MRC Bearings, a div. of SKF, Jamestown, N.Y. (, now offers precision-finished, silicon-nitride rollers separately, or installed in its line of aerospace hybrid roller bearings. MRC uses Cerama SN-101C silicon nitride ceramic roller blanks from Saint-Gobain Ceramics, East Granbury, Conn. (

Hybrid roller bearings (silicon-nitride roller in metal races) are said to last longer and run faster than their all-steel counterparts. Silicon nitride has just 40% the density of steel, which lowers rotational inertia and centrifugal force. Lower friction and less wear from smooth, hard ceramic surfaces let hybrid bearings run cooler with less lubricant. Applications for ceramic rollers include precision bearings for aerospace, machine tools, and racing.

--Lawrence Kren