Unprecedented high-impact solid particle erosion of borided Inconel 718: Surface degradation and statistical damage assessment

In this study, deeper insights into the erosion response of a nickel boride layer subjected to unprecedented solid particle erosion conditions are presented. The pulsed-DC powder-pack boriding process was performed on Inconel 718 at 950 °C for 1.5 h, applying a direct current intensity of 5 A and inversion cycles of 10 s, resulting in a nickel boride layer of ∼35 μm. The nickel boride layer exhibited effective resistance to extremely aggressive erosion conditions prior to perforation. Solid particle erosion tests were conducted at room temperature using SiO2 particles with an average size of ∼120 μm, under feed rates of 100, 200, and 300 g min−1; impact velocities of 30, 46, and 120 m s−1; and incidence angles of 30°, 60°, and 90°, substantially exceeding those achieved using the test parameters recommended in the ASTM G76-18 standard (2 g min−1, 30 m s−1, and 10 min). The results revealed that the boride layer exhibited high erosion resistance under the test performed at 100 g min−1. However, at an impact velocity of 120 m s−1, the layer perforation occurred between ∼10.26 × 108 and ∼11.97 × 108 particles’ impacts, corresponding to accumulated erodent masses of 2.4 and 2.8 kg, respectively; in these erosive conditions, the failure mechanisms changed from fragile to ductile behavior. Statistical analysis demonstrated that the particle feed rate exerted the strongest influence on mass loss, confirming that the cumulative impact force controlled the erosive degradation and failure of the nickel boride layer under extreme erosion conditions.