Zinc chromate

• Chromic acid zinc salt
• Zinc yellow
• Zinktetraoxychromat
• Chromzinkoxid

Lemon- yellow powder

Fixed

3.40 g · cm -3

648 ° C ( decomposition above 440 ° C)

Practically insoluble in cold water, decomposition in hot water

Risk

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Zinc chromate is a chemical compound (specifically, a chromate ), which is mainly used as a yellow pigment and corrosion inhibitor.

Production and representation

Finely ground zinc oxide ( zinc white ) is partially reacted with sulfuric acid to sulfate and then precipitated with potassium dichromate. After prolonged discontinuation of the precipitate is filtered off and rinsed.

In some wood preservatives formed in aqueous solution from the ingredients Zinkhexafluorosilicat and CK- salt ( containing chromium salts) of zinc chromate.

Use

Zinc chromate is a basic -reacting anti-corrosion pigment (that is, a strong oxidizing agent ). It works by neutralizing acids attacking, cathodic and anodic protection of the metal surface by redox reactions and by the inactivation corrosive chloride and sulfate ions by forming corresponding salts of low solubility (see also chromating). Previously, it has been widely used in " Washprimern " ( adhesion promoter between material and other coatings), but also in corrosion protection colors. In the RAL color system, it has the number 1018.

Safety

Zinc chromate acts (usually via inhalation of dust) carcinogenic and mutagenic.