Striation formation

Birnie, D. P. 2001. Rational solvent selection strategies to combat striation formation during spin coating of thin films./. Mat. Res. 16 1145-1154. 

Fig. 42. Schematic representation of correlation between loading phase with crack propagation, craze growth and striation formation during continuous crack growth (in PMMA)...

We have published a demonstration of this strategy for an isopropanol-based aluminum-titanate sol-gel system.The seleeted addition of ethyl acetate was effective at preventing striation formation for the aluminum-titanium recipe. More... 

Figure 10.3 Reprinted from Smolsky, I.L., Voloshin, A.E., Zaitseva, N.P., Rudneva, E.B., and Klapper, H. (1999) X-ray topographic study of striation formation in layer growth of crystals from solutions, Phil. Trans R. Soc. Lond. A. 357, 2631, with permission from the Royal Society.

Haas (2001c) Detecting the onset of striation formation in reol-time during spinning by laser diffmction method Shkitions were found to be formed on solvent evaporation... 

Striation formation is an essential part of the distributive mixing process. In Chapter 2 it was shown diagrammatically how an individual pellet was transformed into a striation in a simple laminar shear field - the mechanism available for mixing in single screw extruders. 

Fig. 2.25 Clack tip blunting and growth in during loading and closure upon unloading that leads to striation formation through the crack tip plastic slip mechanism [30]...

Laird has given a rather different interpretation of striation formation based on the so called plastic relaxation of crack tip that is schematized in Fig. 2.26 [31]. Figure 2.26a refers to initial condition where crack is idling. Then the load is applied, Fig. 2.26b and crack tip plastic slips occur on both sides. At maximum load, Fig. 2.26c, the tip is fully blunted. With load inversion, Fig. 2.26d, crack tip closure takes place by reverse plastic flow that leaves the crack in the same initial condition, but with a new formed elementary free surface that testifies the crack growth, Fig. 2.26e. Last stage, Fig. 2.26f, represents the new loading phase similar to (b). Note that the process, that Laird called plastic relaxation, is based on the... 

Fig. 2.26 Schematic of striations formation based on crack tip plastic relaxation [31]...

Fig. 2.32 Fatigue striations in 6A1-4 V titanium alloy [35]. Same area shows striations formation...

Fig. 2.40 Schematic of crack tip brittle growth by corrosion fatigue that leads to brittle striations formation a hydrogen abscnption driven by high triaxiality elastic stress field, b brittle growth...

This dependency on the square of is in accordance with all theoretical models of striation formation [16, 34, 35]. However, the exponent n of the Paris-Erdogan Eq. (10.10) varies from 2 to even 5, as in cast iron. Values of n higher... 

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