Interaction mechanisms and high-temperature erosion-oxidation performance of Cr3C2-NiCrCoMo/nano-TiC coatings

Abstract

To improve the erosion resistance of typical Cr3C2-NiCr coatings at high temperature, a novel Cr3C2-NiCrCoMo/nano-TiC (NCT) coating was developed and deposited by the high-velocity oxygen fuel spray (HVOF), which involved a cooperative modification of the multi-alloy binding phase and ceramic phase. This study delves into the influence of nano-TiC on the coating’s resistance to erosion under varying impact angles, particularly at 700 °C and 800 °C. Additionally, it explores the interaction between oxidation and erosion processes within the coating. The results indicated that the NCT1 coating with the addition of 3 wt% TiC features lower erosion rates of 1.97, 2.56, 3.14 mg/g under the impact angles of 30°, 60° and 90° at 700 °C, and 2.16, 2.87, 3.49 mg/g at 800 °C compared with original NCC coating. By comparison, the NCT2 coating with 6 wt% nano-TiC shows a deterioration in erosion resistance. The results show that at high temperatures, the erosion resistance of the coating changes from the micro-cutting at lower angles, to the brittle fracture and spalling at higher angles. The appropriate addition of nano-TiC supports and stabilizes the metal binding phase of the NCT1 coating. However, excessive nano-TiC in NCT2 coating contributes to the separation of coating phases during the erosion. The oxidation of the nano-TiC promotes the diffusion of Cr3+ ions, thus accelerating the coating oxidation and deteriorating the high-temperature erosion resistance eventually. The study is anticipated to enhance the longevity and the high-temperature erosion resistance of Cr3C2 cermet coatings, offering significant advancements in practical applications.