High Temperature Oxidation and Wear Resistant Bi-Layer Coating for Turbocharger Housing

Abstract

An upsurge in the demand of higher power generation has been observed in the last few decades. Consequently, the mechanical components of power generation are forced to operate in the extreme working conditions for longer duration, which results in the accelerated wear and corrosion of the material. Conventional material such as grey cast iron (GCI) is a preferred material of components used for power generation at high temperature. Grey cast iron exhibits poor wear and corrosion resistance at high temperature. On the other hand, an advanced material such as Alloy-718 is capable to withstand the high-temperature wear and oxidation for prolonged duration of time. In the current research, high temperature corrosion and erosive wear performance of grey cast iron (GCI) components has been enhanced by depositing a bi-layerAlloy-718/NiCrAlY coating by using high velocity oxy-fuel (HVOF) thermal spray process. Furthermore, the high temperature corrosion and erosion behaviour of GCI substrate and the deposited coating has been discussed. The various characterization techniques such as scanning electron microscopy (SEM) X-ray diffraction, and Vickers micro-hardness testing were conducted for the GCI substrate and Alloy-718 coating, respectively. The Alloy-718 coting showed the increased resistance against high-temperature erosion and oxidation, which can be attributed to its good bonding with the substrate, high hardness and formation of protective phases at high-temperature.

Applications and Developments of Thermal Spray Coatings for the Iron and Steel Industry

“…Surface properties of hardness, wear and high temperature oxidation determine the quality and surface finish of the steel product. Surface coatings are applied by thermal spray processes to develop specific surface functionalities so that the rolls can operate under these harsh operating environments [ 67 , 68 ]. Chromium has been considered for bridle rolls owing to its surface profile of domed grains, which provides an optimum surface roughness to prevent slippage without degrading the surface properties of the bridle rolls.…”

Isothermal Oxidation Performance of Laser Cladding Assisted with Preheat (LCAP) Tribaloy T-800 Composite Coatings Deposited on EN8

“…Oxidation occurs when metals/alloys are exposed to oxygen/air [1]. It also results in the formation of porous and noncoherent oxides, which leads to the failure of the component [2]. The dispersion of oxygen on the equipment surfaces leads to oxidation, which then propagates into the core of the material.…”

“…Various coatings can be used to subvert the oxidation phenomenon. For instance, Vasudev et al [2] explored the use of superalloys (Inconel 718) for enhancing the elevated-temperature oxidation resistance of turbocharger housing. Inconel 718 exhibited resistance to hightemperature oxidation and erosion due to the formation of protective oxides such as nickel chromite (NiCr 2 O 4 ), chromium oxide (Cr 2 O 3 ) and aluminium oxide (Al 2 O 3 ) at an elevated temperature of 900 • C. Feng et al [3] also investigated the high-temperature oxidation resistance of laser-cladded coatings and concluded that protective oxides prevented the diffusion of oxygen into the coating layer.…”