Closed-cell A356 aluminum foams have been produced by the addition of calcium carbonate (CaCO₃) powder as a foaming agent to the molten aluminum without any stabilizer particles. The foaming process is performed by the addition of 2.5–3.5 wt% CaCO₃ and has relative density ranges of 0.12–0.44 and cell sizes of 1.5–3.1 mm with uniform cell structures. The foaming stabilizing mechanism and effect of foaming conditions such as the amount of foaming agent, casting holding and mixing time at the furnace on the foamed samples were investigated. The stabilizing mechanism is because of the foaming gas (CO₂)/melt reaction during the foaming procedure and producing some solid particles such as CaO, Al₂O₃ and MgO. The optimum foamed aluminum with uniform cell size distribution was obtained at 4-min mixing time and 10-min holding time with 3 wt% CaCO₃ foaming agent. The porosity of aluminum foam increased as the holding time increased from 60 to 86%. Also, the average cell size increased from 1.5 to 3.1 mm when the amount of CaCO₃ increased from 2.5 wt% to 3.5 wt%, respectively.

通过将碳酸钙（CaCO ₃）粉作为发泡剂添加到熔融铝中而没有任何稳定剂颗粒的方法，可以生产闭孔A356铝泡沫。发泡过程是通过添加2.5-3.5 wt％的CaCO _3进行的，相对密度范围为0.12-0.44，孔尺寸为1.5-3.1 mm，孔结构均匀。研究了发泡样品的起泡稳定机理和起泡条件的影响，例如起泡剂的量，铸件的保持和混合时间。稳定机制是由于在发泡过程中发泡气体（CO ₂）/熔融反应并产生一些固体颗粒，如CaO，Al ₂ O ₃和氧化镁。在4分钟的混合时间和10分钟的保持时间下，使用3 wt％的CaCO ₃发泡剂可获得具有均匀泡孔尺寸分布的最佳泡沫铝。泡沫铝的孔隙率随着保持时间从60％增加到86％而增加。另外，当CaCO _3的量分别从2.5wt％增加到3.5wt％时，平均孔尺寸从1.5mm增加到3.1mm 。