Objective
The goals of this project are to characterize biological defacement of military coatings applied to Department of Defense (DoD) Army and Marine Corps tactical vehicles (land, amphibious and air) by establishing a model laboratory biofilm reactor system to improve replication of methods used to assess coating defects related to biological deterioration that will enable improved prediction and understanding of bio-induced coating degradation. Biological (and related chemical) defacement is a term within the coating industry used to describe visible natural biological activity (e.g. mold and mildew) on a coated surface leading to undesirable appearance and/or coating performance. The current standard test methods have proved to be inadequate at providing reliable predictions of coating performance due to biological defacement.
Three coatings application use cases that are known to be susceptible to biological defacement will be assessed: ground and amphibious vehicle interior topcoat (MIL-PRF-22750), ground and amphibious vehicle exterior topcoat (MILDTL-53039), and air vehicle interior topcoat (MIL-PRF-85285). Studies will be completed in three steps: 1) Fundamental biological characterization of multi-domain biofilm (MDB) (Bacteria and Eukarya) collected from DoD assets along with the environmental and nutritional conditions of the three coating application use cases by leveraging Montana State University (MSU) Center for Biofilm Engineering expertise on MDB, 2) Develop a laboratory screening method which reproducibly assesses MDB defacement using a modified agar plate reactor model and a more relevant biofilm reactor model and assess microbial induced changes to the coatings’ mechanical, chemical, and electrochemical (corrosion protective) properties to assess coating deterioration, and 3) Assess cleaning procedures relevant to each coating application use case for the ability to remediate MDB defacement as well as the impact cleaning has on the kinetics of microbial regrowth, coating deterioration, and durability of military coatings. Research will be performed by a cross-disciplinary, multi-organizational team including several experts at MSU in collaboration with The Sherwin-Williams Company and the Naval Surface Warfare Center, Carderock Division.
Technical Approach
The approach described in the objectives section will i) advance understanding of present and active microorganisms on DoD tactical vehicle surfaces, ii) improve kinetic assessment of coating deterioration by MDB, and iii) determine how mechanical and chemical cleaning impact the longevity of DoD coating efficacy. The project will fill direct knowledge gaps on coatings currently in use on DoD assets. The findings have high potential to inform the DoD industrial complex on the biological impacts on coating performance, provide insights into current cleaning practices, and enable strategies to optimize performance of surfaces all ultimately helping to develop more effective coatings for future applications.
Benefits
The project team will help close gaps in understanding associated with biological impacts on aviation, amphibious and terrestrial coatings for DoD assets. This will enable stakeholders from all DoD services to gain from a better understanding of natural MDB biological activity and its impacts on coating properties, performance and kinetics of coating deterioration. These results will also be used by team member and advanced coating developer Sherwin-Williams to strategize for future improvements to coatings formulations, for the next generation of advanced military coatings.