Tribological Properties of Oil Soluble Polyacrylates with Hydroxyl Group *Kenji YAMAMTO 1, Kenta NAKAMURA 2, Masayoshi MURAKI 3 1: Surface Specialties Department, ADEKA Corporation, Tokyo, Japan. 2: Research and Development Division, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan. 3: Mechanical Design Engineering, Shonan Institute of Technology, Kanagawa, Japan.
Contents Back ground Oils tested and polymers Rheological properties Film forming properties and EHL traction characteristics Anti wear properties Friction speed characteristics and surface analysis Summary May 17, 2016 STLE2016 2
Contents Back ground Oils tested and polymers Rheological properties Film forming properties and EHL traction characteristics Anti wear properties Friction speed characteristics and surface analysis Summary May 17, 2016 STLE2016 3
Back ground Oil soluble polymers VM and/or VII Functionalized polymers and short alkyl chain containing polymers contribute to increase oil film thickness. Muraki, M., et al., Proc. Instn Mech. Engr., Part J: J. Engineering Tribology, (2010)223, 55 63. May 17, 2016 STLE2016 4
The objective of this study is To study the tribological performance of polyalkylacrylate in comparison with PAMA. To confirm the effect of hydroxyethyl group based on film forming properties and traction properties under the EHL conditions and anti wear performance under the boundary lubrication conditions. H CH 2 C COOR n CH 3 CH 2 C COOR May 17, 2016 STLE2016 5 m OH
Contents Back ground Oils tested and polymers Rheological properties Film forming properties and EHL traction characteristics Anti wear properties Friction speed characteristics and surface analysis Summary May 17, 2016 STLE2016 6
Oils tested Abbreviation Viscosity at 40 C, mpa s α at 40 C, GPa 1 PAO4 14.6 16.7 PAO8 39.1 18.7 May 17, 2016 STLE2016 7
Polymers H H H CH 2 C CH 2 C CH 2 C COOC 12 H 25 COOC 12 H 25 COOC 2 H 5 OH n n m a) polylaurylacrylate (PLA) b) polylaurylacrylate with hydroxyethyl group (PLA/HEA) CH 2 CH 3 CH 3 CH 3 C CH 2 C CH 2 C COOC 12 H 25 n c) polylaurylmethacrylate (PLMA) COOC 12 H 25 n COOC 2 H 5 OH m d) polylaurylmethacrylate with hydroxyethyl group (PLMA/HEMA) May 17, 2016 STLE2016 8
Contents Back ground Oils tested and polymers Rheological properties Film forming properties and EHL traction characteristics Anti wear properties Friction speed characteristics and surface analysis Summary May 17, 2016 STLE2016 9
Rheological properties Abbreviation Conc. Viscosity mass% mpa s k M Mw PLA 7.4 37.4 0.25 110,000 PLA/HEA 9.9 37.5 1.67 110,000 PLMA 6.9 36.4 0.40 100,000 PLMA/HEMA 9.8 36.6 4.43 110,000 Hydroxyethyl group tends to give larger k M. May 17, 2016 STLE2016 10
Contents Back ground Oils tested and polymers Rheological properties Film forming properties and EHL traction characteristics Anti wear properties Friction speed characteristics and surface analysis Summary May 17, 2016 STLE2016 11
Disk on roller tester for oil film thickness measurements 1. Load 15 N (0.24 GPa) 2. Mean rolling speed 0.001~1.0 m/s 3. Temperature 40 C 4. Roller & disk roller φ25.4 mm SUJ 2(AISI 52100) Ra 4 nm disk φ100 x 12 mm Glass coated with a Cr oxide semi reflective layer. May 17, 2016 STLE2016 12
The effect of viscosity on the tester Analysis result follow the Hamrock & Dowson s equation. May 17, 2016 STLE2016 13
Film forming properties in comparison with PAMA HE group enhances the oil film thickness in the low rolling speeds. May 17, 2016 STLE2016 14
Film forming properties: the effect of OH group Strong adsorption of PLA/HEA is indicated May 17, 2016 STLE2016 15
Disk on roller tester for EHL traction measurements 1. Load 40 N (0.67 GPa) 5. Roller & disk 2. Mean rolling speed 0.004~1.0 m/s roller φ25.4 mm 3. Slide/roll ratio 0.5 SUJ 2(AISI 52100) Ra 7 nm 4. Temperature 40 C disk φ100 x 12 mm May 17, 2016 STLE2016 Ra 4 nm Sapphire 16
EHL traction characteristics Coefficient of traction Polymers with HE group are effective for reducing friction compared to non functionalized polymers. May 17, 2016 STLE2016 17
Relation between oil film thickness and traction The reduced friction can be explained by the increased oil film thickness. May 17, 2016 STLE2016 18
Contents Back ground Oils tested and polymers Rheological properties Film forming properties and EHL traction characteristics Anti wear properties Friction speed characteristics and surface analysis Summary May 17, 2016 STLE2016 19
Ball on disk tester for evaluating anti wear properties Load 1. Load 100, 300 N 2. Amplitude 1.0 mm 3. Frequency 50 Hz 4. Temperature 80 C 5. Test Period 60 min 6. Ball & Plate Ball φ10 mm SUJ 2(AISI 52100) Plate φ24 7.8 mm Ra=0.045 μm SUJ 2(AISI 52100) #SUJ 2. High Carbon Chromium Bearing Steel(760HV) May 17, 2016 STLE2016 20
Anti wear property PLA with HE group shows better AW performance than non HE polymer and HE containing PLMA. May 17, 2016 STLE2016 21
Contents Back ground Oils tested and polymers Rheological properties Film forming properties and EHL traction characteristics Anti wear properties Friction speed characteristics and surface analysis Summary May 17, 2016 STLE2016 22
Pin on disk type tribometer 1. Load 100 N (1.37 GPa) 2. Sliding speed 0.001 ~ 0.2 m/s 3. Temperature 90 C 4. Test specimens Pin r: 3mm SUJ 2(AISI 52100) Ra 0.5 μm Plate φ32 x 8 mm SUJ 2(AISI 52100) Ra=0.05 μm #SUJ 2. High Carbon Chromium Bearing Steel(760HV) May 17, 2016 STLE2016 23
Test result (example) May 17, 2016 STLE2016 24
Friction speed characteristics PLA with HE group contributes to stabilize μ V characteristics. May 17, 2016 STLE2016 25
Surface analysis on the disk (C1s spectra) XPS analysis result indicates tribofilm formation on the rubbed surface from PLA with HE group. May 17, 2016 STLE2016 26
Surface analysis on the disk (O1s spectra) XPS analysis result indicates tribofilm formation on the rubbed surface from PLA with HE group. May 17, 2016 STLE2016 27
Contents Back ground Oils tested and polymers Rheological properties Film forming properties and EHL traction characteristics Anti wear properties Friction speed characteristics and surface analysis Summary May 17, 2016 STLE2016 28
Summary Tribological properties of PLA with HE group were studied compared to PLMA under the partial EHL and the boundary lubrication conditions. An increased oil film thickness and reduction in friction were achieved by presence of HE group for both PLA and PLMA under rolling sliding conditions. PLA with HE group was superior to the others on anti wear performance under the boundary lubrication conditions. This effect probably because of tribofilm generated on the rubbing surface from acrylate polymer. Further work is required to explore the cause of better tribological performance of PLA with HE group. May 17, 2016 STLE2016 29
Thank you for your attention. May 17, 2016 STLE2016 30