Investigation Of The Tribological Properties Of Cu-α-ZrP As Solid Lubrication Additive In Lubrication Oil

With the development of mechanical equipment, the friction parts oftenneed to work under harsh conditions, such as high temperature, heavy load,strong radiation, low speed, etc. So the conventional lubricating oils can notmeet the demand. Solid lubricants can effectively increase the bearing capacityand reduce the friction and wear. Layered zirconium phosphate is a new kind ofsolid lubricant additive, α-ZrP and Cu-α-ZrP have showed excellent lubricationability in the lithium grease and lubricating oils. In order to investigate thetribological properties of Cu-α-ZrP in different base oils, Cu-α-ZrP as anadditive was evaluated with an oscillating reciprocating friction and wear tester.Meanwhile the traditional solid lubricant MoS2, graphite and α-ZrP were used asreferences under the same experimental conditions.Firstly, the tribological properties of1.0wt.%Cu-α-ZrP in PEG400wasinvestigated under fixed frequency of5Hz, applied loads varied from100N to300N. The results showed that the dynamic friction coefficient curves weresteady, and the average friction coefficients were reduced from0.129,0.110,0.121to0.102,0.087,0.079, respectively. Under the applied load of200N andfrequency of1Hz, the dynamic friction coefficient curve of Cu-α-ZrP was no fluctuation. But α-ZrP, MoS2, graphite and base oil PEG400failed to completethe test. When the frequency was10Hz, the dynamic friction coefficient curveof1.0wt.%of Cu-α-ZrP was also steady, the average friction coefficient ofPEG400reduced from0.099to0.066. When the load and the frequency were300N and5Hz, the values of wear volumes (106μm3) were as follows:5.371ofPEG400,2.673of Cu-α-ZrP,3.491of α-ZrP,3.176of MoS2, and4.022ofgraphite. Cu-α-ZrP showed excellent friction-reducing and antiwear (AW)properties in the base oil of PEG400.The tribological properties of Cu-α-ZrP in100SN were investigated underthe applied loads ranging from100N to300N and the frequency of5Hz. Thedynamic friction coefficient curves of1.0wt.%Cu-α-ZrP were stable, and theaverage friction coefficients were dropped from0.082,0.080,0.100to0.066,0.070,0.078, respectively. Under the applied load of200N and the frequencyranging from1Hz to10Hz, the average friction coefficients reduced from0.131,0.080,0.084to0.127,0.070,0.059of1.0wt.%, respectively. When theload and the frequency were300N and5Hz, the values of wear volumes (105μm3) were as follows:2.697of100SN,2.127of Cu-α-ZrP,2.398of α-ZrP,2.500of MoS2, and2.593of graphite. Cu-α-ZrP displayed better anti-wearproperties and good friction-reducing performance in the base oil of100SN.The tribological properties of Cu-α-ZrP in liquid paraffin were alsoinvestigated at the applied loads ranging from100N to300N and the frequencyof5Hz. The dynamic friction coefficient curves of Cu-α-ZrP were smooth, and the average friction coefficients decreased from0.100,0.113,0.132to0.084,0.087,0.089, respectively. At the applied load of200N and frequency of1Hz,the dynamic friction coefficient curve of Cu-α-ZrP was no fluctuation, but thefriction coefficient curves of α-ZrP, MoS2, and graphite showed manyfluctuations for the entirely testing time. When the frequency was10Hz, thefriction coefficient curve of Cu-α-ZrP was smooth, and the average frictioncoefficient reduced from0.087to0.067. At applied load of300N and thefrequency of5Hz, the values of wear volumes (106μm3) were as follows:5.541of liquid paraffin,3.297of Cu-α-ZrP,4.065of α-ZrP,4.078of MoS2, and4.777of graphite. Cu-α-ZrP possessed excellent AW performances.The SEM micrographs and EDS of the worn surfaces showed that the wornsurfaces of the steel plates lubricated by Cu-α-ZrP were smooth, only a littlegrooves and gougings, especially under the higher applied loads and frequencies.The order of friction-reducing and antiwear properties of Cu-α-ZrP in threekinds of base oils was100SN> PEG400> liquid paraffin. Cu-α-ZrP particlesin the base oil are as the―third body‖to protect the friction pair.