Driving force for reactive wetting

From these results and other experiments (Kritsalis et al. 1994, Landry et al. 1996, Landry et al. 1997), it has been concluded that wetting in reactive systems is governed by the final interfacial chemistry at the triple line rather than by the intensity of interfacial reactions. The key question is to determine the interfacial 

An example which confirms the validity of equation (2.15) is Au-Ti alloy on A1203. Pure Au does not wet A1203 (at 1150°C, 00 = 135°) but a Au-6 at.% Ti alloy wets this substrate (0 = 69°) due to the formation of Ti203 at the interface (Zhuravlev and Turchanin 1997). Effectively, the same angle is displayed (9 = 67°) 

This example shows that, when the contact angle on the reaction product, 0P, is higher than the contact angle on the substrate, 0S, and in the absence of perturbation, the final contact angles 0F are characteristic of the reaction product and not of the initial substrate (0F 0P). This is the same conclusion as that drawn in the previous Section for the case when 0P is lower than 6s (equation (2.15)). 

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