Details
| Original language | English |
|---|---|
| Article number | 3 |
| Journal | Lubricants |
| Volume | 8 |
| Issue number | 1 |
| Publication status | Published - 19 Dec 2019 |
Abstract
In recent years, graphene-based lubrication was in the focus of nano-and microtribological studies. While the sliding properties of graphene based dry lubrication were previously investigated on the nano-and micro-scale, few studies can be found in the literature for the application of graphene as an additive to oil and grease in rolling contacts. In order to apply graphene platelets as dry lubricants and as grease additives in machine elements, tests were carried out on a rolling bearing test rig under typical load conditions. For these investigations, multilayer graphene platelets of varied staple thickness were functionalized on angular contact ball bearing surfaces as a dry lubricant, which forms a thin film. In addition, bearings were lubricated with grease containing graphene platelets. In this case, a small ratio of graphene was dispersed with grease. The graphene platelets were divided into three groups of dierent thickness: 2 nm, 6-8 nm, and 11-15 nm. Additionally, the tests were compared to graphite nanoparticles (spheres with a size of 3-4 nm) as dry lubricant and graphite-containing grease. The experimental studies were carried out under oscillating motion. The respective load in the tribological contact was 1.5 GPa. During the tests, the pivoting angle was measured by utilizing a rotary encoder. In addition, the friction torque was recorded under a frequency of 0.2 Hz. As the balls' velocity at the reversal point is zero, the lubrication conditions are critical. The dry lubricated bearings were compared to grease lubricated bearings. Additionally, the frictional properties of the respective greases were investigated by applying a sliding tribometer. In this case, a ball rotates against three contact planes, which causes a tribological contact under a contact pressure of 1 GPa. It was shown that applying graphene as a dry lubricant and as a grease additive under rolling contact conditions reduces friction significantly.
Keywords
- Dry lubrication, Graphene, Grease lubrication, Nano particles, Rolling contact
ASJC Scopus subject areas
- Engineering(all)
- Mechanical Engineering
- Materials Science(all)
- Surfaces, Coatings and Films
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In: Lubricants, Vol. 8, No. 1, 3, 19.12.2019.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Investigations on Graphene Platelets as Dry Lubricant and as Grease Additive for Sliding Contacts and Rolling Bearing Application
AU - Pape, Florian
AU - Poll, Gerhard
PY - 2019/12/19
Y1 - 2019/12/19
N2 - In recent years, graphene-based lubrication was in the focus of nano-and microtribological studies. While the sliding properties of graphene based dry lubrication were previously investigated on the nano-and micro-scale, few studies can be found in the literature for the application of graphene as an additive to oil and grease in rolling contacts. In order to apply graphene platelets as dry lubricants and as grease additives in machine elements, tests were carried out on a rolling bearing test rig under typical load conditions. For these investigations, multilayer graphene platelets of varied staple thickness were functionalized on angular contact ball bearing surfaces as a dry lubricant, which forms a thin film. In addition, bearings were lubricated with grease containing graphene platelets. In this case, a small ratio of graphene was dispersed with grease. The graphene platelets were divided into three groups of dierent thickness: 2 nm, 6-8 nm, and 11-15 nm. Additionally, the tests were compared to graphite nanoparticles (spheres with a size of 3-4 nm) as dry lubricant and graphite-containing grease. The experimental studies were carried out under oscillating motion. The respective load in the tribological contact was 1.5 GPa. During the tests, the pivoting angle was measured by utilizing a rotary encoder. In addition, the friction torque was recorded under a frequency of 0.2 Hz. As the balls' velocity at the reversal point is zero, the lubrication conditions are critical. The dry lubricated bearings were compared to grease lubricated bearings. Additionally, the frictional properties of the respective greases were investigated by applying a sliding tribometer. In this case, a ball rotates against three contact planes, which causes a tribological contact under a contact pressure of 1 GPa. It was shown that applying graphene as a dry lubricant and as a grease additive under rolling contact conditions reduces friction significantly.
AB - In recent years, graphene-based lubrication was in the focus of nano-and microtribological studies. While the sliding properties of graphene based dry lubrication were previously investigated on the nano-and micro-scale, few studies can be found in the literature for the application of graphene as an additive to oil and grease in rolling contacts. In order to apply graphene platelets as dry lubricants and as grease additives in machine elements, tests were carried out on a rolling bearing test rig under typical load conditions. For these investigations, multilayer graphene platelets of varied staple thickness were functionalized on angular contact ball bearing surfaces as a dry lubricant, which forms a thin film. In addition, bearings were lubricated with grease containing graphene platelets. In this case, a small ratio of graphene was dispersed with grease. The graphene platelets were divided into three groups of dierent thickness: 2 nm, 6-8 nm, and 11-15 nm. Additionally, the tests were compared to graphite nanoparticles (spheres with a size of 3-4 nm) as dry lubricant and graphite-containing grease. The experimental studies were carried out under oscillating motion. The respective load in the tribological contact was 1.5 GPa. During the tests, the pivoting angle was measured by utilizing a rotary encoder. In addition, the friction torque was recorded under a frequency of 0.2 Hz. As the balls' velocity at the reversal point is zero, the lubrication conditions are critical. The dry lubricated bearings were compared to grease lubricated bearings. Additionally, the frictional properties of the respective greases were investigated by applying a sliding tribometer. In this case, a ball rotates against three contact planes, which causes a tribological contact under a contact pressure of 1 GPa. It was shown that applying graphene as a dry lubricant and as a grease additive under rolling contact conditions reduces friction significantly.
KW - Dry lubrication
KW - Graphene
KW - Grease lubrication
KW - Nano particles
KW - Rolling contact
UR - http://www.scopus.com/inward/record.url?scp=85079001651&partnerID=8YFLogxK
U2 - 10.3390/lubricants8010003
DO - 10.3390/lubricants8010003
M3 - Article
AN - SCOPUS:85079001651
VL - 8
JO - Lubricants
JF - Lubricants
SN - 2075-4442
IS - 1
M1 - 3
ER -