Sliding wear of cadmium against alumina

As cast cadmium rods were slid against alumina at a load of 50 N and slidin g speeds from 0.1 ms(-1) to 4 ms(-1). The wear characteristics of cadmium w ere related to its strain rate response under uniaxial compression between strain rates of 0.001 s(-1) to 100 s(-1) and temperatures in the range of 3 23 K to 573 K. In uniaxial compression, cadmium undergoes adiabatic shear b anding at strain rates > 10 s(-1) and temperature up to 423 K. The intensit y of this adiabatic shear banding reduces as the temperature is increased o r the strain rate is reduced. This adiabatic shear banding is the only majo r microstructural response, in the present test region, that promotes crack ing. At temperatures greater than 473 K the flow becomes homogeneous and no adiabatic shear banding is observed. The strain rates and temperatures exi sting during sliding are estimated using a simple non-iterative procedure a nd superimposed on the strain rate response map. At sliding speeds < 1.0 ms (-1) the near surface regions are likely to undergo adiabatic shear banding induced cracking. As the velocity of sliding increases the subsurface temp erature increases making the regions close to the surface move towards regi ons of lower adiabatic shear banding intensity and finally to regions of ho mogeneous flow. It is seen that wear rates when the near surface strain rat e response is expected to be adiabatic shear banding, which promotes cracki ng, is higher than when the near surface regions are in the homogeneous flo w region. This indicates that when the strain rate response of a material p romotes cracking at near surface regions the wear rates are higher. Thus, i t can be said that the strain rate response of a material plays an importan t role in deciding the wear mechanism and wear rate of a material. (C) 1999 Published by Elsevier Science S.A. All rights reserved.