Sprayed coatings physical properties

The metals most used for corrosion protection by metal spraying are aluminium and zinc, both of which are anodic to steel in most environments. Physical properties of these coatings are shown in Table 12.6. 

PRINCIPLES OF APPLYING COATINGS BY METAL SPRAYING Table 12.6 Physical properties of sprayed zinc and sprayed aluminium... 

The physical and metallurgical properties of plasma sprayed coatings are generally superior to all other flame spraying methods, with the exceptions of hypersonic combustion and detonation gun systems. 

Polymers, specifically rubbery, amorphous polymers, have several inherent advantages as chemically sensitive sensor coatings diey can be deposited as thin, adherent, continuous films of fairly uniform thickness by solvent casting or spray coating techniques they are nonvolatile and of homogeneous composition and their chemical and physical properties can be modified to some extent by judicious choice of monomers and synthetic procedures. 

Bertrand, G., Collonges, G., Combes, C., Parco, M., Braceras, I., Alexis, J., Balcaen, Y., and Rey, C. (2014b) Comparison of physical-chemical and mechanical properties of chlorapatite and hydroxyapatite plasma sprayed coatings. Open Bioeng. J., in press. 

The properties required of plasma sprayed coatings may vary considerably depending upon the application for example, low porosity is necessary for wear resistance and corrosion protection but very porous deposit may be more suitable for thermal barriers. The physical properties of a coating of a given material will largely depend upon the spraying conditions. 

Powder coatings have been widely accepted in the industrial coating market because they are completely solvent free and show excellent mechanical and physical properties (13). Usually they contain a synthetic binder, a reactive cross-linker, pigments, and several additives to improve flow and other film eharacteristics. Various application techniques have been developed in reeent years. Powder coatings are normally sprayed electrostatically on grounded substrates and are heat-cured thereafter. Because these systems do not contain organic solvents, no emission of organic solvents takes place. However, the need for an oven to melt the resin and start the chemical reactions makes this environmentally friendly process unsuitable for do-it-yourself markets. 

This chapter introduced and briefly described a number of industrial surface treatments. These treatments are made to material surfaces for various reasons. One is to enhance the appearance of a finished product to attract potential buyers. Another is to improve the safety of products. Other purposes are to promote corrosion control and wear resistance, and to improve mechanical and electrical properties. The treatments discussed include electroplating, electroless plating, spray coating, galvanization, painting, anodizing, physical vapor deposition (PVD), and chemical vapor deposition (CVD). 

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