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Research on fabrication of aluminum foam vacuum foaming

Author: WangJun
Tutor: ZuoXiaoQing
School: Kunming University of Science and Technology
Course: Materials Science
Keywords: Aluminum alloy foam Initial bubble Vacuum foaming Mechanical property Mechanism
CLC: TG146.21
Type: Master's thesis
Year: 2013
Downloads: 33
Quote: 0
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Abstract


Aluminum alloy foam possess these properties as low density, high specific strength, sound absorbing, vibration attenuation, insulation and others. It is widely used in the filed of aeronautics and astronautics, transportation, constructional engineering, mechanical engineering and so on.To overcome the high cost, bad dispersion, difficult to match the foaming technology of foaming agent TiH2, and provide a new foaming method for other foam metal materials, this thesis put forward a new foaming method for aluminum alloy foam-aluminum alloy foam vacuum foaming technology. The technology is to add thimbleful TiH2in the aluminum alloy melt, to make the initial bubbles by TiH2decomposition and by the high-speed stirring. Then well-distribution, large quantity, well cell diameter distribution initial pores will appears in the internal of the aluminum melt. And then foaming the aluminum alloy foam in vacuum. Through this technology, aluminum alloy foam has the advantages of low cost, pore structure easily control, craft stable and so on. The aluminum alloy vacuum foaming processing, the mechanical properties of fabricated aluminum alloy foam, and the preparation mechanism of aluminum alloy foam were studied in this paper. The conclusions of the research are obtained as follows:(1) The optimal processing parameters of Aluminum alloy foam vacuum foaming technique is:melting temperature of aluminum alloy620℃; heat preservation maintains lh; proportion of SiC1%; proportion of Pb1%; proportion of TiH20.02%; viscosity increasing stirring speed2000r/min, stirring time10min; initial pores stirring speed2000r/min, stirring time6min; foaming vacuum degree5Pa,10Pa; foaming time10s,20s; cooling time under vacuum6min.(2)The compression properties of aluminum alloy foams through two different kinds of increasing viscosity, increasing viscosity through2%Ca and1%SiC, and increasing viscosity through10%SiC were studied. The results indicated that:under the condition that the pore structure is similar, the yield strength and energy absorption of the former is13.9～9.6MPa and8.271-6.048MJ/m3. The yield strength and energy absorption of the latter is10.4～5.6MPa and4.805～3.472MJ/m3. The yield strength and energy absorption of the former is higher than the latter,and the toughness of the former is better.(3) The micro-structure analysis of aluminum alloy foam (porosity78%) obtained by2%Ca and1%SiC viscous agent together. The results indicated that the grain size is40～100μm, and the average grain size is60μm. The main reasons of aluminum alloy foam without excellent compressive properties are big grain diameter, wide rang of grain size and composition segregation.(4) The initial bubble occurrence mechanism have been analyzed, the second phase in the melt is bubble core of the initial bubble. The initial pores occurrence control model that coincide with the experimental results is established:gas reserves volume control model a=2.5×10-3A/t[l-(v-1500)/10000], average pore size of initial pores control model r=1/2t [1-(v-1500)/2500].Initial pores occurrence was controlled by managing melt viscosity, surface tension, bubble core and other parameters reasonably.(5) Vacuum foaming process have been analyzed, control model of vacuum foaming method have been established:pore control model r2=(21～46)(0.5+t/60) r1, porosity control model K=(104～105)(0.5+t/60)3V1/[(104～105)(0.5+t/60)3V1+V3].

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallic materials > Non - ferrous metals and their alloys > Light non-ferrous metals and their alloys > Aluminum
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