Research On Preparation Of Nano Metal Films By High Gravity Fields

Electrodeposition of platinum from chloroplatinic acid and hydrochloric acid solution and nickel from nickel sulfate and boric acid solution were studied through constant current electrodeposition. The influences of gravity coefficient, current density and deposition time on surface morphology and crystal structure of coating were discussed.The experimental results of the electrodeposition of platinum show that platinum coating grows as branches in normal gravity conditions, and the coating changes into smooth surface in super gravity conditions. With the increase of super gravity coefficient, the particle of the platinum coating decreases. This shows that the super gravity can enhance the mass transfer process of the electrodeposition of platinum. With the increase of current density, the particle of platinum coating becomes small at first, then larger, the coating grain reaches the minimum in the current density of 3mA/cm2 at G=50 and 4 mA/cm2 at G=100.With the increase of deposition time, the particles of the coating become smaller, more uniform, smooth and compact. Hydrochloric acid is added to make the coating more smooth and compact.The experimental results of the electrodeposition of nickel show that the coating of nickel becomes more uniform, smooth and compact when the high gravity coefficient increases. The advantage of crystal surface changes when the high gravity fields are joined in, which means that the high gravity field can change the crystal structure of the coating. When the current density is low, the coating surface is a smooth surface, and with the increase of current density, the coating becomes more compact. The surface becomes a granular structure, the particle size increased with the increase of current density,and the advantage of crystal surface changes into (111)surface when the current density is more than 5mA/cm2, which means that the current density can change the crystal structure of the coating.The nickel coating cannot be electrodeposited by the electrolyte without boric acid,which means that the the boric acid has a very important effect on the electrodeposition of nickel film.