Nanotribology studies of Cr, Cr2N and CrN thin films using constant and ramped load nanoscratch techniques

The nanotribological behavior of DC magnetron sputtered Cr, Cr2N and CrN thin films has been studied using nanoscratch techniques. Constant and ramped load (5 mN) scratches were made using a Nano Indenter II system on 500-nm-thick Cr, Cr2N and CrN thin films. Ramped-load scratch studies have been carried out on 10-nm-thick Cr, Cr2N and CrN. Wear tracks were imaged by atomic force microscopy. The dependence of the displacement, residual wear depth, percent elastic recovery, and friction coefficient on load is compared in constant load and ramped load tests. Under the same (maximum) load, constant load tests exhibit higher displacements, residual depths and friction coefficients, but lower percent elastic recoveries. The chromium nitride films (Cr2N and CrN) show less permanent damage, lower coefficients of friction and higher percent elastic recovery than pure chromium under the same (maximum) load. However, the adhesive strength of Cr2N needs to be improved.