Summaries - Office of Research & Innovation
Back Evaluation of Low Pressure Cold Spray Deposition for Repair of Corrosion Damage and Cracking in Steel Structures
|Division||Graduate School of Engineering & Applied Science|
|Department||Mechanical & Aerospace Engineering|
|Investigator(s)||Brewer, Luke N.|
|Sponsor||Office of the Secretary of Defense (DoD)|
This program will evaluate the potential of low-pressure cold spray deposition as a repair approach for steel and aluminum structures using austenitic stainless steel and 7xxx series aluminum. Low pressure (<300 psi) cold spray is more readily applied in the field and will be the focus of this program. This program will support corrosion repair efforts at NAVFAC Engineering Expeditionary Warfare Center and at NAVAIR-PAXRIVER and will be divided into two tasks:
1.) Establish microstructure-property relationships for cold spray deposited stainless steel:
We will evaluate the basic microstructure-property relationships for cold sprayed austenitic stainless steel coatings. In FY2013, we are determining which powders and spray conditions allow for reasonable cold spray deposition of austenitic stainless steel onto cast iron substrates. We are currently making the connections between gas type, temperature, and pressure with the critical velocity needed for deposition. In FY2014, we would like to examine, in detail, the microstructures and properties of the most promising coatings. In particular, we need to characterize the tensile strength and the adhesion strength of these coatings. In addition, we will measure the cyclic polarization response of the cold spray-coated cast iron to gauge the effectiveness of the coating for corrosion protection.
2.) Assess the potential of cold spray deposition for repair of AA7075 structures:
We will perform an initial experimental assessment of the ability to cold spray deposit AA7075 powder onto a AA7075 substrate as a means of repairing corrosion damage on this alloy. We will procure AA7075 powders from a commercial source (e.g. Valimet Inc.). These powders will be sprayed at NPS using our low-pressure cold spray deposition system. We will assess the resultant microstructures, residual stresses, hardness, and cyclic polarization behavior of the deposited material. Time permitting, we will also evaluate a graded deposition approach that starts with AA7075 and finishes with pure aluminum for corrosion protection. A recommendation will be provided on the potential for cold spray deposition of AA7075 to repair corrosion damage.
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