Wear at high sliding speeds and high contact pressures

• A unique high speed electromagnetic tribometer has been implemented.
• Wear of an Al alloy at extreme sliding speeds and pressures has been conducted.
• Systematically studied melt lubrication wear in Al alloys.
• The conditions for transition to melt lubrication wear have been identified.
• Melt lubrication wear of the Al alloy is viscous and turbulent in nature.

Metal on metal wear at high sliding speeds and high contact pressures results in the melting of one or both of the sliding solid bodies due to heat generated at the contact interface. Understanding the influence of sliding speeds and contact pressures on normalized wear rates is important in developing predictive models for designing more efficient and effective engineering system components. Typical engineering applications subjected to extreme sliding conditions include ultrahigh speed machining, rocket sleds, large caliber cannon, and electromagnetic launchers. Sliding speeds on the order of 1000 m/s and contact pressures in excess of 100 MPa are common in these applications and difficult to replicate in a laboratory environment. A unique electromagnetic tribometer based on a minor caliber electromagnetic launcher has been designed and implemented to characterize wear deposition of a 6061-T6 aluminum pin (slider) on a UNS C11000-H2 copper flat (guider) at sliding speeds from 0 to 1200 m/s and contact pressures from 100 to 225 MPa. Optical microscopy and 3D profilometry were used to investigate and quantify slider wear. Three distinct wear regions were observed. Test results provided evidence that the aluminum slider contact interface was molten and experimental wear data showed a dependence on both pressure and velocity. Comparisons between melt lubrication theory and experimental data provide insight into the nature of the contact interface under the sliding conditions tested.