COLD/KINETIC SPRAY – CURRENT AND POTENTIAL APPLICATIONS

Cold spray is a deposition process that relies on accelerating fine (1-50 μm) particles to supersonic speeds (600 to 1000 m/s) where, upon impact to a substrate, the particles fuse onto the surface or previously deposited particles to form a coating. The fine particles are entrained in a heated gas (typically helium, nitrogen or air) that is accelerated through a de Laval-type nozzle.

Kinetic spray process [1] has many comparable features to cold spray, including its reliance on high kinetic energy to compensate for low thermal energy to form a deposit.  There are, however, notable differences in that kinetic spray:

• can spray powders with particle size exceeding 50 μm; and,
• at lower mean critical velocity for a given material.

Both processes can produce coatings at relatively high rates with low oxide content, low thermal stress, low porosity, and high adhesion.  In addition to these attractive attributes both low temperature, high kinetic energy processes allow for retention of fine grain structure, absence of phase change, capability for thick deposits, and promotion of compressive residual coating stress. Coating materials must have a certain degree of plasticity to allow for the particle’s kinetic energy to be transformed into strain and heat energy so as to form a dense well adhered coating. Viable feedstock materials include metals, polymers, and their composites (can incorporate some ceramics).  The bonding mechanism for these processes is similar to dynamic explosive powder compaction [2]. 

As a result of having similar attributes and capabilities between the two low-temperature spray processes, there are overlaps in existing and potential applications. Typical applications revolve around depositing protective coating, near net-shape spray forming, and repair of worn/damaged components.  Examples of typical protective coatings applications include [3]: MCrAlY coatings for high temperatures; CuCr for oxidation protection; Al and Zn sacrificial cathodic coatings; thermal management layers of Al- or Cu-base metals or their MMCs.  Potential coating applications include: nanostructured materials for corrosion, wear and repairs [4, 5]; Al and its alloys for repair of space shuttle solid rocket boosters; repair and of plate stocks used in aircraft structures; Al, Cu, and steel for electronics; Ti and Ta for bioengineering and corrosion protection; CuNiIn for anti-fretting in gas turbine engines.

As far as existing near net-shape spraying applications are concerned, Karthikeyan [3] mentions cold spray fabrication of slabs and plates of high strength Cu alloys.  Potential applications may include spray forming of temperature-sensitive materials such as Ti and Al.  As with protective coatings, cold and kinetic spray processes provide very suitable conditions for spray forming nanostructured metal-base materials.  With the continual rise in cold and kinetic spray research, there should be a continued rise and acceptance in the use of these technologies in many industries.

1.     T.H. Van Steenkiste, J.R. Smith, R.E. Teets, J.J. Moleski, D.W. Gorkiewicz, R.P. Tison, D.R. Marantz, K.A. Kowalsky, W.L. Riggs, II, P.H. Zajchowski, B. Pilsner, R.C. McCune, K.J. Barnett, “Kinetic spray coatings”, Surface and Coatings Technology 111 (1999) pp. 62–71

2.     T.H. Van Steenkiste, J.R. Smith, R.E. Teets, “Aluminum coatings via kinetic spray with relatively large particles”, Surface and Coatings Technology 154 (2002) pp. 237-252

3.     J. Karthikeyan, “Cold Spray Technology: International Status and USA Efforts”, ASB Industries, Inc., December 2004 publication [http://www.asbindustries.com/media/1381/int_status_report.pdf]

4.     L. Ajdelsztajn, J. Schoenung, B. Jodoin, G.E. Kim, “Cold spray deposition of nanocrystalline aluminum alloys”, Metallurgical and Materials Transactions A, Volume 36, Number 3, March 2005, pp. 657-666(10)

5.     G.E. Kim, Angela L. Moran, Kenneth Scandell, Tony Addona, Matthew Trexler, Victor K. Champagne, “Potential Use of Cold Sprayed Nanostructured Aluminum for Corrosion and Wear Protection”, keynote presentation at U.S. Army Corrosion Summit 2009, Clearwater, FL

George E. Kim, Ph.D.

F.W. Gartner

Perpetual Technologies, Inc.

email: gkim@perpetualtech.ca

Comments

[Cold Laser]

thanks for defining cold spray. This will help me do my assignments. It adds to my knowledge about what you have posted. Thank you!

[Cold Laser]

I wanna have this one. Ill try to invent perhaps another application for this.

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