Electrodeposition of Submicro- and Microdispersed Molybdenum Carbide Powders from Carbonate–Molybdate Melts

The laws of the joint electrical precipitation of carbon and molybdenum from carbonate–molybdate melts in the temperature range 1023–1123 K are studied. In the carbonate–molybdate melt containing weakly polarizing cations (K+, Na+), carbonate and molybdenum ions are shown not to participate in cathodic reduction processes up to the alkali metal precipitation potentials. They are shown to be electrically reduced to metallic molybdenum and carbon at a cathode in the molten system K2CO3–Na2CO3–Li2CO3‒Li2MoO4 containing the Li+ cation due to acid–base interactions and the subsequent formation of the cationized complexes Lix $${\text{MoO}}_{4}^{{(x - 2)}}$$ and Lix $${\text{CO}}_{3}^{{(x - 2)}}$$ . Their further interaction on the atomic level leads to the formation of molybdenum carbide. The results of electrochemical diagnostics by voltammetry are used to perform electrodeposition of molybdenum carbide over a wide temperature range of 1023–1073 K at current densities of 0.5–3.0 A/cm2 as a function of the electrolyte composition. When the temperature increases, the content of impurity phases (MoC, C) is found to decrease; at 1173 K, these phases are not detected in the product. The elemental and granulometric composition, the morphology, and the microstructure of molybdenum carbide powder particles are investigated The results obtained indicate that the particle sizes of the molybdenum carbide fabricated by electrochemical synthesis are in submicro- and microranges.