Combustion synthesis of tungsten powder from sodium tungstate

Tungsten powders were prepared by Self-propagating High-temperature Synthesis (SHS) method directly from hitherto unreported system: sodium tungstate (Na2WO4) and magnesium (Mg). The adiabatic temperatures of self-propagating combustion reactions with different amount of Mg in Na2WO4 + Mg system were calculated. The influences of different starting conditions (molar ratios of Mg/Na2WO4 and relative densities of samples) on the compositions and microstructure of reaction products were investigated. It shown that, the complete reduction of WO3 required a 60% excess of magnesium over the stoichiometric molar ratio Mg/Na2WO4 of 3. The amount of the impurities is minimal at appropriate relative density. At last, tungsten powders can be obtained after the acid enrichment and distilled water washing.

► Phase compositions of the combustion products synthesized at different mole ratios of Mg/Na2WO4.
► Phase compositions of combustion products synthesized at different relative densities.
► Phase compositions of combustion product after the acid enrichment and distilled water washing.
► Morphology of the combustion product after the acid enrichment and distilled water washing.