(1. 清華大學(xué) 機(jī)械工程系，北京 100084；
2. 教育部先進(jìn)成形制造重點(diǎn)實(shí)驗(yàn)室，北京 100084)
摘 要: 研究加入Ca元素對吹氣法制備泡沫鋁工藝中顆粒分散程度和泡沫穩(wěn)定性的影響，考察加入質(zhì)量分?jǐn)?shù)為1%的Ca后A356鋁合金熔體中陶瓷顆粒團(tuán)聚尺寸、臨界吹氣深度、泡壁厚度和Al2O3顆粒在氣泡界面處浸潤角的變化。結(jié)果表明：加入Ca使熔體中顆粒團(tuán)聚尺寸減小，令微小顆粒的分散變得容易，但使臨界吹氣深度增加，不利于泡沫的穩(wěn)定；吹氣法工藝中，Al2O3顆粒在氣泡界面處的浸潤角約為65°，小于理想值90°，加入Ca使顆粒的浸潤性進(jìn)一步遠(yuǎn)離理想值，因此，盡管加入Ca使顆粒團(tuán)聚尺寸減小，但同時(shí)增大壁厚，泡沫的穩(wěn)定性依然變差。
關(guān)鍵字: 泡沫鋁；吹氣法；穩(wěn)定性；浸潤角；活性元素
gas injection foaming process
（1. Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China;
2. Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084, China）
Abstract:The effect of Ca addition on particulate dispersion and foam stability in gas injection foaming process was investigated. The particulate size in the melt, the critical injection depth, the thickness of foam cell wall and the wetting angle of Al2O3 particulate on the bubble surface were viewed without and with Ca addition into A356 melt, respectively. The results show that the particulate size is smaller with addition of 1% (mass fraction) Ca. Thus, it’s easier to be dispersed for fine particulates with Ca addition. The critical injection depth of the melt becomes larger, so, the stability of aluminum foam becomes worse when adding calcium. The wetting angle of Al2O3 particulate on the bubble surface is about 65°, less than the ideal angle of 90°. With Ca, the wetting angle of the particulate decreases away from the ideal value. As a result, although the average size of the particulates decreases and the thickness of foam cell wall increases with Ca addition, the stability of the foam still becomes worse.
Key words: aluminum foam; gas injection; stability; wetting angle; active element
