An initiative to accommodate higher in-cylinder pressure as a way to comply with regulations governing diesel engine emissions and fuel consumption

→Slide bearings for engines help to accommodate higher contact pressure values

Issues pertaining to Bi-alloy overlay bearings

  • Bismuth (Bi) on its own exhibits low mechanical strength, such that fatigue damage occurs.
  • Bi oxides are created at high working temperatures or in an environment of prolonged operations.

→By forming a Bi-Sb alloy, dramatic improvements in terms of fatigue resistance and oxidation resistance are achieved.

Bi :bismuth

Description of development

The world’s first adoption of a Bi-Sb alloy for overlay bearings.

  • Antimony (Sb) is an element that does not lower the melting point, which would affect high-temperature strength, and that enables electroplating.
Solute strengthening with Sb increases hardness
by a factor of two.

Results of XPS analysis

The production of Bi-Sb-O compounds inhibits the progression of oxidation.

Fatigue resistance is also improved for copper alloy linings.

  • Adding tin (Sn) and nickel (Ni) as solute strengthening elements improves fatigue and corrosion resistance.
  • Adding bismuth (Bi), which has a solid lubricating effect, and silver (Ag), which produces Sn compounds with low adhesion properties, ensures seizure resistance.


Fatigue resistance

Fatigue test results

75% Reduction in Fatigue Delamination Area

Oxidation resistance

Results of heating test conducted in oil

Oxide layer thickness reduced by 97%

Seizure resistance

Results of seizure test

According to the material concept
No sign of any reduction in seizure resistance