SOLID PARTICLE EROSION BEHAVIOUR OF PLASMA SPRAYED COATINGS ON A FE-BASED SUPERALLOY

摘要

In the present investigation plasma sprayed metallic coatings of NiCrAlY and Ni-20Cr were deposited on a Fe-based Superalloy (32Ni-21Cr-1.5Mn-1Si-0.3Ti-0.3Al-0.1C and Balance Fe) by shrouded plasma spray process. NiCrAlY was used as bond coat in both the cases. Erosion studies were conducted on uncoated as well as plasma spray coated superalloy specimens using an air-jet erosion test rig at a velocity of 40m/s and impingement angles of 30° and 90°. Silica sand particles of size ranging between 150 and 212 μm were used as erodent. The coatings have been characterised for porosity, microhardness and microstructure. Erosion behaviours of the superalloy and plasma spray coatings are discussed. Of the two plasma sprayed coatings, the NiCrAlY coating gave the lowest erosion rate regardless of the impact angle.