Degradation mechanism for high temperature erosion in surface modified IN718 superalloy

Abstract

Nickel based superalloy, Inconel 718, is one of the main candidates for high temperature applications such as air craft, land base and marine turbines. This technical paper deals with high temperature erosion behaviour and its mechanism of Al₂O₃–40TiO₂ (A40T) coating on Inconel 718 alloy. Al₂O₃–40TiO₂ coatings through plasma spray method were made on Inconel 718. The erosion behaviour of the A40T coating was studied using hot air jet erosion experiments at 800°C with varying parameters like angle of impingement and erodent velocity. Characterisation of the samples was carried out using SEM images, and mechanisms of erosion are discussed. Images (SEM) reveal that the A40T coating exhibit ductile and brittle behaviour by ploughing and network cracking with grain chipping at 45° angle of impingement, while at 90°, it is brittle behaviour by network cracking and grain ejection. This investigation concludes that A40T coating on IN718 provides good erosion resistance at elevated temperatures.

Keywords:

• Superalloy
• Plasma spray
• Erosion
• Alumina coating
• SEM