US Patent 7207770 Variable stator vane bushings and washers

Materials, heretofore unknown for use in bearing assemblies, which produce equal or better wear resistance at reduced materials cost have been identified. These alternatives fall into four general categories: solid materials from which bushings and washers can be fabricated, coatings bonded to metallic vanes to minimize total system wear, solid lubricant coatings placed on any bushing or vane stem to reduce friction, and porous ceramic material from which seals can be fabricated.