GALVANIZING 2.0

Equipment, machinery and buildings used in the agricultural sector are subjected to a wide range of stresses - and this also applies for the parts and components they contain. As a result, in addition to the function of corrosion protection, surface protection for these components needs to satisfy a large number of different requirements. For example, coatings used here typically need to withstand high levels of chemical stress, such as from fertilizers or silage. They need to display optimal adhesive properties and be temperature resistant, particularly when used in the vicinity of the engine and wheels. In addition, the coating process should be characterized by ease of handling, including for large parts, optimized warping and setting behavior, the avoidance of brittling and ensuring of lubricating properties. Finally, the entire process should be as efficient and economical as possible, as well as environmentally friendly.

This complex blend of requirements is faced with a wide range of potential surfaces, typically selected and specified by the constructor of the respective component. Thus far, blue passivation or chromium(VI)-based yellow chromating have frequently been used, with these largely able to fulfill the corrosion protection requirements specified by the agricultural machinery manufacturers. However, due to the continuing raising of requirements, these galvanic systems currently employed are no longer sufficient for the task. Galvanic zinc alloy systems are sometimes the solution. In the majority of cases the components of agricultural machines and equipment receive a KTL coating followed by a powder coating. The reason for the favored use of this system is above all the good appearance, but also economy and process-safe and relatively unproblematic application. However, KTL reaches its limits when faced with damage to the surface: cathodic corrosion protection cannot be provided here. If damage to the KTL coating extends to the base metal, the substrate will always corrode quickly. As a consequence, many manufacturers of agricultural machinery accept signs of corrosion - also in view of the fact that the large dimensions of the components mean that they are not initially inhibited in their function by even severe red rust. However, premium manufacturers in particular are increasingly placing value on the long-term, high-quality appearance of their products, or their functionality calls for a higher level of corrosion protection. Hot-dip galvanization represents an
alternative here. It provides cathodic protection, but is limited in handling, as well as regarding the high temperatures employed. The frequent reworking required and subsequent considerable weathering can also be a problem.

Under this motto Dörken Coatings offers high-performance, chromium(VI)- free alternatives to standard electroplating, but also other coating structures. DELTA-PROZINC^® is an electroplating range that encompasses the entire process - from pretreatment to zinc-based baths and onto passivation and sealing, with and without integrated lubricant. The nickel and cobalt-free system is distinguished from, for example, classic blue passivation by its chromium(VI)-free surfaces and significantly higher corrosion protection. The process-safe, standardized surface protection system offers resistance for the 8 μm to 15 μm galvanic coating of at least 360 hours against coating corrosion and 720 hours against base metal corrosion in salt spray testing as per DIN EN ISO 9227. In the event of damage to the surface the cathodic protection takes action, with the zinc in the surface sacrificing itself. The systems are free of solvents and complexing agents, making them innocuous to health and resource preserving. The surfaces also boast a long-lasting decorative metal finish.

In addition to DELTA-PROZINC^®, with the DELTA-PROTEKT^® series Dörken Coatings offers a zinc flake system as a capable alternative to KTL coating or hot-dip galvanization. The Dörken zinc flake systems offer cathodic corrosion protection via the sacrificial effect of a particular zinc alloy. With a film thickness around 10-25% of the standard thickness. The scale-like arrangement of the flake layers creates a barrier effect that significantly retards the onslaught of corrosive media such as moisture and oxygen in comparison to conventional galvanic corrosion coatings. The risk of application-related hydrogen embrittlement in high-strength components does not exist, as no hydrogen is present in the coating process. A further advantage is that the zinc flake systems can be used on large components as a spray application, in addition to dipping.

The choice of the coating technique to be applied depends on the respective part as well as individual customer requirements. Dörken Coatings helps you to develop your own special requirements profile and develops a combination of coating system and technique tailored specifically to this. Dörken Coatings has a free sampling and testing service as well as “The Academy" training center, tailored to the individual requirements of agricultural machinery construction.