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Materials Science in Additive Manufacturing Cold spray additive manufacturing of Cu-based materials

reinforcements in copper-based cold spray coatings. The of wear resistance, lesser oxidation, hardness, electrical
electrical conductivity of pure copper and copper-based conductivity, and so on when compared to other coating
cold spray coatings considerably depends on the deposition processes. The cold-sprayed copper coatings also retained
parameters and porosity in the coatings. In general, the inherent characteristic properties of reinforcements
higher porosity leads to lower electrical conductivity. The without causing much damage to the reinforcements. This
addition of reinforcements may or may not contribute could be because of the low operating temperatures of
to the increase in electrical conductivity, possibly due to the cold spray process that avoids any kind of melting or
the ineffectiveness of deposition, effective deformation of oxidation.
copper matrix, the amount of reinforcement used, and Copper-based cold spray coatings have immense
characteristic property of the reinforcements. Another scope for the future research works. The correct type and
property with commercial importance is the friction amount of reinforcements that can give the best desirable
coefficient and wear rate. The addition of reinforcements properties for copper-based coatings must be explored. The
such as graphite and MoS imparts good lubrication deposition efficiency of these copper-based coatings with
2
properties, which decreases the friction coefficient and wear the help of powder architecture and powder morphology is
rates of the copper-based cold spray coatings. However, in
such coatings, there could be a decrease in hardness values, yet to be investigated thoroughly. The higher the deposition
possibly due to the weak interface bonding between metal efficiency, the lesser wastage of powder feedstock used
matrix and reinforcement. Furthermore, this decrease in for the cold spraying process. Recycling of process gases
microhardness trend was not visible for reinforcements and feedstock powder from economic and environmental
specifically used to improve the strength and hardness of point of view is important, and research on it is inevitable.
copper-based cold spray coatings. The research works must include the incorporation of
two reinforcements in the metal matrix that can provide
6. Conclusions and scope for future work enhanced mechanical and tribological properties. The
electrical and thermal properties of copper-based cermets
Pure copper and copper-based cold spray coatings are an according to the various reinforcements used are a matter
interesting area of research in power industries. Copper- of further investigation, and this can be compared with the
based cold spray coatings can enhance electrical and other coating processes such as HVOF, CVD, sintering,
thermal conductivity, wear, and corrosion resistance, and so on. The comparisons can also be made among
along with proper hardness and strength of components. the various copper-based cold-sprayed coatings with
The deposition parameters required for the cold spray of several types of reinforcements. A thorough investigation
the copper-based coatings discussed in this work mainly of preserving the original grain sizes desired phases,
consist of the gases used for cold spray, the pressure of the and the chemistry of materials is desirable. The research
gas, standoff distance, and powder feedstock preparation works on bond strength and bonding characteristics,
for cold spraying by milling process with the incorporation fatigue strength, thermal shock resistance, oxidation, and
of surfactants. Surfactants play a huge role in powder corrosion resistance of copper-based cold spray coatings
preparation, according to the size range required for can be beneficial in creating worthwhile coatings having
cold spraying process. The mechanical milling process great commercial importance.
is an effective method to produce powder feedstock
with homogeneity. The homogeneous distribution of Acknowledgments
reinforcement particles in the metallic copper matrix
provides uniform mechanical and tribological properties. The authors acknowledge with gratitude funding received
from the Natural Sciences and Engineering Research
Numerous research works focused on different types of Council of Canada (NSERC), the Canada Foundation
reinforcements in copper-based cold spray coatings have for Innovation (CFI), Transport Canada, and the New
been done. These different reinforcements provide unique Brunswick Innovation Foundation (NBIF).
properties to the copper-based coating according to their
characteristics. The deformation and recrystallization of Funding
copper grains in pure copper coatings have been focused
on in this work, along with the variation in properties This work is funded by the NSERC, the CFI, Transport
with different amounts of reinforcements have also Canada, and the NBIF.
been discussed. These reinforcements have also been Conflict of interest
responsible for increasing the deposition efficiency and
significant reduction in porosity. The copper-based cold The authors have no conflicts of interest to declare that are
spray coatings have shown superior qualities in terms relevant to the content of this article.

Volume 1 Issue 2 (2022) 16 https://doi.org/10.18063/msam.v1i2.12