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Compression and Damping Properties of Glass Cenospheres/Al Syntactic Foams

Author: SuHang
Tutor: ZhangQiang
School: Harbin Institute of Technology
Course: Materials Engineering
Keywords: porous materials microstructure compression energy absorptionperformance low frequency damping properties
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Type: Master's thesis
Year: 2013
Downloads: 41
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Abstract


In this paper, pressure casting is used to prepare for the glass cenosphere/Alsyntactic foams with the volume fraction of glass cenosphere63%~67%. We useX-ray component analysis machine(XRD), scanning electron microscopy (SEM),electron universal testing machine, Gleeble1500D thermal-mechanical simulationtesting machine, split Hopkinson pressure bar (SHPB), dynamic mechanicalanalyzer (DMA) and other analytical tools to research the microstructure of porousmaterials, different strain rates compression behavior and relative energy absorptionproperties, low frequency damping properties, then figure out the relationshipbetween microstructure and relative properties.We select3M Company produces hollow glass cenospheres named as S38, K46respectively. Characterize the original glass cenospheres (average particle size40μm) properties and found that the main components of glass cenospheres are SiO2and CaO, density of0.38g/cm~3and0.46g/cm~3, porosity of85.1%and81.9%, glasscennospheres ratio of wall thickness of1.0μm and1.3μm respectively. XRD resultsshow that the original glass cenospheres are amorphous. SEM results show that thegeometric shape to the glass cenospheres are round, with smooth surface, no cracksor holes and other defects can be found on that. The density of K46/Al and S38/Alsyntactic foams prepared respectively are1.1g/cm~3and1.3g/cm~3.In the quasi-static compression, glass cenospheres/Al porous materials’compression strength increases with enhance of hollow glass cenospheres’ wallthickness and the strength of the matrix aluminum alloys. The quasi-staticcompression strengths of S38/1100and K46/1100porous materials are76MPa and86MPa, the energy absorption capacities are33MJ/m~3(=49%)and35MJ/m~3(=53%), while the S38/6061and K46/6061porous materials’ compressivestrengths were106MPa and121MPa, energy absorption capacity of38MJ/m~3(=42%) and43MJ/m~3(=43%); after peak aging heat treatment technology,the S38/6061and K46/6061porous materials’ compressive strength increased to125MPa and145MPa, energy absorption capacity increased to about53MJ/m~3(=47%)and55MJ/m~3(=45%) respectively.In the high strain rate dynamic compression, glass/Al syntactic foams’compressive strength were improved to some extent compared to the quasi-staticcompress, porous materials exhibit strain rate sensitivity. Strain rate sensitivity ratesdetermine by primarily the matrix alloy,1100aluminum strain rate sensitivity ishigher than6061aluminum alloy and relative porous materials show the same trends. The strain rate sensitivity of syntactic foams keep stable with the increase ofthe strain rate.Using dynamic mechanical thermal analyzer (DMA) researches the glasscenospheres/Al syntactic foams’ low frequency damping properties, explore theinfluence of the strain, temperature and frequency trends to the porous materials’damping properties; the results show that the porous materials’ damping valueincrease with the increase of strain and its value peaks to0.14; porous materials’damping values increases with temperature, which peaks to0.15relatively, and theporous materials’ damping value decreases as the frequency increases. The porousmaterials after the heat treatment technology was significantly lower for thedamping values.The low-frequency damping mechanism of porous materials of can be obtainedby relative analysis, the porous materials’ damping mechanism under strain effect isthe dislocation damping mechanism and interface damping mechanism play asignificant role for the damping mechanism under the effect of temperature. Afterheat treatment technology, the porous materials’ damping values is lower becausethe dislocation strong pinning point density increases and the bonding strength ofthe composites increased.

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