1 Introduction
2 Previous Work
3 Test Methods
3.1 EHD Friction Curves
3.2 EHD Film Thickness
4 Test Fluids
E1 | Dibasic acid ester | Di(2-ethylhexyl)phthalate |
E2 | Dibasic acid ester | Di-n-octyl phthalate |
E3 | Dibasic acid ester | Bis(2-ethylhexyl)terephthalate |
E4 | Dibasic acid ester | Bis(2-ethylhexyl)adipate |
E5 | Dibasic acid ester | Di(2-ethyhexyl)azelate |
E6 | Dibasic acid ester | Bis(2-ethylhexyl)sebacate |
E7 | Dibasic acid ester | Diisodecylazelate |
E8 | Polyol ester | NPG dioleate |
E9 | Polyol ester | NPG diisostearate |
E10 | Polyol ester | TMP C8/C10 |
PG1 | Polyalkylene glycol | TMP 3:1 EO:PO |
PG2 | Polyalkylene glycol | Glycerol 1:1 EO:PO |
PG3 | Polyalkylene glycol | Butanol propoxylate (22cSt) |
PG4 | Polyalkylene glycol | Butanol propoxylate (30cSt) |
PG5 | Polyalkylene glycol | C12–C14 propoxylate |
PG6 | Polyalkylene glycol | PPG-10 cetyl ether |
PG7 | Polyalkylene glycol | PPG-3 myristyl ether |
PAO1 | Polyalphaolefin | PAO (1.7 cSt at 100 °C) |
PAO2 | Polyalphaolefin | PAO (5.5 cSt at 100 °C) |
PAO3 | Polyalphaolefin | PAO (7 cSt at 100 °C) |
PAO4 | Polyalphaolefin | PAO (12 cSt at 100 °C) |
MO1 | Mineral oil | Group 1 |
MO2 | Mineral oil | Group 2 |
MO3 | Mineral oil | Group 3 (4 cSt at 100 °C) |
MO4 | Mineral oil | Group 3 (6.5 cSt at 100 °C) |
MO5 | Mineral oil | Group 3 (7.5 cSt at 100 °C) |
TF1 | Traction base fluid | 2,4-Dicyclohexyl-2-methylpentane |
TF2 | Traction base fluid | 2,3-Dimethyl-2-[(3-methylbicyclo[2.2.1] hept-2-yl)methyl]bicyclo[2.2.1]heptane |
PIB | Polyisobutylene | PIB |
PFPE1 | Perfluoropolyether | Z25 |
PFPE2 | Perfluoropolyether | Z09 |
PFPE3 | Perfluoropolyether | Krytox 15–25 |
NO1 | Natural oil | High oleic sunflower oil |
NO2 | Natural oil | Soybean oil |
NO3 | Natural oil | Castor oil |
IL1 | Ionic liquid | Methyltrioctylammonium bis(trifluoromethylsulfonyl)imide |
IL2 | Ionic liquid | 1-Ethyl-3-methylimidazolium ethyl sulphate |
IL3 | Ionic liquid | 1-Butyl-3-methylimidazolium tetrafluoroborate |
5 Results
5.1 Viscometics
Fluid | KV40 (mm2/s) | KV100 (mm2/s) | VI |
η
60 °C (mPas) |
η
80 °C (mPas) |
η
100 °C (mPas) |
---|---|---|---|---|---|---|
E1 | 26.9 | 4.20 | 86 | 11.6 | 6.27 | 3.89 |
E2 | 17.9 | 3.67 | 80 | 8.85 | 5.16 | 3.37 |
