GF98.00-P-2010A Galvanizing, General

GF98.00-P-2010A Galvanizing, General

The use of zinc as corrosion protection - e.g. the use of galvanized panels in vehicles - is problematic with regard to the availability of zinc. Sound estimates from experts assume that the availability of this metal worldwide will meet the requirements for a maximum of 20 to 25 years.
For this reason, DaimlerChrysler only uses galvanized panels (and even then, only in combination with organic protective coatings) in locations where extreme corrosion strain can be expected due to road salt, for example.

A fully galvanized body is therefore more than questionable from an ecological point of view. By accurately checking and weighing economic and ecological aspects, for DaimlerChrysler a mixed construction in all products (a combination of different materials) depending on the profile of requirements has proved its worth.

Ever-increasing amounts of different plastics and aluminum are being used as basic materials in areas that are susceptible to corrosion, which also make the structure lighter.

Corrosion protection using zinc
There are numerous ways of galvanizing steel (plate). A distinction is made between electrogalvanized (galvanic), sendzimir galvanized and hot-dip galvanized.

The corrosion protection that is provided by coating with zinc occurs because of the electrochemical reaction between the protective metal (zinc) and the basic material (steel). If the protective zinc coating is broken through at any point, a local galvanic cell is created because of the effect of the electrolyte (aqueous, electrically conductive solution).

The zinc represents the anode and the steel base metal represents the cathode. Being a base metal, the zinc goes into solution. The surface of the steel is therefore not attacked.

The cathodic protective effect of the zinc can be explained by examining positions of zinc and steel in the electrochemical series. This is known as zinc acting as the sacrificial anode. In combination with organic protective coatings, this produces the best possible corrosion protection.

Bona zinc corrosion protection
The Bona zinc treatment introduced with the A-class represents a new item in the area of corrosion protection on DaimlerChrysler vehicles. Bona zinc is the trade name of the PPG company and designates an organic zinc compound suitable for all requirements in automotive construction.
Among other things, the material is characterized by the fact that the Bona zinc layer adheres extremely well to the carrier material beneath it.
As a rule, electrolytically galvanized sheet metal is coated with Bona zinc. However, it is possible to protect the "bare" sheet metal surface with Bona zinc.

At the end of the manufacturing process in the steel manufacturing plant, the plates run through a station where a layer of liquid Bona zinc is applied.
The coat thickness that is achieved is approximately 3 to 4 micro m. The panels are coated on one side or both sides depending on the application.

The use of Bona zinc is a major advantage since no cavity preservation whatsoever is required, and the amount of PVC seam sealing is reduced to a minimum.