EFFECT OF REFRIGERANT GASES ON THE TRIBOLOGICAL BEHAVIOR OF A CrN-SiDLC MULTIFUNCTIONAL COATING APPLIED TO SOFT SUBSTRATE

DLC coatings have been extensively studied and recognized as a promising solution to avoid wear and friction problems. However, the effect of the environment on the tribological behavior is little studied yet. The present study aims to analyze the tribological behavior of DLC coatings in refrigerant gases HFC134a and HC600a used by refrigeration industry, in particular the tribo-chemical reactions. Tests performed in HFC134a atmosphere presented higher friction coefficient and durability than those performed in HC600a refrigerant gas. The differences observed were justified in terms of the tribo-chemical reaction between DLC coating, the counter body and the refrigerant gases. Both results presented traces of Oxygen, but in the tests with HFC134a gas it was observed the presence of Fluorinated compounds on the tribo-layer. In the tests performed in HC600a gas atmosphere it was found only Carbon and Silicon indicating different interactions of the environment.