AVS 47th International Symposium
    Surface Engineering Monday Sessions
       Session SE-MoA

Paper SE-MoA6
Tribological Performance and Initial Finite Element Modeling of Reactively Sputtered Single and Multi-layer Chromium Nitride Thin Films

Monday, October 2, 2000, 3:40 pm, Room 201

Session: Coatings for Extreme Environments: Wear Resistant, Lubricious, Anti-corrosive, High Temperature Coatings
Presenter: S.L. Rohde, University of Nebraska
Authors: S.L. Rohde, University of Nebraska
L. Olson, University of Nebraska
S.M. Aouadi, University of Nebraska
D.M. Mihut, Multi-Arc Scientific Coatings
B. Neville, Iowa State University
D.M. Hornyak, University of Nebraska
Correspondent: Click to Email
Tribological properties of Cr-N based single- and multi-layer thin films are compared with FEA modeled stress fields under similar loading, to evaluate the feasibility of "building-in" load support, with alternating hard/soft film layers to optimize performance on both traditional tool steels and more compliant substrates. The first phase involved the deposition and evaluation of coatings on substrates of both hardened A2 tool steel and 2024-alloy aluminum. Next, the wear behavior was assessed using pin-on-disk (PoD) tests, performed unlubricated at 40 to 50% humidity using alumina and/or tungsten carbide 'pins'. The wear was reduced in most cases, with the multi-layered structures performing best on all substrate materials. PoD tests on the A2 tool steel substrates, favored the hardest thin film structures; however, these same films did not perform as well on the more compliant Al-substrates. For the Al-substrates, neither the stiffest nor the most compliant films excelled, instead multi-layer films with alternating hard/soft structures designed to provide a more graded compliance from the substrate up to the rigid top layer yielded the best results. In this case, wear rates were reduced by as much as much as three orders of magnitudes over uncoated 2024 Al. In the final stage, finite element modeling studies have been initiated to try to understand the behavior of these multilayered coating/substrate combinations under specific loading conditions. First generation models are matched to their respective wear systems and the results compared. These models will then be used to guide the development of second generation coatings, that will be used to verify and improve the efficacy of the models. The goal of the modeling program is thus to facilitate specification and optimization of application specific coating structures into the original component designs.