Research On Properties Of Open-cell Magnesium Foams With Spherical Pore

As a new engineering material,the magnesium foam shows excellent properties,it not only can be used as functional materials,also can be used as structural materials.The magnesium foams has vastly potential application in the fields of aerospace,automobile,transport.etc,where lightweight,high sound absorption and high energy absorption are important.In previous studies,the cell shape of the magnesium foam is polygonal,which leads to the poor repeatability of properties,therefore,it is necessary to develop magnesium foam with regular shape.Beyond that,the electrochemical corrosion is easily occurred on the surface of the magnesium foam,for its low self-corrosion potential,this also limit the development of the magnesium foam.In order to solve above problems,this paper aims at developing high performance magnesium foams,the pure magnesium was used as matrix material,the spherical particles of CaCl₂ were used to fabricate preforms,the open-cell magnesium foam with spherical pore was successfully fabricated by infiltration casting process under Argon gas atmosphere.On base of that,the surface of the magnesium foam was treated by the micro-arc oxidation（MAO）and the electroless plating,differently.The influencing factors and the influencing laws on the compressive properties and the sound absorption properties of the open-cell magnesium foam with spherical pore were studied systematically.The effects of the MAO treatment and the electroless plating treatment on the corrosion resistance and compressive properties of the open-cell magnesium foam with spherical pore were investigated,andthe strengthening mechanism was revealed.The research results prove that:1.The compressive properties of open cell magnesium foams with spherical pores are affected by pore structure characteristic parameters and compression temperature.The compressive stress and energy absorption capacity are decreased with the increasing of the porosity;however,the porosity has no regular affection on energy absorption efficiency.When the porosity of open-cell magnesium foams with spherical pore increases from 60%to 70%,the compressive stress decreases by27.7MPa,and the energy absorption capacity decreases by 6.4 MJ/m³（the strain is at70%）.Increasing the compression temperature,the compressive stress and the energy absorption performance of open-cell magnesium foams with spherical pore was reduced,but the pore sizes have no effect on them.The compressive stress decreases by 14.1MPa,and the energy absorption capacity decreases by 3.8 MJ/m³,When the compression temperature rises from room temperature to 200℃.2.The porosity,the thickness and the cavity could give a great influence on the sound absorption properties of the open-cell magnesium foam with spherical pore.Increasing the thickness of the specimen in a certain range,the sound absorption properties of the open-cell magnesium foam with spherical pore could be significantly improved;increasing the porosity shows the same result.When the porosity of open-cell magnesium foams with spherical pore increases from 67%to 79%,the absorption coefficient of the first wave peak increases from 0.67 to 0.78.The sound absorption performance of the open-cell magnesium foam with spherical pore in1000Hz-2500Hz region could be improved by giving a cavity.When the thickness increases from 15 mm to 26 mm,the sound absorption coefficient corresponding to the first wave crest increases by 26.4%,and the corresponding frequency of the first wave peak moves 1100Hz to the lower frequency region.3.The compression strength and the corrosion resistance of the open-cell magnesium foam with spherical pore could be improved by the electroless plating treatment.Comparing with the untreated open-cell magnesium foam with spherical pore,a coating of Ni-P help the open-cell magnesium foam with spherical pore obtains the bigger compression strength and energy absorption efficiency,the better energy absorption property and the superior corrosion resistance property.Compared with open-cell magnesium foams with spherical pore without electroless plating,the corrosion potential was increased by 0.5V_SCE,the compressive stress was increased by21.8MPa,and the energy absorption capacity was increased by 2.7 MJ/m³（when the strain was at 70%）.4.Comparing with the untreated open-cell magnesium foam with spherical pore,the magnesium foam with MAO treatment shows the bigger compression strength,the better energy absorption property and the superior corrosion resistance property.The compressive stress was increased by 43.8MPa,and the energy absorption capacity was increased by 6.4 MJ/m³when the strain was at 70%),and the corrosion potential was increased by 0.14V_SCE.