Study on Grant Additions of (NH₄)₂ HPO₄ or Na₂HPO₄·12H₂O and Values of pH in the Chloroplatinic acid Plating Solution

Studies on Platinum Plating (3)

Abstract

(1) Even if (NH₄)₂HPO₄ is added more than 30g the current density and depositing quantity do not increase.
(2) If Na₂HPO₄·12H₂O is added more than 300g the current density and depositing quantity decrease.
(3) If much (NH₄)₂HPO₄ is added brightness of plating surface immediately fade away.
(4) Influence of Na₂HPO₄·12H₂O on brightness of plating surface is very small.
(5) As plating time goes on color of plating surface changes to light brown, then to brown and then to black.
(6) The platinum amount of electrodeposition increases with a decrease in pH value in the plating solutions, More than 12.3pH, plate hardly. When the pH value becomes over 12.3 platinum is not deposited.
(7) When the plating solution of lower pH values is used, the brightness of plating surface soon fades away.
(8) That the color of plating surface changes to black is accounted for the electrodeposition of platinum black.