Magnetically isotropic Sm–Co permanent magnets with anisotropic electrical conductivity were produced by hot-pressing SmCo5 ultrathin flakes with or without insulating additions of mica, MoS2, CaF2, and B2O3. The laminated structures of the magnets were assured by the natural packing of the flakes in the die. In the additive-free magnets, the resistivity is increased due to oxidized flake boundaries. Additives with platelet-shaped particles (mica, MoS2) and especially those with low-melting temperature (B2O3) form more continuous insulating layers. On the other hand, the CaF2 additive does not react with the magnetic Sm–Co phase. The characteristic values of the maximum energy product and electrical resistivity, measured in orthogonal directions, were 9.7 MG Oe and 130 μΩ cm for the additive-free magnet, 5.7 MG Oe and 640 μΩ cm for the magnet made with 2 wt. % B2O3 and 5.7 MG Oe and 330 μΩ cm for the magnet made with 10 wt. % CaF2.

The effects of different amounts of Y 2 O 3 addition (0, 0?25, 0?50, 0?75 and 1?00 wt-%) on the lattice parameters, sintering behaviour and mechanical properties of Al 2 O 3 /15 wt-%ZrO 2 porous composite ceramics have been investigated. It is found that Y 2 O 3 and Al 2 O 3 tend to form Al 5 Y 3 O 12 rather than a solid solution of (Al 1-X Y X ) 2 O 3 , while Y 3z can displace Zr 4z of ZrO 2 to form a solid solution and increase the lattice constants of tetragonal zirconia (t-ZrO 2 ). The additions of Y 2 O 3 into Al 2 O 3 /15 wt-%ZrO 2 porous composite ceramics not only stabilise t-ZrO 2 but also act as a sintering aid for promoting the sintering process. In addition, Y 2 O 3 additions are beneficial to improving the modulus of rupture and cold crushing strength of Al 2 O 3 /15 wt-%ZrO 2 porous composite ceramics; their maximum values are obtained at 0?75 wt-%Y 2 O 3 , which are 56 and 118 MPa respectively.