Spray deposition techniques

Leeuwenburgh, S.C.G., Wolke, J.G.C., Schoonman, J., and Jansen, J.A. (2006) Deposition of calcium phosphate coatings with defined chemical properties using the electrostatic spray deposition technique. /. Fur Ceram. Soc., 26 (4-5), 487 —493. 

A lightweight mat, not greater than 300 g/m may be used behind the gel coat in order to minimise the risk of air entrapment at the back of the gelcoat. This applies to both hand laminating and spray depositing techniques. 

Several methods for the incorporation of catalysts into microreactors exist, which differ in the phase-contacting principle. The easiest way is to fill in the catalyst and create a packed-bed microreactor. If catalytic bed or catalytic wall microreactors are used, several techniques for catalyst deposition are possible. These techniques are divided into the following parts. For catalysts based on oxide supports, pretreatment of the substrate by anodic or thermal oxidation [93, 94] and chemical treatment is necessary. Subsequently, coating methods based on a Uquid phase such as a suspension, sol-gel [95], hybrid techniques between suspension and sol-gel [96], impregnation and electrochemical deposition methods can be used for catalyst deposition [97], in addition to chemical or physical vapor deposition [98] and flame spray deposition techniques [99]. A further method is the synthesis of zeoUtes on microstructures [100, 101]. Catalysts based on a carbon support can be deposited either on ceramic or on metallic surfaces, whereas carbon supports on metals have been little investigated so far [102]. 

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

The suspension-free spray or cold spray deposition technique was proposed for the first time in 1999 as a simple method for the preparation of dense piezoelectric films at room temperature (Akedo and Lebedev 1999). The corresponding setup which can be used for suspension-free spray deposition of metal oxides consists of the parts shown diagrammatically in Fig. 20.29. In a continuously shaken... 

Fig. 2.2 Structures and scanning electron microscopy (SEM) photographs of different MALDI matrices deposited onto a stainless steel plate. Lower SEM photographs show E. coli cells cocrystallized with different MALDI matriees (matrix applied with a spray deposition technique). Arrows point to intact cells within the erystalline matrix. (Adapted from Toh-Boyo et al. 2012, eopyright American Chemical Society)...

Slurry Tape Casting In this method, a slurry or catalyst layer ink similar to that used in the spray deposition technique is spread onto the DM or directly onto the electrolyte via a doctor blade (Figure 6.4). This method produces high dimensional tolerance but is slower than physical spray deposition and less suitable for mass production. 

Drawbacks of these processes are capital cost and limited flexibility. Use of plasma spray deposition techniques requires sufficiently smooth surface of the underlying layer to be coated. Preformed perforated alloy sheets are thus preferably used for these processes. If the alloy is to be processed by powder metallurgy methods, fine-grained alloy powder is more favorable to produce substrate with small pore size and surface roughness. On the other hand, the resulting enhanced specific surface area may yield, after a certain operating time to Cr depletion in the porous substrate. This might induce non-protective breakaway oxidation if the critical Cr threshold is reached and subsequent breakdown in electrochemical performance. 

The use of spray deposition increases the range of solvents which can be used in moving-belt LC-MS and the range of solutes that can be studied by this technique. Since less heat is required to remove the solvent, it is less likely that the solute will be inadvertently removed from the belt or undergo thermal degradation. It is not, however, unknown for particularly volatile and labile analytes to be lost when using spray deposition. 

Particularly desirable among film deposition processes are solution-based techniques, because of the relative simplicity and potential economy of these approaches. However, the covalent character of the metal chalcogenides, which provides the benefit of the desired electronic properties (e.g., high electrical mobility), represents an important barrier for solution processing. Several methods have been developed to overcome the solubility problem, including spray deposition, bath-based techniques, and electrochemical routes, each of which will be discussed in later chapters. In this chapter, a very simple dimensional reduction approach will be considered as a means of achieving a convenient solution-based route to film deposition. 

Ion layer gas reaction (ILGAR) is an alternative sequential chemical deposition technique for which a metal-containing precursor solution is first transferred to the substrate by dipping (dip-ILGAR) or spraying (spray-ILGAR)... 

Allsop, N. A. Hansel, A. Visbeck, S. Niesen, T. R Lux-Steiner, M. C. Fischer, Ch.-H. 2006. The dry and damp heat stability of chalcopyrite solar cells prepared with an indium sulphide buffer deposited by the spray-ILGAR technique. Thin Solid Films 511-512 55-59. 

Liu et aU622] used a laser Doppler velocity and size (LDVS) measurement technique to determine the local size, velocity, and number flow density of droplets in the spray cone during spray deposition of a liquid steel. The experimental setup is schematically depicted in Fig. 6.7.1615] The measured results showed that smaller... 

Atmospheric Plasma Spray (Triplex APS). These deposition techniques will be used within this project to deposit the various layers in planar SOFC. 

Hardfaeing and Wear-resistant Alloys. These materials, essentially quaternary alloys of cobalt chromium, tungsten (or molybdenum) and carbon, are widely used for industrial hardfaeing purposes. They can be deposited by welding techniques, sprayed on as powders, or produced as separate castings. By using the weld deposition technique, a highly alloyed heat-, wear-, and corrosion-resistant surface can be applied to a... 

Chemical and physical vapor deposition technique has been widely applied for the preparation of such photocatalytic thin films. Since these vapor methods need an instrumental setup which enables control of temperature and pressure, their initial and running costs are generally high and the size of substrate is limited. Spray method, in which titanium alkoxide and water is sprayed on a substrate heated at a desired temperature, affords Ti02 thin films.69) However, like the sol-gel route, the physical properties and photocatalytic activity of Ti02 strongly depend on many factors such as temperature of substrate, flow rate of carrier gas, and partial pressure of starting material in the system. 

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