GB/T 26416.5-2022Chemical analysis method for rare earth ferroalloy—Part 5: Determination of oxygen content—Impulse-infrared absorption method (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for Standardization Work Part 1: Structure and Drafting Rules for Standardization Documents" drafting.

This document is part 5 of GB/T 26416 "Methods for Chemical Analysis of Rare Earth Ferroalloys". GB/T 26416 has issued the following parts.

--- Part 1: Determination of the total amount of rare earth;

--- Part 2: Determination of rare earth impurity content Inductively coupled plasma emission spectrometry;

--- Part 3: Determination of calcium, magnesium, aluminum, nickel, manganese content Inductively coupled plasma emission spectrometry;

--- Part 4: Determination of iron content Potassium dichromate titration method;

--- Part 5: Determination of oxygen content pulse - infrared absorption method.

This document replaces GB/T 26416.5-2010 "Methods for Chemical Analysis of Dysprosium-Fe Alloys Part 5: Determination of Oxygen Pulse-Infrared Absorption Compared with GB/T 26416.5-2010, except for structural adjustment and editorial changes, the main technical changes are as follows.

a) The measurement range (mass fraction) of oxygen content has been changed from "0.010%~0.50%" to "0.0050%~0.60%" (see Chapter 1, Chapter 1 of the 2010 edition);

b) Changed the cleaning agent, changed "carbon tetrachloride" to "acetone" (see 5.1, 3.2 of the 2010 edition);

c) Changed the flux, changed "nickel bag with cover" to "nickel basket or nickel bag" (see 5.2, 3.1 of the 2010 edition);

d) Changed the gas, changing "high-purity helium" to "high-purity helium or argon" (see 5.5, 3.3 of the 2010 edition);

e) Changed the weighing amount, changed "0.1g~0.2g" to "0.1g~0.3g" (see 8.1, 6.1 of the 2010 edition);

f) The sample preparation requirements have been changed, and the processing methods for samples of different shapes have been added (see Chapter 7, Chapter 5 of the 2010 edition);

g) Changed "precision" and changed "permissible difference" to "reproducibility" (see Chapter 10, Chapter 8 of the 2010 edition).

Introduction

The rare earth iron alloy referred to in this document refers to the master alloy composed of iron and one or more rare earth elements, which is generally adopted by molten salt electrolysis or fusion It is mainly used as an additive for magnetic materials such as NdFeB permanent magnet materials, magnetostrictive materials, optical and magnetic recording materials, or as a deoxidizer, Additives, etc. are used in iron and steel smelting. Chemical composition is an important assessment index of rare earth ferroalloys.

GB/T 26416 integrates industry standards XB/T 616-2012 "Chemical Analysis Methods of Gadolinium-Fe Alloys", XB/T 621-2016 "Chemical Analysis Methods of Holmium-Fe Alloys", XB/T 623-2018 "Cerium-Fe Alloy Chemical Analysis Method", XB/T 624-2018 "Yttrium-Fe Alloy Chemical Analysis Method", etc., established for all current implementations Large-scale production of rare earth iron alloys (including iron lanthanum, iron cerium, iron lanthanum cerium, iron neodymium, iron dysprosium, iron gadolinium, iron holmium and iron yttrium, etc.) production and application needs The standard of chemical analysis method for the assessment indicators, including the detection of the total amount of rare earth, the content of rare earth impurities, and the content of non-rare earth impurities. According to detection Due to differences in objects and detection methods and substrates, etc., GB/T 26416 is proposed to be composed of 9 parts.

--- Part 1: Determination of the total amount of rare earth;

--- Part 2: Determination of rare earth impurity content Inductively coupled plasma emission spectrometry;

--- Part 3: Determination of calcium, magnesium, aluminum, nickel, manganese content Inductively coupled plasma emission spectrometry;

--- Part 4: Determination of iron content Potassium dichromate titration method;

--- Part 5: Determination of oxygen content pulse-infrared absorption method;

--- Part 6: Determination of molybdenum, tungsten and titanium content Inductively coupled plasma emission spectrometry;

--- Part 7: Determination of carbon and sulfur content High-frequency-infrared absorption method;

--- Part 8: Photometric method for the determination of the amount of silicon;

--- Part 9: Determination of phosphorus content Bismuth phosphomolybdenum blue spectrophotometry.

The above-mentioned standards have clarified the scope of application, standardized reagents, materials, test equipment and procedures, and have been tested repeatedly by many laboratories.

The precision data given by the test and verification enhances the consistency and comparability of data between different laboratories, and establishes a standard for the quality verification of rare earth ferroalloys. Rigorous and standardized basis for standardization work.

This revision to GB/T 26416.5 increases the scope of determination from ferrodysprosium to iron holmium, iron lanthanum, iron gadolinium, iron lanthanum cerium and other rare earth iron alloys.

The common technical points of the oxygen content test methods for different rare earth iron alloys are included, and the test steps are standardized, so as to determine the oxygen content in rare earth iron master alloys.

Quantitative determination provides a fast and accurate method basis. The precision data in this document were tested by 7 laboratories in 2020 for holmium-iron alloy, 6 samples with different oxygen content levels, such as neodymium-iron alloy, lanthanum-cerium-iron alloy, and dysprosium-iron alloy, were jointly tested and determined.

The oxygen content of the horizontal sample was independently measured 7 times under repeatability conditions, and the joint test data were statistically analyzed in accordance with GB/T 6379.2.

1 Scope

This document describes a method for the determination of oxygen content in rare earth iron alloys.

This document applies to the determination of oxygen content in rare earth iron alloys. Measuring range (mass fraction). 0.0050%~0.60%.

2 Normative references

The contents of the following documents constitute the essential provisions of this document through normative references in the text. Among them, dated references For documents, only the version corresponding to the date is applicable to this document; for undated reference documents, the latest version (including all amendments) is applicable to this document.

GB/T 8170 Numerical rounding off rules and expression and determination of limit values

3 Terms and Definitions

This document does not have terms and definitions that need to be defined.

4 Method Summary

Put the sample and flux into the high-temperature degassed graphite crucible, heat and melt under the protection of helium or argon. Oxygen and graphite in the sample The carbon in the crucible is combined to generate carbon monoxide and a small amount of carbon dioxide, and the mixed gas is loaded into the infrared detector by the carrier gas for direct detection of carbon monoxide or detection Measure the carbon dioxide converted from carbon monoxide through a heated catalytic furnace, and compare the oxygen content in the standard sample with the analysis software to obtain the sample oxygen content.

5 Reagents or Materials

5.1 Acetone.

5.2 Nickel basket or nickel capsule. w(O)<=0.0010%.

5.3 Graphite crucible. spectrally pure.

5.4 Standard sample. Select an appropriate standard sample within the range of 0.0050% to 0.60% oxygen content (volume fraction).

5.5 High-purity helium or argon (volume fraction >= 99.999%).

6 Instruments and equipment

6.1 Pulse-infrared oxygen measuring instrument. the temperature is higher than 2000°C, and the detector sensitivity is 0.01µg/g.

6.2 Electronic balance. the division value is 0.1mg.