Overview
ISO 5196-2:1980 specifies a titrimetric method for determining thorium content in magnesium alloys. This international standard, published by ISO, is essential for quality control and chemical analysis of magnesium alloys containing thorium in concentrations ranging from 0.2% to 5.0% by mass. The document outlines the principle, reagents, apparatus, sampling techniques, detailed procedure, result expression, and reporting requirements to ensure consistent and accurate thorium measurement.
Key Topics
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Scope and Application
Applicable to magnesium alloys without silver with thorium content between 0.2% and 5.0% (m/m). Suitable for precise thorium determination critical in materials manufacturing and quality assurance.
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Principle of Determination
The method involves dissolving a test sample in hydrochloric acid, forming complexes with iron, cerium, and zirconium using hydroxylammonium chloride and EDTA. Thorium is then titrated at about 90°C using xylenol orange as the indicator.
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Reagents and Solutions
- Hydrochloric acid solutions (various concentrations)
- Hydroxylammonium chloride solution
- Ammonium hydroxide solution
- Buffer solution
- Standard zirconium solution for complexing interferences
- Disodium EDTA (0.01 mol/l) for titration
- Xylenol orange indicator
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Sampling and Sample Preparation
Laboratory samples are milled or drilled into chips no greater than 1 mm thickness. Accurate weighing (±0.001 g) of approximately 1 g test portions ensures reliability.
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Apparatus
Ordinary laboratory equipment including pH meter, mechanical or magnetic stirrer with hotplate, volumetric flasks, and titration vessels.
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Testing Procedure
Detailed stepwise instructions are provided for dissolving samples, blank determination, complex formation, titration, and temperature control to ensure consistent endpoint detection.
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Result Expression
Thorium content is calculated as a percentage by mass using titration volumes, correction factors, and sample weight, expressed precisely for standardization.
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Reporting Requirements
The test report must include the method reference, results with expression method, any anomalies, and optional or additional operations executed during testing.
Applications
ISO 5196-2:1980 is critical for industries where magnesium alloys with thorium content are used or produced, including:
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Metallurgy and Alloy Production
Ensures compliance with material specifications for aerospace, automotive, and electronics where magnesium alloys with controlled thorium content are used for strength and corrosion resistance.
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Quality Control Laboratories
Provides a reliable chemical analysis method for routine testing, batch verification, and quality assurance in production and research labs.
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Material Certification and Regulatory Compliance
Supports manufacturers and regulatory bodies in verifying material composition for safety, performance standards, and export-import requirements.
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Research and Development
Facilitates accurate thorium quantification aiding metallurgical research and development of new magnesium alloys.
Related Standards
- ISO 5196-1 - Magnesium alloys - Determination of thorium - Part 1: Gravimetric method
- Standards on sampling of magnesium alloys (forthcoming)
- ISO standards on chemical analysis of light metals and alloys, providing complementary approaches and protocols.
Keywords: ISO 5196-2, magnesium alloys, thorium determination, titrimetric method, chemical analysis, EDTA titration, xylenol orange indicator, standard zirconium solution, hydrochloric acid dissolution, magnesium alloy testing, international standards, metallurgical analysis.
