Passivation of Laser-Treated Nickel Aluminum Bronze as Measured by Electrochemical Impedance Spectroscopy

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Authors
  1. Klassen, R.D.
  2. Hyatt, C.
  3. Roberge, P.R.
Corporate Authors
Royal Military Coll of Canada, Kingston ONT (CAN) Dept of Chemistry and Chemical Engineering;Defence Research Establishment Atlantic, Dartmouth NS (CAN)
Abstract
Although laser welding and cladding of nickel aluminum bronze (NAB) surfaces involves a fraction of the energy input of conventional welding, a heat affected zone (HAZ) is still formed as well as an as-deposited zone. The main objective of this work was to determine whether the corrosion resistance of the HAZ due to laser treatment was different from the as-deposited zone or a surface without laser treatment. Electrochemical impedance spectroscopy (EIS) was employed to measure the corrosion rates of samples immersed in 3.5% neutral saline. The following specimens of a nickel aluminum bronze (Alloy D) were tested over an immersion time of 50 hours: (i) polished (not laser treated), (ii) laser-treated and polished, (iii) the as-deposited region of laser-treated and polished specimen, (iv) the HAZ region of a laser-treated and polished specimen and (v) laser-treated and unpolished. A pseudo steady-state level of passivation was reached in all the samples within 40 hours. As expected, laser treatment increased the short-term rate of passivation and therefore improves the long-term resistance to corrosion. The HAZ region clearly passivated more slowly than the as-deposited region. The long-term susceptibility of part of the HAZ to corrosion was confirmed with SEM micrographs. TRUNCATED
Keywords
Nickel aluminum bronzes;Laser cladding;Electrochemical impedance spectroscopy
Report Number
DREA-SR-1999-162-PAP-21 — CONTAINED IN CA000150
Date of publication
01 Oct 1999
Number of Pages
10
DSTKIM No
CA000171
CANDIS No
511895
Format(s):
Hardcopy;Document Image stored on Optical Disk

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