Segregation phenomena during deposition of functionally graded zirconia-based ceramics with Stellite 21 on a steel substrate

Abstract

This report describes the co-deposition of ceramic-metal systems based upon yttria-stabilized zirconia, and gadolinium zirconate, with Stellite 21 via laser direct energy deposition (LDED). The segregation of un-melted ceramic particles and the depletion of stabilizing dopants observed in previous work [1] is replicated. The segregation of un-melted ceramic particles results in a surface coating which prevents further deposition. The depletion of stabilizing dopants from the ceramics results in phases which are known to lack stability at the high temperatures expected in such applications. We provide a mechanistic explanation for the compositional segregation phenomenon, which suggests that the pairing of lanthanide series – based ceramics such as yttria-stabilized zirconia and gadolinium zirconate with transition metal alloys such as Inconel and Stellite may be difficult to effectively utilize in a functionally graded coating.