Electric arc metallization is a coating process that uses electricity to heat / melt zinc wire material. Direct current of different polarity is supplied to two consumable zinc wires, due to which the arc is ignited, the zinc wires are melted and the separated material particles are transferred to the spraying surface by a stream of compressed air. The use of direct current allows the arc discharge to be stabilized and the spraying parameters to be carefully controlled.
Electric arc metallization is characterized by excellent, in comparison with other technologies, productivity, high efficiency. In addition, equipment for electric arc metallization is distinguished by ease of use, unpretentious use, low requirements for the connection infrastructure, which allows it to be used both in a workshop with stationary electricity and compressed air lines, and in conditions outside the workshop, where it is sufficient to additionally use widespread industrial compressor and power generators.
Materials for electric arc metallization are produced in the form of zinc wires, including flux-cored wires.
Electric arc metallization involves the use of electrical energy to melt the material. The absence of open flame and combustion, such as such, allows the use of electric arc metallization in closed spaces. The use of electric arc metallization for spraying the inner surfaces of tanks for storage and transportation of food and oil products, ballast tanks is widely known; it is allowed to use metallization inside ventilated mines, etc.
The range of materials used is limited by the obligatory presence of conductive elements in the supplied material. Electric arc metallization is not applicable for the application of polymer, ceramic and other non-conductive materials.
The most common use of electric arc metallization is the deposition of low-melting materials (Zn, Al, their alloys).
The following zinc alloys are provided by Special Materials:
- AERIS 1427 — Russian analogue Ts0 — Alloy Zn 99.97%
- AERIS 1430 — Russian analogue Ts0 — Alloy Zn 99.995%
- AERIS 1435 — Russian analogue — no analogue — Alloy ZnAl15
- AERIS 1440 — Russian analogue — no analogue — ZnAl4 alloy
- AERIS 1445 — Russian analogue — no analogue — ZnAl2 alloy
Coating systems based on zinc and zinc alloys are characterized by a low electrochemical potential, which makes them suitable for corrosion protection of structural steels.
Such coatings prevent corrosion not only by insulating steel surfaces from corrosive environmental influences like paints and varnishes. The electrode potential, negative in relation to steel, galvanically protects the surface from corrosion even in the event of local damage to the coating. In addition, when using such coatings, the development of underfilm corrosion is in principle impossible, which very often occurs when using paints and varnishes.
Another significant advantage of metallized coatings is the high adhesion of metal coatings. Moreover, over time, adhesion only increases due to the mutual diffusion of metals, while any paint and varnish coating sooner or later loses adhesion and peels off due to the fundamental heterogeneity of materials.
In addition to anti-corrosion coatings, electric arc metallization can be used to apply wear-resistant coatings.
The use of specially designed flux-cored wires implies a three-stage coating formation process: first, the energy of the metallizer melts the flux-cored wire sheath, melting is an endothermic reaction; the heat released during the melting of the shell melts the charge mixture that fills the cord material.
Electric arc metallization, in contrast to high-speed spraying, which is widely used for the application of wear-resistant coatings, has a higher productivity and mobility, which makes it an excellent alternative for creating wear-resistant coatings, while the application of EDM coatings is much cheaper, but a distinctive feature of HVOF coatings is high porosity, which can in some cases lead to corrosion, as well as a lower level of adhesion.