袁源平1 陈乐平1 周 全1 陈 舸2
摘 要：研究了白云石作为发泡剂和增粘剂制备泡沫镁合金的工艺，考察了白云石作为发泡剂时，其加入量、颗粒尺寸和加入温度对泡沫镁合金结构的影响。结果表明,以白云石为发泡剂和增粘剂，可以制备孔隙结构均匀、孔隙率高的泡沫镁合金，但所制备的泡沫镁合金中有气体空腔和底部无泡层的缺陷；泡沫镁的密度最小为0.38 g/cm3，孔隙率最高为78.7%；白云石在650 ℃以上大量分解，适合作泡沫镁发泡剂；白云石作为增粘剂和发泡剂，并不能完全分解，其残留物和分解产物在基体中基本均匀分布，在孔边缘局部团聚。在1%~2.5%范围内，随着白云石加入量的增加，泡沫镁合金密度逐渐减小；在74~250 μm范围内，随着发泡剂颗粒尺寸增大，泡沫镁合金的密度先减小后增大，转折点为150 μm；在620~710 ℃内，随着白云石加入温度提高，泡沫镁合金密度先减小后增大，转折点为680 ℃；泡沫镁合金的孔隙率变化规律与其密度变化规律相反。
Preparation of Foamed Magnesium Alloy by Dolomite
Yuan Yuanping1, Chen Leping1, Zhou Quan1, Chen Ge2
(1.School of Aeronautical Manufacturing Engineering, Nanchang Hangkong University; 2.Shanghai Spaceflight Precision Machinery Institute)
Abstract: Preparation of foamed magnesium alloy with dolomite as foaming agent and thickener was carried out. The effects of dolomite amount, particle size and adding temperature on structure of foamed magnesium alloy were investigated. The results reveal that dolomite can be used as foaming agent and thickener to prepare foamed magnesium alloy with uniform pore structure and high porosity. However, it has the defects of gas cavity and pore free layer at the bottom. The minimum density of magnesium foam is 0.38 g/cm3, and the maximum porosity is 78.7%. Dolomite is decomposed in large quantities when heated above 650 ℃, which can be used as foaming agent of magnesium foam. As thickener and foaming agent, dolomite cann’t be decomposed completely, and its residues and decomposition products are basically distributed evenly in the matrix and locally agglomerated at the edge of the hole. The density of foamed magnesium alloy is decreased with the increase of dolomite content in the range of 1%~2.5%. The density of foamed magnesium alloy is decreased at first and then increased with the increase of the size of foaming agent in range of 74~250 μm, and the turning point is 150 μm. In range of 620~710 ℃, as the temperature of dolomite increases, the density of the foamed magnesium alloy is decreased firstly and then increased. The turning point is 680 ℃. The change of porosity of foam magnesium alloy is the opposite to that of density.
Key Words: Dolomite, Foamed Magnesium Alloy, Structure, Density