GB/T 5121.8-2024Methods for chemical analysis of copper and copper alloys - Part 8: Determination of oxygen, nitrogen and hydrogen contents (English PDF)

4.2.4 Glacial acetic acid (rho =

4.2.5 Anhydrous ethanol or acetone.

4.2.6 Mixed acid. Nitric acid (4.2.2), phosphoric acid (4.2.3), glacial acetic acid (4.2.4) are mixed in a volume ratio of 10.28.62.

4.2.7 Standard substances/standard samples. Oxygen and nitrogen standard substances/standard samples of copper and copper alloys, or other applicable standard substances/standard samples.

4.2.8 Nickel basket. 1 g, purity not less than 99.9%, oxygen content not greater than 0.0010%, nitrogen content not greater than 0.0002%. Except for the no-wash nickel basket, the surface should be cleaned as follows before use. Soak in a mixed acid (4.2.6) for 5 minutes; then quickly remove and rinse with running water for 2 ~ 3 minutes. After cleaning with anhydrous ethanol or acetone (4.2.5), soak in fresh anhydrous ethanol or acetone (4.2.5) for later use. Dry with cold air before use.

4.2.9 High-purity carrier gas (helium or argon). Purity not less than 99.999%.

4.2.10 Power gas (nitrogen, argon, or compressed air). Impurities (oil or water) not greater than 0.5%.

4.2.11 Graphite crucible. Made of high-purity or spectrally pure graphite.

4.3 Instrumentation and equipment Inert gas melting-infrared/thermal conductivity detection system (including electrode furnace, dust collection device, carrier gas purification and analytical gas conversion system, infrared detector and thermal conductivity detector, computer and software control system). If only oxygen or nitrogen content needs to be detected, an instrument equipped with a separate infrared detector or thermal conductivity detector can be selected.

4.4 Samples

4.4.1 Process the sample into round bars or strips with a diameter of 2 mm ~ 5 mm or a cross-section of 2 mm × 2 mm ~ 5 mm × 5 mm and a length greater than 40 mm, or other small pieces with suitable size and weight, according to YS/T 668.Wires and filaments can be sampled directly.

4.4.2 Use a lathe and steel file to remove surface contamination or oxide layers, exposing the fresh metal surface. Overheating shall be avoided during processing to prevent oxidation.

4.4.3 Use a special steel file, hand saw, or wire cutter to process the sample to the required weight. The processed sample shall be free of defects visible to the naked eye, such as pores and cracks.

4.4.4 Immerse the sample in a mixed acid (4.2.6) for 10 minutes; remove it; wash it quickly with water; then wash it with anhydrous ethanol or acetone (4.2.5); dry it with cold air; analyze it immediately. The prepared sample must be free from contamination before and during testing. Clean tweezers shall be used to handle the sample during the testing process. If the sample is oxidized, this step shall be repeated.

4.4.5 If only nitrogen content is being tested, procedures

4.4.1 To

4.4.4 can be followed, or the sample can be prepared into a shaving form according to YS/T 668 for analysis.

4.5.1 Sample Weigh

0.10 g ~

2.00 g of sample (4.4), accurate to 0.0001 g.

4.5.2 Parallel test Perform two measurements repeatedly; take the average of the results.

4.5.3 Blank test Perform a blank test along with the sample (4.5.1). The blank test shall be repeated at least three times; the average value shall be used for blank compensation or subtraction. The blank value (absolute value) after compensation or subtraction shall not exceed 0.00005%. If a nickel basket (4.2.8) is used when analyzing samples, the blank test shall also include a blank in the nickel basket (4.2.8).

4.5.4 Instrument calibration

4.5.4.1 Single standard point calibration Select a standard substance/standard sample (4.2.7) whose oxygen and nitrogen contents are close to the expected contents of the sample to be tested, or make the oxygen and nitrogen masses in the standard substance/standard sample (4.2.7) similar to those in the sample to be tested by controlling the mass of the sample. Perform the single standard point calibration procedure, according to the instrument manual; repeat the analysis at least three times, taking the average value and calibrating the oxygen and nitrogen calibration curves, respectively. For the sample to be tested with unknown contents, the instrument's built-in original working curve or other similar working curves can be used to pre-analyze the sample (4.5.1) according to 4.5.5, to obtain the expected contents of oxygen and nitrogen in the sample to be tested.

4.5.4.2 Multi-point calibration Select two or more standard substances/standard samples (4.2.7). The oxygen and nitrogen content in the standard substances/standard samples (4.2.7) shall cover the oxygen and nitrogen content in the sample to be tested, or the oxygen and nitrogen mass in the standard substances/standard samples (4.2.7) shall cover the oxygen and nitrogen mass in the sample to be tested by controlling the sample mass. Perform multi-point curve calibration according to the instrument manual. Each standard substance/standard sample (4.2.7) shall be analyzed at least three times; the average value shall be used to calibrate the oxygen and nitrogen calibration curves, respectively.