Electric Arc Spraying
Schematic Diagram of the Electric Arc Wire Thermal Spray Process
As early as 1914, Schoop in collaboration with Bauerlin, an electrical engineer, experimented with electrical heating for spraying. In the Arc Spray Process a pair of electrically conductive wires are melted by means of an electric arc. The molten material is atomized by compressed air and propelled towards the substrate surface. The impacting molten particles on the substrate rapidly solidify to form a coating. This arc spray process carried out correctly is called a “cold process” (relative to the substrate material being coated) as the substrate temperature can be kept low during processing avoiding damage, metallurgical changes and distortion to the substrate material.
Electric arc spray coatings are normally denser and stronger than their equivalent combustion spray coatings. Low running costs, high spray rates and efficiency make it a good tool for spraying large areas and high production rates. Disadvantages of the electric arc spray process are that only electrically conductive wires can be sprayed and if substrate preheating is required, a separate heating source is needed. The main applications of the arc spray process are anti-corrosion coatings of zinc and aluminium and machine element work on large components.
Arc Spray Coatings
Arc Wire Sprayed 13Cr Steel on aluminium .