DAI Inc., a major designer and manufacturer of satellite antennas ranging in size from 7.5 meters to 21 meters, uses ZRC Cold Galvanizing Compound to protect its products around the world. Based in Dallas, Texas, DAI is an international business and its customers can be found in every corner of the globe. The company has been using and recommending ZRC as a highly reliable rust-preventative since DAI's inception.
Each antenna is custom designed to specific user requirements. Typical DAI applications include parabolic antennas for telecommunications, Intelsat satellite A earth stations and TT&C (telemetry, tracking and control). DAI antennas are used widely in both new construction and refurbishing projects.
Lasting Protection Without Hot-Dip Galvanizing
DAI's Director of Materials Sandy Boog-Scott reports that regular field inspections indicate that this coating will last the 15 year expected life span of the antenna installations with only minor touch-up.
"DAI needed a coating that was equivalent to hot-dip galvanizing since many major components are too big to fit in the galvanizing tanks," explains Boog-Scott. "ZRC provides the equivalent corrosion protection of ASTM A 123 galvanizing and is applied directly over sandblasted A 36 steel prior to topcoating with chlorinated rubber or epoxy."
Specially Formulated For Use Over Hot-Dip Galvanizing
The company also uses ZRC as a primer over hot-dip galvanizing. Galvanizing, primarily due to its very smooth and hard surface, can be difficult to paint. ZRC is specially formulated to be applied directly to the galvanized surface (with no passivation necessary) to allow/improve topcoat adhesion, while providing additional rust protection.
Applied like paint, ZRC provides the galvanic protection of zinc and a physical barrier from contaminants. As the zinc is sacrificed, insoluble corrosion by-products are formed. These by-products fill voids and pores in the zinc primer film, forming an insoluble barrier which further prevents attacks on the zinc film and steel substrate. Many of these corrosion by-products also tend to inhibit the rusting process by increasing the Ph level.
Unlike ordinary paint, zinc-rich primers continue to provide protection against rust and rust creepage even if the protected surface is scratched to the bare metal. The zinc forms a layer of insoluble zinc salt over the exposed area, thereby "healing" the break and providing continued protection against corrosion.
According to Sandy Boog-Scott, most customers request zinc protection. "ZRC is our standard finish. If it is not requested, we recommend it."
The results have been outstanding. The curtain assemblies are in full operation with no sign of corrosion. This despite being in an environment of total immersion.
