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FEATURE ARTICLE

The advantage of using FIB is to attain location-specific

characterization of the cold-sprayed coating. Sometimes, FIB

is used to enable preparation of thin electron-transparent

samples for transmission electron microscopy.

Electron probe microanalysis is a spatially resolved,

quantitative elemental analysis technique based on gener-

ating characteristic x-rays using a focused beam of energetic

electrons. It is used to measure the concentration of elements

at levels as low as 100 parts per million (ppm) and to develop

lateral distributions by mapping, using both an energy-dis-

persive x-ray spectrometer and a wavelength-dispersive

spectrometer. Electron probe micro-

analysis has been used in cold-sprayed

coating characterization primarily to

understand the bonding mechanism at

the coating-substrate interface. It is a

valuable characterization tool for accu-

rately understanding the type of bond-

ing, as shown in the case of a Ni-20Cr

cold-sprayed coating on an AISI 4130

steel substrate in the as-sprayed versus

heat treated condition (Fig. 2). It has been

used to understand the coating relax-

ation process in the as-sprayed condition

and after heat treatment in the vicinity

of the substrate.

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For more information:

Dheepa Sri-

nivasan is a principal engineer at GE

Power, GE India Technology Center,

Bangalore,

dheepa.srinivasan@ge.com

www.ge.com

. This article series is adapt-

ed from

Chapter 5, Cold Spray—Advanced

Characterization

, in High Pressure Cold

Spray—Principles and Applications, edit-

ed by Charles M. Kay and J. Karthikeyan

(ASM, 2016).

References

1. P.C. King and M. Jahedi, Relationship between Particle

Size and Deformation in the Cold Spray Process,

Appl. Surf.

Sci.,

Vol 256, No. 6, p 1735-1738, 2010.

2. D. Srinivasan, et al., Characterization of Cold Spray IN625

and NiCr Coatings, Sixth Asian Thermal Spray Conference,

Nov. 24-26, 2014; accepted for publication in

J. Therm.

Spray Technol.