Multilayer Erosion Resistant Coatings for the Protection of Aerospace Components

Open Access
Author:
Borawski, Brian
Graduate Program:
Engineering Science and Mechanics
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
June 23, 2011
Committee Members:
  • Judith Todd, Committee Chair
  • Douglas Edward Wolfe, Committee Chair
  • Jogender Singh, Committee Member
  • Albert Eliot Segall, Committee Member
Keywords:
  • impact
  • coating
  • thin film
  • fracture
  • mechanics
  • ceramics
  • erosion
  • physical vapor deposition
  • titanium nitride
Abstract:
Application of a monolithic layer of titanium nitride (TiN) has been found to increase the erosion resistance of engine compressor components such as turbine blades. However, there is very limited public domain research on the erosion resistance conveyed by multilayer hard coatings. In addition, data from multilayer coating studies may present seemingly contradictory results due to the wide variation in coating systems and coating architectures investigated. This thesis presents a systematic study of multilayer coatings based on TiN/Ti and TiN/X, where X = Zr, Hf, or Nb, in order to determine the effect of multilayer coating design and interlayer materials on the hard particle erosion resistance of these coating systems. Multilayer coatings were eroded using glass beads, quartz and alumina media, with particle velocities ranging from 75 to 180 m/s. Erosion performance was found to depend strongly on the TiN/Ti coating multilayer design architecture and the erosion conditions. Coatings with two layers, one of TiN, the other a thin titanium bond layer, gave optimal erosion performance against the alumina erodent, whereas coatings with 32 layers (16 each of TiN and Ti) with a high volume fraction of titanium, offered the best erosion performance against the glass bead erodent. TiN-based coatings with interlayers of Ti, Zr, Hf, and Nb were compared to determine the effect of interlayer material on erosion performance. High values of Vickers microhardness were found to correlate with poor erosion performance. The TiN/Zr multilayer coatings exhibited the worst durability for all erosion conditions, followed by TiN/Hf. The TiN/Nb multilayer coatings provided the best durability for quartz and glass bead erodents. Although TiN/Ti coatings showed better durability than TiN/Nb against alumina particles, this discrepancy was attributed to the thinner than anticipated total thickness of the TiN/Nb coatings.