GB/T 26416.7-2023 (English Version)

Standard No.: GB/T 26416.7-2023
Language: Chinese, Available in English version
Release Date: 2023
Published By: General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China
Latest: GB/T 26416.7-2023

Scope: This document describes the determination method of carbon and sulfur content in rare earth iron alloys. This document is applicable to the determination of carbon and sulfur content in rare earth iron alloys. The determination range (mass fraction) is carbon 0.0050%~0.30%; sulfur 0.0015%~0.050%

Introduction

1. Background and significance of the standard

GB/T 26416.7-2023 is the 7th part of the chemical analysis method for rare earth iron alloys, which is specifically used to determine the carbon and sulfur content. This standard integrates the industry standards XB/T616-2012, XB/T621-2016, XB/T623-2018 and XB/T624-2018, and establishes a unified chemical analysis method system.

Rare earth iron alloys are important functional materials and are widely used in magnetic materials and steel smelting. Their chemical composition is an important indicator for assessing product quality, so it is of great significance to formulate a unified analysis standard.

2. Overview of determination methods

This standard uses high-frequency-infrared absorption method to determine carbon and sulfur content. This method uses flux to introduce oxygen flow into a high-frequency induction furnace to cause the sample to burn at high temperature, generating carbon monoxide, carbon dioxide and sulfur dioxide gases.

The mixed gas first enters the sulfur dioxide infrared cell to determine the sulfur content, and then is converted into sulfur trioxide through catalytic oxidation and absorbed. The remaining gas enters the carbon infrared cell to determine the carbon content, which has the characteristics of a wide measurement range and accurate and reliable results.

3. Comparison table of standard frameworks

Standard part	Determination object	Detection method	Scope of application
Part 1	Total amount of rare earth elements	ICP-OES method	Applicable to the determination of rare earth elements such as lanthanum, cerium and neodymium
Part 2	Rare earth impurity content	ICP-OES method	Applicable to the determination of non-rare earth impurities in rare earth iron alloys
Part 7	Carbon and sulfur content	High frequency-infrared absorption method	Applicable to carbon with a mass fraction of 0.0050%~0.30% and sulfur with a mass fraction of 0.0015%~0.050%

4. Implementation suggestions and precautions

Sample preparation: Block samples need to remove the surface oxide layer and be made into chips or granules. Samples should be free of contamination and cleaned with acetone and air-dried when necessary.

Instrument maintenance: The combustion chamber of the high frequency-infrared carbon and sulfur analyzer should be cleaned and the filter replaced regularly. When restarting after shutdown, it is necessary to stabilize for a period of time and test similar samples to ensure accuracy.

Data processing: The carbon and sulfur content calculation formula is:

$$ \uptau = \uptau_{2} - k\uptau_{1} $$

Wherein, $\varpi_{2}$ is the sum of the carbon or sulfur content of the sample and the blank test, $k$ is the mass ratio of flux to sample, and $\varpi_{1}$ is the carbon or sulfur content of the blank test.

GB/T 26416.7-2023 Referenced Document

GB/T 8170 Rules of rounding off for numerical values & expression and judgement of limiting values

GB/T 26416.7-2023 history

2023 GB/T 26416.7-2023 Chemical Analysis Methods of Rare Earth Ferroalloys Part 7: Determination of Carbon and Sulfur Content by High Frequency-Infrared Absorption Method

GB/T 26416.7-2023