Splat model

Further extensions of Madej ski s mod ell4011 may include (a) turbulence effect, (b) Rayleigh instability or Taylor instability and droplet breakup, (c) vibrational energy, and (d) influence of solidification on flow)514 Some issues related to the deformation and solidification of droplets on a flat substrate in splat quenching have been addressed in Refs. 380 and 514. To date, analytical models addressing droplet impingement on a semi-solid surface have not been found in available literature. 

Figure 5.22 Schematic model of a flattened particle splat exhibiting a sombrero-type morphology (Heimann, 2008).

And what does that mean In the 1920s Louis DeBroglie described electrons as both particles and waves because they have precise mass, go splat-splat-splat (or click-click-click ) into Geiger counters yet show interference like radio and light waves. It is one thing to say particle-waves and quite another to really picture them. Try it. Our problem is that electrons are outside of both our direct senses and experiences. As Bronowski notes, twentieth-century physics introduced abstraction and uncertainty and the need for what he describes as tolerance in modeling nature." The nineteenth-century satire Flatland by Shakespearean scholar Edwin A. Abbott illustrates our limitations. ... 

Dhiman and Chandra [20] developed an analytical model to predict the substrate temperature at which splashing would occur by using a one-dimensional model for solidification of a molten metal droplet in contact with a semi-infinite substrate. They assumed that splashing occurred if the thickness of the solid layer reached that of the splat by the time the droplet had finished spreading. The thermal contact resistance between the droplet and surface was found to play a critical role in... 

FIGURE 9.13 Simulated mass spectra forrhodamine 101 using three model geometries 1, 5, and 8. Note that the m/z scale is reconstructed from the recorded time of ion splat. 

The finite array will be modeled by a finite number of infinitely long column arrays (also called stick arrays see Fig. 4.1). This approach has been widely used by several researchers [74-80]. One of them, Usoff, wrote as part of his dissertation [24] the computer program Scattering fi om a Periodic Array of Thin Wire Elements (SPLAT). The excitation can be either in the form of an incident plane wave propagating in the direction 5 = + ysy + zsz (passive case). Or... 

The second kind of surface wave denoted Type II can exist only on finite periodic structures with or without dielectric slabs. It will therefore not show up in computer codes based on infinite array theory such as the PMM program. But it does show up in the SPLAT code that incidentally can model only dielectric shells around the elements and not dielectric slabs. This kind has been investigated in this book but is less documented than Type I. In contrast to Type I, Type II can exist only for Dx/ < 0.5 and if we also typically are 20-30% below resonance (for simple straight elements). 

Fig. D.9 The scan Impedance for the center column when all three columns are fed with identical voltage generators with generator impedances equal to 100 ohms (to suppress surface waves). Dielectric cylinders are placed around the elements to model the undenwear. Includes matching section (see text). From the SPLAT program.

Thus it seems premature to further quantify the measured R-curve behaviour and to describe the toughening effect in a model. Yet an important conclusion can be drawn from the present study. Tailoring plasma sprayed TBCs with low crack resistance for segmentation cracks and high delamination resistance should focus on a reduction of the density of inter-splat mieroeraeks. Variation of the spraying parameters has the potential to systematieally ehange APS-TBCs with respect to the ratio of inter- and intra-splat defects in the lamellar microstructure. 

Figure 16.2 Mechanical application of SPLAT. Here, SPLAT is dispensed from a 57-L drum using a pneumatic pump supplied by an air tank (alternatively, a gas-powered air compressor may be used). This basic model can be replicated in any number of ways depending on the equipment available and field characteristics.

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