Effect of the interface morphology and initial nanocrack on the fracture property of a ceramic reinforced plasma-sprayed coating

The introduction of ceramic particles can greatly improve the mechanical properties of plasma-sprayed coatings. The coating morphology obtained during deposition and thermal stress inducement at the ceramic/alloy interfaces affect the initial nanocrack formation and the failure mechanism, which were investigated in this study. Scanning electron microscopy and scanning transmission electron microscopy with energy dispersive X-ray spectroscopy were used to examine the morphology of the initial nanocracks, the phase composition at the ceramic/alloy interfaces and the fracture characteristics. During plasma spraying, different ceramic particle morphologies resulted in different deposition structures with various curvatures. The fracture results indicated that the interface between two adjacent ceramic particles or areas with small ceramic particles were weak areas. Nanocracks formed at the ceramic/alloy interfaces and then developed along the interface between ceramic particles. The effects of the morphology of ceramic particles on the inducement of thermal stress, the formation and evolution of nanocracks and the fracture characteristics of plasma-sprayed coatings are discussed.