42 / 82
iTSSe
TSS
A D V A N C E D M A T E R I A L S & P R O C E S S E S | F E B R U A R Y / M A R C H 2 0 1 7
4 2
10
iTSSe
TSS
Ni-20Cr coating on an AISI 4130 steel versus an aluminum sub-
strate. The softer aluminum substrate does not provide any
resistance to the particles that impinge on it at high velocity,
Fig. 7 —
SEMs of aluminum cold spray coating on magnesium
substrate: (a) without heat treatment, air cooled; (b) 250°C (480°F),
1 h holding time, air cooled; (c) 300°C (570°F), 1 h holding time, air
cooled.
as shown by the first layer of particles, which undergo little
or no deformation (Fig. 6 b), compared to the steel substrate
(Fig. 6 a). In each case, upon heat treatment, a thin diffusion
layer forms along the interface, as shown in the scanning elec-
tron micrograph in Fig. 6 (c). The nature of the interdiffusion
layer is established by EDS analysis of the chemistry, as shown
in Fig. 6 (d). Similarly, SEM is also used extensively to study the
intersplat coating characteristics in the as-sprayed versus heat
treated condition, as shown in Fig. 7 (a) to (c).
~iTSSe
For more information:
Dheepa Srinivasan is a principal en-
gineer at GE Power, GE India Technology Center, Bangalore,
dheepa.srinivasan@ge.com,
www.ge.com. This article series is
adapted from
Chapter 5, Cold Spray—Advanced Characteriza-
tion,
in High Pressure Cold Spray—Principles and Applications,
edited by Charles M. Kay and J. Karthikeyan (ASM, 2016).
FEATURE ARTICLE