ISO 795:1976 PDF

Overview

ISO 795:1976 outlines the Oxalyldihydrazide photometric method for the precise determination of copper content within aluminium and aluminium alloys. This internationally recognized standard, established by the International Organization for Standardization (ISO), specifies a reliable chemical analysis technique to measure copper concentrations in the range of 0.002% to 0.8% by mass. It is primarily applicable to aluminium, magnesium, and their alloys, with particular considerations provided for alloys containing silicon exceeding 1% by mass.

Copper determination is critical in aluminium alloys due to its influence on mechanical properties such as strength, corrosion resistance, and electrical conductivity. The ISO 795:1976 standard serves as a practical guideline for laboratories and industries engaged in quality control, materials testing, and compliance verification.

Key Topics

• Scope & Applicability: The method focuses on aluminium and magnesium alloys, applicable between copper contents from 0.002% up to 0.8% by mass. Special modifications are noted for alloys with silicon >1%, detailing extra processing steps to accurately measure copper despite silicon’s interference.

• Chemical Reagents: The procedure involves hydrochloric acid, hydrogen peroxide, ammonia solution, citric acid, acetaldehyde, and oxalyldihydrazide. These reagents facilitate the formation of a violet-colored copper-oxalyldihydrazide complex detectable at approximately 540 nm wavelength.

• Sample Preparation: Test samples should be prepared as chips or powders ensuring homogeneity. Precise dissolution using acids and controlled pH adjustment with ammonia are key steps to achieve accurate copper quantification.

• Photometric Measurement: After sample reaction, absorbance is measured spectrophotometrically at about 540 nm. A calibration graph prepared with known copper standards ensures proper interpretation of results.

• Special Annex for Silicon-Rich Alloys: For aluminium alloys with high silicon content (>1%), an additional procedure involving filtration, washing, ignition, and acid digestion of residue ensures all copper is recovered and accurately quantified.

• Expression of Results: Copper content is calculated by correlating absorbance readings with calibration standards, yielding mass percentage values vital for material specification and compliance assessment.

Applications

• Quality Assurance in Aluminium Manufacturing: Enables producers to verify copper content accurately, which directly impacts mechanical and corrosion performance of aluminium alloys.

• Metallurgical Research and Development: Critical for characterizing alloys during design and testing phases where copper optimization is necessary for targeted properties.

• Regulatory Compliance: Provides standardized methodology complying with international norms for material certification and supplier qualification.

• Failure Analysis: Helps identify abnormal copper levels in alloy samples contributing to performance issues or defects in finished products.

• Magnesium Alloy Testing: The method’s application extends to magnesium alloys, supporting multi-metal alloy industries requiring cross-metallic element analysis.

Related Standards

• ISO 4287 – Surface texture: Profile method – Terms, definitions, and parameters (relevant for understanding surface finish after sampling and preparation).

• ISO 4954 – Aluminium and aluminium alloys – Chemicals analysis – General rules for photometric chemical analysis.

• ISO 14284 – Steel and steel products – Sampling for the purpose of chemical analysis.

• ISO 11426 – Chemical analysis of aluminium and aluminium alloys by spectrophotometry (alternative spectroscopic techniques for alloy elements).

• ASTM E1415 – Standard test method for Copper in aluminium alloys by volumetric analysis (related copper determination methods).

By adhering to ISO 795:1976, laboratories and manufacturers can ensure reproducible, accurate copper content measurement essential for maintaining material quality and meeting stringent international standards in aluminium alloy production and analysis.