AVS 53rd International Symposium
    Advanced Surface Engineering Thursday Sessions
       Session SE-ThA

Paper SE-ThA7
Magnetron Sputtered Nanolaminate Coatings for Debonding of Segmented Structures

Thursday, November 16, 2006, 4:00 pm, Room 2007

Session: Hard and Nanocomposite Coatings: Synthesis, Structure, and Properties
Presenter: J.D. Demaree, US Army Research Laboratory
Authors: J.D. Demaree, US Army Research Laboratory
J.K. Hirvonen, US Army Research Laboratory
M.P. Blickley, The Pennsylvania State University
N.A. Soroka, United States Military Academy
P.G. Dehmer, US Army Research Laboratory
M.A. Minnicino, US Army Research Laboratory
Correspondent: Click to Email
Reactive coatings consisting of repeated bilayers of aluminum and nickel/vanadium capable of self-propagating reactions were deposited onto carbon composite and steel coupons using magnetron sputtering. Such sacrificial coatings, when embedded in an adhesive joint, can provide reliable on-demand debonding of segmented structures when ignited. Adhesion of the metallic nanocomposite coating to carbon composite substrates was enhanced by in-vacuum plasma treatments. The energy required to initiate the self-propagating intermetallic reaction and the propagation velocity of that reaction was measured before and after low temperature annealing, using a spark gap and high speed video photography. Rutherford backscattering spectrometry (RBS) was used to calibrate the deposition process and to characterize the interfacial interdiffusion induced by annealing. Increases in required initiation energy and decreases in propagation velocity were observed with increased anneal times and temperatures, in agreement with the RBS results and existing literature discussion of reaction mechanisms that show sensitivity of these to interface reactions. Initiation sensitivity and propagation velocity were both impacted by varying the stoichiometric ratio of Al to Ni/V, and the propagation rate was also affected by the nature of the substrate. These results allow for the optimization of both reliable initiation and long term, low temperature storage stability of said reactive coatings as required for Army applications. Scale-up demonstration of this process has begun, which will use a dual-source magnetron sputter system with a computerized sample manipulator, and will be capable of coating structural segments of carbon composite or steel up to 20 inches long. Once the adhesion, reactivity, and durability of these reactive coatings has been demonstrated on a component scale, such coatings are envisaged to become useful debonding agents in a number of future Army systems.