3。14 Digital images of scuffing tests with MIL-PRF-23699 oil under starved lubrication conditions; ground, chemically polished and highly polished specimens 64

3。15 Measured surface bulk temperature of rollers during the scuffing test with 5120 specimens with ground, CP and NiB coated surfaces under full and starved 80W90 lubricant conditions 67

3。16 Measured traction torques during the scuffing test with 5120 specimens with ground, CP and NiB coated surfaces under full and starved 80W90 lubricant conditions 68

3。17 Digital images of scuffing tests with 80W90 oil under full lubrication conditions; ground, chemically polished and NiB coated specimens 69

3。18 Digital images of scuffing tests with 80W90 oil under starved lubrication conditions; ground, chemically polished and NiB coated specimens 70

4。1 Gear efficiency test machine used in this study 73

4。2 Top view cross-section of the gear efficiency test machine with its main components labeled 74

4。3 A close-up view of the test gearbox with the side cover removed to expose the test gear pair and nozzle 76

4。4 Examples of 23 tooth test gears used in this study; ground, chemically polished, highly polished and NiB coated gears 78

4。5 Measurement of the profiles of a test gear on a gear CMM 84

4。6 Measurement of a test gear of a surface roughness profiler 85

4。7 Images of the NiB coated test gear teeth after completion of efficiency tests; NiB coated gear (not heat treated) and NiB coated gear (heat treated) 88

4。8 CMM lead traces of NiB coated teeth after completion of efficiency test; NiB coated gear (not heat treated) and NiB coated gear (heat treated) 89

4。9 Comparison of measured spin power losses of gear pairs having different surface treatments 91

4。10 Comparison of measured mechanical power losses of gear pairs having different surface treatments at              92

4。11 Comparison of measured mechanical power losses of gear pairs having different surface treatments at              93

4。12 Comparison of measured mechanical power losses of gear pairs having different surface treatments at              94

4。13 Comparison of measured mechanical power losses of gear pairs having different surface

treatments at Ω = 2000 rpm 96

4。14 Comparison of measured mechanical power losses of gear pairs having different surface

treatments at Ω = 4000 rpm