The reaction of uranium monocarbide with liquid zinc was investigated in the temperature range of 540-800° C. At temperatures below 725° C the uranium monocarbide reacts with the liquid zinc to form a uranium-zinc compound and an oxygen enriched uranium monocarbide phase. There is no reaction at 800° C. This indicates that the standard free energy of formation of uranium monocarbide is equal to the free energy of UZn8 . 5 at about 725°C. No other uranium carbide phase is ever observed as a reaction product.
Robinson, William C. Jr. and Chiotti, Premo, "Reactions of uranium carbide in a fused KC1-LiC1/zince system" (1964). Ames Laboratory Technical Reports. 100.