Fluidity and Mechanical Properties of Open Cell AZ31 Mg Alloy Foam

Abstract

Abstract 발포금속은 초경량 재료로서 폐기공과 개기공의 두 가지 형태의 구조를 지니고 있으며 폐기공은 내충격성, 흡음성, 단열성의 기능을 지니고 있고, 개기공은 필터, 생체지지대, 촉매재, 열방출재 등으로 사용되고 있다. 개기공발포재는 삼차원구조모양으로 프리커서를 이용한 압력정밀주조나 기공입자용출법으로 제조하고 있으나 기공의 크기나 셀의 형상, 두께 등을 조절하기에 어려움이 있다. 이를 해결하기 위하여 환경친화적인 펄라이트를 사용하여 목적하는 크기의 그래뉼을 제조한 후, 용융마그네슘합금을 감압주조법으로 주조하여 그래뉼의 크기로 기공율을 조절하고, 주형의 온도와 압력에 따른 유동의 길이를 측정하였다. 그래뉼 직경이 2.3 mm ∅ 일때에 주형의 온도300 o C 이상, 압력이 5000 Pa 이상에서 유동길이6.5 cm이상을 얻었다.Key words: Open-cell foam, Metal foam, Mg alloy, Gravity casting method, Infiltration, Fluidity.(Received March 23, 2012 ; Accepted June 22, 2012) 1. Introduction Metal foam is revolutionary materials that exhibitdifferent attractive characteristics when compared to theirsolid material counterparts [1]. The pores can be sealed(closed-cell foam), or they can form an interconnectednetwork (open-cell foam). Open-cell metal foam is a newclass of materials with low densities and novel physical,mechanical, thermal, electrical, and acoustic properties[2,3]. They offer potential for thermal management, catalystsupport, filtration, steam generation, energy absorption,acoustic absorption, and filters. Al and Al alloy foams havebeen developed successfully and have been employed inthe new generation of crash boxes. Mg and Mg alloy foamsare denitely expected to be particularly advantageous due tolower densities of their metal matrix, which are approximatelytwo thirds that of Al and good mechanical properties [4,5].Many methods for their manufacture, characterization andapplication are being developed [6,7]. In this research, weused investment casting method. It was simple and low costto cast by vacuum pump. A. Jinnapat and A. Kennedy studied on open cell Al foamsmade by infiltration molten al into porous salt [8]. M. Grohnand C. Hintz. investigated determination of parameters ofinfiltrated metallic foam composites. The open cell structurereticulated polyurethane foams were used [9]. I. N. Orbulov,A. Nemeth and J. Dobranszky carried out composite produc-tion made by pressure infiltration. Open cell foams, syntacticfoams and carbon fiber reinforced metal matrix compositeswere produced by pressure infiltration method [10]. Fluidity isan important factor for the successful production of castings,and yet the study on the fluidity of open cell AZ31 Mg alloyfoam is empty in the world [11]. So in the present work, experiments were performed in orderto determine the importance of parameters on fluidity of opencell AZ31 alloy metal foam. The inuence of characteristic wasinvestigated along with the inuence of vacuum assistance andthe preheat temperatures of mould. The mechanical propertiesand energy absorption were investigated and discussed.