A review on the stability of magnetorheological materials

Magnetorheological materials, as a type of intelligent controllable material, have broad application prospects in the engineering field. However, stability issues (such as sedimentation, particle agglomeration, and extreme temperature adaptability) severely limit the practical application of magnetorheological materials. In this paper, the research progress on the stability of magnetorheological materials was summarized and categorized, and analyzed from three aspects: material systems, testing methods, and improvement strategies. First, the compositional characteristics and stability challenges of magnetorheological materials with different matrix morphologies were compared, and it was pointed out that sedimentation issues in magnetorheological fluids and particle migration issues in magnetorheological elastomers are key research focuses. Second, the currently available stability testing methods were summarized, including sedimentation observation, particle concentration testing, redispersibility testing, and temperature stability testing, and the applicable scenarios, advantages and disadvantages of different methods are discussed. Third, the technical measures to enhance stability were discussed in detail, such as additive optimization (surfactants, thixotropic agents, nanoparticles, etc.), magnetic particle surface modification (polymer coating, composite structure design, etc.), and matrix carrier modification (magnetic matrix carriers, fluid-solid carrier conversion, etc.), and the enhancement mechanisms and characteristics of different methods were compared. Finally, current research limitations in terms of performance trade-offs and long-term reliability were identified, and future directions such as smart responsive materials and standardized testing were proposed. This study provides theoretical references and technical guidance for the stability design and engineering applications of magnetorheological materials.