Optimization Of Preparation Process And Control Of Pore Structure Of Aluminum Foam By Investment Casting

Aluminum foam has attracted more and more attention because of its excellent properties.How to prepare aluminum foam with high porosity and high strength is one of the important topics in this field Aluminum foam with high porosity can be obtained by investment casting method.However,due to the problems such as too fine sinew of motherboard material and imperfect preparation process,it will be difficult to fill mold during pouring and the obtained aluminum foam sinew is too thin,resulting in insufficient strength.In this paper,the aluminum foam with different thickness is obtained by improving the process of preparing aluminum foam.In this way the strength of aluminum foam is improved.The main research contents and results are as follows:(1)The ethanol varnish diluted in accordance with a certain proportion is used to roughen the polyurethane foam with a thickness of 0.3mm.A good roughening effect can be obtained by using the mixture of varnish and thinner.The ratio of varnish to thinner is 3.5:1.And the thickness of the sinew can reach about 0.8mm after 8 times of roughening.(2)A mathematical model was established to analyze the coarsening effect theoretically.After comparing the coarsening effect of the mathematical model with that of the actual measurement,the relationship between the degree of coarsening and the number of coarsening under this ratio is obtained.It is found that the actual coarsening effect is less than the theoretical coarsening effect when the coarsening times are less,and the actual coarsening effect is greater than the theoretical coarsening effect when the coarsening times are more.(3)A large number of experiments were carried out on the allocation of gypsum slurry,and through the analysis and optimization of orthogonal test,the volume composition and the mass ratio of gypsum slurry with good slurry fluidity,the required gypsum type strength and the better water-soluble and collapsibility were finally obtained:M(gypsum):M(kaolin):M(anhydrous magnesium sulfate):M(water)=160:20:25:110(4)The condition for the complete filling of liquid aluminum: make sure the pouring mold has good air tightness and the vacuum degree is 0.04 mpa during pouring.Before pouring,the gypsum mold should be preheated to 550? and the aluminum ingots are heated to 740? to melt and refine.(5)Residual gypsum in aluminum foam can be completely removed by using an 8% ammonium acetate solution.