Characterizing the micro-impact fatigue behavior of APS and HVOF-sprayed ceramic coatings

The fatigue life of thermally sprayed Al2O3- and Cr2O3-based coatings has been studied under low -energy (0.7-5 mJ) impact conditions. A threshold impact energy and amount of repetitions the coatings can endure with said energy before catastrophic failure was obtained. The catastrophic failure was determined to occur when the fracture mode of the coating switched from brittle cone cracking to quasi -plastic radial cracking. The results are examined relative to the microstructural features along with other properties of the coatings -hardness and cavitation resistance. The experiment provided a new approach for a straightforward comparison of the micro scale impact fatigue life of thermally sprayed coatings unachievable with previous methods.