Effect of internal nitridation on microstructure and mechanical properties of cobalt-based superalloy under high-temperature nitrogen atmosphere

Chen, Yipeng; Cai, Yong Q.; Chào, Y.; Kong, Weiwen; Wang, Yongqiang; Xu, Wen; Liu, Xin

doi:10.1016/j.matchar.2023.112851

Cited by 6 publications

(2 citation statements)

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“…Numerous studies have been conducted to form carbide precipitates to improve the mechanical properties of cobalt, nickel, or iron superalloys [4,5,[7][8][9]. While some of these studies aimed to form regional carbides throughout the alloy's microstructure [4,5,[7][8][9], others focused on forming aluminide nitride, boride, carbide, etc., on the surface of these alloys [10][11][12][13]. These advanced surface coatings often offer a more cost-effective approach to increasing service life.…”

Section: Introductionmentioning

confidence: 99%

“…However, cobalt-based superalloys have many applications in high-temperature abrasive environments such as gas turbines, nuclear power plants, high-temperature furnaces, and the oil and gas industry [1,2,22]. When thermomechanical coatings are applied to the surfaces of these superalloys, they improve surface hardness and chemical inertness and provide a thermal barrier effect, resulting in enhanced oxidation, corrosion, and wear resistance at high temperatures [10][11][12][13][14][17][18][19][20][21]. These advantages enhance the performance of cobalt-based superalloys, enabling their use in more challenging operating conditions.…”

Section: Introductionmentioning

confidence: 99%

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A Comparative Study on Characterization and High-Temperature Wear Behaviors of Thermochemical Coatings Applied to Cobalt-Based Haynes 25 Superalloys

Günen

Ergin

2023

Coatings

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This study investigated the characteristic properties of aluminizing, boronizing, and boro-aluminizing coatings grown on Haynes 25 superalloys and their effects on the high-temperature wear behavior. The coating processes were conducted in a controlled atmosphere at 950 °C for 3 h. Characterization studies were performed using scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction analysis, nanoindentation testing, and high-temperature wear tests. It was determined that the thickness values of aluminide, boride, and boride–aluminide coatings were 140 ± 1.50 µm, 37.58 ± 2.85 µm, and 14.73 ± 1.71 µm, and their hardness values were 12.23 ± 0.9 GPa, 26.34 ± 2.33 GPa, and 23.46 ± 1.29 GPa, respectively. The hardness of the coatings resulted in reduced wear volume losses both at room temperature and at 500 °C. While the best wear resistance was obtained in the boronized sample at room temperature due to its high hardness, the best wear resistance at 500 °C was obtained in the boro-aluminized sample with the oxidation–reduction effect of Al content and the lubricating effect of B content in the boro-aluminide coating. This indicates that the presence of aluminum in boride layers improves the high-temperature wear resistance of boride coatings. The coated samples underwent abrasive wear at room temperature, whereas at 500 °C, the wear mechanism shifted to an oxidative-assisted adhesive wear mechanism.

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