Study On Fabrication Of Foamed Magnesium By Melt Foaming Method

Foam metal is a new kind of engineering material,which has the structural characteristics and excellent properties of metal materials and porous materials.It not only has the characteristics of light weight and high strength,but also be able to vibration damping,Sound absorbing,heat dissipation,absorb shocks,electromagnetic shielding and so on.Foamed metals have been widely used in the field of industry and high technology both in domestic and foreign.Today,Magnesium is the lightest metal material that can be used in industry.The foaming of magnesium alloys is of great significance to the application of foam metal and the development of industry.In this paper,using the method of solution foaming,coating foaming agent by sol-gel process,the optimum process for preparing high quality foamed magnesium alloy is obtained by analyzing the influence of different foaming process on the quality of foam Mg alloy.The effect of CaCO₃ coating by sol-gel method on the thermal decomposition temperature was investigated.The results show that the temperature range of CaCO₃ decomposition increases obviously,and the decomposition rate can be effectively delayed at the same temperature.Using Ca particles as tackifier and coated CaCO₃ as foaming agent,the influence of tackifier content,tackifing temperature,foaming agent content,foaming temperature and holding time on the porosity,pore size and density of foamed magnesium are analyzed.The experimental results are as follows: with the increase of the additive content,the raise of the experimental operating temperature and the extend of holding time,porosity increased first and then decreased,the average pore size and density decreased first and then increased,the change regulation of average pore size and density is opposite to porosity;When the tackifier content,tackifing temperature,foaming agent content,foaming temperature and holding time were 3 %,720 ?,2 %,740 ?,5 min,respectively,the porosity reaches the maximum,the average pore diameter and density reach the minimum value.The results show that the porosity range of the Fabricated foam magnesium sample is 56.06 ? 81.6 %,the density range is from 0.32 to 0.76 g/cm³,and the average pore diameter range is from 1.95 to 3.85 mm.The optimum technological parameters for the Fabrication of foamed magnesium is: after the magnesium ingot melt completely,add the 3 % preheating Ca particles at 720 ?,Stir 5min with the speed of 500 r/min to make Ca particles dispersed evenly;make the temperature rise to 740 ?,add the 2 % preheated CaCO₃ powder,stir 30 s with the speed of 800r/min;Heat preservation for 5 minutes at 740 ?,Coo by air cooling,foamed magnesium material has been obtained.