Aqueous lubrication and surface microstructures of engineering polymer materials (PEEK and PI) when sliding against Si3N4

Abstract

Polyether-ether-ketone (PEEK) and polyimide (PI) are two kinds of engineering polymer materials widely used as roller bearing cages and rings under extreme environment because of their noise reduction and corrosion resistance properties. The Si 3 N 4 ceramic is the most common ball bearing material. Many current engineering applications of ball bearings require aqueous lubrication. Therefore, this study presents the aqueous lubrication of tribopairs formed by PEEK and PI material sliding against Si 3 N 4 ceramic. Experimental results show that two tribopairs exhibited the similar tribological properties under the dry condition. Water as a lubricant for the PI-Si 3 N 4 tribopair pairs effectively reduces both friction coefficients by 35.5% and wear rates by 32%. The water absorption of PI induces better tribological properties by changing the tribopair surface properties. In addition, the dimples appearing on the PI tribopair surface under water generate additional hydrodynamic lubrication and further improve the friction properties of surface. The PEEK-Si 3 N 4 tribopair shows similar friction coefficients under two kinds of environments. The wear rates under water are approximately more than two times of that under dry sliding. However, water inhibits the appearance of the crush phenomenon and enhances the carrying capacity of the tribopair. Energy dispersive spectroscopy and X-ray diffraction spectra demonstrate no chemical corrosion. The 3D profiler and SEM morphologies illustrate that the transfer film would be formed from the surface of PEEK under water but hindered under dry friction. Overall, the PI-Si 3 N 4 tribopair exhibits better properties than PEEK under water and is promising for future applications in the bearing industry.

Fabrication of Self-Lubricating Porous UHMWPE with Excellent Mechanical Properties and Friction Performance via Rotary Sintering

“…The influence of the different process parameters on the porous structure and mechanical properties of UHMWPE porous materials, as well as the tribological properties, was investigated in depth. This study verified the versatility of rotary sintering of a more uniform porous structure, and the tribological properties were improved, which is closer to special engineering materials such as PI and PEEK [ 36 ]. Meanwhile, it could simplify the conditions and eliminate the pre-pressing process to achieve economical and environmentally friendly effects.…”

A review of recent advances in tribology

“…Some of the coatings associated with superlubricity have been introduced in the superlubricity section and are not covered in detail again. Here, several new advances in tribological-related coating technology are briefly introduced, such as oxide coating [183][184][185][186], metal coating [187,188], composite coating [183,185,189,190], ceramic coating [191,192], and so on.…”

“…Wang et al [190] reported that the friction coefficient of carbon fiber-reinforced polyetheretherketone (CFRPEEK) is the lowest and fluctuates at approximately 0.11 and it has the lowest wear rate of 2×10 -5 mm 3 /(N•m) among the experimental materials, including CFRPEEK, carbon fiberreinforced polyamide-imide, polytetrafluoroethylene, polyoxymethylene, polyetheretherketone (PEEK), acrylonitrile butadiene styrene resin, and glass fiberepoxy resin under seawater lubrication. Wang et al [191] presented the aqueous lubrication of tribopairs formed by PEEK and PI material sliding against Si 3 N 4 ceramic. Their experimental results indicated that water as a lubricant for the PI-Si 3 N 4 tribopairs effectively reduces both friction coefficients by 35.5% and wear rates by 32% which is due to dimples appearing on the PI tribopair surfaces under water which generated additional hydrodynamic lubrication and further improved the friction properties of surface.…”

A new kind of resin-based wet friction material: Non-woven fabrics with isotropic fiber networks as preforms

“…As such, boundary lubrication might occur during braking. When operating in boundary lubrication or mixed lubrication, the hydrodynamic membrane might be a major factor that affects the friction coefficient of the samples [29][30][31][32]. It is evident from Fig.…”