For decades, sedimentation stability has been an important research topic of magnetorheological fluid (MRF), which is closely related to the preservation and engineering application of MRF. In this paper, a stable MRF was prepared with CI-MXene composite particles as dispersed phase. MXene nanosheets are a novel inorganic two-dimensional material, which have the characteristics of low density, large specific surface area and strong adsorption capacity. MXene nanosheets were prepared by chemical etching, and then were attached to the surface of carbonyl iron particles (CIPs) by ultrasonic dispersion and freeze-drying to prepare CI-MXene composite particles. The successful preparation of MXene nanosheets and the adhesion of MXene on CIPs were confirmed using well-established techniques such as SEM, TEM, XRD and XPS. The magnetization test showed that MXene nanosheets are non-magnetic, and CI-MXene particles have high saturation magnetization. CI‑MXene based MRF exhibits excellent magnetorheological properties, and its maximum yield stress reaches 49 kPa. The shear stress curves were fitted by the Bingham and R-S models, where the R-S model was in better agreement with the experimental data. On the other hand, the attachment of MXene reduces the density of magnetic particles, thus reducing the density mismatch between dispersed phase magnetic particles and carrier liquid silicone oil. The sedimentation experiment demonstrates that the sedimentation ratio of MRF reduced from 24.3% to 2.0% after mixing CIPs with 3 wt% MXene nanosheets. Therefore, the sedimentation stability of CI-MXene based MRF is significantly improved while maintaining high yield stress. This work provides meaningful guidance for the development of MRF with high magnetorheological performance and stability.

magnetorheological fluid,MXene,magnetic particles,shear stress,sedimentation stability