Various inorganic metallic chlorides, sulfates and phosphates were studied for friction, wear and seizure characteristics in four-ball wear and EP testers. Some metallic chlorides and sulfates in aqueous fluid provide improved tribological activities and the rate at which they act is largely dependent on the metal employed in these salts. The interactions of zinc sulfate-zinc chloride and aluminium sulfate-zinc chloride have been shown to be beneficial in improving the adhesion property. Other aqueous solutions of sodium salts of phosphorus in comparison with sulfur salts show better anti-seize tendencies. In these cases, it is believed that a transfer layer formation can explain the lubrication mechanism.
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