Improving Tribological Behaviors of Invar 36 Alloy under Extremely Cryogenic and Dry Conditions Through Surface Micro-Texturing

Abstract

Invar 36 alloy is an iron-nickel alloy with an ultra-low coefficient of thermal expansion, which is widely used in cryogenic fields of liquefied natural gas (LNG) and aerospace. However, the wear under extremely cryogenic and dry conditions is a key problem for Invar 36 alloy applied in the bearing of cryogenic submersible pump. In this work, we are mainly for improving the cryogenic tribological performance of Invar 36 alloy through laser surface texturing. Three different types of surface micro-textures were prepared on Invar 36 alloy specimens. And the effects of these micro-textures on the friction and wear properties of Invar 36 alloy were investigated. The results show that groove-channel micro-texture has the lowest coefficient of friction and wear rate under normal and -196 °C. Further research shows that this is because the channel structure of groove-channel micro-texture is more conducive to the transfer of most debris generated caused by wear, which successfully reduces the occurrence of abrasive wear. Scanning Electron Microscopy/Energy-dispersive X-ray spectroscopy was utilized to explain the cryogenic tribological performance of the micro-textures.