Electrochemical Behavior of Ion-Plated TiN and Cu-Cr Coatings
Abstract
The electrochemical (corrosion) behaviors of titanium nitride (TiN) and metastable copper-chromium (Cu-Cr) alloy coatings grown on glass, aluminum, and copper substrates using a plasma-assisted physical vapor deposition (ion- plating) technique were investigated. Various polarization techniques were used for corrosion tests in oxygen-saturated and deaerated 5 percent Na2SO4 and 3.5 percent NaCl solutions of two different acidities (pH--6 and 3). The structure, chemistry, and morphology of the coating surfaces before and after corrosion testing were analyzed with scanning electron microscope, x-ray diffraction, Auger, and x-ray photoelectron spectroscopic techniques. Titanium nitride coatings are chemically passive but do not provide effective protection for metallic substrates, under conditions involving pitting corrosion, due to the presence of pinholes in the as-deposited TiN coatings. The inherent properties of TiN do appear suitable for electromagnetic interference/electromagnetic pulse shield applications provided the problem of film defects (porosity, pinholes) can be solved or if the substrate type and corrosion conditions are such that passivation of the substrate surface occurs. Cu-Cr alloy coatings show a general corrosion behavior, with corrosion rates of a few mils per year at the free corrosion potential, which is unsatisfactory for a thin film coating application. Electromagnetic shielding, Cu-Cr Coatings, Coatings, Corrosion resistance, TiN Coatings.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1993
- Accession Number
- ADA273411
Entities
People
- J. M. Rigsbee
- M. Metzger
- Y. W. Lee
Organizations
- Construction Engineering Research Laboratory