Modern aircraft such as spacecraft, artificial satellites and rockets, missiles, supersonic aircraft is towards high speed, high altitude, big thrust, long distance, high accuracy and safety in the direction of the development of zirconium and hafnium compounds (and) for some excellent performance, in addition to small nuclear structure and coating materials, also used in the Apollo spacecraft on the relevant parts. Hafnium can also be used as a small and energetic propellant for rockets.
Hafnium compounds have the comprehensive properties of refractory, oxidation resistant and corrosion resistant. Hafnium carbide of high melting point, more than 500 ℃ the tungsten carbide. Four tantalum carbide and 1 copy of hafnium carbide mixture and its melting point 4215 ℃, thus can make the structure of jet engines and missiles on lining material and high melting point metal melting crucible.
Boride hafnium (HfB2) with high temperature properties and good oxidation resistance, and can be used as materials, high-speed space rockets in 2000-2200 ℃ in the atmosphere. Hafnium - containing boron compounds have 10 times greater antioxidant properties than zirconium boride.
Hafnium carbide (HfC) with 3890 ℃ high melting point and high elasticity, good electric conductivity, the thermal expansion of small and good impact resistance, very suitable for rocket nozzle, for re-entry space rocket nose cone parts.
Tantalum - hafnium sandwich structure material, the heat of 2200 ℃ high temperature performance, as a rocket nozzle and other structural materials.
By means of roller cladding, plasma arc spraying and spraying, hafnium alloy is applied to tube and extruded profile, which leads to tantalum hafnium alloy tube and profile can be used as rocket nozzle, turbine engine and spacecraft.
Hafnium can be used for welding and brazing materials. Due to its ductility, oxidation resistance and high temperature resistance, hafnium can be used as a brazing alloy for heat shield and space rocket. Contain hafnium alloy such as Ta - W (8%) - Hf (2%) and Ta - W (9.6%) - Hf (2.4%) of the alloy honeycomb structure and tested in the framework of brazing, soldering temperature is 2175-2200 ℃. Brazing alloys of hf-ta (40%) and hf-ta (19%)-Mo(2.5%) are still in use today.
Hafnium can be used as a structural material for jet engines and missiles because of its rapid heat absorption and heat release (twice as fast as zirconium and titanium). Hafnium's infusible nature makes it useful as a blade for turbojet aircraft, used in condensing point pressure jet engines. They can also be used to make valves, nozzles and other high-temperature parts. Examples of applications of zr - hafnium alloys are shown in table 5-46.
