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The results from the hydrogen permeation tests demonstrate that the untreated membrane showed a higher saturation concentration and longer time to reach saturation than the lubricant additive treated case. This confirms that the lubricant additive reduces the amount of hydrogen that permeates into the steel membrane.
The formation of a superior tribofilm provides excellent protection against WEC. The ability of the additive tribofilm to inhibit hydrogen diffusion through a steel membrane is a critical factor. The results from the FAG FE8 bearing rig tests demonstrate the effectiveness of the additive to prevent WEC formation.
The key findings from this study are listed below:
1. FAG FE8 bearing rig test results show that a low reference oil had WEC formation after only 30 hrs of testing, whereas the oil containing the new lubricant additive did not result in WEC failure after more than 400 hrs.
2. The lubricant additive is able to build comprehensive tribofilms that reduce friction and also provide wear protection.
Figure 7: Hydrogen permeation test results
The vacuum test results show that untreated and treated oil both produce free hydrogen. This demonstrates that the lubricant additive does not inhibit the generation of hydrogen from lubricant. It must, however, play a key role in inhibiting hydrogen diffusion into the metal surface.
There are a number of possible mechanisms which could explain the positive effects of the additive. It could be due to the tribofilm creating a simple physical hydrogen barrier on the surface of the metal. Another possibility is that the intermixing of the tribofilm into the near metal surface might modify the structure and make it less porous to hydrogen.
A third possibility is that the tribofilm absorbs hydrogen by forming metal hydrides. In any event, it is clear that less hydrogen diffuses into steel when the additive is present. As a consequence, steel surfaces lubricated with the additive show reduced WEC formation. It can also prevent hydrogen embrittlement and other failure mechanisms related to hydrogen.
Conclusions This work presents significant findings about how the new lubricant additive can be used to produce high performance wind turbine gear oils.
20 LUBE MAGAZINE NO.161 FEBRUARY 2021
3. The amount of hydrogen that diffuses into the steel membrane in hydrogen permeation tests is reduced by the lubricant additive.
4 The new lubricant additive is also capable of preventing micro-pitting, hydrogen embrittlement, hydrogen wear, and other related mechanical failures.
5. Nanoparticles form effective tribofilms that prevent metal-metal contact in boundary lubrication conditions, which reduce surface stresses. The nanoparticles intermix into the near-surface of the metal to accumulate, which modifies the tribo-chemical composition and micro-structure. This inhibits hydrogen diffusion into the metal surface. As the tribofilm is worn away, new layers of tribofilm are formed on the metal surface to give sustained protection, and stops the propagation of WEC on a continuous basis.
The new lubricant additive discussed in this article has been developed by Nanol Technologies, using the principles of nanotechnology. The chemistry and functionality of the additive have been patented.
LINK
www.nanol.eu
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