Col
d Spray for Aircraft Structural Repair of Corrosion Damage
Sar
ah E. Galyon Dorman, Justin W. Rausch, and Moriah Ausherman
SAFE I
nc
P.
O. Box 3388
Monum
ent, CO 80132
United States
AB
STRACT
Cold spray (CS) is currently in use in both civil aviation and military aircraft fleets as a method for repairing
obsolete or damaged nonstructural parts. Ongoing researched by the United States Office of Naval
Research examines the corrosion and mechanical property equivalency of CS repairs on aluminum alloys
for structural repairs on aircraft. Prior testing of CS repaired fatigue coupons with 15-30% blend outs are
capable of fatigue life improvement near that of an undamaged coupon at two stress ratios. Testing of
CS repaired tensile coupons with 15% blend outs have shown properties near or exceeding 90% of
wrought material for two alloy systems. Other material property investigations using this repair process,
such as corrosion testing are currently underway. This is important in understanding corrosion
development of CS in the highly corrosive environments aircraft experience. These combined results are
critical to the future of CS and its use for structural repair of aircraft components.
Key words: Cold spray, aluminum alloys, salt fog testing
INT
RODUCTION
Cold
Spray (CS) is a solid-state deposition repair method that uses compressed gas to deposit 1-50 µm
powder particles onto a substrate. The carrier gas accelerates the particles through a converging-
diverging nozzle onto the substrate at supersonic speeds [1]. Bonding between the particles and the
substrate occurs when critical impact velocity is reached. CS process parameters such as temperature
and air pressure and powder properties such as particle size and processing are used to achieve such
velocities [2]. The type of carrier gas will also change the spray velocity. The low molecular weight of
helium allows for higher gas and particle velocity upon impact than nitrogen or compressed air [3,4,5].
Hi
storically, CS has been used as a surface coating, preventing corrosion and surface wear, and as a
repair technique, dimensionally repairing defects in non-structural parts. As improvement is shown in
mechanical properties, understanding the corrosivity of CS is required to start structurally repairing parts.
Previous testing showed an increase in porosity led to an increase in corrosivity. There is also a direct
© 2023 This work is open for public use with permission of the author(s). Positions and opinions advanced in this work are those of the author(s) and not necessarily
those of DoD. Responsibility for the content of the work lies solely with the author(s). This work is open for public use with permission of the author(s). Positions and
opinions advanced in this work are those of the author(s) and not necessarily those of DoD. Responsibility for the content of the work lies solely with the author(s).
1
Paper No. DOD-AUG22-19854
