Science Success Story

Supercomputer Models Describe Chloride's Role in Corrosion

Comet, Stampede2 serve as testbeds for simulations of how chloride degrades iron

By Kimberly Mann Bruch, SDSC Communications

Surface structural changes to iron passive films caused by the adsorption of OH and/or Cl. (a) Fe(OH)3, (b) Fe(OH)2Cl, (c) Fe(OH)Cl2, d FeCl3. The location of the edge Fe atom prior to the adsorption is shown with an orange dashed line. Atoms types indicated by white (H), royal blue (Cl), large pink (Fe) and small red (O) spheres. Credit: Oregon State University College of Engineering.

Researchers have been studying chloride's corrosive effects on various materials for decades. Thanks to high performance computers at the San Diego Supercomputer Center (SDSC) and the Texas Advanced Computing Center (TACC), detailed models have now been simulated to provide new insight on how chloride leads to corrosion.

Conducted by a team from Oregon State University's (OSU) College of Engineering, a study discussing this newfound information was published in Materials Degradation, which is a Nature partner journal.

"Steels are the most widely used structural metals in the world and their corrosion has severe economic, environmental, and social implications," said study co-author Burkan Isgor, an OSU civil and construction engineering professor. "Understanding the process of how protective passive films break down helps us custom design effective alloys and corrosion inhibitors that can increase the service life of structures that are exposed to chloride attacks."

Isgor worked closely with OSU School of Engineering colleague Líney Árnadóttir as well as graduate students Hossein DorMohammadi and Qin Pang on conducting the study. As a chemical engineering associate professor, Árnadóttir said her work often uses computational methods to study chemical processes on surfaces with applications in materials degradation.

"We frequently collaborate with experimental groups and use experimental surface science tools to complement our computational methods," she said. "For this study we relied on allocations from the National Science Foundation's (NSF) Extreme Science and Engineering Discovery Environment (XSEDE) so that we could use Comet and Stampede2 to combine different computational analyses and experiments applying fundamental physics and chemistry approaches to an applied problem with potentially great societal impact." 

The OSU team used a method called density functional theory to investigate the structural, magnetic, and electronic properties of the molecules involved. Their XSEDE-allocated simulations were corroborated by simulations using reactive molecular dynamics (Reax-FF MD), which allowed them to accurately model the chemistry-based nanoscale processes that lead to chloride-induced breakdown of iron passive films.  

"Modeling degradation of oxide films in complex environments is computationally very expensive, and can be impractical even on a small local cluster," said Isgor. "Not only do Comet and Stampede2 make it possible to work on more complex, more realistic and industrially relevant problems, but these high performance computers do so within a reasonable timeframe moving knowledge forward."

This work was supported by the NSF, CMMI (1435417). Part of the calculations used the XSEDE (TG-ENG170002, TG-DMR160093), which is supported by NSF (ACI-1053575).

At a Glance

  • Oregon State University School of Engineering researchers recently utilized XSEDE allocations for new insight regarding the degradation of oxide films.
  • Comet and Stampede2 were used to create simulations to model the nanoscale processes that lead to chloride-induced breakdown of iron passive films. 
  • The research has been published in a Nature partner journal and explains how protective passive films can help the design of effective alloys and corrosion inhibitors to increase the service life of structures.