Page 53 - MSAM-3-4

Materials Science in Additive Manufacturing Directed energy deposition

A B

Figure 8. Microhardness of coatings and substrates (A) and average values (B)
Abbreviations: B-DED: Broad-beam laser-directed energy deposition; H-DED: High-speed directed energy deposition; DI: Ductile iron
A B C

D E

Figure 9. Dry friction wear results for each specimen. (A) Three-dimensional local morphology of the specimens. (B) Two-dimensional wear track profile
of the specimens. (C) Specific wear rate (SWR) of the specimens. (D) Friction coefficient curve of the specimens. (E) The average friction coefficient of
the specimens
Abbreviations: SWR: specific wear rate; DI: ductile iron

to crack initiation, material spalling, and delamination, on the surface of the H-DED coating, which contributes to
ultimately reducing wear resistance. Consequently, the improving the wear resistance of the specimen. The grooves
wear mechanisms of the DI specimen include three-body on this oxide layer further confirm its role in reducing
abrasive wear and adhesive wear, accompanied by slight wear during sliding. Therefore, the wear mechanism of
oxidation and fatigue. the H-DED coating is primarily characterized by abrasive
As displayed in Figure 10B and B , almost no voids or wear and oxidative wear, with minor adhesive wear.
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cracks were observed on the worn surface of the H-DED Similarly, Figure 10C and C demonstrated that the
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coating, and delamination was not evident. This indicates worn surface of the B-DED coating is similar to that of the
that adhesive wear and fatigue wear are less severe in the H-DED coating, but delamination is more pronounced, and
H-DED specimen compared to the DI specimen. The the oxide layer is incomplete. This is due to the lower degree
magnified view in Figure 10B reveals a dense oxide layer of sub-surface microstructure refinement in the B-DED
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Volume 3 Issue 4 (2024) 8 doi: 10.36922/msam.4974