Cold Spray Materials Deposition Technology

Kumar Sridharan

University of Wisconsin, Madison, USA

International Thermal Spray Conference, Houston, TX

May 21st to 24th , 2012

Presentation Outline

Introduction Overview of Cold Spray Materials Deposition Process Examples of Research and Development Activities

World-Wide Cold Spray Research Program at the University of

Wisconsin, Madison Concluding Remarks

Historical Perspective

A. Papyrin, “The Cold Spray Materials Deposition Process”, Woodhead Publishers, 2007.

Invented by Prof. Anatolii Payrin at the Institute of Theoretical and Applied Mechanics - Russian Academy of Sciences (mid-1980s)

Discovered incidentally while studying two-

phase flow = particles of Al and Cu entrained in high velocity gas incident on target (left), stuck to the target (below)

Examples of Cold Spray Systems World-Wide

Germany: Helmut Schmidt University, Linde, Innovaris, EADS, Praxair, FNE Freiberg, OBS, RWTH Aachen , H.C. Starck, Hermle , Siemens, TU Chemnitz France: Critt Lorius, CEA, UTBM, Ecole des Mineurs de Paris USA: ASB Industries, Army Research Laboratory, Penn State University, Inovati, University of Wisconsin, United Technology Research Center, Sandia National Laboratory Netherlands: FST Belgium: Advanced Coating Italy: Nanofab UK: Cambridge University. TWI Technology Czech: Newspray Brazil: Mahle Canada: Centerline, McGill University Korea: Hanyang University Australia: CSIRO, DSTO, KIRK Group India: ACRI China: Bao Steel Japan: Toyohashi University of Technology, Plasma Giken Singapore: Nanyang Technological University

A good blend of industries, national laboratories, and universities is indicative of strong potential of the technology

Brief Overview of Cold Spray Materials Deposition Process

Cold Spray Materials Deposition Process

High velocity powder particles propelled by a gas onto the surface of a part or a substrate to form a coating

Particle temperature is low – particles are not melted and deposition occurs in solid state

High deposition efficiency

Low Powder Particle Temperatures

Low particle temperature confers several advantages: Little or no oxide inclusions in the coating/deposited material

No porosity due to solidification shrinkages

Ideally suited for spraying metallic materials (e.g., Al, Cu, Ni)

Low temperature, high velocity process

High Deposition Efficiency

High deposition efficiencies allow for:

Repair and dimensional restoration

Manufacture of near-net shape products

Celloto et al, “The Cold Spray Materials Deposition Process”, Woodhead Publishers, 2007.

Cold Spray is not just a coating process – it is also a process for dimensional restoration and for manufacturing 3-D products

Merits and Limitations of Cold Spray Process

Compressive stresses in the coating

Good adhesion to substrate without inter-layers

No thermally-induced differences in powder vs. coating (what is in the powder is in the coating)

No liquid effluents

Limited for now to metallic materials, not suited for ceramic material coatings

High gas consumption (economics are effected if helium has to be used)

Line-of-sight process Work-hardening of coating can

lead to loss in ductility

Additional Merits Limitations

Critical Particle Velocity

A critical velocity is required to form an adherent coating, which depends on powder material and its temperature

High Velocity Particle Impact

Kinetic energy of particles converts to plastic deformation and heat leading to a transient temperature increase in particles

From: M. Grujicic in The Cold Spray Materials Deposition Technology, Woodhead Publishing, UK, 2007

Modeling of Al particles on Cu

Deformation occurs at high strain rates

Structural and Interfacial Effects

Transient temperature spike and high strain rate can lead to interesting materials effects: Dynamic recrystallization that may lead to novel structures Fragmentation of native oxide monolayers on particles In situ surface cleaning Metallurgical bonding on nanometer length scales (possibly due to

temperature spike)

Al coating on Al substrate showing a bond layer (~8 -10nm) from: Hanyang University, Korea Kang, Won, Bae, Ha, Lee, J. Materials Science, 2012.

