Cyclic Oxidation Behavior Of Bare And Cr3C2-25 (NiCr) Coated Super Alloy At Elevated Temperature

Abstract

High temperature oxidation is the main cause for the degradation of materials used at elevated temperature which is responsible for the major shut down of turbines, boilers and incinerators used in large units. An attempt has been made to use Cr3C2-25%NiCr coating deposited by D-gun technique on Superni 600 alloy. These coatings are generally used for wear applications. This coating has been studied for oxidation at 900C under cyclic conditions. Sound and adherent coatings of 150-250 μm can be obtained by D-gun process. The bare and coated alloys were subjected to cyclic oxidation in air for 100 cycles. Weight change/area has been plotted against number of cycles and to monitor the oxidation kinetics. The scale formed after oxidation both on the bare and coated alloys has been examined using FESEM/EDX, XRD, and Cross-sectional/Mapping analysis. The weight gain by coated Superni 600 was found to be about 80% less than that of bare Superni 600. D-gun sprayed Cr3C2-NiCr coating has contributed to increase in the oxidation resistance of coated superalloy. These types of coatings can be developed for high temperature applications for both corrosion and erosion resistance.

High Temperature Erosion-oxidation Resistance of Thermally Sprayed Nanostructured Cr3C2-25(Ni-20Cr) Coatings

“…Their study presented not only a brief review of the main parameters related to erosion at room and high temperature, but also the mechanism that governed the E-O process. A number of investigations have been carried out about the E-O behavior of coatings produced by HVOF and similar processes 13,[40][41][42][43][44][45][46][47] . Further, Roy et al 22 compared properties of coatings produced with nanostructured and as-received Cr 3 C 2 -25(Ni-20Cr) powders and Matthews et al [48][49][50] studied the high temperature erosion of thermally sprayed Cr 3 C 2 -NiCr coatings.…”

Coatings: A Review

“…Kumar et al [8] investigated the cyclic oxidation behavior of bare and Cr 3 C 2 -25 (NiCr) coated super alloy at elevated temperature He observed that coated sample weight gain was one -fourth of weight gain of bare specimen and for 100 cycles coating at 900 0 C proved influenced. Parabolic rate constant(kp) for coated superni600 was 28 times less than bare .XRD analysis showed the presence of Cr 2 O 3 , Cr 23 C 6 , NiCr 2 O 4 and Cr 7 C 3 in scale after oxidation which made coated superni600 oxidation resistant.…”

Pengaruh NiCrAlY, Ni/Cr2O3/CrxCy Sebagai Variasi Bond Coat Dengan Penambahan Lapisan Al2O3 dan YSZ Pada Inconel 625 Terhadap Struktur Mikro Lapisan Menggunakan Metode Flame Spraying

“…Kromium sendiri terkonsentrasi persebarannya diatas lapisan antar-permukaan antara lapisan oksidasi dan substrat. Kromium dimungkinkan untuk terdifusi dari substrat menuju lapisan oksida yang baru [11]. Hal ini sesuai seperti yang ditunjukkan pada gambar 9(c), dimana persebaran Kromium menandakan lapisan oksida yang sebenarnya karena hasil dari difusi tersebut akan menghasilkan lapisan Cr2O3 Gambar 3(c) merupakan sampel yang terdeposisi Al2O3 dan ZrO2 -8%Y2O3.…”