Investigating the micropitting and wear performance of copper oxide and tungsten carbide nanofluids under boundary lubrication

• Published in: Wear Vol. 428-429; pp. 55 - 63
• Main Authors: Roy, Sougata, Jazaa, Yosef, Sundararajan, Sriram
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.06.2019; Elsevier Science Ltd
• Subjects: Boundary lubrication; Copper oxides; Fatigue cracks; Fatigue tests; Lubricant additives; Lubrication; Micropitting; Nanofluids; Nanoparticles; Nickel chromium molybdenum steels; Oleic acid; Rolling contact; Rolling contact fatigue; Surface cracks; Tungsten carbide; Ultrasonic testing; Wear mechanisms; Wear resistance; Nanoparticles; Rolling contact fatigue; Boundary lubrication; Micropitting; Lubricant additives
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2019.03.007

The potential of copper oxide (CuO) and tungsten carbide (WC) nanofluids in enhancing micropitting and wear behavior of AISI 8620 steel under boundary lubrication conditions was investigated. The nanofluids consisted of 1% nanoparticles by weight and 1% by weight of oleic acid surfactant in Polyalphaolefin (PAO). Rolling contact fatigue tests were conducted using a micropitting test rig (MPR). Both the nanofluids exhibited increased micropitting life compared to the base oil. Tungsten carbide nanofluids showed significantly higher micropitting and wear resistance behavior than the CuO nanofluids under the boundary lubrication regime. Analysis of the surfaces showed different mechanisms to inhibit micropitting and wear for the two nanofluids. The WC nanofluid formed a tribofilm whereas the CuO nanofluids tended to fill surface cracks with the nanoparticles. •Surface topography of both nanofluid lubricated surfaces was significantly improved compared to base oil.•WC nanofluid was the best performing candidate in terms of micropitting and wear resistance.•WC nanoparticle based tribofilm formation was the main mechanism behind the improved RCF life.