Electrified Tribology: Understanding the Impact of Voltage on Wear & Lubrication

MTM-EC

Why Electrical Tribology Matters

In our latest study using the PCS Instruments MTM-EC, we examined the effect applied voltage has on surface wear of stainless steels under lubrication. As Industries transition to faster electrified systems, lubrication conditions must be re-understood and re-optimised.

A major industry concern is arcing damage – high energy discharges can occur when there is an increasing potential difference across components. This energy emission may lead to surface damage. Additionally the understanding of electro-chemical lubricant film breakdown due to over currents is not yet fully understood, under non-researched condition this could lead to accelerated wear and potentially to unexpected failures.

Traditional lubrication methods, designed to handle mechanical stress, may not be enough to protect components in electrified environments. This case study review highlights findings on how voltage impacts lubricant performance. By simulating real-world conditions, the MTM-EC provides direct insights for optimising lubrication strategies for electrified systems.

How We Study Electro-Tribology

The PCS instruments MTM EC allows us to control the following parameters: voltage magnitude (ramped or constant), polarity of applied voltage, contact geometry and mechanical parameters (speeds, SRRs, loads). In combination with accessories such as the SLIM tools (see figure 2) we have a powerful insight into electrochemical effects on wear.

Figure 1 - schematic of the MTM-EC conditions across the ball and disc contact
Figure 1 – schematic of the MTM-EC conditions across the ball and disc contact.

Preliminary work conducted by PCS showed a dramatic drop in tribofilm thickness on application of voltage, see figure 2, which lead to wider research using EV fluids.

Mimicking real-world electrified environments test parameters included a speed of 250 mm/s, a load of 50 N, and a temperature of 100°C, using a fully-formulated EV transmission fluid (Vaico V60-0278 E-TF).

Firgure 2 - Tribofilm growth of fully formulated gearbox oil with 0V and 5V applied.
Firgure 2 – Tribofilm growth of fully formulated gearbox oil with 0V and 5V applied.

Key Findings from Our Study

  • Application of of a small voltage (1V, 1K Ohms) evidence of arching damage was visible – highlighted in figure 3. We believe this occuring due to significant tribofilm protection of the central portion of the wear track creating a larger potetnial difference from point A to point B, resutling in discharges. The combination of current polarirty and contact goemtry may provide further understanding arching behvaiour.
Figure 3 - potential arching damage surrounding central wear track.
Figure 3 – potential arching damage surrounding central wear track.
  • Tribofilm formation changes: Application of electrical voltage seems to prevent the formation of thicker tribofilms in this oil formulation, see figure 4. In this test, the lower set of results have a an additional 30 minute step with no electrical conditions applied at the beginning of the sequence. The images are taken every 15 minutes so the lower set can we seen as one image ahead. It is evident that lower set achieves a much dark (thicker) tribofilm and the upper does to a lesser extent. What is also of interest is that the lower test does not maintain that thick tribofilm. It is possible that the electric voltage applied is altering additive concentration due to additional surface electro-chemistry and is preventing prolonged protection.

Tribofilm formation speed and tribofilm thickness conservation are two key parameters in steel surface protection so ‘running in’ conditions and optimal running conditions are very important for machine lifecycle.

Figure 4 - upper - 1V applied immediately in test. Lower - 30 minutes non -electrified step applied initially. all other conditions identical.
Figure 4 – Upper – 1V applied immediately in test. Lower – 30 minutes non -electrified step applied initially. all other conditions identical.

Future Research Directions

These preliminary results begin many further conversation for industry. To expand on the data collected, future research should focus on some of the following:

  • Investigating Alternating Current (AC) Effects
    Since the study focused on DC electrical potentials, further research is needed to assess how alternating current (AC) conditions impact tribological performance and lubricant stability. [1]
  • Expanding Lubricant Testing
    Testing additional commercially available lubricants could provide a broader understanding of which formulations perform best under varying electrical stresses. [1]
  • Assessing Long-Term Impact
    While the study provided valuable short-term results, extended-duration tests are essential to explore the long-term effects of sustained electrical exposure on tribofilm integrity and component lifespan. [1]

These research directions will help build on the case study’s insights and drive advancements in lubrication for electrified systems.

For a more detailed analysis, download our full case study or contact our team to learn how these insights can benefit your applications.

References

[1] PCS Instruments. Effect of Applied Voltage on Component Wear: A Case Study Using the MTM-EC. PCS Instruments, 2025.