COMPARATIVE TRIBOLOGICAL STUDY OF CHROMIUM COATINGS WITH DIFFERENT SPECIFIC HARDNESS

The wear resistance in dry friction of two electrolytic and two PVD hard chromium coatings deposited on construction steel substrates is studied by means of standard pin-on-disc and unidirectional multipass scratch testing. For both of these friction modes, low cycle-high load operation with cemented carbide pins leads to essentially coating-hardness-controlled, abrasive wear. For the well adhering commercial coatings, critical loads (both for through-thickness cracking and for spalling failure) assessed by standard scratch testing are inadequate for quality ranking with respect to wear resistance. Steady state friction corresponds to a stabilized third body, essentially composed of chromium oxide.