Plasma spraying technique schematic diagram

The plasma spray technique has been used for about 30 years. Figure 10.12 shows a simple schematic diagram of a plasma torch. Basically, a powder is fed into the plasma, which is used as a heater, and the molten product is sprayed onto the substrate to form just about any thickness. The coatings tend to be porous and of poor adhesion. The adhesion can be improved by increased surface roughness of the substrate, which can be produced by grit blasting. An interlayer bond coat of Ni-Al... 

Figure 1.13 (a) Schematic diagram of the plasma spray process and (b) experimental setup of the electrostatic spray deposition technique. 

Like DART, DESI has received widespread acceptance as evidenced by more than 750 papers and conference presentations till mid-2014, referring to the technique since its introduction in 2004 by Cooks and coworkers [195, 196]. The technique makes use of electrospray ionization (ESI) that is widely used in the mass spec-trometiy of larger molecules in which a solution is nebulized to create a fine spray of very small droplets. In DESI, a standard electrospray of charged droplets hits the surface where the molecules of interest are present or adsorbed (including larger biomolecules), detaches them from the siuface, and delivers them as desolvated ions in the mass spectrometer. DESI is thus similar to DART (Sect. 8.4) where the gaseous plasma of ions from the ion source desorbs molecules from a surface. A schematic diagram of the main aspects of a DESI ion source is shown in Fig. 8.9. 

For use in ICP-MS, ions are sampled directly from the inductively coupled plasma. Special precautions are required related to the high temperatures in the plasma. A schematic diagram of an ICP-MS system is shown in Figure 2. In most cases, the liquid sample, which can be introduced directly from a vial, of a liquid-phase separation technique such as LC is nebulized into a separate spray chamber. The aerosol, containing the smaller droplets, is transported by argon to the torch, where the ICP is generated and sustained. In this so-called ICP flame, the analytes are atomized and ionized. The ions are directly sampled from the flame by the ion sampling aperture for mass analysis. 

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