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The new substance displays a 25 times increase in thermal conductivity under stress-free conditions.
THE SEARCH CONTINUES FOR NEW MATERIALS that provide better performance and are lighter in weight. This leads to the potential for machinery using these materials to be more productive with better operating efficiency.
One area of major concern is oxidation resistance. A past TLT article describes the development of a boride based on molybdenum, boron and aluminum that can display oxidation resistance up to a temperature of 1,300 C.1 This feature may enable future use of this material, not just as a surface coating (its main current use) but as a bulk material.
Seals perform an important function to minimize the movement of lubricants out of a specific machine and also to prevent contaminants such as dust, dirt and water from coming into contact with the lubricant. Elastomers used as seals include nitriles, fluoroelastomers, polyurethanes and EPDM.
One challenge in working with elastomers is that they are not thermally conductive. Excessive heat build-up in lubricant systems can lead to premature failure. Carmel Majidi, associate professor of mechanical engineering at Carnegie Mellon University in Pittsburgh, says, "There is a tradeoff between a material's thermal conductivity and flexibility. Soft materials such as elastomers are not able to conduct heat effectively because the only way to move heat is through vibrations in the polymer that are known as phonons. The speed of propagation of phonons is directly proportional to the stiffness of the polymer."
Attempts to improve thermal conductivity...