fluid-film bearings, polycrystalline diamond, PCD, process-fluid-lubricated
Polycrystalline diamond thrust and radial bearings have proven to be successful in harsh environments, such as those encountered in down-hole oil and gas drilling tools. They are particularly well suited for applications where a harsh or abrasive fluid is serving as the bearing lubricant. In oil and gas drilling tools, the bearings are cooled and lubricated directly by the drilling fluid. Marine hydrokinetic machines have the potential need for bearings that can operate directly in the water environment without the use of seals or hydrocarbon-based lubricants. Polycrystalline diamond bearings may be ideally suited for such use where they will be required to last for several years as opposed to hundreds or thousands of hours in oil and gas applications. Recent tests conducted by the authors have shown that polycrystalline diamond bearings can operate successfully as fluid-film bearings where the bearing surfaces are completely separated by a thin layer of lubricant. Fluid film bearings have the advantages of very low friction and, in theory, infinite life. This new development means that polycrystalline diamond bearings may be well suited for use in marine hydrokinetic machines or in other renewable energy applications such as wind or geothermal.