In-situ electrochemical reconstruction of tungsten carbide using Na2CO3-containing molten salt

Abstract

This paper reports a novel method for rapid atomic-level reconstruction of tungsten carbide (WC) using Na2CO3-containing molten salt. Herein, WC was used as consumable anode and Na2CO3 was active species on WC anode and carbon donor. Thermodynamic calculations were used to verify the feasibility of this electrolytic method for reconstructing WC. Experimental results showed that the addition of Na2CO3 significantly enhanced dissolution efficiency of WC. Therefore, more tungsten (W) source was supplied. Electrochemical analysis demonstrated that Na2CO3 also supplied carbon by two-step reduction process, which led to the formation of WC. These experiments confirmed that cathode product was converted from W to WC by the introduction of Na2CO3 additive into molten salt. WC phase started to form at cell voltages above 2.2 V. In initial stage of reaction, carbonate was preferentially reduced in cathode region to form amorphous C. As the reaction proceeded, W ions migrated from anode and began to participate in reduction process, forming W. Finally, W was transformed to WC by carbonization process.