Abstract
An approach combining the plasma nitriding with lubrication additive is proposed to improve the durability of the antifriction bearing.The nitrided layer on GCr15 steel is prepared in a plasma nitriding furnace.Its surface morphologies,phase structure,and hardness are analyzed by means of scanning electron microscope(SEM),X-ray diffractometer(XRD) and microhardness tester.Its friction and wear behaviors are examined on a four-ball friction and wear tester under lubrication with borate containing nitrogen additive,compared with that of plain GCr15 steel.The composition and chemical binding state of tribofilm formed on the wear steel surface is analyzed by X-ray photoelectron spectroscope(XPS).The results show that an unexpected excellent synergistic effect occur between the nitrided surface and additive,the nitrided steel exhibits lower friction coefficient and better anti-wear properties compared with untreated steel,especially when 1.25% additive is used,the friction coefficient and wear scar diameter reduce by 34% and 45% separately.The main mechanism of this effect is attributed to that the borate containing nitrogen additive can produce a tribofilm containing higher content of BN on the nitrided surface,which is not found on the plain steel surface.
Published Version
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