Porous flow fields distribute fuel and oxygen for the
electrochemical
reactions of proton exchange membrane (PEM) fuel cells through their
pore network instead of conventional flow channels. This type of flow
fields has showed great promises in enhancing reactant supply, heat
removal, and electrical conduction, reducing the concentration performance
loss and improving operational stability for fuel cells. This review
presents the research and development progress of porous flow fields
with insights for next-generation PEM fuel cells of high power density
(e.g., ∼9.0 kW L–1). Materials, fabrication
methods, fundamentals, and fuel cell performance associated with porous
flow fields are discussed in depth. Major challenges are described
and explained, along with several future directions, including separated
gas/liquid flow configurations, integrated porous structure, full
morphology modeling, data-driven methods, and artificial intelligence-assisted
design/optimization.
Purpose
This paper aims to find out the tribological performance and self-lubricating mechanism of the laser-textured surface filled with solid lubricant in rolling friction pair.
Design/methodology/approach
The textures on the surfaces of GCr15 bearing steel were produced by acousto-optic Q diode-pumped yttrium aluminum garnet laser with the technology of “single pulse one time, repeating at intervals” and filled with composite solid lubricant. The tribology tests were conducted on the MMW-1A universal friction and wear testing machine.
Findings
It was found that the solid-lubricated micro-textured surface can reduce the friction coefficient effectively. The MoS2/PI composite solid lubricant works better than the single MoS2 solid lubricant, and the ratio of PI/MoS2 + PI at 20 per cent is the best recipe. The friction coefficient of the sample surfaces decreases first and then increases with the increase in texture densities, and a texture density of 19.6 per cent has the best effect on friction reduction. The friction coefficient of the textured surfaces gradually decreases with the increase in both rational speed and load. For the same texture density, the friction coefficient of textured surfaces decreases slightly with the increase in diameter. Furthermore, the mechanism of “rolling-extrusion-accumulation” occurred on the textured surface can collect the solid lubricant, thereby, improve the effect of lubricating and anti-friction.
Originality/value
The results of the experimental studies demonstrated the application prospect of laser surfaces texturing combined with solid lubricant in rolling friction pair.
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