| Popis: |
The effects of applied load, sliding speed & temperature on the wear behavior of pure M50 alloy steel (M sample) and M50 reinforced with 10 wt.% Al2O3 (MA sample) & M50 hybrid reinforced with Al2O3 and graphene (MAG sample) were studied. The powders were mechanically mixed and sintered by spark plasma sintering (SPS) technique under Argon atmosphere at 1000 °C for 5 min under 35 MPa pressure. The sample surfaces were mechanically prepared to study the wear & friction behaviors via applying mechanical polishing using 0.05 μm diamond pastes and 1200 grit emery papers to enhance the surface roughness. The phase structure and microstructure were estimated using XRD, Electron Probe Micro-Analysis (EPMA, JAX-8230) and Energy Dispersive Spectroscopy (EDS, GENESIS 7000). The hardness and density of all samples were investigated according to HVS-1000 Vickers' hardness test and Archimedes’ principles, respectively. Friction and wear tests were carried on a high-temperature pin-on-disk tribometer (HT-1000). The investigated samples were cut into disk-shaped specimens with 8 mm thickness and 25 mm diameter. Then, the prepared specimens were sliding against silicon nitride (Si3N4) balls. The samples were exposed to four different loads (2, 5, 8, and 11 N). Also, four different sliding speeds (0.18, 0.36, 0.54, and 0.72 m/s) was performed at room temperature (RT). Another group of samples were tested at constant applied load of 11 N and constant sliding speed of 0.72 m/s for four different temperatures (RT, 150, 300, and 450 °C). MAG exhibited enhanced tribological properties compared with M and MA thanks to the synergic action between Al2O3 and graphene as well as the creation of iron oxides, aluminum dioxide, chromium oxide, molybdate, and silicon oxide on the formed tribo-film. |
