Elevated temperature erosive wear behavior of superalloy coatings deposited using cold spray technology

Abstract

The boiler tube components in thermal power plants and steam generating systems suffer from erosion and corrosion problems and are even today posturing a grave threat to industries, resulting in forced outages. Unrelenting efforts to decrease the components’ maintenance costs have been made by protecting with coatings. Among the various coating methodologies are thermal spray, chemical vapour deposition (CVD), physical vapour deposition (PVD), etc., in vogue. However, recently, the additive manufacturing-based cold spray technique is gaining interest among material scientists, incorporating high-velocity impacts associated with the low-temperature regime. Nickel-based superalloy Inconel 625 has been chosen and cold sprayed on The American Society of Mechanical Engineers (ASME) T11 and T22 boiler steels. The coated surface is characterized by scanning electron microscopy and energy dispersive X-ray analysis (EDAX), X-ray diffraction, micro-hardness, and elemental X-ray mapping techniques. The solid particle erosion studies have been carried out both at room and an elevated temperature of 700 °C as per American Society for Testing and Materials (ASTM) standard for 30°C and 90 °C impact angles. An optical profilometer has been used to evaluate the erosion volume loss. The results showed that the coated samples exhibit superior erosion resistance than the uncoated samples at both room and elevated temperatures. The erosion data obtained have been substantiated using scanning electron microscopy by analyzing the damage features and correlating with the erosion data.