Comparison of the cohesive and delamination fatigue properties of atomic-layer-deposited alumina and titania ultrathin protective coatings deposited at 200 degrees C

作者：Sadeghi Tohidi Farzad^*; Samet David; Graham Samuel; Pierron Olivier N

来源：Science and Technology of Advanced Materials, 2014, 15(1): 015003.

DOI：10.1088/1468-6996/15/1/015003

• fatigue
• ALD
• harsh environment
• titania
• alumina
• ultrathin coatings

The fatigue properties of ultrathin protective coatings on silicon thin films were investigated. The cohesive and delamination fatigue properties of 22 nm-thick atomic-layered-deposited (ALD) titania were characterized and compared to that of 25 nm-thick alumina. Both coatings were deposited at 200 degrees C. The fatigue rates are comparable at 30 degrees C, 50% relative humidity (RH) while they are one order of magnitude larger for alumina compared to titania at 80 degrees C, 90% RH. The improved fatigue performance is believed to be related to the improved stability of the ALD titania coating with water compared to ALD alumina, which may in part be related to the fact that ALD titania is crystalline, while ALD alumina is amorphous. Static fatigue crack nucleation and propagation was not observed. The underlying fatigue mechanism is different from previously documented mechanisms, such as stress corrosion cracking, and appears to result from the presence of compressive stresses and a rough coating-substrate interface.

• 出版日期2014-2