Anticorrosive materials

Catalog. Zinc-filled materials (Cold galvanizing of metal)

Zinc-filled materials are the VMP Holding "trademark". They were developed and entered into the Russian corrosion protection market in 1990s. Technology of metal corrosion protection by zinc-filled coatings is "cold" galvanizing, it has become a worthy alternative to hot-dip galvanizing.

Advantages of "cold" galvanizing of metal

The VMP complex anticorrosive coatings with zinc-filled primers ensure protection of metal structures used in industrial atmosphere, up to 30 years.

In zinc-filled compositions cathodic protection of steel is performed due to the high content of zinc powder (as a rule, 85-96 % wt) and difference in electrochemical potential of zinc and iron, similar to zinc metal coatings. When exposed to corrosive media or when a defect appears on a coating, zinc oxidizes, preventing steel corrosion and removing the damage.

Therefore, the use of zinc-filled compositions can be considered a special protection technology, named “cold” galvanizing (by analogy with hot galvanizing).

Along with the cathodic (protector) protection mechanism, zinc-filled coatings have a barrier mechanism characteristic of standard paintwork materials. The importance of the latter increases during operation. This is due to the fact that during the oxidation of metal powder, insoluble zinc corrosion products are formed in coating micropores that prevent the access of corrosive agents to steel. Due to this property, the zinc oxidation rate in zinc-filled compositions is lower compared to hot galvanized coatings, and their service life is consequently longer.

Zinc-rich coatings allow implementing the unique protective properties of zinc where traditional galvanizing methods almost cannot be used, for example, on large-sized structures, during repair, at a construction site, where a production base necessary for galvanizing is unavailable.

Development and production of zinc-filled compositions is one of the main areas of activity of VMP. In this regard, in recent years, a range of zinc-filled compositions based on effective film-formers have been developed, considering the global development trends in the field of anticorrosive paintwork materials. These are ZINOTAN polyurethane composition, ZINEP epoxy primer, ZINOL paint based on modified polymer base, as well as special purpose materials: ZINOTERM heat-resistant composition, ZINOL-SV paint designed for painting under contact welding, material designed for temporary and inter-operational protection of steel products – ZFES-MO.

Based on the produced materials, complex coating systems have been developed for long-term protection of different facilities: steel structures of industrial enterprises, bridges, tanks and pipelines for different purposes, hydraulic facilities, etc. They are based on widely used in the world principles of design of coating systems with increased reliability, including: 

• combination of layers with different protection mechanisms (cathodic, barrier, inhibitive), providing qualitative improvement of reliability of the whole system in general;
  
• use of paintwork materials based on polymers that are highly effective in terms of insulating properties and chemical resistance (for example, polyurethanes, epoxides and their modified forms) and pigments, that allow to implement any of the protection mechanisms to the full extent.
  

Complex VMP coating systems contain 1-2 layers of zinc nanopowder converter and 1-2 layers of coating materials (intermediate and top layers). The binding base in the coating system, as well as the properties of zinc powder, are determined by the facility type, for which they are designed, and operating conditions.

The following materials are widely and successfully used in VMP coating systems as coating materials:

• compositions based on flake pigments with increased barrier properties: based on micaceous iron ore – FERROTAN; based on aluminum powder – ALPOL, ALUMOTAN, ALUMOTERM;
  
• urethane and acrylic enamels of POLYTOn brand that are tinted according to the RAL color catalog. The function of the coasting layers is to enhance the barrier properties of the coating and protect the primer against atmospheric aggressive factors that, in general, slows down the zinc oxidation and prolongs its protective effect. Furthermore, they provide greater strength, resistance to abrasive wear and, at the same time, decorate the painted surface.
  

Polyurethane-based VMP materials that are represented as both one-pack materials cured by air moisture – ZINOTAN, FERROTAN, ALUMOTAN, POLYTON-UR and two-pack enamels – POLYTON-UR (UV) – characterised by increased resistance to UV-radiation.

So, the main feature of VMP coating systems is that they provide double protection of steel – by protector and barrier mechanism. Increased reliability and durability of zinc-filled coatings (service life more than 30 years even in the severe operating conditions) corresponds to the recognized international standards.