【简答题】过共析钢液 η=0.0049Pa . S ,钢液的密度为 7000kg/m 3 ,表面张力为 1500mN/m ,加铝脱氧,生成密度为 5400 kg/m 3 的 Al 2 O 3 ,如能使 Al 2 O 3 颗粒上浮到钢液表面就能获得质量较好的钢。假如脱氧产物在 1524mm 深处生成,试确定钢液脱氧后 2min 上浮到钢液表面的 Al 2 O 3 最小颗粒的尺寸。
【简答题】Many Chinese high school students are tired of their parents’ nagging(唠叨). They think their parents’ high expectations are burdens (负担). But a recent survey found that they are much luckier than a...