Study On Stable Formation Of Aluminum Foam Prepared By Non-thickening Foaming Technology

Aluminum foam,a kind of metal foam,has the characteristics of high specific strength and high energy absorption performance,which can make it used in automobile manufacturing,aerospace and other fields.However,it is necessary to increase the viscosity of the aluminum melt in the process of preparing the aluminum foam material,and the long-term stirring during the thickening process will cause the excessive oxidation of the aluminum melt,and the large amount of composite oxides generated by adding Ca to increase the viscosity will reduce plasticity.Therefore,based on the traditional use of melt foaming to prepare aluminum foam,this article intends to adopt non-thickening foaming technology,and replace a single foaming agent with a foamed mixture to realize that the aluminum foam material does not increase the viscosity of the aluminum melt.The main research contents are as follows:(1)Investigate the coating effect of Al powder on the foaming agent TiH₂in the process of preparing aluminum foam using non-thickening foaming technology.The experimental results show that low-energy ball milling can reduce the size of particles and make them evenly embedded in Al powder;The thermo-gravimetric analysis shows that the decomposition temperature of the foaming mixture is greater than that of TiH₂after pure pretreatment;The endothermic peak changed from a single peak at 410?550? to a double peak at 480?560? and 650?675?;with the continuous increase of Al powder in the foaming mixture,the endothermic density of the first peak keeps decreasing while the endothermic density of the second peak keeps increasing.(2)This paper studies the influence of different component ratios of the foaming mixture on the foaming effect and mechanical properties of aluminum foam.With the improvement of the quality of the aluminum powder in the foamed mixture,the height of the prepared aluminum foam samples increased from 75 mm to 130 mm,while the thickness of the non-foam layer decreased from 40 mm to 20 mm.From the static unidirectional stress-strain curve of the sample prepared by the non-thickening melt foaming method,it can be seen that with the increase in the quality of aluminum powder in the foamed mixture,the compressive strength of the corresponding aluminum foam shows a slight upward trend.In addition,it can be seen from the bending load displacement curve that the bending yield point of the aluminum foam sample prepared by the thickening method is 1.7 mm?3 mm,while the bending yield point of the aluminum foam sample prepared by the non-thickening method is 3.8 mm?4 mm,the bending toughness is close to twice of the former;It can also be seen from the bending energy absorption curve of the sample that under the same bending deformation,using the non-thickening melt foaming method to prepare aluminum foam have higher bending energy absorption characteristics.(3)In this paper,Al powder,TiH₂,SiC(0.5?m/2?m)and are mixed according to a certain composition ratio as a foamed mixture to prepare aluminum foam to explore the effect of introducing ceramic particles on the properties of aluminum foam.Then Compressive tests were carried out from room temperature to elevated temperature(300? and 500?).Compressive deformation behavior and energy absorption capacity have been studied at elevated temperatures.Experimental results show:for the first group of samples(SiC/0.5?m),the compressive yield stress of the sample decreases as the temperature increases;while for the second group of samples(SiC/2?m),the compressive yield stress of the sample increases first lower after high.The trend of energy absorption efficiency with temperature is also the same.