SEDL / STP / STP546-EB / STP35504S

Evaluation of Graphite Fiber Reinforced Plastic Composites for Use in Unlubricated Sliding Bearings

Brown, RD
Southwest Research Institute, San Antonio, Tex

Blackstone, WR
Southwest Research Institute, San Antonio, Tex

Pages: 20    Published: Jan 1974

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Abstract

Conforming shoe-type specimens of radial fiber graphite/epoxy, tangential fiber graphite/epoxy, and radial fiber graphite/polyimide were fabricated and evaluated as bearing materials. Their performance was compared against that of specimens cut from commercially available Teflon-lined (TFE-lined) bearings of MS 21240 type. All the test specimens were run against hardened steel sleeves. Test conditions included bearing loads ranging from 9 to 30 ksi (6.2 × 10⁷ to 20.7 × 10⁷ N/m²); oscillatory motion of ±25 deg at 30 or 60 cpm (0.5 or 1.0 Hz); equilibrium sleeve temperatures at the start of test ranging from 80 to 400°F (300 to 477 K); and test durations of 2 h except where earlier specimen failure occurred. Compressive strength and thermal conductivity measurements were also made on the graphite/epoxy materials.

At temperatures of 350°F (450 K) and lower, the TFE material exhibited the best friction and wear characteristics of the four materials tested. The graphite/polyimide material exhibited friction and wear performance superior to that of either of the graphite/epoxy materials over the range of conditions used. At combinations of high load and temperatures in excess of 350°F (450 K), the wear rate of graphite/polyimide material was comparable to that of the TFE material, although friction was higher.