Space carbon nitrides

In a vacuum, uncoated molybdenum metal has an unlimited life at high temperatures. This is also tme under the vacuum-like conditions of outer space. Pure hydrogen, argon, and hehum atmospheres are completely inert to molybdenum at all temperatures, whereas water vapor, sulfur dioxide, and nitrous and nitric oxides have an oxidizing action at elevated temperatures. Molybdenum is relatively inert to carbon dioxide, ammonia, and nitrogen atmospheres up to about 1100°C a superficial nitride film may be formed at higher temperatures in the latter two gases. Hydrocarbons and carbon monoxide may carburize molybdenum at temperatures above 1100°C. 

As previously stated, uranium carbides are used as nuclear fuel (145). Two of the typical reactors fueled by uranium and mixed metal carbides are thermionic, which are continually being developed for space power and propulsion systems, and high temperature gas-cooled reactors (83,146,147). In order to be used as nuclear fuel, carbide microspheres are required. These microspheres have been fabricated by a carbothermic reduction of UO and elemental carbon to form UC (148,149). In addition to these uses, the carbides are also precursors for uranium nitride based fuels. 

Carburisation of (-Nitride with Carbon Monoxide and Ht-CO Mixtures at 360°C. Space velocity = 80-100 per hour... 

Turbostratic A type of crystalline structure where the basal planes, such as graphene layers, have slipped sideways relative to each other, causing the spacing between planes to be greater than ideal. This structure is found in incompletely heat-treated carbon and boron nitride. 

Table 11.5 Space groups, lattice dimensions, and densities of boron nitride compared to carbon modifications.

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