GB/T 26416.7-2023Chemical analysis methods for rare earth ferroalloy—Part 7: Determination of carbon and sulfur contents—High frequency - 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 7 of GB/T 26416 "Methods for Chemical Analysis of Rare Earth Ferroalloys". GB/T 26416 has issued the following part.

--- 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.

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, generally adopts 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", established for all current implementation standards The production and application of rare earth ferroalloys (including ferro-lanthanum, ferrocerium, ferro-lanthanum, ferro-ndium, ferro-dysprosium, ferro-gadolinium, ferro-holmium and ferro-yttrium, etc.) need to be considered in the production and application.

Standards for chemical analysis methods of nuclear indicators, including the detection of total rare earth content, rare earth impurity content, and non-rare earth impurity content. According to detection Due to differences in image and detection methods and substrate differences, GB/T 26416 consists of the following nine 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 parts have clarified the scope of application, standardized reagents, materials, test equipment and procedures, and have undergone repeated trials 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 document uses the high frequency-infrared absorption method to determine the carbon and sulfur content in rare earth iron alloys. This method has a wide measurement range and accurate analysis results.

It is reliable, easy to operate, and can simultaneously measure carbon and sulfur content.

The precision data in this document is in 2021, and 5 different carbon content levels of lanthanum iron, cerium iron, gadolinium iron, etc. and 4 Samples with different sulfur content levels were determined through collaborative experiments. The carbon and sulfur content of each level sample in each laboratory under repeatable conditions 11 independent determinations. The test data shall be counted according to GB/T 6379.2. The test results show that the carbon recovery rate is 89%~101%, which is relatively The standard deviation (RSD) was 1.3%-3.9%, the sulfur recovery rate was 91%-113%, and the RSD was 1.3%-17.7%.

1 Scope

This document describes a method for the determination of the carbon and sulfur contents of rare earth iron alloys.

This document is applicable to the determination of carbon and sulfur content in rare earth ferroalloys. The measurement range (mass fraction) is carbon 0.0050%~0.30%; sulfur 0.0015%~0.050%.

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

In the presence of flux, an oxygen flow is introduced into the high-frequency induction furnace to burn the sample at high temperature, and the carbon generates carbon monoxide or/and carbon dioxide. carbon gas, and sulfur produces sulfur dioxide gas. The mixed gas first enters the sulfur dioxide infrared cell to measure the sulfur content, and then undergoes catalytic oxidation, and the The sulfur dioxide is converted to sulfur trioxide and absorbed. The remaining gas enters the carbon infrared cell to determine the carbon content.

5 Reagents or Materials

5.1 Tungsten flux. wC<=0.0008%, wS<=0.0008%.

5.2 Tin flux. wC<=0.0008%, wS<=0.0008%.

5.3 Pure iron flux. wC<=0.0008%, wS<=0.0008%.

5.4 Special crucible for carbon and sulfur. burn at 1100°C for 2 hours, cool naturally in a muffle furnace, and then place it in a desiccator for use.

5.5 Standard sample. within the range of carbon content (mass fraction) 0.0050%~0.30%, sulfur content (mass fraction) 0.0015%~0.050% Select an appropriate certified steel standard sample.

5.6 Caustic soda asbestos. the particle size is 0.85mm~1.7mm (10 mesh~20 mesh).

5.7 Anhydrous magnesium perchlorate. the particle size is 0.85mm~1.7mm (10 mesh~20 mesh).

5.8 Acetone (analytical grade).