Corrosion of the lead in copper-lead and lead-bronze alloys, and of lead base whitemetals, may be caused by acidic oil oxidation products formed in service, by ingress of water or coolant liquid into the lubricating oil, or by the decomposition of certain oil additives. Removal of overlays by abrasive wear or scoring by dirt exposes the underlying lead in copper-lead or lead-bronze interlayers to attack, while in severe cases the overlays may be corroded.
Fig. 18 - Severely corroded surface of unplated copper-lead lined bearing caused by attack of lead phase by acidic oil oxidation products.
Fig. 19 - Fractured section of bearing shown in Fig. 18 indicating depth of corrosion of lead.
Fig. 20 - Corrosion of marine turbine whitemetal bearing. Water in the oil has caused formation of smooth hard black deposit of tin dioxide on surface.
Fig. 21 - “Sulphur corrosion” of phosphor bronze small end bush, caused by decomposition of lubricating oil additive and gross pitting and attack of bearing surface.
Scrap bearings. Investigate oil condition to ascertain cause of corrosion. Eliminate water in oil. In case of “sulphur corrosion” change bearing material from phosphor bronze to phosphorous-free alloys such as
• lead-bronze, silicon bronze or gunmetal after consultation with oil and bearing suppliers.
|Scoring Due to Foreign Matter or "Dirt"
|Damage Caused by Faulty Assembly
|Black Scab / Wire Wool Damage
|Pitting Due to Electrical Discharge
|Wiping of Bearing Surfaces
|Fretting Damage from Vibration
|Damage Due to Oveheating
Mobirise site builder - More here