Tin based engine bearing overlays

Dr. Dmitri Kopeliovich

Tin based overlays contain copper (3-6%) as a hardening component.
The alloys are developed to replace toxic lead based overlays.
Tin based overlays possess excellent corrosion resistance and cavitation resistance.

Overlay multilayer system of Sn6Cu alloy deposited on the bi-layer diffusion barrier Ni-SnNi allows to create a microhardness gradient across the overlay thickness due to varying content of copper (soft top layer and hard bottom layer of the overlay). Such multilayer bearings are capable to withstand alternating loads up to 11600-13000 psi (80-90 MPa).
Hardness of tin-copper overlays is 20-30 HV.

Tin-copper overlays are deposited by the electroplating methods.

Nickel diffusion barrier (nickel dam) is deposited between the intermediate layer and tin containing overlay in order to prevent migration of tin from the overlay into the intermediate material (copper).
Diffusion of tin into copper causes formation of brittle Cu-Sn intermetallic compounds (Cu₃Sn, Cu₆Sn₅), which decrease the adhesion strength of the overlay to the intermediate layer. In addition to this decrease of the tin content in the overlay due to migration into intermediate material deteriorates the Corrosion resistance of the lead-based overlay alloy.
Thickness of nickel diffusion barrier is about 0.00004”-0.00006” (1-1.5 µm).
Nickel electroplating methods (Watts nickel plating solutions or nickel sulfamate solutions) are used for the diffusion barrier deposition.

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• Bearings in internal combustion engines
• Engine parameters determining bearing loading
• Lubrication regimes
• Hydrodynamic journal bearing
• Hydrodynamic lubrication theory
• Geometrical parameters of engine bearings
• Mechanisms of wear
• Requirements to engine bearing materials
• Engine bearing fatigue test
• Engine bearing materials
• Copper based bearing materials
• Manufacturing bi-metal strips for copper bearings
• Aluminum based bearing materials
• Continuous casting of aluminum based bearing alloys
• Manufacturing bi-metal strips for aluminum bearings
• Lead based engine bearing overlays
• Sputter bearing overlays
• Polymer based engine bearing overlays
• Engine bearing failure
• Selection of engine bearing materials
• Effect of low viscosity oils on engine bearings
• pMax Black™ - Strengthened Tri-metal Bearing Materials for High Performance Bearings
• U-Groove™ Modified Design of Oil Groove for High Performance Bearings
• ElliptiX™ Oil Hole of New Design for High Performance Bearings
• EccentriX™ Optimal Eccentricity for High Performance Bearings
• RadiaLock™ - Design of Crush Height for Reliable Press Fit of High Performance Bearings
• Modern Trends In Materials For High Performance Engine Bearings
• Optimization of Clearance Design for High Performance Engine Bearings
• Camshaft Bearings
• Ecological Aspects Of Engine Bearings
• Consistency in Bearing Wall Thickness
• Soft Strength of Racing Bearings
• Effect of oil viscosity on hydrodynamic friction of engine bearings
• Bearing Materials For Race Engines
• Oil Clearance and Engine Bearings
• Polymer Coated Bearings
• Development of Performance Bearings for Race Engines of Modern Design
• Failures of Engine Bearings and their Prevention
• Engine Bearing Housing and How it Affects Engine Bearings
• Polymer Coatings for Race Engine Bearings
• Heavy Duty Engine Bearings - Materials, Geometry, Failures
• Hydrodynamic Bearing – Calculations and Design
• Geometry of Engine Bearings
• Crush Height of Engine Bearings
• Materials for Engine Bearings
• Tin alloy electroplating
• Nickel electroplating

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