ASTM-C760:90(R2020) pdf free download – Standard Test Methods for Chemical and Spectrochemical Analysis of Nuclear-Grade Silver-Indium-Cadmium Alloys.
16.1 This test method is applicable to the determination of the trace impurities listed in 19.1 in silver-indium-cadmium alloys.
17. Summary of Test Method
17.1 The sample is cleaned, and a weighed quantity is dissolved in nitric acid. An equivalent weight of graphite is added to the solution and it is evaporated to dryness at 85 ± 5°C. The residue is moistened with a few drops of water and mixed until a slurry is obtained. A dilute hydrochloric acid solution is added and mixed well. The slurry is evaporated to dryness at 85 ± 5°C in subdued light.
17.2 The dried sample mixture is blended with a barium fluoride-graphite calTier. weighed into graphite anode caps. and excited in a d-c arc. The spectrum is recorded photographically, and the spectral lines of interest are compared visually with standards exposed on the same plate.
18. Apparatus
18.1 Spectrograph—A spectrograph with sufficient resolving power and linear dispersion to separate the analytical lines from other lines in the spectrum of the sample in the spectral region from 220 to 400 nm is recommended. Instruments with a reciprocal linear dispersion of 0.3 nm/mm or less are satisfactory.
18.2 Exciratiomi Source—A d-c arc source capable of sustaining a 12-A d-c arc.
1 8.3 Excitation Stand—Conventional type with adjustable water-cooled electrode holders.
18.4 Balance—A torsion-type balance with a capacity of 1.0 g and capable of weighing to the nearest 0.5 ing.
18.5 Pulverizer-Mixer—A mechanical mixer with a plastic vial and ball.
18.6 Comparator—Conventional type is satisfactory.
20. Procedure
20. 1 Preparation of Standards:
20.1.1 A minimum of four standards containing 1 to 1000 tg/g of each impurity element to be determined by blending known amounts of each impurity oxide or salt with a graphite matrix.8
20.1.2 Dissolve 20.00 g of silver metal. 3.75 g of indium metal, and 1.25 g of cadmium metal in 75-mL of 8 N HNO1. Cool and dilute to 200-mL in a volumetric flask with double- distilled water.
20.1.3 Pipet 2 mL of the Ag-In-Cd solution (see 20.1.2) into each of five TFE-fluorocarbon beakers (25-mL capacity). Weigh 250 ± I mg of graphite into the first beaker and 250 ± I mg of each graphite base standard (see 20.1 . 1) into the four remaining beakers, one standard in each of the beakers.
20.1.4 Thoroughly mix the graphite and the solution using a TFE-fluorocarbon stirring rod and carry through the sample preparation procedure starting with 20.2.5.
20.2 Preparation of Samples:
20.2.1 Clean 0.5 to 1.0 g of sample with file, wash with organic solvent, and air dry.
20.2. 11 Use a mechanical mixer to blend 100 mg of sample with 100 mg of BaF,-graphite carrier in a plastic vial with a plastic ball for 30 s.
NOTE I—The actual carrier is the mixture of BaF, and AgCI. The BaF2-graphite is not sufticient if the silver in the sample is not converted to AgCI.
20.2.12 Weigh duplicate 50-mg charges of samples and standards into ASTM Type S-2 anode caps.
20.2.13 Tap pack, vent the charge, and electrically excite under conditions listed below.
20.3 Spectrographic Procedure—Excitation and exposure conditions.