Online analysis of copper, tin, and zinc in white bronze baths by XRF

Importance of the topic

Galvanic white bronze plating deposits a copper-tin-zinc alloy layer on base metals to enhance corrosion resistance, wear protection and visual appeal. Maintaining precise Cu, Sn and Zn ratios is critical to ensure uniform deposits and prevent defects. Traditional lab-based analyses introduce delays, increase costs and involve hazardous cyanide handling.

Objectives and Study Overview

This application note assesses the Metrohm 2060 XRF Process Analyzer for continuous, online monitoring of Cu, Sn and Zn concentrations in white bronze baths. The goal is to compare its speed, accuracy and operational benefits against conventional sampling and titration approaches.

Methodology

Samples are analyzed inline by an energy-dispersive XRF spectrometer with a tungsten anode source. Characteristic X-ray peaks for Sn (25–28 keV) and Cu/Zn (around 9 keV) are captured in real time. Data acquisition is automated to provide continuous readings and support rapid decision-making.

Instrumentation

The 2060 XRF Process Analyzer integrates into industrial processes with up to 20 sampling points. It employs EDXRF technology for nondestructive, near-real-time analysis of liquid streams. This platform can be combined with titration or photometry modules for comprehensive process control.

Main Results and Discussion

The XRF analyzer demonstrated the following performance for white bronze bath monitoring:

• Tin range: 21–40 g/L, RSD 0.87 %
• Copper range: 6–15 g/L, RSD 0.33 %
• Zinc range: 0.6–2.5 g/L, RSD 0.58 %

Distinct spectral peaks confirmed reliable element identification. The system’s speed and nondestructive nature eliminate sampling delays and reduce exposure to toxic reagents.

Benefits and Practical Applications

• Real-time bath control enables precise chemical dosing and consistent plating quality.
• Reduced chemical waste and environmental impact through accurate measurements.
• Lower labor costs by minimizing manual sampling and laboratory analyses.
• Enhanced safety by avoiding frequent handling of cyanide solutions.

Future Trends and Opportunities

Integration with voltammetric methods could enable speciation of free metal ions and oxidation states. Expanding XRF monitoring to other plating chemistries and coupling with automated dosing systems will support Industry 4.0 frameworks. Advances in sensor miniaturization and data analytics promise even tighter process integration.

Conclusion

The Metrohm 2060 XRF Process Analyzer offers a fast, accurate and nondestructive solution for online monitoring of Cu, Sn and Zn in white bronze plating baths. Continuous, real-time data improve bath stability, reduce costs and enhance safety, making it a valuable tool for industrial electroplating operations.

References

• White Bronze, Copper-Tin-Zinc Tri-metal: Expanding Applications and New Developments in a Changing Landscape. Products Finishing.
• Replacing Nickel with Tri-Metal in Electronics Plating. Products Finishing.
• White Bronze Decorative Electroplating Chemistry. Technic Inc.
• Zanella C., Xing S., Deflorian F. Effect of Electrodeposition Parameters on Cu–Sn Coatings. Surface and Coatings Technology 2013, 236, 394–399.
• Guidelines for Cyanide. National Academies Press (US), 1995.