LAUSR

Abstract CrN coating, as a hard coating, could be hopefully applied to components in sodium-cooled fast reactor. Some studies on compatibility of metallic materials with liquid sodium have been reported, but little about tribological properties of materials in liquid sodium. In this study, the friction and wear behavior of CrN coating on 316L stainless steel surface in liquid sodium was first studied using self-made reciprocating-type tribometer at 250 °C and 550 °C, respectively. The worn surfaces of CrN coatings after friction tests were analyzed by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results showed that compared with the friction of CrN coating in Ar atmosphere at room temperature, liquid sodium had a positive effect on friction performance of CrN coatings at the temperature of 250 °C, and the friction coefficient is as low as 0.2, which is mainly attributed to the lubricating oxide layer formed by the chemical and tribochemical reactions between the oxide impurities in sodium and the coating. However, since liquid sodium can well wet CrN coating at 550 °C, it can reduce the contact between oxide impurities and CrN coating to a certain extent, resulting in increase of friction coefficient. This study provides guidance for the design of coatings served in the liquid sodium environment.