Study On The Properties Of Open-cell Zn-Al Alloy Foams

Metallic foam is regarded as a kind of excellent engineering material with the advantages of both solid metal and foam material,and it has been widely applied in aviation,construction and other fields as structural and functional materials.Zn-Al alloy attracts more and more attentions,it is not only low melting-point,small latent heat but also excellent mechanical properties,Zn-22 Al is a superplastic material with many characteristics,such as high elongation and energy absorption capacity,Zn-27 Al has high strength,and its comprehensive mechanical properties are optimal,so these two materials are of great research value.The above two alloys can be made into open-cell Zn-Al foams with spheroidal pore to study its mechanical properties and corrosion resistance properties,which is helpful to expand the application scope of Zn-Al alloys foams in industrial production.Zn-Al alloy foam is easily corroded,which seriously affects its use value,however the corrosion resistance property of Zn-Al foams can be effectively improved by electroless plating on the surface of the foams to obtain a uniform layer of Ni-P coating.However,there are little studies on the open-cell Zn-Al alloy foams with spheroidal pore.In particular,the reports of electroless nickel plating on the surface of the ZnAl alloy foams are extremely limited.Therefore,studying the mechanical and corrosion properties of Zn-Al foams is of great significance for promoting the application in production.In the present study,spheroidal CaCl2 grains are chosen as raw material for the space holder,and Zn-Al alloy foams with spheroidal pore are made by infiltration casting,and studied the quasi-static compressive properties at room temperature,elevated temperatures and corrosion environment.In addition,the effects of electroless plating of Ni-P coating on the mechanical properties and corrosion resistance properties of Zn-27 Al foams are investigated.Experimental results show:(1)Porosity and temperature are the main factors that influence the compressive mechanical properties of open-cell Zn-22 Al foams with spheroidal pore.The increase of porosity and temperature will reduce the compressive yield strength and energy absorption capacity of Zn-22 Al foams,but its energy absorption efficiency is almost not affected by these two factors.The failure forms of cell edge of open-cell Zn-22 Al foams are transformed from fracture to bending with the increase of temperature.(2)The compressive mechanical properties of the open-cell Zn-22 Al foams are more sensitive to the corrosion environment.The surface of Zn-22 Al foams occurred serious corrosion in Na Cl solution,which affects the compressive yield strength,energy absorption capacity and energy absorption efficiency of Zn-22 Al foams.(3)At room temperature,the compressive yield strength and energy absorption ability of open-cell Zn-27 Al foams will increase with the decrease of porosity,but the energy absorption efficiency will not change significantly.As the temperature increases,the compressive mechanical properties of Zn-27 Al foams show a certain degree of attenuation.When the experiment temperature increases from room temperature to 200 ℃,the fracture forms of Zn-27 Al foams are changed from brittle to bending or buckling.(4)Corrosion reduces mechanical properties of the Zn-27 Al foams.The surface of foams occurred pitting corrosion,and the compressive yield strength,energy absorption capacity and energy absorption efficiency of Zn-27 Al foams decrease correspondingly.(5)The electroless Ni-P coating on the surface of Zn-27 Al foams has better quality,which significantly increases the compressive yield strength,energy absorption capacity,and improves the corrosion resistance property of Zn-27 Al foams.For electrochemical experiment,the corrosion potential of foam by electroless plating is obviously improved.For immersion corrosion experiment,the surface of electroless coating is corroded slightly,and the compressive mechanical properties of the foam decrease slightly.