The dissociation of NZP (Ca_(0.5)Sr_(0.5)Zr_4P_6O_(24)) during plasma spraying during plasma spraying

Sodium zirconium phosphate (NaZr_2P_3O_(12) or NZP) was first systematically evaluated in the early 1980s by Roy and co–workers, who demonstrated its extremely low coefficient of thermal expansion (CTE). It was later shown that other group IA and IIA atoms can be ionically substituted into the NZP crystal structure to adjust the CTE. As a result of their low and tailorable CTEs, NZP’s have potential use as a protective coating for silicon–based ceramics and carbon–carbon composites. One technique for the application of ceramic coatings employs plasma–spraying. In this process, powders are injected into a plasma flame, melted, and propelled onto a substrate. The resulting coating microstructure is typically composed of thin lamellae (from each melted particle) stacked on top of one another during each pass of the torch. In the current research, NZP has been plasma–sprayed using the recently patented small particle plasma–spray process. The microstructure was then analyzed using transmission electron microscopy and x–ray diffraction to identify the phases in the complex coating that resulted