TIME RESOLVED SLIDING OF METAL-ON-METAL AT NEAR MELT TEMPERATURES

摘要

Plate impact pressure-shear friction experiments have been conducted to study time-resolved frictional characteristics of sliding interfaces under extreme conditions. By utilizing tribo-pair materials comprising hard tool-steel along with low melt point FCC metals such as 7075-T6 aluminum alloys, interfacial normal pressures ranging from 1-2 GPa and slip speeds of approximately 100m/s have been obtained. The resulting relatively large shear tractions (100 to 400 MPa) combined with the high slip speeds generate conditions conducive to interfacial temperatures approaching the near melt regime of the lower melt point metal (aluminum alloy) comprising the tribo-pair. At higher impact speeds transition in interfacial slip occurs from near-melt to the fully melt temperature regime. Under these conditions the inter-facial frictional resistance is expected to approach the shearing resistance of the molten aluminum alloy under high hydrostatic pressures and extremely high shear strain rates. The results of the present study indicate that under the present experimental conditions molten aluminum maintains a shearing resistance as high as ～100 MPa.