Effects of Wear Metal on Lubricant Deposition.

The effects of wear metal on deposit forming characteristics of turbine engine lubricants were investigated, employing hot-wall deposition test rigs. The hot-wall section of the rigs was redesigned, fabricated and assembled for testing. A recently designed wear-metal generator was employed. Eight MIL-L-7808 or MIL-L-7808-type lubricants were evaluated under five different test conditions. Then a brief statistical analysis was performed to determine the micronic filtration tests to be performed in a mitigation of wear-metal effects phase of the effort. Also, the effects on both kinematic viscosity and neutralization number of the test lubricants were determined. A direct calculation of wear-metal generation was provided by weight-loss measurements of the wear coupons mounted below the lubricant level in the sump. Also, the concentration of wear metals in samples of the test lubricants taken during testing was determined by atomic absorption spectrophotometer. The energy dispersive X-ray fluorescence technique was employed to determine trace elements in hot-wall deposit scrapings. The preliminary statistical analysis for all eight lubricants consisted of a one-way analysis of variance, then an analysis of covariance using an adjustment for wear, and finally an unadjusted analysis of variance.