One-Layer Zinc Flake Base Coat for Fastener Protection

The demand for economic and reliable finishing products—especially with fastener coatings—is on the rise, and the same can be said about the growing need for corrosion protection systems.

Several markets requiring up to 720 hours in neutral salt spray test (NSST) are calling for simplified production processes, and Atotech’s silver inorganic zinc flake base coat, Zintek One, aims to exceed those requirements with only a single application layer.

Designed to reduce costs, energy consumption and coating line occupancy, the product removes the need for a second coating commonly required for reliable corrosion protection.

Atotech’s one-coat system can currently achieve 720 hours without base metal corrosion in NSST per ASTM B117. According to Dr. Volker Krenzel, Atotech technical manager, zinc flake coatings, this makes Zintek One a cost-effective alternative to standard zinc flake applications, hot dip galvanizing and conventional acid zinc-based corrosion protection finishes.

“This is a superior achievement for only one layer,” he says.

The base coat is applied in a single dip-spin coating step that achieves a layer thickness of 6 - 8 μm, which Dr. Krenzel says is comparable to the thickness of common two-layer zinc flake coatings. Offering a uniform surface even after mechanical stress, Zintek One is well-suited for bolts, screws, springs and parts used in construction, automotive and heavy industry applications.

“With Zintek One’s optimized flow characteristics, customers achieve uniform coating thickness distribution,” Dr. Krenzel adds. “Touch marks can be minimized and the layer thickness distribution made more homogenous, which in turn leads to more reliable and reproducible corrosion protection capabilities.”

Presenting no risk of hydrogen embrittlement, the company says the coating is ideal for high tensile fasteners (class 10.9 and higher). The coatings are also free of Pb, Hg, Cd, Ni, Co, and Cr⁶ and can be cured at moderate temperatures, minimizing concerns over annealing of high strength steel components.
According to Atotech, the company’s zinc flake coating systems can be modularly and individually adapted to various OEM requirements, utilizing various top coats.

“Successful trials in Germany, Italy, Asia and the U.S. have raised great interest towards Atotech’s one-coat system,” says Neil Patton, Atotech business manager, zinc flake coatings, “largely because of the beneficial qualities that improve throughput capacities, resulting in less handling, thus reducing potential damage to the customer’s parts.”

Atotech NA business development manager of zinc flake coatings, Scott J. McEuen, adds that it’s not just the one-coat quality that is gaining popularity.

“The excellent aesthetics provide a uniform silver appearance combined with outstanding corrosion protection make Zintek One, as a single-layer system, very appealing to coating companies, parts manufacturers and OEMs alike,” he says.

For more information, visit atotech.com.

Originally published in the June 2017 issue.