The interplay of crack hopping, delamination and interface failure in drying nanoparticle films

Abstract

Films formed through the drying of nanoparticle suspensions release the build-up of strain through a variety of different mechanisms including shear banding, crack formation and delamination. Here we show that important connections exist between these different phenomena: delamination depends on the dynamics of crack hopping, which in turn is influenced by the presence of shear bands. We also show that delamination does not occur uniformly across the film. As cracks hop they locally initiate the delamination of the film which warps with a timescale much longer than that associated with the hopping of cracks. The motion of a small region of the delamination front, where the shear component of interfacial crack propagation is believed to be enhanced, results in the deposition of a complex zig-zag pattern on the supporting substrate.

Controlling the drying-induced peeling of colloidal films

“…Although much literature has dealt with eliminating cracking in thin colloidal films, very few studies exist with regards to the prevention of drying-induced peeling of such films. [26][27][28] Peeling occurs when the film detaches from its substrate, and a peeling film typically also curves upwards as it dries (as is commonly seen for example in drying clay or mud 44 ). A Griffiths-like criterion for peeling can be made for when the strain energy stored in the film overcomes the adhesion energy holding the film in contact with the substrate.…”

Thick Free-Standing Metallic Inverse Opals Enabled by New Insights into the Fracture of Drying Particle Films

“…Delamination cracks (Figure 1B), also known as interface cracks, propagate along the film−substrate interface and delaminate films from substrates. 46 Channeling cracks, on the other hand, propagate in the body of films and create channels normal to the substrate surface that break the film into separated domains (Figure 1C). 47 For simplicity, we abbreviate delamination and channeling cracks as D-cracks and C-cracks.…”

Deformation of Single Crystals, Polycrystalline Materials, and Thin Films: A Review

“…However, owing to the large differences in sample requirements and test environments, the results of different test methods for the same sample may be inconsistent. Nanoindentation and nanoscratch are widely used to characterize the mechanical properties of small-scale homogenous materials and the adhesion of thin films [82].…”