Hydrostatic pressure–dependent wear behavior of thermoplastic polymers in deep sea

Abstract

It is generally acknowledged that wear behavior of approved water-lubricated thermoplastic polymers are not susceptible to hydrostatic pressure in seawater environment.However, in our recent study reported in this letter, it has been shown that the wear behavior of thermoplastic polymers sliding in seawater is strongly dependent on the hydrostatic pressure. The correlation between hydrostatic pressure and wear rates of thermoplastic polymers can be expressed in an identical form of exponential function, which has been found to be susceptible to some factors, such as polymer property, seawater absorption, filler type, sliding condition, and counterpart material. Moreover, in this letter, a primary model has been proposed to illuminate the effect of hydrostatic pressure on the wear behavior of thermoplastic polymers sliding in deep sea. KEYWORDS deep sea, hydrostatic pressure, thermoplastic polymers, wear Nowadays, environment-friendly and energy-efficient seawater lubrication model is being strongly recommended and becomes more and more popular in modern ships and marine machineries, especially for various deep-sea hydraulic systems. 1,2 Accordingly, research and development of seawater-lubricated antifriction/antiwear materials are in full swing. Thermoplastic polymers and their composites have proven to be promising seawater-lubricated materials because of excellent corrosion resistance, low friction, and high wear resistance under seawater lubrication. 3,4 Some high-performance thermoplastic polymers, eg, poly(ether ether ketone) (PEEK) and poly(tetrafluoroethylene) (PTFE), have well served as seawater-lubricated friction components in seawater at normal pressure. 5,6 In recent years, with the rapid development of deep-sea exploitation, application of thermoplastic polymers and their composites as seawater-lubricated components are increasingly expanding toward deeper seawater environment. With the seawaterdepth increasing, however, the hydrostatic pressure of seawater will also correspondingly increase; specifically, every 100-m increase in seawater depth is probably associated with 1-MPa increase in the hydrostatic pressure. In some practical applications, it has been found that with the seawater hydrostatic pressure increasing, the reliability of such seawater-lubricated polymer friction components becomes more and more hard to be assured, often leading to unexpected accelerated failure in great depth. It seems that the seawater hydrostatic pressure may have some considerable effects on the wear behavior of thermoplastic polymers in the deep sea. But this has never been firmly confirmed by experiments because of the lack of professional friction tester by which the deep-sea environment with high pressure can be simulated, and meanwhile, in situ tribology tests can be achieved in the simulated environment. 7 However, the correlation between deep-sea hydrostatic pressure and wear behavior of seawater-lubricated thermoplastic polymers cannot be well supported by traditional lubrication and friction theory.First...

Comparative study on the effects of water pressure on water absorption of ultra‐high molecular weight polyethylene and polyformaldehyde

“…Therefore, polymer materials have great application prospects as friction pair component materials in wading environment. [5][6][7][8] For a tribological system in water environment, its tribological characteristics are affected by many factors. Among them, the water absorption of polymer friction materials is an important factor that must be considered.…”

Effect of Powder on Tribological and Electrochemical Properties of Nylon 66 and Ultra-High Molecular Weight Polyethylene in Water and Seawater Environments

“…Polymers and their composite materials are widely used in seals, piston rings, valves, lubricating bearings, and bearing retainers for sea-related equipment, owing to their superior properties [ 7 , 8 ]. In particular, polymers and their composites have proven to be promising seawater-lubricated materials because of their excellent corrosion resistance, low friction, and high wear resistance under seawater lubrication [ 9 , 10 , 11 , 12 , 13 ].…”

“…Some studies have focused on the effects of pressure, running speed, marine environment, and other factors on the tribological properties of polymers [16][17][18]. Liu [13] investigated the relationship between hydrostatic pressure and the wear behavior of thermoplastic polymers sliding in seawater. It was demonstrated that an increase in the hydrostatic pressure increased the wear rate of the polymer.…”

The Influence of Deformation under Tension on Some Mechanical and Tribological Properties of High-Density Polyethylene

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