Nano Multilayer Structure Toughening of Hard Coatings-Method, Mechanism and Application

Abstract

The toughening of hard coating is becoming very important from engineering point of view. Nano multilayer structure is one of the effective way towards toughening. A comprehensive discussion on composition and toughening mechanism of structure toughening was presented. The effect of period, period ratio and microstructure on toughening, and the application of multilayer structure toughening in wear and erosion were also discussed. Micro-crack deflection is the main mechanism of toughening, but the more interface, the more initiation of cracks, results in spalling failure in case of little interfacial toughness. It can be concluded that interface quality rather quantity dominates toughening effect. In order to show the advantage of nano multilayer film, a good interfacial toughness must be obtained,and the blocking of the propagation of micro cracks should be considered from fracture mechanics point of view.

Keywords

• hard film
• nano multilayer
• toughening
• interfacial toughness
• erosion