Samarium-cobalt permanent magnets are used in generators that produce electricity for aircraft electrical systems. In addition, small high-powered rare-earth magnet actuators are employed in moving the flight control surfaces of aircraft, including flaps, rudder, and ailerons.
Yttria-stabilized zirconia, a high-temperature resistant ceramic coating, is used as a thermal barrier in the “hot” sections of jet engines to protect the metal alloys. Yttria keeps the zirconia from changing from a tetragonal to monoclinic structure, which would degrade the ceramic’s high-temperature stability and strength. The ceramic coating is used in the Pratt & Whitney F100-PW-229 turbofan engine for the McDonnell Douglas Corp. F15 Eagle and the Lockheed Martin F16 Fighting Falcon fighter jets.
Color televisions and computer monitors are essential components in many defense system control panels to display and quickly communicate data, especially in avionic displays and vision enhancement screens. Rare earths have been used in color cathode ray tube (CRT) phosphors since the early 1960s. Europium-yttrium compounds have long been used as a red phosphor in CRT screens because of its sharp excitation color peak at 611 nanometers (nm). Color super video graphics array (SVGA) monitors typically use medium-to-short persistence phosphors. This enables faster SVGA image changes and eliminates ghosts. Cerium oxide is an additive in CRT glass to reduce “browning” from electron emissions and as a glass polishing compound for CRT faceplates. Recent technology uses liquid crystal digital (LCD) displays in flat panel displays (FPD) for computers, avionics, and weapon system monitors. FPDs typically use either twisted nematic/super-twisted nematic (TN/STN), thin film transistor (TFT) LCD technology, or plasma display panels (PDP). All of these FPDs have glass panels or substrates that are polished with cerium oxide. Avionic displays use terbium-doped gadolinium oxysulfide and lanthanum oxysulfide phosphors for high-luminescence. The rare-earth avionic phosphors emit yellow-green light at 542 nm and 545 nm wavelengths, respectively
Rare earths are used in several applications in radar systems. Rare-earth permanent magnets, typically samarium-cobalt, are used in the radar’s TWT to focus the microwave energy. Yttrium-iron garnets (YIG) and yttrium-gadolinium garnets (YGG) are used in phase shifters, tuners, and filters. These systems are used in the PATRIOT (Phased Array Tracking to Intercept of Target) air defense missile system’s guidance and radar control group. Samarium-cobalt magnets are used in both the missile’s and radar system’s TWT. YGG’s are used in the toroids in the PATRIOT’s phased array elements and in the radio frequency (RF) circulators in the radar and missile. RF circulators magnetically control the flow of electronic signals.
Samarium-cobalt permanent magnets are used to focus the electron beam of radar magnetron tubes. Magnetron tubes are used in ground-based systems for air traffic control and surveillance radar, search radar, and weapon fire-control radar. Defense radar also is used for anti-collision and avoidance, weather detection, and as a navigational aid in aircraft and naval applications. Cross field amplifiers (CFA) generate moderate bandwidth, moderate gain, and output signals in a smaller and lighter weight unit than traditional microwave tubes. CFA are used in ground based, airborne, and phased array radar applications. Output is typically focused with samarium cobalt magnets. CFA are used in the phased array system of the AN/SPY-1 radar in the Navy’s AEGIS system. The AEGIS radar and missile array is the most advanced shipboard system deployed for antiaircraft and antimissile defense. Yttria also is used in some electron-emitting cathodes in TWT, magnetrons, and other devices.
Gadolinium metal applied as paint or coating, was used as a defensive measure against neutron radiation. Gadolinium, which has the highest neutron capture cross section of all the elements, is the material of choice for absorbing high-energy neutrons. Examples: Satellite Housings, Alternative Energy Applications, Aerospace Applications, and Display Lighting.