Oxidation is the most common reaction of a lubricant, and thus one of the leading causes of lubricant failure. In most cases, it can’t be prevented, but steps can be taken to increase the active life of the lubricant by slowing down its rate of oxidation. Because oxidation is such a significant problem for lubricants, chemists have developed controlling methods to prevent it. Why is oxidation such a problem, and how can it be prevented?
What is oxidation’s effect on lubricants?
Oxidation has several effects on lubricants. It increases viscosity and causes varnish, sludge and sediment formation, as well as additive depletion and several other issues. These cause the lubricant to lose its lubricating properties, and stop working properly, potentially resulting in damage to machine components.
How can oxidation be prevented?
The primary method of combating oxidation is to include antioxidants in lubrication formulas. These work sacrificially, breaking down to prevent the main, active components of the lubricant from doing so. Oxidation can also be managed by interrupting any one of its three stages: initiation, propagation and termination. This is done by limiting the supply of oxygen (to prevent initiation), shortening the number of reaction cycles (propagation), or adding alternate stopping methods (increasing termination). Preventing initiation is the first line of defense, so limiting the presence of oxygen is key.
How do you measure oxidation?
Chemists use two systems to measure oxidation: Linear Scanning Voltammetry (LSV) and Fourier-transform infrared spectroscopy (FTIR). These two tests measure the concentration of the antioxidant additives present in the lubricant. When compared to the quantities of the antioxidant that were initially added to the lubricants, the test results indicate how much oxidation has taken place, and therefore, how oxidative life remains in the product. This can help users know how much longer the lubricant will be effective before reapplication becomes necessary.
Dry lubricants as a solution
In nuclear applications, the prevention of oxidation becomes more tricky. The high temperatures involved tend to accelerate oxidation. The most effective solution in these applications is to use dry film lubricants with extreme resistance to both temperature and oxidation. Molybdenum disulfide, for example, is virtually impervious to oxygen and maintains its nature and function at very high temperatures. This makes it a highly durable lubricant, even when the heat and oxygen levels are high.
Huron Industries is a supplier of dry film lubricants to the nuclear and aerospace industries, as well as the military. Our lubricant solutions are all developed for high resistance to oxidation for prolonged, stable use in the extreme environments of nuclear reactors. Contact us for more information.