“…Unlike the AE monitoring of bulk ceramics and metals, the cracking mechanism in overlay coatings is dependent on the adhesive nature as well as microstructures of thin layer and substrate. AE response during indentation of thin films has indicated that it is dominated by the 'high intensity AE peaks' due to a number of failure modes such as film cracking 96,110,[141][142][143][144][145][146][147][148][149][150][151] and delamination 98,110,143,149,[152][153][154] with some evidence of AE associated with plastic deformation. 141,147 Research has focused on thin films deposited using techniques such as physical vapour deposition (PVD), 110,141,144,151 chemical vapour deposition (CVD), 143,145,147 microwave plasma chemical vapour deposition (MPCVD) 149,150,153,154 or plasma assisted chemical vapour deposition (PACVD), 142 and other process such as sputtering 152 or pulsed laser deposition.…”