Spray deposition process

FIGURE 6.13 Schematic diagram of plasma spray deposition processing, (a) Radial injection of feedstock into plasma torch, showing partial entrainment of feed particles into the plasma jet and (b) axial injection of feedstock into plasma torch, showing more complete entrainment of feed particles into the plasma jet. 

Figure 1.8. Schematic showing (a) plasma spray deposition process and (b) droplet formation, acceleration, surface impact, and coating formation.

Generally a very narrow droplet spectrum is obtained and the relative uniformity of the coating is improved accordingly. A further advantage of this method is that the gas flow rate is independent of the aerosol flow rate, which is not the case with pneumatic spraying. A modern spray deposition process can be described by relatively few parameters such as flow of carrier gas Q, concentration of the solution C, solution flow q, droplet radius r, distance between nozzle and substrate d, temperature of the gaseous environment Te, temperature of the substrates Ts and their speed... 

Herman, H. 1988. Plasma spray deposition processes. Mater. Res. Soc. Bull. 13 60. 

Spray deposition The spray deposition process, which was developed by Osprey Ltd during the late 1970s for producing monolithic alloys [365], has been adapted by several manufacturers to produce particulate-reinforced MMC billets with a residual porosity of 5% [366]. The porosity is eliminated by a secondary processing, such as extrusion or rolling. A spray gun is used to produce an atomized stream of aluminum alloy, into which heated SiC particles are injected. An optimum particle size is... 

Some review articles pertaining to spray pyrolysis processing and the range of thin films deposited by this technique for various appKcations have appeared in the literature. Viguie and Spitz [74] have classified chemical spray deposition process according to the type of reaction. A most recent survey on thin-film materials prepared by spray pyrolysis and advances in the field, especially different atomization techniques, was presented [12j. The critical operations for the spray pyrolysis technique are (1) preparation of uniform and fine droplets and (2) the controlled thermal decomposition of these droplets in terms of environment, location, and time. 

Spin-spray deposition process is a novel technique to plate high crystalline quality spinel ferrite film... 

Chamberlin R.R., Skarman J.S. Chemical spray deposition process for inorganic films. J. Electrochem. Soc. 1966 113 86-89... 

The chemically deposited tin oxide suffers from two important disadvantages as compared to the vacuum-deposited indium-tin oxide. At the high temperatures necessary for the spray deposition process, soft glass loses its flatness. The different approaches previously listed for creating the indium-tin oxide films can all be performed at sufficiently low temperature that the soft glass substrates do not warp. In liquid-crystal displays, where a relatively narrow spacing between opposite electrodes is required, the loss in flatness caused by the spray process is a distinct drawback. 

Chamberlin, R.R. Skarman, J.S. (1966). Chemical Spray Deposition Process for Inorganic Films. Journal of the Electrochemical Society. Vol. 113, pp. 86. 

Metal injection mol ding (MIM) holds great promise for producing complex shapes in large quantities. Spray forming, a single-step gas atomization and deposition process, produces near-net shape products. In this process droplets of molten metal are coUected and soHdifted onto a substrate. Potential appHcations include tool steel end mills, superalloy tubes, and aerospace turbine disks (6,7). 

The selection of a particular deposition process depends on the material to be deposited and its availabiUty rate of deposition limitations imposed by the substrate, eg, maximum deposition temperature adhesion of deposit to substrate throwing power apparatus required cost and ecological considerations. Criteria for CVD, electro deposition, and thermal spraying are given in Table 2 (13). 

Spray Pyrolysis. In spray pyrolysis, a chemical solution is sprayed on a hot surface where it is pyrolyzed (decomposed) to give thin films of either elements or, more commonly, compounds (22). Eor example, to deposit CdS, a solution of CdCl plus NH2CSNH2 (thiourea) is sprayed on a hot surface. To deposit Iu202, InCl is dissolved in a solvent and sprayed on a hot surface in air. Materials that can be deposited by spray pyrolysis include electrically conductive tin—oxide and indium/tin oxide (ITO), CdS, Cu—InSe2, and CdSe. Spray pyrolysis is an inexpensive deposition process and can be used on large-area substrates. 

Protecting a surface from corrosion by coating can be accomplished by a number of well-established processes which include paints, metal plating (with zinc or cadmium), diffusion, thermal spraying, and, more recently, vapor deposition processes. Of these physical vapor deposition (PVD) is used extensively in corrosion protection. Typical applications are ... 

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. 

Henne R. Solid oxide fuel cells a challenge for plasma deposition processes. J. Therm. Spray Tech. 2007 16 381-403. 

---