Residual Stresses in TiN Coatings
	Users and Staff D. Bhat, University of Arkansas Thomas R. Watkins,  Burl Cavin, OR A researcher from the University of Arkansas visted the Residual Stress User Center to characterize the residual stress state of TiN coatings on “Life-Saver”-shaped WC substrates.  The Univ. of Arkansas samples are representative of cutting tools where the relationship of residual stress to the hardness, tribological behavior and response to metal-cutting environments of coatings is critical.  A series of coatings deposited by various methods, such as PVD, CVD, etc, were being investigated.  The stresses in the 2-3 µm thick coating are challenging to characterize.  Measurements found large, compressive equi-biaxial (σ11=σ22) residual stress state of 3 to 10 GPa, which is not uncommon for TiN coatings.  These results are being correlated with the composition (Auger Electron) profiles as a function of depth in order to understand the observed hardness profiles.       Dr. Bhat (right) mounting a sample on the four-axis PTS rotating anode unit.
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