Electric propulsion systems for space exploration require materials and components that can perform reliably under a vacuum of 10−5 Torr and at temperatures of over 400 °C. Scanning electron microscopy analysis shows that when Sm–Co magnets are exposed to temperatures up to 550 °C for up to 240 h in a vacuum of 10−5 Torr, the surface alteration is morphologically similar to oxidation in air. However, the scale of the affected region is much smaller and consists of about 1–2 μm of a top outermost Sm-depleted oxide layer and about 10–20 μm of a more complex layer in which the constituent atoms redistribute with oxygen penetration. No excessive Sm depletion was observed in the second layer. For all Sm–Co magnet samples, the maximum energy product decreased by less than 10% even at temperatures of 100 °C above their specified maximum operating temperature TM. The residual induction of the magnets with TM=550 °C decreased by 8.5% after baking at 700 °C under vacuum for 240 h.

Glass ceramic materials were fabricated based on BaO-ZnO-B 2 O 3 (BZB) glass with Ba 623x (Nd 12y Bi y ) 8z2x Ti 18 O 54 ceramics. It was investigated that the dielectric properties and the sintering behaviour of glass ceramics. Doped by BZB glass, the sintering temperature of Ba 623x (Nd 12y Bi y ) 8z2x Ti 18 O 54 ceramics was significantly lowered to 900uC in comparison to 1300uC for samples without glass. The low softening point BZB glass provided good wetting between BZB and Ba 623x (Nd 12y Bi y ) 8z2x Ti 18 O 54 , and the reaction between glass and ceramics was increased. The dielectric constant of BZB-Ba 623x (Nd 12y Bi y ) 8z2x Ti 18 O 54 system was increased with increasing firing time. The composite sintered at 900uC for 2 h exhibited excellent dielectric properties were achieved, with dielectric constant of 75, the dielectric loss of 5610 25 and the temperature coefficient of ¡30 ppm uC 21 .