SYNTHESIS-STRUCTURE-PROPERTY-PERFORMANCE RELATIONSHIPS OF TiN, CrN, AND NANOLAYER (Ti,Cr)N COATINGS DEPOSTIED BY CATHODIC ARC EVAPORATION FOR HARD PARTICLE EROSION RESISTANCE
Open Access
Author:
Gabriel, Brian M.
Graduate Program:
Materials Science and Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
December 19, 2008
Committee Members:
Douglas Edward Wolfe, Thesis Advisor/Co-Advisor Douglas Edward Wolfe, Thesis Advisor/Co-Advisor
Keywords:
cathodic arc erosion titanium nitride chromium nitride hard particle impingement
Abstract:
Hard particle erosion due to sand particles can cause significant damage to metallic turbine engine components. Hard coating systems such as TiN, CrN, and (Ti,Cr)N offer a potential solution. TiN, CrN, and (Ti,Cr)N coatings were deposited with a multi-source cathodic arc system using high purity Ti and Cr cathode targets in a partial N2 atmosphere. The coatings were characterized using X-ray diffraction, scanning electron microscopy, electron probe microanalysis, scanning transmission electron microscopy, and scratch adhesion testing. Erosion testing was performed using an in-house high-velocity erosion rig with glass beads and alumina media. For the TiN coatings, erosion resistance was strongly dependent on the evaporator current and substrate bias; these parameters influenced crystallite size, preferred crystallographic orientation, and residual stress. CrN coatings were determined to have significantly more macroparticles than the TiN coatings deposited under similar conditions. This was primarily attributed to the lower melting point of the solid phases in the Cr-N system versus the Ti-N system. A nanolayered (Ti,Cr)N coating system comprised of alternating TiN and CrN rich layers was created by co-evaporating Ti and Cr cathode targets with a rotating substrate configuration. Erosion resistance increased along with decreasing density of nanolayer interfaces as well as increasing volume percentage of the CrN rich layers with respect to the TiN rich layers. In all three coating systems, macroparticle defect concentrations were not believed to degrade high impact angle erosion performance.
