A Feasibility Study of Electro-Spark Deposit 'Sandwich-Like' Coating on Thermal Sensitive Superalloy
Gas turbine components are subjected to high temperature and high stress during engine operation, so they often become physically damaged due to the formation of cracks, voids and worn surfaces. In order to develop a new process for repairing gas turbine components with high strength filler materials, an attempt has been made to prepare IN738/NiCrSi/IN738 sandwich-like coating on thermal sensitive superalloy IN738 substrate and heat-treat it in a vacuum furnace. The microstructure morphologies, hardness and element distribution of as-deposited and as- heat-treated coatings have been investigated. The results showed that there were lot of cracks and voids in the deposited ‘sandwich-like’ coating but they could be eliminated by heat treatment. The diffusion of activated element Si in the sublayer NiCrSi of ‘sandwich-like’ coating was beneficial to healing cracks.
Xianghua Liu, Zhengyi Jiang and Jingtao Han
J. Zhang et al., "A Feasibility Study of Electro-Spark Deposit 'Sandwich-Like' Coating on Thermal Sensitive Superalloy", Advanced Materials Research, Vols. 148-149, pp. 783-787, 2011