Mullite Coated Silicon Carbide Fiber Reinforced Alumina-Zirconia Ceramic Composite Bore Insulator Materials for a Naval Electromagnetic Launcher

The US Navy seeks high performance toughened electrically insulative bore materials of significant lengths used to separate copper conducting rails in an electromagnetic launcher (EML) for long range naval surface fire support. An EML consists of two electrical conductor rails, a moving element, and an armature. The rails of an EML are supported a certain distance apart from each other by a pair of perpendicular electrically insulative bore pieces. Insulator materials need to be capable of withstanding the severe mechanical, electrical, and thermal environment during launching, thus needs to be tough, have a high compressive strength, minimize thermal expansion, and capable of withstanding sliding contact aluminum and nylon at velocities up to 2.5 km/sec. Inframat proposes to demonstrate the feasibility of exploiting a mullite coated silicon nitride fiber reinforced alumina-zirconia ceramic composite as the bore insulator materials for Navy's EML applications. In this approach, particulate reinforcement toughening induced by nanostructured zirconia, phase, combined with the silicon carbide fiber reinforcement, will significantly improve the fracture toughness and promote the resistance to thermal shock and erosion for the alumina ceramics. The silicon carbide fiber will be coated with a mullite layer to ensure high electrical resistance.