(Grp+SiCp)/AZ91镁基复合材料的力学及耐磨性能研究

Research on mechanical properties and wear resistance of (Grp+SiCp)/AZ91 magnesium matrix composites after hot extrusion

摘要:

本文采用半固态搅拌技术制备出了5μm10vol%Grp/AZ91、(5μm5vol%Grp+5μm5vol%SiCp)/AZ91和 (5μm5vol%Grp+10μm5vol%SiCp)/AZ91共3种镁基复合材料,并对其在300℃,0.05mm/s的条件下进行了热挤压,研究了SiCp对挤压态复合材料的显微组织、力学性能和耐磨性能的影响规律。研究结果表明,与Grp/AZ91相比,SiCp的引入导致基体晶粒尺寸增大,引起石墨颗粒碎化；随着SiCp尺寸增加,晶粒尺寸增大,石墨碎化现象更为显著。SiCp的加入提高了Grp/AZ91复合材料的抗拉强度、延伸率和硬度,随着SiCp尺寸增加,力学性能进一步提升。SiCp的引入降低了Grp/AZ91复合材料的磨损率,同时摩擦系数上升,随着SiCp尺寸增加,磨损率进一步下降,摩擦系数进一步上升,磨损机制由剥层磨损转变为磨粒磨损。

Abstract:

Stir casting was employed to fabricate three kinds of magnesium matrix composites, which is 5μm10vol%Grp/AZ91、(5μm5vol%Grp+5μm5vol%SiCp)/AZ91 and (5μm5vol%Grp+10μm5vol%SiCp)/AZ91 respectively. Subsequently the composites was subjected to hot extrusion at 300℃ with ram speed of 0.03mm/s. And the effect of SiCp on microstructures、mechanical properties and wear resistance was studied. The results showed that the grain size of composites increase and the phenomenon of fragmentation of graphite among the three composites became more remarkable along with the adding and increasing size of SiCp. Extruded 5μm10vol%Grp/AZ91 composite possesses poor tensile strength、hardness and plasticity which was all improved after mixing 5μm SiCp, and the mechanical properties was further enhanced by increasing the SiCp size from 5μm to 10μm. And the wear rate of 5μm10vol%Grp/AZ91 composite was decreased along with the adding and elevated size of SiCp. On the contrary, the friction coefficient was significantly increased by enlarging the SiCp size. The dominant wear mechanisms of 5μm10vol%Grp/AZ91 composite was delamination wear which totally turn into abrasive wear in 10μmSiCp hybrid reinforced composites by increasing the size of SiCp.