E3 | 28.9 | 4.64 | 58 | 12.6 | 6.89 | 4.28 |
E4 | 7.75 | 2.34 | 121 | 4.21 | 2.84 | 2.03 |
E5 | 10.7 | 3.04 | 151 | 5.66 | 3.69 | 2.61 |
E6 | 11.5 | 3.18 | 150 | 6.00 | 3.88 | 2.73 |
E7 | 18.1 | 4.46 | 168 | 8.96 | 5.58 | 3.81 |
E8 | 27.6 | 6.54 | 205 | 13.3 | 8.2 | 5.54 |
E9 | 46.5 | 8.13 | 149 | 19.6 | 11.0 | 6.88 |
E10 | 20.1 | 4.51 | 143 | 9.90 | 5.98 | 3.99 |
PG1 | 968 | 158 | 280 | 478 | 262 | 162 |
PG2 | 137 | 21.6 | 186 | 64.9 | 35.3 | 21.8 |
PG3 | 128 | 22.3 | 204 | 58.9 | 33.0 | 20.9 |
PG4 | 175 | 30.2 | 215 | 80.4 | 44.9 | 28.3 |
PG5 | 133 | 23.5 | 209 | 45.9 | 26.0 | 21.8 |
PG6 | 29.1 | 6.10 | 165 | 13.7 | 8.14 | 5.33 |
PG7 | 15.9 | 3.66 | 116 | 7.57 | 4.62 | 3.11 |
PAO1 | 5.22 | 1.69 | – | 2.51 | 1.73 | 1.26 |
PAO2 | 28.1 | 5.37 | 120 | 11.5 | 6.63 | 4.17 |
PAO3 | 43.1 | 7.12 | 118 | 16.8 | 9.09 | 5.57 |
PAO4 | 92.0 | 12.0 | 118 | 32.7 | 16.6 | 9.50 |
MO1 | 32.9 | 5.59 | 108 | 13.2 | 7.34 | 4.59 |
MO2 | 32.1 | 5.53 | 109 | 12.8 | 7.15 | 4.48 |
MO3 | 19.0 | 4.11 | 118 | 8.4 | 5.11 | 3.21 |
MO4 | 36.8 | 6.38 | 125 | 14.5 | 8.10 | 5.04 |
MO5 | 47.2 | 7.72 | 131 | 18.2 | 9.97 | 6.12 |
TF1 | 18.77 | 3.49 | 28 | 7.89 | 4.50 | 2.95 |
TF2 | 22.7 | 4.07 | 57 | 10.33 | 5.85 | 3.77 |
PIB | 29.7 | 4.8 | 70 | 11.1 | 6.09 | 3.79 |
PFPE1 | 160 | 50 | 351 | 180 | 120 | 84.4 |
PFPE2 | 55.2 | 17.6 | 338 | 61.7 | 41.6 | 29.5 |
PFPE3 | 82.6 | 10.7 | 114 | 64.8 | 32.5 | 18.8 |
NO1 | 40.9 | 8.75 | 201 | 20.0 | 12.1 | 7.51 |
NO2 | 41.2 | 8.90 | 204 | 20.6 | 12.5 | 7.77 |
NO3 | 254 | 19.5 | 86 | 82.9 | 36.0 | 17.6 |
IL1 | 208 | 19.7 | 108 | 84.8 | 38.7 | 25.6 |
IL2 | 39.0 | 7.76 | 174 | 24.1 | 14.1 | 9.21 |
IL3 | 43.9 | 7.76 | 147 | 25.0 | 14.1 | 8.92 |
5.2 EHD Film Thickness
5.3 EHD Friction
6 Discussion
6.1 Fluids with High Friction Coefficient
6.2 Fluids with Low Friction Coefficient
6.3 Friction and Molecular Structure of Esters
6.4 Effect of Base Oil Group on EHD Friction
6.5 Effect of Viscosity on EHD Friction
6.6 Shear Stress Versus Strain Rate Curves
6.7 Temperature Effect
Fluid |
p
mean = 1.5 GPa |
p
mean = 2 GPa |
---|---|---|
E1–E10 | 0.35 | 0.38 |
PG1–PG7 | 0.33 | 0.36 |
PAO1–PAO4 | 0.37 | 0.41 |
MO1–MO5, PIB | 0.31 | 0.35 |
TF1, TF2 | 0.27 | 0.30 |
