Abstract: The present disclosure provides an expanded coating, a preparation method and use thereof, and a permanent magnet comprising same. The expanded coating described herein comprises pores and a filler resin arranged among the pores; the pores comprise at least a spheroid pore having a cross section with a long diameter and a short diameter; in the cross section of the expanded coating, the area of the spheroid pores accounts for 50%-60% of the cross-sectional area of the expanded coating. The permanent magnet of the present disclosure comprises the expanded coating. The expanded coating has high strength and can exhibit excellent mechanical properties and corrosion resistance at high temperatures (such as 170° C.), with a shear strength greater than 2 MPa, a tensile strength greater than 2 MPa, an oil resistance greater than 1800 h and a neutral salt spray performance greater than 288 h at 170° C.

Abstract: A sintered R—Fe—B permanent magnet has at least a grain boundary and composite main phase grains. The grain boundary has an RH-rich phase distributed in the form of an agglomerate within the grain boundary between the composite main phase grains, preferably at the intersection of any adjacent three or more composite main phase grains. The RH-rich phase is continuously distributed along the grain boundary in the form of a thin-layer stripe. The composite main phase grain has a core-shell structure, which includes a core structure having an R-T-B type phase structure and a shell structure on the outer layer of the core structure. The core structure contains Ce-rich main phase grains and Ce-poor main phase grains.

Abstract: Disclosed are a coating composition, a preparation method therefor and use thereof. The coating composition comprises a composition of at least 60% heat-expandable microspheres having a wall thickness of less than or equal to 5 ?m, a water-based thermoplastic resin, a water-based thermosetting resin, and a hot-melt filling resin. By means of the coating composition of the present invention, thin-shell spheres can be quickly softened and destroyed within a short time in the heat-expansion process, and with the volatilization of an organic solvent, the coating composition cross-links, on the surface and inside of the coating, with a resin matrix in the coating to form a cross-linked network structure, thus strengthening the gap support of the coating, and enabling the coating to achieve stepped expansion, and after expansion, some polymer materials wrap an airbag and harden to form a stable hollow structure.

Abstract: A neodymium-iron-boron (NdFeB) magnet is represented by a chemical formula R1-R2-Fe-M-B, and has a composite structure of a high-coercivity region and a high-remanence region. In the formula R1 is a rare earth element comprising at least Nd, R2 is a heavy rare earth element comprising at least Dy and/or Tb, and M is a transition metal element comprising at least Co. The neodymium-iron-boron magnet can greatly improve resistance to high-temperature demagnetization and inhibit reduction of magnetic flux of a magnet by adopting a small amount of Dy/Tb. The magnet can be used in an embedded high-speed motor. The preparing method for the magnet improves the material utilization and the production efficiency, and is feasible for a large-scale production.