High temperature erosion behaviour of high-velocity oxy-fuel sprayed CNT/NiCr-Cr3C2 composite coatings

Abstract

In the present work, the effect of different weight percentages of carbon nanotubes on the high-temperature erosion behaviour of NiCr-Cr3C2 composite coatings is demonstrated. The high-velocity oxy-fuel (HVOF) spraying process was employed for the deposition of coatings on ferritic low-alloy steel (SA-213 T12). The solid particle erosion test of the coating with and without carbon nanotubes was conducted at a temperature of 600 °C with 30, 45, 60, and 90° impact angles using Al2O3 erodent particles. This work exhibited high erosion resistance for composite coatings with the highest CNT content of 7 %. However, as the impact angle was increased from 30° to 90°, the erosion rate of all coatings, irrespective of CNT content, increased. An Optical 3-Dimensional Profilometer was used to estimate lower crater depths for lower impact angles and deeper crater depths for higher impact angles observed through surface topography. The effect of the addition of CNTs in NiCr-Cr3C2 coatings resulted in a reduction in weight loss and erosion rate at different angles of impingement working under high temperatures. The outstanding mechanical properties of CNTs impart improved erosion resistance.