Page 64 - MSAM-1-2

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

A B

C D

E

Figure 10. Scanning electron microscopy micrographs of Cu-based solid lubricating cold spray coatings: (A) Copper, (B) copper-alumina, (C) copper-
alumina-copper-coated graphite 5 wt.%, (D) copper-alumina-copper-coated graphite 10 wt.%, and (E) copper-alumina-copper-coated graphite 20 wt.% .
[31]
(Reprinted from Journal of Thermal Spray Technology, 27(8), Chen, W., Yu, Y., Cheng, J., Wang, S., Zhu, S., Liu, W., and Yang, J., Microstructure, Mechanical
Properties and Dry Sliding Wear Behavior of Cu-Al O -Graphite Solid-Lubricating Coatings Deposited by Low-Pressure Cold Spraying, 1652 – 1663,
3
2
2018, with permission from Springer Nature).
sprayed coatings, respectively. The wear rate of these In Figure 11, the worn-out cross-section of pure
copper-based coatings also improved with the addition copper, copper-alumina, and copper-alumina (10 wt.%)-
of copper-coated graphite. The reported values were copper-coated graphite (10 wt.%) cold-sprayed coatings is
2.53 × 10 mm /Nm, 2.18 × 10 mm /Nm, and 1.2 × presented. As reported and seen in the microstructure, a
-4
3
-4
3
10 mm /Nm for copper-alumina (10 wt.%)-copper- mixed tribolayer was formed on the pure copper coatings,
3
-4
coated graphite (5 wt.%, 10 wt.%, and 20 wt.%) cold- with a thickness of around 5 – 10 µm with a mixture of large
sprayed coatings, respectively. Graphite helps in the and ultrafine grains, possibly due to the plastic deformation
formation of tribolayer, and the alumina particles of pure copper. The presence of ultrafine grains improves
provide load support. The combination of both provides the plastic deformation and, thereby, the strength and wear
the lowest wear rate for the copper-alumina (10 wt.%)- resistance of the material. However, the addition of alumina
copper-coated graphite (20 wt.%) cold-sprayed coating. ceramic particles may induce cracks during wear test because
The increase in the amount of graphite in the coatings of the incompatibility at the ceramic metal matrix interface.
leads to a lower wear rate of the coating. However, for the case of copper-alumina (10 wt.%)-copper-
Volume 1 Issue 2 (2022) 8 https://doi.org/10.18063/msam.v1i2.12