Coloring of metals in the electrochemical way
In the same electrolyte it is possible to receive the oxidic films distinguished on coloring having high protective properties on steel, brass and copper.
Composition of electrolyte:
Copper vitriol of 60 g
Refined sugar of 90 g
Caustic rubbed 45 g
Water of 1000 cubic cm
To add 90 g of refined sugar to solution of copper vitriol of 200 — 300 cubic cm and to mix it before full dissolution. Separately in 250 cubic cm of water to dissolve caustic rubbed in number of 45 g and to this solution in the small portions, constantly stirring slowly, to flow solution of copper vitriol with sugar. To add the rest of water to its total quantity 1 l. Specific weight of the received electrolyte has to be 1,1 at the temperature of 16 °C.
Carefully polished and degreased parts (to full wettability of the surface water) are suspended in the bathtub. As the anode serves pure copper. Working temperature of electrolyte has to be 25 — 40 °C. It is necessary to provide reliable contacts, otherwise undesirable shades can appear. In the chain of the bathtub it is necessary to vklyuyochit the ampermeter and the rheostat. One ZT-U-ZO element (dry) or one accumulator element can be the current source.
Current joins after parts are submerged in electrolyte (in 1 — 2 min.). Minus of the current source happens to the part, and plus — to copper.
Metals are painted in the next colors: brown, violet, blue, blue, light green (salad), yellow, orange, red-lilac, green blue, green, rose-red. For coloring these colors at the current density of 0,01 And / the sq. dm is required the next time (in min.) courses of current:
to 2 — brown 2 — 3,5 — violet
3,5 — 5,3 — blue 5,3 — 6,3 — blue
6,3 — 8,5 — pale green 8,5 — 12 — yellow
12 — 13 — orange 13 — 15,5 — red-lilac
15,5 — 17 — green-blue 17 — 21 — green
21 — 25 — rose-red
At the smaller current densities time intervals between change of flowers увеличатся. In process of evaporation of electrolyte it is necessary to add water as increase in concentration of electrolyte leads to deterioration in process of coloring.
For receiving more contrast colors of coloring it is necessary to add to ready elekyotrolit 20 g of carbonic sodium (anhydrous salt).
If the film turned out unsuccessful, it is easy to remove it, for this purpose the part should be pogruyozit for 1 — 2 min. in weak solution of ammonia (liquid ammonia).
After process of coloring of the part are washed out by water, dry and pokryvayotsya by the thin film of colourless varnish.Top