Masters Theses

Keywords and Phrases

Chromate Conversion Coating; Corrosion; Electrochemistry; Zinc Nickel; Zirconium

Abstract

“Performance requirements for Department of Defense (DoD) electrical components include corrosion and electrical contact resistance. Historically, electroplated cadmium with a chromate conversion coating (CrCC) has been used to meet corrosion and contact resistance standards. However, replacements are needed for these materials because they are toxic and carcinogenic. Electroplated γ-ZnNi has been identified as an acceptable alternative to Cd. This study evaluated commercially available Zr-based thin films and sealers as passivations for potential replacement of CrCCs. Ten different passivations were tested and compared with bare γ-ZnNi. X-Bond and Zircobond passivations were found to provide some improvement to the bare ZnNi corrosion performance, but none of the evaluated coatings met the requirements for DoD electrical connectors. Bare ZnNi, X-Bond 3000, and Chemseal 59 were able to meet the electrical contact resistance requirement of < 5 mΩ/in2 before salt spray exposure, but none of the samples were able to meet the post salt spray exposure contact resistant requirement of < 10 mΩ/in2. The corrosion performance of the X-Bond coatings was more heavily influenced by surface preparation than coating chemistry variations, with improvement observed upon using an alkaline cleaner. On the other hand, Zircobond 4200 coatings were negatively influenced by an alkaline cleaner and also a deoxidizer but saw some improvement with the use of Zircoseal on top of the standard coating. Chemseal 59 provided improvement when directly applied to the bare γ-ZnNi but degraded corrosion performance when applied to the Zircobond 4200. Overall, the X-Bond coatings showed the most promise having the least corrosion product and contact resistance”--Abstract, page iv.

Advisor(s)

O'Keefe, Matthew
Fahrenholtz, William

Committee Member(s)

Schlesinger, Mark E.

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Metallurgical Engineering

Comments

The author is thankful to PPG for providing the project and funding on which her thesis is based.

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2018

Journal article titles appearing in thesis/dissertation

  • Evaluation of zirconium-based passivations as a sustainable alternative to chromate conversion coatings: X-bond
  • Evaluation of zirconium-based passivations as a sustainable alternative to chromate conversion coatings: Zircobond

Pagination

xii, 77 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2018 Madison Morgan Reed, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Thesis Number

T 11813

Included in

Metallurgy Commons

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