Bismuth Sulfide
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Bismuth Sulfide (Bi2(SO4)3) is an anti-wear, extreme-pressure additive that reduces friction and wears in high-load applications. It forms a protective layer on metal surfaces and reduces surface-to-surface contact. Bismuth Sulfate is often used in EP (Extreme Pressure) greases for applications such as heavy machinery, automotive, and industrial equipment.
The bismuth-containing EP additives replace partly or completely known EP additives, such as lead/sulfur or Sulfur / phosphorous additives in extreme pressure lubricant compositions.
When the Bismuth compound is used as an EP additive, it can be added to the Soap, the oil, or the already-formed mixture of the oil and the Soap thickener. Usually, and preferably the additive is mixed with the oil.
The Bismuth containing EP additives are used in the usual amounts; generally, the part of Bismuth will be 0.1-5% by weight of the total lubricant composition. Mixtures of one or more Bismuth compounds can be used, optionally in admixture with one or more other EP additives. Further conventional additives for lubricant compositions can be used in usual amounts if desired.