Thermal spray coatings applications

Deshpande, S., Kulkarni, A., Sampath, S., and Herman, H. (2004) Application of image analysis for characterization of porosity in thermal spray coatings and correlation with small angle neutron scattering. Surf. Coat. Technol., 187, 6-16. 

Fauchais P, Vardelle A (2012) Thermal sprayed coatings used against corrosion and corrosive wear. In Jazi HS (ed) Advanced plasma spray applications. Published under CC By 3.0 license, doi 10.5772/34448. www.intechopen.com... 

In Thermal spray processes the nature of the process was described here, applications to adhesion are presented. Thermal spray coatings for applications involving adhesion are in three general areas, metallic bond or anchor coating, ceramic bond coat, and sprayed polymer as the adhesive. In many cases, the surface modification by the deposition of a thermally sprayed coating is an alternative to environmentally hazardous methods. The thermal spray process is a dry process in which the effluent is collected in a dry cartridge system and usually recycled. 

Thermal-spray coatings consist mostly of WC, Cr2C3, and to a lesser degree TiC and AIN. They are relatively inexpensive and widely used in corrosion and wear applications particularly in the gas-turbine industry. 

Ceramographic methods have proven indispensable in the characterization of thermally sprayed coatings, in which non-destructive testing methods for purposes of quality assurance have only limited applicability. Characteristic properties of a coating, such as its thickness, structure, porosity, and adhesion to the base material, as well as the hardness of individual phases or the overall composite, can be accurately evaluated by applying these ceramographic methods to the polished section. 

Guide for Selecting One-Coat Preconstruction or Prefabrication Painting Systems Interim Specification for the Application of Thermal Spray Coatings (Metallizing) of Aluminum, Zinc, and Their Alloys and Composites for the Corrosion Protection of Steel Latex Painting System for Industrial and Marine Atmospheres, Performance-Based... 

Longo, F. N. Thermal Spray Coatings New Materials, Processing and Applications. Metals Park, OH ASM International, 1985. 

Table 14.7 Limits and Applicability of the Main Techniques for Producing Thermal Spray Coatings...

For critical applications, and since thermal-sprayed coatings are not homogeneous materials, it is... 

This is the case, for instance, for K2Sip6 which in an aluminothermic reaction provides in situ the Al-Si clad (molten fiUer metal) normally used for controlled atmosphere brazing (CAB) of aluminium. In the case of zinc, the primary objective is not only to form a clad but to obtain a homogeneous diffusion layer into the aluminium, which is needed for some applications and which would have to be otherwise applied by costly intensive methods like electrochemical galvanization, plasma coating or thermal spray coating. 

Ramaswamy P, Seetharamu S, Varma KB, Rao KJ. Thermal barrier coating application of zircon sand. Journal of Thermal Spray Technology. 1999 8 447-453. 

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 ... 

Chemical vapor deposition competes directly with other coating processes which, in many cases, are more suitable for the application under consideration. These competing processes comprise the physical vapor deposition (PVD) processes of evaporation, sputtering, and ion plating, as well as the molten-material process of thermal spray and the liquid-phase process of solgel. A short description of each process follows. For greater detail, the listed references should be consulted. 

Most metals and many refractory compounds can be thermal-sprayed. Applications include coating of gas-turbine components for aircraft and industrial use, components of steam turbines and diesel engines, components for the oil and gas industry, paper and pulp industry, and chemical processing industry. 

Chromium carbide is important in powder preparations designed for thermal spray applications of corrosion and wear-resistant coatings on tool and machine parts. Lower carbon carbides of chromium are important in hardfacing rods and electrodes for weld-applied overlays on machine wear surfaces. However, these carbides are usually formed in situ from Cr and C in the rod and not added as preformed carbides. The properties of Cr3C2 are listed in Table 2. 

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