Sodium Dichromate Most popular product for Hot dip galvanizing and Protective coatings

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After thorough cleaning, the stainless steel part is ready for immersion in a passivating acid bath. Any one of three approaches can be used--nitric acid passivation, nitric acid with sodium dichromate passivation and citric acid passivation. Which approach to use depends on the grade of stainless steel and prescribed acceptance criteria.

More resistant chromium-nickel grades can be passivated in a 20 percent-by-volume nitric acid bath . As indicated in the same table, less resistant stainless grades can be passivated by adding sodium dichromate to the nitric acid bath to make the solution more oxidizing and capable of forming a passive film on the surface.

Another option, used in place of nitric acid plus sodium dichromate, is to increase the concentration of nitric acid to 50 percent-by-volume , The sodium dichromate addition and lit : higher nitric acid concentration both reduce the chance of undesirable flash attack.

APPEARANCE :: Odourless orange crystal grain
Na2Cr2O7· 2H2O :: 98.0% min
SULPHATES :: 0.4% max
CHLORIDES :: 0.2% max

Dichromates are power oxidizing agents which find applications in:

Chromium source in preparing chromium compounds
Leather tanning and screen printing
Electroplating
Pyrotechnics and explosives
Pigment preparation
Wood Preservative
Metal Treating and corrosion inhibitor
Oil drilling
Catalyst for the chromium metal production
Photographic engraving

In biological field, potassium dichromate is used as a fixative for used for conservation of tissue sections.

10588-01-9 (Anhydrous)

7789-12-0 (Dihydrate)

PHYSICAL AND CHEMICAL PROPERTIES

PHYSICAL STATE Odorless Orange to Red crystals or granules
MELTING POINT 357 C
BOILING POINT 400 C

SPECIFIC GRAVITY 2.35
SOLUBILITY IN WATER Highly soluble (74.0% at 25°C)

pH 3.0 - 4.6 upon concentration

VAPOR DENSITY 10

NFPA RATINGS
Health: 4; Flammability: 0; Reactivity: 2; Special Hazard: OX

FLASH POINT 400 C

STABILITY Stable under ordinary conditions

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