PFPE1–PFPE3 | 0.17 | 0.18 |
NO1–NO3 | 0.35 | 0.38 |
IL1 | 0.37 | 0.40 |
IL2 | 0.49 | 0.54 |
IL3 | 0.35 | 0.38 |
6.8 Isothermally Corrected Shear Stress and Friction Coefficient
Fluid |
p
mean = 1.5 GPa | ||||||||
---|---|---|---|---|---|---|---|---|---|
60 °C | 80 °C | 100 °C | |||||||
c
0 (MPa) |
c
1 (MPa) |
\( \dot{\gamma }_{\hbox{max} } \)
× 106
|
c
0 (MPa) |
c
1 (MPa) |
\( \dot{\gamma }_{\hbox{max} } \)
× 106
|
c
0 (MPa) |
c
1 (MPa) |
\( \dot{\gamma }_{\hbox{max} } \)
× 106
| |
E1 | −86.2 | 13.3 | 3 | −105.6 | 13.4 | 5 | −132.0 | 14.1 | 10 |
E2 | −124.4 | 14.0 | 6 | −152.9 | 14.6 | 8 | −170.8 | 14.8 | 13 |
E3 | −63.0 | 10.6 | 3 | −86.3 | 11.3 | 6 | −111.2 | 11.9 | 12 |
E4 | −171.1 | 16.3 | 11 | −187.8 | 16.2 | 16 | −189.2 | 15.4 | 20 |
E5 | −164.2 | 16.0 | 7 | −190.9 | 16.6 | 12 | −199.1 | 16.0 | 17 |
E6 | −160.0 | 15.6 | 8 | −195.9 | 16.6 | 13 | −196.5 | 15.5 | 21 |
E7 | −99.7 | 13.2 | 4 | −140.6 | 14.5 | 8 | −166.2 | 15.0 | 11 |
E8 | −124.6 | 13.1 | 4 | −159.8 | 14.2 | 9 | −162.8 | 13.4 | 13 |
E9 | −63.0 | 10.5 | 3 | −113.3 | 12.9 | 5 | −147.6 | 14.1 | 7 |
E10 | −122.8 | 13.2 | 5 | −160.1 | 14.8 | 7 | −185.6 | 15.3 | 13 |
PG6 | −86.4 | 12.8 | 3 | −138.8 | 15.0 | 5 | −159.8 | 15.0 | 8 |
PG7 | −133.3 | 14.4 | 6 | −159.0 | 14.8 | 11 | −178.7 | 15.1 | 16 |
PAO1 | −176.0 | 16.2 | 12 | −184.2 | 15.6 | 17 | −194.1 | 15.3 | 21 |
PAO2 | −133.0 | 14.8 | 4 | −162.8 | 15.5 | 6 | −181.1 | 15.7 | 10 |
PAO3 | −117.6 | 14.0 | 3 | −148.4 | 14.9 | 5 | −164.0 | 14.9 | 8 |
PAO4 | −87.2 | 12.8 | 1.5 | −134.7 | 15.1 | 2 | −141.8 | 14.2 | 4 |
MO1 | −67.2 | 12.0 | 2 | −100.0 | 13.1 | 4 | −122.3 | 13.6 | 6 |
MO2 | −54.6 | 11.0 | 2 | −91.5 | 12.5 | 4 | −122.1 | 13.6 | 8 |
MO3 | −90.5 | 12.3 | 5 | −126.1 | 13.5 | 8 | −156.2 | 14.4 | 12 |
MO4 | −82.4 | 12.8 | 2 | −115.1 | 13.9 | 4 | −136.7 | 14.2 | 6 |
MO5 | −70.2 | 12.0 | 1.5 | −115.4 | 13.9 | 3 | −136.3 | 14.2 | 6 |
PIB | 24.0 | 7.9 | 1 | 16.2 | 7.7 | 3 | −22.5 | 9.7 | 4 |
NO1 | −123.6 | 12.7 | 5 | −140.6 | 12.5 | 9 | |||
NO2 | −105.2 | 11.7 | 4 | −138.4 | 12.8 | 7 | −144.7 | 12.3 | 11 |
NO3 | −2.8 | 5.6 | 1.5 | −82.7 | 10.2 | 3 | −120.8 | 11.6 | 6 |
IL1 | −78.3 | 11.6 | 0.6 | −122.7 | 13.5 | 2 | −144.9 | 13.8 | 4 |
IL2 | −61.8 | 8.2 | 7 | −95.1 | 9.5 | 10 | −124.6 | 10.6 | 16 |
