Sources of Silver
Silver is a wear metal used as an overlay on some bearings, such as journal bearing for gas turbines or wrist pin bearings on EMD locomotive engines. Silver from these parts will increase disproportionately with iron. Zinc additized oils will accelerate the corrosion of silver in these applications, therefore the use of tricresyl phosphate (TCP) additives is warranted.
Silver can also be found in some solders, therefore silver, lead, and tin may also appear due to leaching from the solder used to attach cooler tubes, often in conjunction with an increase in Acid Number.
Watch for the next article in the Elemental Spectroscopy blog series: Calcium
