CONCEPT, THEORY, DESIGN AND EXPERIMENTAL TESTS OF SELFPOWERED LUBRICATION IN CERAMIC COMPOSITE AND ROTORS

Due to a modulus of elasticity higher than that of high carbon chrome bearing steel,ceramic rolling elements exhibit less deformation at contact points and therefore agreater stress under the same load. Combined with a lower thermal conductivity,their working temperature increases and their load capacity decreases more rapidlyin operation. In Nature, we have a ceramic composite system, Bone, known for itssuperior load-bearing capacity, and its self-protection at the high-stress movingcontactpoints (joints) with built-in lubrication. Less known but no less important isthe fact that it has a built-in capillary networks for self-powered supply of lubricantsand coolants, as well as nutrient and growth factor, from within. It has served as aninspiration to an effort and a model system for the study we report here that aim toIncorporate some of these functionalities into man-made composite structures. Inthis report, we first highlight our attempt to develop a method for generating networksof micro- and nano-capillaries within a ceramic composite structure during thesintering process. We then present test results of self-powered supply of fluids tothe contact (load-bearing) surface via the capillary networks from the fluid reservoir.As a further extension, a self-regulation mechanism is added into the design toenable temperature-controlled self-powered lubrication, and tested in a modelsystem. The method is adaptable to various structural shapes, and scalable in size,and to both biophysiologic and mechanic composite systems.