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Titanium, Aluminum and Other Light Metals as Mechanism Parts

In spite of continuous efforts to reduce weight of planes, helicopters and spacecraft, only structural members are manufactured of light metals. While the strength and fatigue life of such materials can compete successfully with steel, their surface tendency to stick to counterparts in relative motion, as well as their limited contact load capabilities forbid their use in mechanisms. As a result, most power transmission parts (gears, shafts with splines, clutches, latches, etc) are made of steel and coated with hard chromium, that has serious environmental problems.

SSC technology can alter the behavior of light metal surfaces, allowing their use in the construction of mechanisms and power transmission parts, with improved life and fatigue behavior and emergency lubrication capabilities. Compressive stresses built into the coating act in the same way as shot-peening, a well established method to control generation and development of microcracks from the surface of cyclically loaded parts, and increase the fatigue life of parts 2 – 3 times. Multilayer coatings stop an initiated crack at the interface between layers. Dry lubricants (Diamond-Like-Carbon, molybdenum or tungsten disulfide, etc) incorporated into the coating function as emergency lubrication in case of accidental or battle-loss of oil, until the equipment can be safely shut-off. In the case of a damaged helicopter power train, for instance, this emergency lubrication can provide time for a safe landing.