Uranium carbides hardness

Thorium carbides (ThC, ThC2) and uranium carbides (UC, UC2) exhibit metallic properties, but in other properties differ significantly from the carbides of the subgroups of the IVth, Vth and Vlth groups of the periodic table. Their hardnesses are substantially lower (see Table 5.6-1), they are pyrophoric and are easily hydrolyzed in water or weak aeids. Their only economic importance is as carbidie fuels in nuelear technology, particularly for high temperature and breeder reactors which are currently in the evaluation phase. 

Carbide-based cermets have particles of carbides of tungsten, chromium, and titanium. Tungsten carbide in a cobalt matrix is used in machine parts requiring very high hardness such as wire-drawing dies, valves, etc. Chromium carbide in a cobalt matrix has high corrosion and abrasion resistance it also has a coefficient of thermal expansion close to that of steel, so is well-suited for use in valves. Titanium carbide in either a nickel or a cobalt matrix is often used in high-temperature applications such as turbine parts. Cermets are also used as nuclear reactor fuel elements and control rods. Fuel elements can be uranium oxide particles in stainless steel ceramic, whereas boron carbide in stainless steel is used for control rods. 

Uranium and thorium carbides are not typical hard materials... 

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