Creation and Tribology of Extremely Low Friction Super Lattice Solid Lubricant Films

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1. Development of nano-period multilayer solid lubricant films: To develop the solid lubricant films with a much lower friction and a longer life, the mechanism of improving the hardness of nano-period multilayer films was investigated and the model of novel solid lubricant films was proposed. In order to reduce a friction coefficient and increase a hardness, after the preparation of nano-period multilayer films using materials with low shear resistances, new nano-period solid lubricant films synthesized in our works exhibit extremely low frictions, whereas usual simple film and mixed film materials do not have such superior friction properties. Concretely, those are specified as follows.(1) Nano-period carbon and boron solid multilayer films: (C/BN)n multilayer films with periods of several nanometers were prepared and their heat resistances were expectedly improved. It has been confirmed that the 4-nm-period multilayer film exhibits the lowest friction coefficient., the neglectable d … More estruction and the superior wear resistances investigated in the wear test at a high temperature of 200^oC as compared with other multilayer films. (2) Electro-conducive An and Ag nano-period multilayer films: Since electro-conducive nano-period multilayer solid lubricant films were deposited using Au and Ag by layers, they are provided with a extremely low friction coefficient and superior wear durability, i.e. the 4-nm-period multilayer film indicates a low friction coefficient as μ= 0.05 and its wear durability was significantly improved. On the other hand, the changes of the electrical resistivity of the nano-period multilayer films are less than those of simple layer films after the sliding test. That is to say, it is possible to prepare superior solid lubricant films with steady electrical resistivity. (3) Nano-period tungsten disulfide and molyddenum disulfied multlilayer films: For those of nano-period multilayer films such as MoS_2 and WS_2 synthesized in our studies, their friction coefficient is as low as μ= 0.04 even under a condition of 58% humidity. Moreover, their wear durability evaluated in the repetitive wear tests is over 6 times longer than that of simple films. (4) Realization of nano-scale processing: As a result of deterring from the defect ductlility of layers on multilayer films, it becomes possible to carry out nano-scale processing in each layer.2. Nano-composite thin films: In the basic researches of the three dimensional nanocomposite, metal containing DLC (diamond like carbon) films were deposited and their tribological properties were evaluated in the nanoindentation and microwear tests. The Ti containing DLC film shows superior micromechanical properties. The boundary lubrication properties were improved by the metal addition. In particularly, the Ti containing DLC film shows the low friction coefficient less than 0.04. The superior tribological property of the film has significant potential and it is possible to realize the application of the superior lubricant and durable films in automobile sliding parts which can be expected to work well under a super low friction environment. Less