Examples of Research and Development Activities World-Wide

Cold Spray Deposition of Al for Repair of Mg Aircraft Components

Mg components used extensively in DoD aircrafts

Susceptible to corrosion in marine environments

Cold spray technology [with Al, 6061 Al-alloy] being extensively used for repair and maintenance resulting in millions of dollars of savings

U.S. Army Research Laboratory Courtesy V. Champagne and B. Gabriel

Corroded Sites on Mg Flange

Repaired with Cold Spray of Al Powder

MIL-STD-3021, 2008 (test standards for corrosion, fatigue, bond strength, microstructure etc.)

Copper Cold Spray for Spent Nuclear Fuel Applications

10mm thick Cu encasement on prototype cast iron canisters for storing spent nuclear fuel disposal

Use of 10mm thick encasement rather than a use a 50mm thick Cu

container, 600 tons of Cu can be saved per canister

CS Cu had no oxides and showed very good corrosion resistance, but loss in ductility

Korea Atomic Energy Institute Choi, Lee, and Lee, Nuclear Engr. Design, 240 (2010) 2714-2720.

Cold Sprayed Cu encasement

Ni Cold Spray Coatings on Ti-Alloy to Reduce High Temp. Fretting Wear for Aerospace Applications

High temperature fretting wear is an issue in Ti-alloy/Ti-Alloy metallic contacts in aerospace applications

Ni-cold spray coatings on one of the mating surfaces reduced friction and fretting wear

United Technology, Air Force, and Penn State C.H. Hager, J. Sanders, S. Sharma, A. Voevodin, and A. Segall, Tribology International, 42 (2009) pp. 491-502

Low friction lubricious Ni ‘glaze’ oxide film forms on surface at high temperatures and reduces galling and fretting wear

Annealing of cold sprayed Ni coating

Ti-alloy against Ni-cold sprayed Ti-alloy

Nano-crystalline Ni Coatings by Cold Spray

After cryo-milling (0.51% O and 0.19% N); ball milled in L-N2 for 15 hrs to form nano-crystalline structure

University of California, Davis, and University of Ottawa, Canada Ajdelsztjan, Jodoin, Schoenung Surface and Coatings Technology, 201 (2006) pp. 1166-1172.

Pore free coating achieved with hardness of 605 HV

Ni3N and NiO nanoparticles pin grain boundaries at high temperatures Ring patterns typical of nano-crystalline materials

Ni-50Cr Cold Spray Coatings for High Temperature Power Plant Boiler Applications

T22 Steel

SA 516 Steel

Indian Institute of Technology, Roorkee, India and ASB Industries, USA; N. Bala, H. Singh, and S. Prakash, Materials and Design, 31 (2010), pp. 244-253.

Testing in Na2SO4-60%V2O5 power plant effluents at 900oC

CS Ni-50Cr significantly reduced corrosion in power plant steels

Cold Spray of Refractory and Reactive Metals

Cold sprayed Ta Ductile fracture in as-coated Ta

Ductile fracture in as-coated Nb Ductile fracture in as coated Ti

Intl. Advanced Research Centre for Powder Metallurgy and New Materials, India Courtesy: Dr. S. Joshi High strain rate deformation may be

responsible for ductility

Cold Spray Amorphous Alloy Coatings

Amorphous alloys (metallic glasses) have high hardness and corrosion resistance, but they are also quite brittle

Fe 44Co6Cr15Mo14C15B6 amorphous alloy cold spray coatings successfully deposited by balancing gas pre-heat temperature (~950oC), particle temperature, and substrate heating

Helmut Schmidt University, Hamburg Germany List, Gartner, Schmidt, and Klassen, J. Thermal Spray Technology, February 2012.

Amorphous structure retained in the coating

High hardness: 1100Hv Deposition Efficiencies up to 70%

Helmut-Schmidt University, Hamburg, Germany Cold Spray

Ti-Mo being Cold Sprayed Courtesy Prof. T. Klassen, Helmut Schmidt University, Germany

Nanocrysatlline Structures in Amorphous Cold Spray Coatings

Strain induced nanocrystallization of amorphous Cu54Ni6Ti18Zr22 has been discovered using cold spray

Hanyang University, Korea Yoon, Bae, Xiong, Kumar, Kang, Kim, Lee, Acta Materialia, 2009, 6191-6199.

