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.