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Cyclic oxidation of 304L and 316L stainless steel coated and uncoated with Cr3C2–NiCr at elevated temperatures

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Mar 31, 2025

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Figure 1

Macrographs of specimens. (a) Uncoated AISI 304L steel substrate. (b) Uncoated AISI 316L steel substrate. (c) Cr3C2–25% NiCr-coated AISI 304L steel substrate. (d) Cr3C2–25% NiCr-coated AISI 316L steel substrate.
Macrographs of specimens. (a) Uncoated AISI 304L steel substrate. (b) Uncoated AISI 316L steel substrate. (c) Cr3C2–25% NiCr-coated AISI 304L steel substrate. (d) Cr3C2–25% NiCr-coated AISI 316L steel substrate.

Figure 2

Schematic diagram of the D-gun method.
Schematic diagram of the D-gun method.

Figure 3

Coating thickness: (a) substrate SS 316L and (b) substrate SS 304L.
Coating thickness: (a) substrate SS 316L and (b) substrate SS 304L.

Figure 4

Cross-section SEM image after oxidation.
Cross-section SEM image after oxidation.

Figure 5

Schematic diagram of the muffle furnace.
Schematic diagram of the muffle furnace.

Figure 6

Weight gain/area vs the number of cycles for bare and coated 304L and SS 316L in dry air at 850°C.
Weight gain/area vs the number of cycles for bare and coated 304L and SS 316L in dry air at 850°C.

Figure 7

Weight gain/area vs the number of cycles for bare and coated SS 304L and SS 316L in dry air at 750°C.
Weight gain/area vs the number of cycles for bare and coated SS 304L and SS 316L in dry air at 750°C.

Figure 8

Macrographs of specimens in dry air at 850°C. (a) Uncoated 304L. (b) Coated 304L. (c) Uncoated 316L. (d) Coated 316L.
Macrographs of specimens in dry air at 850°C. (a) Uncoated 304L. (b) Coated 304L. (c) Uncoated 316L. (d) Coated 316L.

Figure 9

Macrographs of specimens in dry air at 750°C. (a) Uncoated 304L. (b) Coated 304L. (c) Uncoated 316L. (d) Coated 316L.
Macrographs of specimens in dry air at 750°C. (a) Uncoated 304L. (b) Coated 304L. (c) Uncoated 316L. (d) Coated 316L.

Figure 10

SEM images of Cr3C2–NiCr-coated (a–c) SS 304L and (d–f) SS 316L.
SEM images of Cr3C2–NiCr-coated (a–c) SS 304L and (d–f) SS 316L.

Figure 11

SEM images of Cr3C2–NiCr coated (a) SS 304L at 750°C, (b) SS 316L at 750°C, (c) SS 304L at 850°C, and (d) SS 316L at 850°C after the oxidation cycle.
SEM images of Cr3C2–NiCr coated (a) SS 304L at 750°C, (b) SS 316L at 750°C, (c) SS 304L at 850°C, and (d) SS 316L at 850°C after the oxidation cycle.

Figure 12

XRD patterns of as-sprayed and oxidized coatings.
XRD patterns of as-sprayed and oxidized coatings.

Powder coating process parameters_

Parameters Cr3C2–NiCr coating
Proportion 75% Cr3C2/25% NiCr
Oxygen flow rate (O2) 2720 SLPH
Acetylene (C2H2) flow rate 2320 SLPH
Pressure (P) 0.2 MPa
Nitrogen flow rate (N2) 720 SLPH
Pressure (P) 0.14 MPa
Power 450 VA
Spray distance 165 mm
Spray angle 90o
Coating thickness (average) 450 µm
Fire rate 10 Hz (10 shots per second)

304L and 316L SS chemical composition (%)_

Substrate C Mn P S Si Cr Ni Mo Fe%
SS 304L 0.030 2.00 0.45 0.03 1.00 18.0–20.0 8.00–12.00 Bal.
SS 316L 0.030 2.00 0.45 0.03 1.00 16.0–18.0 10.00–14.00 2.00–3.00 Bal.