Analysis of wear metals in oil under ambient air using the ARL QUANT’X EDXRF

Significance of the Topic

Monitoring wear metals in lubricants is a key preventive maintenance strategy for engines and rotating equipment. Early detection of elements such as iron, copper and lead in oil helps avoid costly failures and unplanned downtime.

Objectives and Study Overview

This application note evaluates the performance of the ARL QUANT’X EDXRF spectrometer for quantifying common wear metals in oil under ambient air. The goal is to demonstrate fast, accurate and repeatable analysis without the need for a helium purge.

Methodology and Instrumentation

Instrument Used:

• ARL QUANT’X EDXRF spectrometer with 50 kV, 50 W silver target X-ray tube
• Latest-generation silicon drift detector (SDD)
• Primary filtered radiation with nine interchangeable filters optimized from F to Am

Sample Preparation:

• 3 g of oil in a 32 mm sample cup
• Sealed with a 4 μm polypropylene film

Excitation Conditions:

• Three filter setups (Mid Za, Mid Zc, High Zb) covering 14 elements
• 100 s live time per condition in ambient air

Calibration Protocol:

• Standards based on Conostan S21 at 10, 20, 50 ppm in blank 75 cSt oil
• Linear calibrations with RMSE from 0.03 to 0.95 ppm

Limit of Detection:

• Determined using ten blank oil replicates
• LoDs ranging from 0.1 to 2.3 ppm (3σ criterion)

Main Results and Discussion

The ARL QUANT’X EDXRF achieved precise quantification of Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Mo, Ag, Cd, Sn, Ba and Pb with low RMSE and sub-ppm detection limits. Analysis in air provided high peak-to-background ratios without helium.

Benefits and Practical Applications

Advantages include:

• Elimination of helium gas reduces running costs
• Rapid multi-element analysis in under 5 minutes
• Minimal sample handling for routine monitoring
• Applicable to engine oils, gear oils, greases and other machine fluids

Future Trends and Applications

Emerging opportunities:

• Extending detection to lighter and trace elements with advanced filtering
• Integration into continuous online oil monitoring systems
• Automated data analysis using machine learning for predictive maintenance
• Portable EDXRF devices for field diagnostics

Conclusion

The ARL QUANT’X EDXRF spectrometer delivers a fast, accurate and cost-effective approach for monitoring wear metals in lubricants under ambient conditions, supporting proactive maintenance and equipment reliability.

References

Thermo Fisher Scientific. Application Note AN41953: Analysis of wear metals in oil under ambient air using the ARL QUANT’X EDXRF.