IL3 | −70.8 | 9.0 | 4 | −102.8 | 10.2 | 8 | −124.7 | 10.8 | 12 |
Fluid |
p
mean = 2.0 GPa | ||||||||
---|---|---|---|---|---|---|---|---|---|
60 °C | 80 °C | 100 °C | |||||||
c
0 (MPa) |
c
1 (MPa) |
\( \dot{\gamma }_{\hbox{max} } \)
× 106
|
c
0 (MPa) |
c
1 (MPa) |
\( \dot{\gamma }_{\hbox{max} } \)
× 106
|
c
0 (MPa) |
c
1 (MPa) |
\( \dot{\gamma }_{\hbox{max} } \)
× 106
| |
E1 | −70.5 | 15.7 | 2 | −99.7 | 16.4 | 3 | −126.2 | 17.0 | 5 |
E2 | −133.8 | 18.0 | 2 | −151.3 | 17.7 | 6 | −181.4 | 18.4 | 8 |
E3 | −53.7 | 13.3 | 2 | −82.1 | 14.1 | 3 | −120.6 | 15.4 | 7 |
E4 | −156.6 | 19.0 | 5 | −177.5 | 18.9 | 10 | −206.8 | 19.6 | 10 |
E5 | −151.5 | 18.8 | 4 | −178.5 | 19.0 | 7 | −214.6 | 20.0 | 9 |
E6 | −138.1 | 17.6 | 4 | −189.6 | 19.5 | 8 | −227.0 | 20.4 | 13 |
E7 | −125.3 | 19.1 | 3 | −138.4 | 18.1 | 4 | −158.6 | 17.9 | 7 |
E8 | −145.0 | 18.4 | 2 | −181.1 | 19.0 | 4 | −191.5 | 18.2 | 7 |
E9 | −72.9 | 15.4 | 1.5 | −130.2 | 17.8 | 2 | −156.2 | 18.0 | 4 |
E10 | −141.1 | 18.0 | 3 | −187.8 | 20.1 | 4 | −225.5 | 20.9 | 9 |
PG6 | −82.3 | 16.7 | 2 | −122.6 | 17.7 | 3 | −169.6 | 19.3 | 6 |
PG7 | −150.0 | 19.5 | 3 | −150.3 | 17.6 | 6 | −197.5 | 19.4 | 8 |
PAO1 | −165.0 | 18.8 | 8 | −204.0 | 19.9 | 10 | −212.6 | 19.2 | 13 |
PAO2 | −140.2 | 19.1 | 1 | −177.1 | 19.9 | 4 | −200.5 | 20.1 | 6 |
PAO3 | −125.7 | 18.5 | 1.5 | −156.9 | 18.9 | 4 | −176.9 | 19.0 | 5 |
PAO4 | −78.7 | 16.2 | ` | −128.9 | 18.2 | 1.5 | −158.0 | 18.6 | 3 |
MO1 | −51.5 | 14.8 | 1.5 | −89.0 | 16.0 | 3 | −129.4 | 17.5 | 4 |
MO2 | −73.6 | 16.4 | 1.5 | −97.3 | 16.6 | 3 | −130.7 | 17.6 | 4 |
MO3 | −94.8 | 16.4 | 3 | −120.4 | 16.5 | 4 | −155.8 | 17.6 | 7 |
MO4 | −64.8 | 15.5 | 1.5 | −95.0 | 16.2 | 2 | −153.7 | 18.8 | 3 |
MO5 | −65.9 | 15.9 | 1 | −113.1 | 17.5 | 2 | −135.8 | 17.6 | 3 |
PIB | −32.0 | 15.6 | 1 | 15.7 | 11.4 | 2 | −11.3 | 12.5 | 3 |
NO1 | −139.2 | 17.3 | 2.5 | −163.9 | 17.1 | 5 | |||
NO2 | −113.0 | 16.0 | 2.5 | −155.8 | 17.2 | 3 | −171.2 | 16.8 | 5 |
NO3 | 13.0 | 8.5 | 0.7 | −84.3 | 13.9 | 2 | −135.3 | 15.7 | 3 |
IL1 | −77.4 | 15.5 | 0.5 | −131.5 | 17.7 | 1 | −174.6 | 19.0 | 2 |
IL2 | −38.9 | 9.1 | 3 | −75.9 | 10.7 | 6 | −122.5 | 12.9 | 9 |
IL3 | −48.5 | 9.8 | 3 | −94.0 | 11.9 | 5 | −119.6 | 12.7 | 7 |