Copper-Lead Bimetal Bearings & Bushes

 Copper Powder Metallurgy for Bearings:
. Copper readily forms a protective oxide film when heated in air. 
. Copper readily forms a protective sulphide film with oils containing only traces
  of sulphur compounds. 
. Copper has a high thermal conductivity for the dissipation of the frictional heat,
  thus reducing the surface temperature. 
. Tin strengthens copper and hardens it sufficiently to be compatible
  with unhardened steel. 
. The protective Organo-tin films formed with oils have a high
  desorption temperature 
. Hence the copper-tin bronzes result in better bearings than the
  copper-zinc brasses. 
. Copper alloys usually have a face-centered-cubic structure while the
  mating surface is usually a ferrous alloy with a body-centered-cubic structure.
  This difference contributes to the anti-seizure characteristics of copper
  alloys against iron alloys.
  Overlay Plated Copper-Lead Bearings for Heavy Duty Service:
. The Copper-Lead Bearings when plated have higher load carrying capacity
  than straight copper-lead alloys.
. These overlays are very soft and have excellent embeddability,
  conformability and corrosion resistance without impairing higher fatigue
  strength of inner copper-lead-tin alloy.