Oxygen in Copper and Copper Alloys

Importance of the Topic

Oxygen control in copper and its alloys is critical for electrical conductor performance. Residual oxygen affects conductivity, mechanical properties and risk of hydrogen embrittlement. Accurate, precise oxygen determination supports quality grading from oxygen-free electronic (OFE) grades to electrolytic tough pitch (ETP) copper.

Aims and Overview of the Application Note

This application note describes inert gas fusion with infrared detection to quantify oxygen in copper and copper alloys. It outlines sample preparation, instrument setup, method parameters, calibration and typical analytical results using a LECO O/ON/OH analyzer.

Instrumentation

• LECO O836 or O/ON/OH/ONH836 inert gas fusion analyzer
• 776-247 graphite crucibles
• 501-073 graphite powder
• Graphite electrode tips, manual or automated
• Carrier gas: helium (optimized) or argon (requires adjusted parameters)

Methodology

Sample preparation follows ASTM E2575 or simple abrasion:

• Chemical etching removes surface impurities; rinse with methanol and dry.
• Physical abrasion with a file; avoid overheating; wash if desired.
• Analyze within four hours to prevent reoxidation.

Analysis steps:

1. Establish blank values using at least three replicates.
2. Calibrate instrument with nickel-plated copper pins (LECO 501-147 series) at ~1.000 g.
3. Weigh and analyze samples (~0.05 g graphite powder + ~1.000 g copper).
4. Use predefined power, timing and integration settings (e.g., 5800 W outgas, 4825 W analysis, multiple cycles).

Main Results and Discussion

Typical results demonstrate high precision (standard deviation 0.0001–0.0003 % O) across different matrices:

• Electrolytic copper (0.0581 % O)
• Refined copper standards (0.0319–0.0320 % O)
• Oxygen-free high-conductivity (OFHC) copper (<0.00015 % O)

Comparison of etched versus abraded samples shows negligible bias. Single-point calibration forced through the origin produces linear response over the studied range.

Benefits and Practical Applications

• Wide dynamic range from trace to hundreds of ppm oxygen.
• High throughput with automated sample loading and cleaning.
• Minimal sample preparation for plated reference materials.
• Reliable compliance with ASTM E2575 and internal QA/QC protocols.

Future Trends and Applications

Emerging trends include:

• Integration of argon fusion protocols with extended integration times for cost reduction.
• Automation enhancements for unattended high-volume processing.
• AI-driven drift correction and data interpretation.
• Extension to multi-element analysis in copper alloys.

Conclusion

Inert gas fusion with infrared detection provides a robust, reproducible method for oxygen analysis in copper and its alloys. The LECO O836 series delivers high precision, flexible calibration and streamlined workflows that support industrial QA/QC and research laboratories.

Reference

• LECO Corporation. Oxygen in Copper and Copper Alloys Application Note, Form No. 203-821-436, Rev. 1 (2020).