Tribological performance of PEEK composites under
the lubrication of ILs
Yijun Shia, Jian Wub, Xiaohua Lub
a Division
of Machine Elements, Luleå University of Technology, 97187 Luleå, Sweden
b State Key Laboratory of Materials-oriented Chemical Engineering, Nanjing Tech University,
Nanjing 210009, P.R. China
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Outline
 Background
 Motivation & frame of work
 Materials preparation and friction test
 Some results
Wettability of liquid lubricants
Friction coefficient and wear rate
Friction surface studies—SEM, AFM and EDX
 Conclusions
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Background
PEEK
High chemical stability
Excellent thermal and mechanical properties
 High friction coefficient (µ)
PEEK composites
Gr, PTFE and MoS2 and etc. as internal lubricants
 Some original performance of PEEK such as tensile
strength and impact strength will decrease.
PEEK under lubricating oil
Oil has limited working temperature, pressure...
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Ionic liquids as lubricants
4

Very low vapor pressure

Non-flammable substance

High thermally stable

High mechanically stable

Electrochemically stable
Ionic liquids as lubricants for polymers
Citation Report
Topic=(polymer + “ionic liquid” + friction OR wear)
Timespan=All Years. Databases=SCI-EXPANDED, CCR-EXPANDED, IC.
Related results
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Almost no study under high applied load
Most investigations
steel, titanium, alloy …
Few investigations
polymers
Motivation & frame of work
1) Study the tribological properties of PEEK composites in ILs;
2) Compare the lubrication effect of ILs with that of internal
lubricant (PTFE) and lubricating oil.
Test property
Mediums
1) Dry condition
1) Wettability of liquid lubricants
2) Friction coefficient and wear rate 2) In oil: L-HM 46 (Oil)
3) In ILs: [BMIM]PF6 (IL)
3) Worn surfaces
Test conditions:
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1) Sliding velocity: 0.7m/s
2) Load: 150 N-1500 N (1-10MPa)
3) Test time: 60 min
Materials properties
Table 1. The Main Properties of L-HM46 and [Bmim][PF6]
External lubricants
Main components
Main multifunctional additive
Kinetic viscosity at 40 ºC (mm2/S)
Viscosity index
Surface tension at 40 ºC (mN/m)
Density at 20 ºC (kg/m3)
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L-HM46
Neutral mineral oil
ZDDP (Zn ≤ 0.12 wt%)
45.9
97
43.4-48.8
872.8
Fig. 1. Chemical structures of PEEK, ZDDP and [Bmim][PF6].
[Bmim][PF6]
[Bmim][PF6]
/
89.1 [25]
172 [26]
31.85 [27]
1370.0
Friction and wear tests
Fig. 2. Schematic diagram of lubricating ways and frictional contact parts (Unit: mm).
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Wettability of liquid lubricants
Table 2. Details of Different Lubricating Systems.
Number
PEEK composites
Lubricants
1
16 vol%PTFE/PEEK
Internal PTFE
2
PEEK
External L-HM46
3
PEEK
External [Bmim][PF6]
Table 3. The contact angle of L-HM46 and [Bmim][PF6] on the sliding surfaces.
Contact angle
Liquids
PEEK
Steel
9.7±1.4°
10.8±1.9°
51.2±1.0°
52.6±1.0°
L-HM46
[Bmim][PF6]
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Anti-friction/wear performance
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Anti-friction/wear performance
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AFM studies
After
Before
PEEK
Counterpart
(Test condition: [Bmim][PF6], 1500 N, 0.7 m/s, duration: 1 h).
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Tribochemical investigation
Elemental distribution (except commom elements in steel) in the counterpart worn surfaces lubricated with
13 [Bmim][PF ], 1500 N for 1 h, and (b) L-HM46, 800 N for 45 minutes.
(a)
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Mechanism
analysis
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Tack !
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