Study On Melt Foam Preparation Of Foamed Aluminum Core Sandwich Plates

With good physical properties, such as low density, high specific strength and good noise insulation, aluminum foam sandwich （AFS） has vast development space in the automotive, architecture, aerospace and other fields. The application of currently prepared AFS plate is limited, by the unsatisfactory combination of its core and surface layer and poor mechanical property.Therefore, using AlSi12 as raw material, the AFS plates were prepared by melt foaming method on the basis of conventional foaming, and their mechanical properties and the processing and decomposition of TiH₂ were studied in this thesis. The main results were listed as follows:（1） The optimal process parameters of AFS plate derived from experiments were as follows:the amounts of tackifier were 2.5wt% Ca; Foaming agent was TiH₂ which was pre-oxidation treated 6 h under 400 ℃ and then 1 h under 470 ℃ and its addition amount was 0.6wt%; Dispersing time of foaming agent was 50 s and foaming temperature was 610 ℃; Cooling time was 7 min. The AFS synthesised with optimal process parameters possessed excellent metallurgical bonding and their thickness, porosity, aperture and superficial layer thickness were 20-35 mm,73-88%,1.5-5mm,and 0.4-1.2mm, respectively.（2） Compression experiments showed that when porosity increased from 73% to 88%, the yield strength of AFS decreased from 12.2 MPa to 5.4 Mpa and the energy absorption decreased from 4.582 MJ/m3 to 3.325 MJ/m3, which indicates that the yield strength and the energy absorption degree is negative correlation of porosity, When aperture increased from 1.5 mm to 4.5 mm, the yield strength of AFS decreased from 9.8 MPa to 2.8 MPa, and energy absorption capacity decreased from 6.961 MJ/m3 to 2.427 MJ/m3; Compared to aluminum foam without surface layer, the yield strength of AFS increased by 87% and energy absorption capacity 82%.（3） Isothermal decomposition and EDS analysis of TiH₂ showed that:The higher temperature of TiH₂ pre-oxidation treated was, the longer time of TiH₂ decomposed and produced H₂ was. TiH₂ pre-treated 6 h under 400 ℃ and then 1 h under 470 ℃ decomposed slowly to release gas within 0-80 s, and the time between 80 s and 120 s was the fastest stage that TiH₂ decomposed to release gas, and the gas had almost been released out when time was 200 s; The reason of retard decomposition of TiH₂ was that pre-oxidation treatment will form an oxide film on the surface of TiH₂.