FCP Report No. 144

Structure and Properties of Ion Plated Aluminum Coatings

by

Howard S. Savage
J. M. Rigsbee
Department of Materials Science and Engineering

Abstract

This research investigates the mechanical, microstructural, and chemical properties and their interrelationships with deposition parameters for evaporated and ion plated aluminum coatings on a variety of substrate materials. Ion plating is a plasma assisted physical vapor deposition technique. Substrate materials include: aluminum, copper, Formvar, NaCl, silicon, and titanium. Characterization techniques include: adhesion testing, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDX), X-ray diffraction (XRD), Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS), and surface profilometry. Variations in ion plating process parameters include: applied substrate bias, argon pressure, in-situ sputter cleaning, and discharge current enhancement. In general, it was found that variations in parameters which produced increased ion bombardment of the substrate and growing film and hence, increased energy of deposition promoted increased coating adhesion and a coating structural transition from a zone 1 structure typical of evaporated coatings grown at high pressure and low T/Tmp to a zone 3 structure typical of coatings grown at high T/Tmp. The formation of an extended interfacial region was observed for coatings deposited at high energies.

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