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astronautix.com ClF3/Hydrazine





Oxidiser: ClF3. Oxidiser Density: 1.83 g/cc. Oxidiser Freezing Point: -76.00 deg C. Oxidiser Boiling Point: 12.00 deg C.

Chlorine trifluoride was another of the extremely reactive and toxic oxidisers tested in the United States in the late 1950's. As in the other cases, it was found that the handling problems and safety risks outweighed the performance benefits. ClF3 is available commercially in purities of 99+ per cent ClF3. The most likely impurity is hydrogen fluoride. Chlorine trifluoride is a colorless gas at atmospheric pressure and temperature. The liquid has a pale green colour, while the solid is white. The odour of ClF3 has been described as both sweet and pungent, similar to chlorine or mustard. ClF3 is a toxic and corrosive oxidising agent similar to elemental fluorine in nature. It reacts with water. ClF3 is non-flammable with air, but will support combustion with almost all organic vapours and liquids. ClF3 reacts with every element except the rare gases, nitrogen, and possibly platinum and palladium. However, at low or intermediate temperatures, a protective fluoride film is formed on certain metal surfaces, which halts further reaction. Thus, metals such as mild steel, copper, brass, steel, Monel, and nickel may be used as materials of construction.

Chlorine trifluoride is prepared by direct combination of the elements. The 1959 ClF3 production capacity was 12 to 25 tonnes/year; this could be increased in six to eight months to 50 to 100 tonnes per year by enlarging halogen fluoride reactor capacity without incurring a shortage of fluorine. Quantities in excess of this amount would require a lead time of one year, and would involve construction of new fluorine facilities. The projected price of ClF3 $ 6.00 per kg at the existing rate.


Fuel: Hydrazine. Fuel Density: 1.01 g/cc. Fuel Freezing Point: 2.00 deg C. Fuel Boiling Point: 113.00 deg C.

Hydrazine (N2H4) found early use as a fuel, but it was quickly replaced by UDMH. It is still used as a monopropellant for satellite station-keeping motors. Hydrazine marketed for rocket propellant contains a minimum of 97 per cent N2H4, the other constituent being primarily water. Hydrazine is a clear, water-white, hygroscopic liquid. The solid is white. Hydrazine a toxic, flammable caustic liquid and a strong reducing agent. Its odour is similar that of ammonia, though less strong. It is slightly soluble in ammonia and methyl-amine. It is soluble in water, methanol, ethanol, UDMH, and ethylenediamine. Hydrazine is manufactured by the Raschig process, which involves the oxidation of ammonia to chloramine, either indirectly with aqueous sodium hypochlorite or directly with chlorine, and subsequent reaction of chloramine with excess ammonia. Raw materials include caustic, ammonia, and chlorine; these are high-tonnage, heavy chemicals. The cost of anhydrous hydrazine in drum quantities in 1959 was $ 7.00 per kg. The projected price, based on large-scale commercial production, was expected to be $ 1.00 per kg. Due to environmental regulations, by 1990 NASA was paying $ 17.00 per kg.


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Last update 3 May 2001.
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