The variation of the friction coefficient versus time in porous Cr3C2
and Cr3C2/epoxy composite is shown in Fig. 8. It is observed that the friction
coefficient of porous Cr3C2 is lower than that of Cr3C2/epoxy composite.
Higher friction coefficient value in Cr3C2/epoxy composite is
due to the stronger adhesion between the composite material and counter
face.When the pin rubs against the epoxy during pin-on-disc test in
dry air condition, the adhesion of epoxy to the pin will occur to raise the
friction, which consequently increases the friction coefficient. On the