Lube-Tech PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
One DLC is described as 50%sp3 second DLC is described as sp2
; 40% hydrogen content; the ;Cr doped; 0% hydrogen. Both
types of DLC ball were provided by PCS Instruments.
No.110 page 3
Figure 7. Grey-scale and computer enhanced wear images
Figure 8 shows an example of how the wear scar of the disc is estimated. Unlike the ball, it is not possible to measure the wear across the whole circumference of the disc therefore only a small cross-section of the disc is examined. This type of measurement was taken at 8 different points around the wear track and an average value calculated. Whilst we do not measure the whole wear track, the measurement allows quantitative comparisons between oils to be measured.
Table 1. Steel ball and DLC ball profiles used in MTM sliding contact
The effect of friction modifiers in a steel ball – steel disc contact was also investigated and compared to DLC ball – steel disc arrangement.
Friction and Wear tests were conducted using a PCS Instruments Mini Traction Machine, using the following test profile: • Determination of an initial Stribeck curve: • Ball on disc: Pure Sliding • Virgin surfaces • Load 36N (1.01 GPa Hertzian Pressure) • Lubricant temperature 80ºC • Entrainment speeds between 0.05 m/s and 3.0 m/s • No running-in profile, friction measured from high speed to low speed
• Run a rubbing test profile; pure sliding, 0.05 m/s at 30 N and 80ºC for 120 mins
• Determination of a Second Stribeck curve using the same conditions described above for the initial Stribeck curve. Friction and wear performance was determined after the second Stribeck curve was generated.
Following completion of the second Stribeck curve, wear profiles for both balls and discs were studied using 3D imaging (Bruker 3D Optical Profilometer Contour GT).
Figure 7 shows examples of both grey scale images and computer enhanced images of the wear scar observed on the ball. Using these images the volume of the wear scar can be estimated.
Figure 8. Example of wear determination of the steel disc
2.1 Test Samples The 5W30 European ACEA C3 oil was once again used as the base line reference fluid. Friction modifiers were added to this reference oil in order to determine the influence of MoDTC, polymeric friction modifiers and a conventional organic friction modifier, namely glycerol mono-oleate (GMO).
The test samples and tests conducted are shown in Table 2.
Table 2. Samples and tests conducted using MTM sliding conditions LUBE MAGAZINE NO.139 JUNE 2017 35
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72