ADN will make HPA4N maybe 5N but the key is impurities in that...

ADN will make HPA4N maybe 5N but the key is impurities in that last tiny fraction.

Ballistic missiles, such as intercontinental ballistic missiles (ICBMs) or short-range ballistic missiles (SRBMs), require materials that endure high velocities (6–8 km/s during re-entry), extreme temperatures, and aerodynamic stresses. HPA and glass-ceramics are critical for:
Structural Integrity: HPA ceramics reinforce components exposed to thermal & mechanical stress, e.g. re-entry vehicle casings or engine parts.
Payload Protection: Advanced ceramics shield warheads or electronics from environmental stresses during flight.

High-Purity Alumina Plays a Role in Ballistic MissilesDirect use of high-purity alumina in ballistic missiles is used in:Thermal insulation or ceramic components:Alumina-based ceramics could be used in nozzle liners, radomes, or thermal shielding.
Electronics protectionue to its electrical insulating properties, HPA might be used in missile guidance systems or avionics housings.Sapphire windows:Made from single-crystal alumina, sapphire windows are sometimes used in optical sensors or laser systems due to their durability and clarity.