ABSTRACT
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 a
greater stress under the same load. Combined with a lower thermal conductivity,
their working temperature increases and their load capacity decreases more rapidly
in operation. In Nature, we have a ceramic composite system, Bone, known for its
superior load-bearing capacity, and its self-protection at the high-stress movingcontact
points (joints) with built-in lubrication. Less known but no less important is
the fact that it has a built-in capillary networks for self-powered supply of lubricants
and coolants, as well as nutrient and growth factor, from within. It has served as an
inspiration to an effort and a model system for the study we report here that aim to
Incorporate some of these functionalities into man-made composite structures. In
this report, we first highlight our attempt to develop a method for generating networks
of micro- and nano-capillaries within a ceramic composite structure during the
sintering process. We then present test results of self-powered supply of fluids to
the 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 to
enable temperature-controlled self-powered lubrication, and tested in a model
system. The method is adaptable to various structural shapes, and scalable in size,
and to both biophysiologic and mechanic composite systems.