Online zinc/nickel plating bath analysis with X-ray fluorescence

Importance of the Topic

Electroplating baths require precise control of zinc and nickel concentrations to ensure high-quality corrosion-resistant coatings and minimize operational costs. Variations in bath composition can lead to defective coatings, increased rework, and premature part failure, especially in industries such as automotive, aerospace, and marine.

Study Objectives and Overview

This application note presents a solution for continuous inline analysis of Zn/Ni plating baths using the Metrohm 2060 XRF Process Analyzer. The goal is to compare this real-time X-ray fluorescence approach with traditional methods (wet chemistry, AAS, ICP-OES) and demonstrate its ability to maintain optimal bath composition.

Methodology and Instrumentation

The XRF-based system employs an energy-dispersive tungsten X-ray tube with a prolene window (Vanta module) to measure Zn and Ni in-line. A peristaltic pump and PFA solenoid valves direct the sample stream through the XRF sample vessel.

• Analyzer: Metrohm 2060 XRF Process Analyzer
• X-ray source: Tungsten tube with prolene window
• Flow control: Peristaltic pump and PFA solenoid valves
• Sampling points: Up to 20 streams

Main Results and Discussion

Calibration curves were established by spiking bath samples over defined concentration ranges: Zn (6.5–9.5 g/L) and Ni (0.5–2.5 g/L). Each point was measured in triplicate, yielding correlation coefficients (R2) of ~0.998 for both elements. The method provides continuous, near–real time data that detect deviations instantly.

Benefits and Practical Applications

• Eliminates delays inherent in off-line analyses.
• Ensures consistent coating thickness and quality.
• Reduces chemical exposure and manual sampling risks.
• Minimizes material waste and rework.
• Facilitates automated dosing adjustments.

Future Trends and Opportunities

Integration of XRF with other process analytical technologies (e.g., inline titration, photometry) will expand multi-parameter monitoring. Advances in miniaturized detectors and AI-driven analytics are expected to further enhance control of plating baths and reduce downtime.

Conclusion

The Metrohm 2060 XRF Process Analyzer offers a robust, non–destructive solution for continuous monitoring of zinc and nickel in electroplating baths. Its reliable performance and high precision enable improved coating consistency, reduced waste, and optimized process efficiency.

Reference

1. The Soft Cost of In-house Rework. PF Online, accessed 2025-04-23.
2. Westphal, L. Zinc Nickel Electroplating Differences. DeKalb Metal Plating, 2023.
3. Leiden A.; Kölle S.; Thiede S. Model-Based Analysis, Control and Dosing of Electroplating Electrolytes. Int J Adv Manuf Technol, 2020, 111(5), 1751–1766.
4. Why Opt for Acid or Alkaline in Zinc Electroplating? PAVCO, accessed 2025-04-24.