It should be homogeneous in structure , with smooth surface , without the crack , airbubble , flatted , mechanical damage scratch , knife mark and so on .
质地均匀、外观平整、表面光滑，无裂纹、气泡、分层，没有影响使用的机械损伤、刀痕等缺陷。
On this basis , the main reason why surfactants can intensify the boiling heat transfer of water , glycol-water was studied : the additive introduced increases airbubble separation frequency of pure components and mixture and decreases the separation diameter .
