Лако-красочные материалы — производство

Zinc dust is the only sacrificial anticorrosive pigment (see Section 5.2.3) on the market with significant economical importance. Zinc dust is a blue-gray free-flowing powder composed of spheroidal particles [5.56]. In the past, the zinc dust for use in protective coatings was a by-product of zinc metal production. Today, zinc dust pigments for application in […]

Anticorrosive pigments have been divided in Section 5.2.3 according to whether they act as active pigments, barrier pigments or sacrificial pigments. Micaceous iron oxide pigments have been one of the most popular barrier pigments for nearly a century and have been proven in intermediate and topcoats for long-term corrosion protection of structural steel work [5.100]. […]

Zinc cyanamide (Zn(CN)2) was developed as a replacement for lead cyanamide (see Section 5.2.4.1) mainly for application in mirror coatings. The electrochemical effec­tiveness of cyanamides is attributed to a passivation action under alkaline conditions [5.56]. Zinc cyanamide is produced on an industrial scale from pure calcium cyanamide in an aqueous medium with zinc salts or […]

It was mentioned in Section 5.2.5.3, that special synergistic effects in the field of anticorrosives could be observed when using inorganic anticorrosive pigments in combination with organic corrosion inhibitors. Following this theoretical and in practice proven knowledge, there are pigments on the market referred to as syner­gistic hybrid pigment grade corrosion inhibitors. For example in […]

Since 1999, there has been a new anticorrosive pigment on the market, combining the hiding power of a white pigment with anticorrosive properties. This pigment is based on a titanium dioxide carrier material, which provides physical properties like light scattering [5.94, 5.95]. The surface of this titanium dioxide is treated with phosphate-containing anticorrosive substances (manganese […]

Ion-exchange pigments are based on calcium ion exchanged silica gel. These anti­corrosives are described as slightly porous pigments with a basic, calcium-exchanged silica surface, and a relatively high surface area. Therefore these pigments have a different chemical and physical identity compared to other types of anticorrosive pigments [5.92]. The typical properties of two commercially available […]

The inhibitive properties ofmolybdate-based anticorrosive pigments are attributed to the ability ofmolybdate ions to pass into solution, and to migrate to the metal surface resulting in the formation of a protective layer on the substrate, which insulates (passivates) the metal from attack and prevents corrosion [5.91]. The use of the pure molybdate-based pigments available on […]

These pigments, also termed core pigments, such as phosphate silicates (see Section 5.2.5.3), consist of a complex composite of alkaline earth silicates, like calcium silicate. Available commercial grades differ primarily in their B2O3-content and oil absorption value (Table 5.9) [5.53]. Tab. 5.9: Typical properties of calcium borate silicates [5.53]. Characteristic Unit Grade 1 Grade 2 […]

In general borates are alkaline. This alkalinity plays a major role in their inhibitive properties [5.51]. Due to the utilization of borate-based anticorrosive pigments, there is the possibility to maintain a high pH value in the coating [5.56]. Borate pigments may also form soaps (mainly calcium or barium, depending on the pigment) with acidic products […]

Commercial iron phosphide anticorrosive pigments consist of Fe2P, with traces of FeP and SiO2. These pigments are powders with a metallic gray color [5.56]. They are described as conductivity enhancers that are designed as a partial substitute for zinc dust in zinc-rich organic and inorganic coatings. When replacing zinc dust by up to 50% in […]