Time resolved friction during dry sliding of metal on metal

In the present study, plate impact pressure±shear friction experiments are conducted to provide insight into timeresolved dry sliding characteristics of metal on metal at normal pressures of approximately 1.5 GPa, slip speeds up to 60 m/s and interfacial temperatures as high as 8008C. The plate impact friction experiments represent a signi®cant improvement over conventional dynamic friction experiments by allowing control of interfacial tractions with the use of combined pressure±shear loading waves instead of manipulating actuator motion. Also, by measuring the combined normal and transverse motion of the rear surface of the target plate, critical frictional parameters such as the applied normal pressure, the interfacial slip resistance, and the interfacial slip speeds can be interpreted by using the framework of one-dimensional plane wave analysis. The experiments are conducted on a Carpentor Hampden tool-steel (D3)/Ti±6Al±4V tribo-pair. The frictional state at the tribo-pair interface is varied by varying the impact velocity and/or the surface roughness of the impacting surfaces. Moreover, by appropriate selection of ̄yer and target plate thickness the tribo-pair interface is subjected to step changes in normal pressure and step changes in applied shear stress. The results of these experiments provide new insights into the evolution of interfacial sliding resistance with accumulated interfacial slip, and its dependence on surface roughness, slip velocity, normal pressure and interfacial temperature. # 2000 Elsevier Science Ltd. All rights reserved.