Comparison of the Microstructure of Cold Sprayed and Thermally Sprayed IN 718Coatings

摘要

High-temperature nickel-based superalloys such as IN 718 arewidely used in gas turbine components as they remain stableat operating temperatures up to～750°C.There is now agrowing interest in the repair and refurbishment of suchcomponents using spray deposition techniques. A1thoughmany investigations have been carried out to study the effectof conventional processing on the microstructure andmechanical properties of IN718,much less attention has beengiven to the alloy when sprayed to form a coating.Thepurpose of the present study was to investigate and compareIN718 deposits produced by HVOF spraying and cold gasspray deposition Optical microscopy，scanning electronmicroscopy and X-ray difiraction were employed to examinethe microstructural evolution of the coatings and to comparethe deposition behaviour of the two different processesParticular attention was Paid to porosity,oxide couteut and theformation of secondary intermetallic phases. Coatingmicrohardness and bond strength were also measured Resultswill be presented and discussed in the context of the differeutthermal histories of the powder particles in the two processes.