GB/T 15076.3-2019Methods for chemical analysis of tantalum and niobium—Part 3: Determination of copper content—Flame atomic absorption spectrometry (English PDF)

Foreword

GB/T 15076, Methods for chemical analysis of tantalum and niobium, is divided into 16 parts:

-- Part 1: Determination of tantalum content in niobium. Inductively coupled plasma atomic emission spectrometry;

-- Part 2: Determination of tantalum content in niobium;

-- Part 3: Determination of copper content. Flame atomic absorption spectrometry;

-- Part 4: Determination of iron content;

-- Part 5: Determination of molybdenum and tungsten contents. Inductively coupled plasma atomic emission spectrometry;

-- Part 6: Determination of silicon content in tantalum;

-- Part 7: Determination of phosphorus content in niobium;

-- Part 8: Determination of carbon and sulphur contents

-- Part 9: Determination of iron, chromium, nickel, manganese, titanium, aluminum, copper, tin, lead and zirconium contents in tantalum;

-- Part 10: Determination of iron, nickel, chromium, titanium, zirconium, aluminum and manganese contents in niobium;

-- Part 11: Determination of arsenic, antimony, lead, tin and bismuth contents in niobium;

-- Part 12: Determination of phosphorus content in tantalum;

-- Part 13: Determination of nitrogen content. Inert gas fusion thermal conductivity method;

-- Part 14: Determination of oxygen content;

-- Part 15: Determination of hydrogen content;

-- Part 16: Determination of sodium and potassium contents;

This Part is the 3rd part of GB/T 15076.

This Part was drafted in accordance with the rules given in GB/T 1.1-2009.

1 Scope

This Part of GB/T 15076 specifies the methods for determining the copper content in tantalum, niobium and their hydroxides.

This Part applies to the determination of copper content in tantalum, niobium and their hydroxides. Determination range: 0.000 2% ~ 0.060%.

2 Principle

Use hydrofluoric acid and nitric acid to dissolve the sample. After the sulfuric acid smokes, add an appropriate amount of nitric acid; boil to sufficiently hydrolyze tantalum and niobium; dry-filter to remove the tantalum and niobium matrix. Place the filtrate at the wavelength of 324.7 nm of an atomic absorption spectrometer to measure its absorbance; calculate the copper content.

3 Reagents

Unless otherwise specified, all the used reagents are guaranteed reagents and laboratory grade-2 water.

3.1 Hydrofluoric acid (rho = 1.14 g/mL).

3.2 Nitric acid (rho = 1.42 g/mL).

3.3 Sulfuric acid (1+1).

3.4 Copper standard stock solution: weigh 1.000 0 g of metallic copper (wCu >= 99.99%) in a 300 mL beaker; add 40 mL of nitric acid (1+1) to dissolve at a lower temperature. Boil; drive off the nitrogen oxides; take down for cooling; transfer to a 1 000 mL volumetric flask; add 80 mL of nitric acid (3.2); use water to dilute to the mark; mix well. 1 mL of this solution contains 1.0 mg of copper.

3.5 Copper standard solution: pipette 10.00 mL of copper standard stock solution (3.4) into a 1 000 mL volumetric flask; add 50 mL of nitric acid (3.2); use water to dilute to the mark; mix well. 1 mL of this solution contains 10 µg of copper.

4 Instruments and apparatuses

Atomic absorption spectrometer that is equipped with copper hollow cathode lamp.

Under the best working conditions of the instrument, anything that can achieve the following indicators can be used:

-- Characteristic concentration: in the solution that is consistent with the matrix of the measuring solution, the characteristic concentration of copper shall be no more than 0.05 µg/mL;

-- Precision: use the standard solution of the highest concentration to measure the absorbance for 10 times; its standard deviation shall not exceed 1.0% of the average absorbance. Use the standard solution of the lowest concentration (standard solution whose concentration is not "zero") to measure the absorbance for 10 times; its standard deviation shall not exceed 0.6% of the average absorbance of the standard solution of the highest concentration;

-- Linearity of working curve: divide the standard curve into five segments according to the concentration; the ratio OF the absorbance difference of the highest segment TO the absorbance difference of the lowest segment shall not be less than 0.70.

5 Sample

5.1 The particle size of tantalum and niobium powder shall be less than 180 µm.

5.2 The hydroxides of tantalum and niobium shall be preheated at 105°C ~ 110°C for 2 h; place in a desiccator to cool to room temperature.

5.3 From 10 cm to the top of the ingot to any part in the middle, use the planer to remove the epidermis and shave the sample; the clastic particles shall be uniform in size and the particles shall be as thin as possible.

6 Test steps