating the SiC grains is already carbon-saturated and, consequently, Al〓C〓 crystals grow in the particles wherever a temporary local supersaturating is produced; The experimental observation indicated that the types of the interface between SiC and Al are variable and the distribution feature of reaction product, Al〓C〓, were also given in the present work: to be nucleated on SiC, to be aggregated at SiC/Al interface zone or to be aggregated at the crystal boundaries.

通过高分辨透射电镜，本文观察到SiC增强体中6H和15R同质多晶现象及6H-15R SiC转变区，以及另外一种无序的SiC同质多晶，并从其晶体结构的角度解释了6H和15R在晶体内共存的现象。通过高分辨透射电镜，本文给出了Al〓C〓在SiC颗粒内部形核的明证，表明Al〓C〓形核是Al渗透到SiC颗粒内部在C过饱和处在SiC的（0006）面上而形核，而且一种可能的位相关系为A1〓C〓[11〓0]∥SiC[11〓0]。研究结果同时给出了SiC/Al复合材料的界面反应产物A1〓C〓的分布特征：在SiC上形核并生长，聚集于SiC/Al界面去附近，或者聚集于晶界上。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。