Mechanical and wear properties of Mo5Si3-Mo3Si-Al2O3 composites

Abstract Mo 5 Si 3 and Mo 5 Si 3 –Mo 3 Si–Al 2 O 3 composite were synthesized use MoO 3 , Mo, Si and Al as raw materials by mechanically induced self propagating reaction and then consolidated by hot-pressing. The microstructure of the materials was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with X-ray energy dispersive spectroscopy (EDS). The effects of the Al 2 O 3 on the mechanical and tribological properties of Mo 5 Si 3 –Mo 3 Si–Al 2 O 3 composite have been studied. It was found that benefits associated with the addition of the Al 2 O 3 to Mo 5 Si 3 and Mo 3 Si include finer microstructure, higher strength, higher fracture toughness and higher hardness. The dry sliding wear properties of the composite were investigated using against GCr15 bearing steel in ball-on-disk system at room temperature. The results indicated that the friction coefficients and specific wear rates of Mo 5 Si 3 –Mo 3 Si–Al 2 O 3 composite were significantly reduced by the addition of Al 2 O 3 , and its specific wear rates decreased by an order of magnitude compare with the monophase Mo 5 Si 3 . The friction coefficients of test materials decrease with an increasing load. The dominant wear mechanism of the composites was interpreted by several different wear models involving plastic deformation, adhesion, brittle fracture and reaction to form a tribo-oxidation layer.