The new Volkswagen TL 180 specification requires a Cr(VI)-free black zinc flake coating with high corrosion protection for automotive parts. This coating is typically used on small, bulk processed threaded fasteners. Since the zinc flake technology presents no risks of hydrogen embrittlement, the coating is also suited for high tensile fasteners.
Automotive industry's expectations and requirements are particularly high when it comes to finishes appearance. As regards black finishes, uniformity and long-term stability of the color are among the main issues of concern. In addition to that, the TL 180 specification also requires excellent corrosion resistance, constant friction values and very good heat loosening properties.
With its zinc flake system Zintek Black, Atotech has met such challenging demands and gained the TL 180 approval. Combining Atotech's black base coat Zintek 300 B with specialized Techseal Black top coats, the Zintek Black system provides a uniform deep black appearance with no silver shine through even after handling. Furthermore, this system meets Volkswagen's friction values window and boasts excellent heat loosening properties, the company says.
The Zintek Black system also successfully passed TL 180 corrosion protection requirements: 720 h without red rust and 240 h not exceeding the S1 classification according to DIN 34804. At present, Atotech says it offers the only approved coating system to fulfill the requirements of Volkswagen's TL 180 specification for black finishes.