ELECTRIC ARC PROCESS

Electric arc, sometimes also called twin wire arc, is a process that uses two wires, electrically charged and run into a dead short. The heat produced by the electricity in the short is sufficient to melt most materials. Compressed gas — usually air — is then used to project the molten particles onto the work piece.

Process Characteristics
Arc coatings are typically well bonded, although bond coats — special coating layers used to improve the strength of subsequent layers — are often used. Coatings can range from relatively porous to quite dense. Arc spraying is very versatile in terms of applying metals and some cermets. Arc is especially useful for thick overlays or coatings on large areas. It's also especially effective as a process for coating projects done on site.

Materials Used
There has been a great deal of development of materials for arc spraying in recent years. Cored wires have been produced resulting in coatings containing ceramics and cermets that greatly enhance performance characteristics of the coatings making arc spray an even more versatile process.

All materials that can be drawn into wire form may be sprayed with the arc process. In addition, development of a broad range of cored wires — wires that are made of a conductive sheath filled with a different material — has substantially broadened the scope of the arc spray process. Materials exist that combine the metal sheath material with various carbide cermets and with ceramics. These materials often outperform traditional arc spray materials especially in the area of wear resistance and chemical corrosion resistance.