Investigation of spalling mechanism of the thermal sprayed coating under rolling contact by FIB–SEM

The mechanism of the coating spalling under rolling contact was investigated. Fe–Cr coatings were deposited by plasma spray process. The rolling contact fatigue (RCF) experiments of the coatings were conducted. The tests were stopped before mass material losses. RCF traces were examined by a FIB–SEM device. Results show that some round or arc cracks on the coating surface were the origins of spalling. The cross-section SEM image of these cracks revealed that their inceptions are the microdefects within the coating, such as unmelted particles, oxides. The stress resulted from rolling contact was driver for the propagation of crack.

► FIB–SEM technique was used to investigate mechanism of coating spalling.
► Some cracks with round or arc shapes were found on the coating surface.
► Microdefects within the coating were considered to be the origins of coating spalling.