Abstract
© 2022 Elsevier B.V.Mechanical components in future missions to Venus will encounter high pressure (HP) and high temperature (HT) CO2 harsh conditions. Herein, the surface of Inconel 718 (INC 718), a HT nickel-based alloy was modified by applying advanced coatings by different deposition techniques. Three commercial coatings, namely Nedox PF-F™ (nickel-phosphorous alloy, referred as Nedox), Cera Tough™ (titanium-doped molybdenum disulfide alloy, referred as TiMoS2), and Balinit® DLC (amorphous hydrogenated diamond-like carbon, DLC) were coupled with PS400, a NASA-developed HT alloy, and slid against each other under HPHT Venusian-simulated environment. It was found that modifying one of the contacting surfaces (metal-on-coating) via PS400-deposition reduced the friction by 25%, whereas the wear increased significantly, compared to metal-on-metal contact. Sliding of the three coatings against PS400 coating (coating-on-coating) enhanced the frictional and wear performance significantly, in particular for PS400 vs. TiMoS2, attributed to the high wear resistance of the coating and the formation of beneficial oxide particles. The coefficient of friction (COF) was reduced by 38 and 43%, for PS400 vs. TiMoS2, and PS400 vs. DLC tribo-pairs, respectively compared to INC 718 vs. INC 718. In addition, the total wear rate decreased up to ten times, compared to metal-on-metal sliding.
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