Ag–W electrodeposits with high W content from thiourea–citrate electrolytes

• Ag–W electrodeposition onto rotating cylinder electrodes was examined.
• An environmentally friendly, cyanide free electrolyte was developed to deposit Ag–W at low pH.
• The deposit W concentration varied with tungsten ion electrolyte concentration.
• The highest amount of W in the deposit compared to previous Ag–W literature reports was achieved

Thin film deposits containing silver and tungsten were electrodeposited onto rotating cylinder electrodes from non-cyanide, acidic thiourea–citrate electrolytes. The effect of current density and tungsten ion electrolyte concentration on the deposit composition and partial current densities was examined. Deposit composition was measured using X-ray fluorescence with increasing amount of tungsten ion in the electrolyte at high current densities, with silver ion reduction under mass transport control and the tungsten ion reduction under a kinetic control. The highest wt.% W in the deposit was 18 wt.%, SEM-EDS was also used to characterize the deposit morphology and account for sulfur in the deposit, originating from the thiourea in the electrolyte.