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Surface Modification of Alloys for Low-cost Corrosion Protection in Marine Environment: Interim Project Report of Marine Energy Sapling Project

Report

Title: Surface Modification of Alloys for Low-cost Corrosion Protection in Marine Environment: Interim Project Report of Marine Energy Sapling Project
Author:
Niverty, S.; Bonheyo, G.; Rohatgi, A.
Publication Date:
Document Number:
PNNL-35985
Pages:
25
Place Published:
Richland, Washington, USA
Affiliation:
Pacific Northwest National Laboratory (PNNL)
Sponsoring Organization:
US Department of Energy (DOE)
Collection Method:
Lab Data
Operations:
Fouling
Engineering:
Materials
Language:
English

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Citation

Niverty, S.; Bonheyo, G.; Rohatgi, A. (2024). Surface Modification of Alloys for Low-cost Corrosion Protection in Marine Environment: Interim Project Report of Marine Energy Sapling Project (Report No. PNNL-35985). Report by Pacific Northwest National Laboratory (PNNL). Report for US Department of Energy (DOE).
@techreport{Niverty-2024-,
author = {Niverty, S and Bonheyo, G and Rohatgi, A},
title = {Surface Modification of Alloys for Low-cost Corrosion Protection in Marine Environment: Interim Project Report of Marine Energy Sapling Project},
institution = {Pacific Northwest National Laboratory (PNNL)},
year = {2024},
month = {apr},
number = {PNNL-35985},
address = {Richland, Washington, USA},
keywords = {Lab Data, Materials, Fouling},
}
Export Citation to BibTex
TY - RPRT
TI - Surface Modification of Alloys for Low-cost Corrosion Protection in Marine Environment: Interim Project Report of Marine Energy Sapling Project
AU - Niverty, S
AU - Bonheyo, G
AU - Rohatgi, A
AB - This work was undertaken as part of a Sapling project funded by the Marine Energy Program within the DOE’s Water Power Technologies Office. The goal of this work was to explore the role of laser surface processing (LSP) for improving the corrosion and more importantly, the biofouling resistance of Al alloy surfaces. Existing antifouling approaches such as painting/coatings, or using corrosion resistant materials, suffer from durability issues, are expensive, and potentially contain environmentally toxic constituents. LSP offers a swift and effective alternative to protect the material by locally modifying the surface of the material. The efficacy and performance of LSP’d surfaces depends on the alloy system and laser process parameters. The challenge lies in optimizing the laser process parameters to best protect the surfaces of interest from corrosion and biofouling.In this study, LSP was performed using three different laser powers (1.28W, 2.34W, 3.12W) on AA6061 aluminum. Corrosion experiments were performed on the non-LSP and LSP samples by exposing them to natural seawater (in Sequim, WA) and in 3.5 wt.% NaCl solution (in Richland, WA) for durations of 3 and 6 months. Gravimetry, optical and electron microscopy were employed to quantify the changes occurring to the surface and sub-surface regions of the material. Based on these tests, key observations are:LSP AA6061 in seawater showed a complete absence of sub-surface intergranular corrosion. On the other hand, non-LSP AA6061 showed ample evidence of sub-surface intergranular corrosion and corrosion induced grain dissolution.LSP AA6061 (3.12W) tested for 6 months in seawater showed ~40% lower % weight change per unit area due to biofouling, as compared to non-LSP AA6061.These results show that LSP can help reduce susceptibility of Al alloys to biofouling and corrosion in seawater. LSP is also not harmful to local marine life and non-chemical in nature. Further analysis is required to understand the microstructural mechanisms that lead to these improved surface behaviors. As LSP can be applied locally, and in a desired location without affecting the remainder of the material, its applicability at joints and welds of components and structures in marine energy applications should be explored.
CY - Richland, Washington, USA
DA - 2024/04//
PY - 2024
SP - 25
PB - Pacific Northwest National Laboratory (PNNL)
SN - PNNL-35985
LA - English
KW - Lab Data
KW - Materials
KW - Fouling
ER -
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Abstract

This work was undertaken as part of a Sapling project funded by the Marine Energy Program within the DOE’s Water Power Technologies Office. The goal of this work was to explore the role of laser surface processing (LSP) for improving the corrosion and more importantly, the biofouling resistance of Al alloy surfaces. Existing antifouling approaches such as painting/coatings, or using corrosion resistant materials, suffer from durability issues, are expensive, and potentially contain environmentally toxic constituents. LSP offers a swift and effective alternative to protect the material by locally modifying the surface of the material. The efficacy and performance of LSP’d surfaces depends on the alloy system and laser process parameters. The challenge lies in optimizing the laser process parameters to best protect the surfaces of interest from corrosion and biofouling.

In this study, LSP was performed using three different laser powers (1.28W, 2.34W, 3.12W) on AA6061 aluminum. Corrosion experiments were performed on the non-LSP and LSP samples by exposing them to natural seawater (in Sequim, WA) and in 3.5 wt.% NaCl solution (in Richland, WA) for durations of 3 and 6 months. Gravimetry, optical and electron microscopy were employed to quantify the changes occurring to the surface and sub-surface regions of the material. Based on these tests, key observations are:

  • LSP AA6061 in seawater showed a complete absence of sub-surface intergranular corrosion. On the other hand, non-LSP AA6061 showed ample evidence of sub-surface intergranular corrosion and corrosion induced grain dissolution.
  • LSP AA6061 (3.12W) tested for 6 months in seawater showed ~40% lower % weight change per unit area due to biofouling, as compared to non-LSP AA6061.

These results show that LSP can help reduce susceptibility of Al alloys to biofouling and corrosion in seawater. LSP is also not harmful to local marine life and non-chemical in nature. Further analysis is required to understand the microstructural mechanisms that lead to these improved surface behaviors. As LSP can be applied locally, and in a desired location without affecting the remainder of the material, its applicability at joints and welds of components and structures in marine energy applications should be explored.