Multi-mode scratch testing - a European standards, measurements and testing study

This paper presents results of the final state of the art of an E.C. sponsored R and D project of reference coatings (i.e.: 3 mu m thick carbon doped chromium) deposited on HSS substrates. Instrumentation upgrade has led to the integration of an interactive video microscope with a 10(6) pixel resolution, as the sole reliable diagnostic tool for coating damage assessment. Optical resolution allows for post-synchronised off-line crack identification. In addition, highly enhanced acoustic emission sensitivity is implemented. This way post-synchronisation, via online triggering of data storage related to specific (cohesive and/or adhesive) failure events, is achieved. A multi-mode operation software menu comprises instrumented depth sensing macro-indentation, as well as fatigue modes like "multipass scratching" in the same track (or in parallel tracks in the scanning mode) both in unidirectional and reciprocating sliding-in addition to standard modes like constant and progressive load operation. These additional operation modes bridge the gap between single cycle, high contact pressure, accelerated testing and more realistic, low cycle, macro-elastic fatigue testing closer to industrial friction and wear situations. Triboscopic presentation of the on-line friction and AE data as a function of sliding distance and cycle number is introduced as a means of user-friendly data analysis and damage mechanism identification. (c) 2005 Published by Elsevier B.V.