- Calcium chromate is an inorganic compound with the chemical formula CaCrO₄, consisting of calcium (Ca²⁺) and chromate (CrO₄²⁻) ions. It typically appears as a bright yellow, odorless powder or crystalline solid and is highly soluble in water.
- Like other chromates, calcium chromate is a hexavalent chromium compound, which means it contains chromium in the +6 oxidation state—a form known for its strong oxidizing properties and associated toxicity. Its chemical reactivity and pigment-like appearance make it useful in specific industrial applications, though its use is regulated due to environmental and health concerns.
- Calcium chromate has historically been used as a corrosion inhibitor, particularly in protective coatings for metals. When applied to steel or aluminum surfaces, it forms a passive oxide layer that prevents rusting and deterioration, especially in harsh environments such as aerospace and marine industries. It has also served as a pigment and oxidizer in paints, coatings, and primers, where its intense yellow color and oxidative strength were desirable.
- In the aerospace and defense sectors, calcium chromate has been used in chromate conversion coatings and as an ingredient in anti-corrosion primers. These coatings improve the adhesion of subsequent paint layers and enhance the longevity of metal parts exposed to high humidity, temperature extremes, or salt-laden environments. It also finds limited use in pyrotechnics and explosives, where its oxidizing nature contributes to ignition and combustion reactions.
- Despite its utility, calcium chromate poses significant health and environmental hazards. As a hexavalent chromium compound, it is classified as carcinogenic, mutagenic, and toxic upon inhalation or ingestion. Prolonged exposure can damage the respiratory system, kidneys, liver, and skin. Consequently, the use of calcium chromate is heavily regulated or restricted in many countries, with safety protocols requiring protective gear, containment, and environmental controls to prevent exposure and contamination.
- Due to growing environmental regulations and worker safety concerns, alternative materials and formulations are increasingly being adopted to replace calcium chromate in corrosion protection and industrial processes. Modern coatings and inhibitors often rely on non-toxic, environmentally benign compounds that can deliver similar performance without the health risks associated with chromium(VI).
