Neodymium magnets,
built to your drawing.

Do not pick from the grade table alone. At 140 °C an SH grade is the usual starting point, but the decision depends on your permeance coefficient and the peak demagnetising field during stall or short-circuit. Send the magnet geometry, the operating and worst-case temperatures, the load line (or the surrounding steel and air-gap geometry), and the acceptable irreversible loss. A typical outcome is N42SH or N38UH; a thin, poorly-coupled magnet at the same temperature might need EH. If the section is thin, ask whether grain-boundary diffusion can hit the coercivity target at lower Dy content and higher Br.

No. These are sintered NdFeB — a neodymium-iron-boron rare-earth alloy, pressed in an aligning field, sintered, machined and coated. Ceramic (ferrite) is a separate material class, a strontium or barium iron oxide with Br around 0.38–0.43 T and BHmax around 28–34 kJ/m³ (3.5–4.3 MGOe), against NdFeB's 1.17–1.48 T and 263–422 kJ/m³. The two are not interchangeable without redesigning the magnetic circuit. If you arrived here looking for ceramic blocks, ask for ferrite explicitly.

Not as a drop-in. At the same geometry you will get roughly a third of the flux density, because Br is about 0.40 T against 1.30 T for a mid-grade NdFeB. To hold gap flux you need to grow the magnet volume by roughly 6-10 times and usually increase the pole area and the steel yoke with it. The swap makes commercial sense when the package has room and the machine is cost-driven — loudspeakers, separators, low-duty DC motors, holding devices. It rarely makes sense in a servo motor, a compact rotor, or anything where mass or envelope is a specification. The other reason to move is supply and price stability: ferrite is strontium carbonate and iron oxide, with no rare-earth exposure and none of the NdPr or dysprosium price volatility. The trap to watch is that the temperature failure mode inverts — an NdFeB design validated at the hot end has to be re-validated at the cold end.

Default to 2:17 for energy product (24-32 MGOe versus 16-20), better temperature coefficient and higher usable temperature. Choose 1:5 when you need very high intrinsic coercivity in a thin or low-permeance geometry, when the part is small and fragile enough that 1:5's slightly better machinability and lower chipping tendency helps, or when resistance to an opposing demagnetising field matters more than raw flux. Note the trade-off: 1:5 is the harder of the two to saturate and needs a 40-50 kOe magnetising fixture, so confirm your magnetiser before committing.