ASTM E363-09 Chemical Analysis of Chromium and Ferrochromium

Scope:

ASTM E363-09 standard method covers the procedures for chemical analysis of chromium and ferrochromium for defined limits. The following analytical procedures are described:

Test procedure:

Arsenic by the Molybdenum Blue Photometric Test Method- Arsenic is first separated by distillation as the trivalent chloride. Ammonium molybdate is added to form arsenomolybdate, which is then reduced by hydrazine sulfate to form the

molybdenum blue complex. Photometric measurement is made at approximately 850 nm.

                              Figure 1: Arsenic Distillation Apparatus

Lead by the Dithizone Photometric Test Method- After the dissolution of the sample, lead is precipitated with ammonium hydroxide. Interfering metals are complexed with sodium citrate and sodium cyanide, and the lead dithizone complex is extracted with chloroform. Photometric measurement is made at 520 nm.

Chromium by the Sodium Peroxide Fusion-Titrimetric Test Method- The sample is fused in sodium peroxide. After the dissolution of the melt in dilute sulfuric acid, chromium and manganese are oxidized by ammonium peroxydisulfate with silver nitrate as a catalyst. The permanganate ions are reduced with hydrochloric acid, and the chromate ions are reduced by adding an excess of standard ferrous ammonium sulfate salt. The excess ferrous ions are titrated with a standard potassium permanganate solution.

Specimen size: Samples weighing between 0.500 g to 1.000 g are used for the procedures.

Data: 

Where,

A = milligrams of arsenic found in 50 mL of final test solution, B = grams of sample represented in 50 mL of final test solution.

Where,

A = lead found in 10 mL of the final test solution mg, and B = sample represented in 10 mL of the final test solution in g.

Where,

A = millilitres of 0.1 N K₂Cr₂O₇ solution equivalent to 1 g of ferrous ammonium sulfate, B = grams of ferrous ammonium sulfate used, C = millilitres of 0.1 N KMnO₄ solution required to titrate the excess ferrous ammonium sulfate, and D = grams of sample used.