In steel mills and other applications where water spray is common, the service lives of greases and bearings depend critically on the ability of lubricants to repel water and metalworking fluids. This study focused on measuring the response of four types of commonly used greases to water spray: simple lithium soap, lithium complex soap, lithium calcium mixed soap, and overbased calcium sulfonate. Grease consistency, base oil viscosity, two types of polymer additives, and total base number (in the case of overbased calcium sulfonate greases) were varied in this study. All greases were tested for water washout under the same conditions according to ASTM D1264. Grease water repellency was improved by a high molecular weight polymer additive and by using a higher total base number calcium sulfonate to make overbased calcium sulfonate grease. Increasing the kinematic viscosity of the base oil from 150 to 320 mm2 /s (cSt) was also beneficial in the formulations tested.
展开▼