X-ray diffraction and TEM of powders

Nanocrystalline regions in the coating

Nanostructured WC-Co Cold Spray Coatings

WC-17%Co sprayed with helium cold spray process (mild steel substrate) Two WC particle sizes studied: > 1µm and 40 to 800nm

Swinburne University Australia, SIM University Singapore, and Russian Academy of Sciences; Ang, Berndt, and Cheang, Surface and Coatings Technology, 205 (2011) pp. 3260-3267.

WC-Co with > 1µm showed erosion of substrate and little build-up

WC-Co with 40 to 800nm WC good build-up Hardness for finer WC-Co: 10 GPa Adhesion > 60MPa

XRD for 40 to 800nm WC powders and coatings showed no oxidation or decarburization

Cold Spray of Ceramic Coatings

Nanoscale particles agglomerated to a porous structure 10 to 20µm

Primary particles oriented along a single axis

Toyohashi University of Technology, Japan Courtesy: Yamada and Fukumoto

TiO2 coatings deposited !!

Cold Spray Research Program at the University of Wisconsin, Madison

University of Wisconsin Cold Spray System

4000-34 KINETIK System, from ASB Industries/CGT-GmBH

Spray booth from Noise

Barriers Robot controlled (Nachi

system, from Antennen)

Robot controls (left) and spray gun control (right)

Sound-proof spray booth Robot for pre-programmed movement of spray gun

Sample stage and dust collector (below that)

Nitrogen/helium gas cylinders

Safety Features

Downdraft Table collects large fraction of excess sprayed particles (adheres to NFPA 484, i.e. non-sparking motors, etc.)

MERV-11 filter (filter checked frequently and replaced when visibly contaminated

Explosion proof vacuum being purchased to clean up excess powders Class D (metal fires) fire extinguisher

Cut-off switches Oxygen sensors

University of Wisconsin Cold Spray - Live

Aluminum and Copper Cold Spray Coatings on Various Material Substrates

Pure Al coating on 6061 Al-alloy

Pure Cu on 6061 Al-alloy

Pure Al on plasma sprayed alumina

Interface Comparison between Electroplating and Cold spray process: Cu on 4140 steel

0%10%20%30%40%50%60%70%80%90%

100%

-1 -0.5 0 0.5 1C

ompo

sitio

n (W

t. %

) Distance from Interface (µm)

Electroplated Copper on 4140 Steel

Oxygen

Iron

Copper

0%10%20%30%40%50%60%70%80%90%

100%

-1 -0.5 0 0.5 1

Com

posi

tion

(Wt.

%)

Distance from Interface (µm)

Cold Sprayed Copper on 4140 Steel

Oxygen

Iron

Copper

Addressing Problem with Sensitization of 5xxx series Al-alloys with Cold Spray

5XXX series Al-alloys used in Navy ships

Experience sensitization (i.e, segregation of Al3Mg2 β−phase at grain boundaries

Electrochemical potential of β-phase, Al3Mg2 β−phase: -1150mVSCE

Electrochemical Potential of Al-5Mg solid solution: -790mVSCE

Al3Mg2 β−phase corrodes and then leads to stress corrosion cracking (SCC)

5xxx series Al-Mg alloys contain 4% – 5 % Mg

Cross-sectional SEM image of 5083 Al-alloy Cold Spray Coatings

240 µm

Very good coating produced (seamless transition between the coating and the substrate)

Coating Substrate

Knoop Microhardness of 5083 Al-alloy Cold Spray Coatings and Substrate

Higher hardness of cold spray coating is indicative of good densification and work-hardening

Dimensional Restoration by Cold Spray

Cold spray materials deposition model

Concluding Remarks

Metrics such as international workshops, conferences, and publications indicate that interest in cold spray technology is growing world-wide

Originally investigated for soft or low melting point materials, cold spray is now being used for higher melting point and reactive materials (e.g. Ta, Ti), composites (WC-Co), amorphous materials, and nanocrystalline materials, vastly expanding scope of its applications

Modifications in equipment, new designs, and development of portable systems are making the process even more attractive and economical

Strong interest and R&D programs at universities, national laboratories, and industry alike are indicators of a bright outlook for the cold spray deposition technology

University of Wisconsin Cold Spray Laboratory, Madison, WI, USA

UW Cold Spray Laboratory

Thank you !