US Patent No. 3,850,701

EXAMPLE 1

A previously polished titanium plate 200 mm by 50 mm and 1 mm thick was defatted in a boiling 10 percent NaOH solution, and was dipped into a 5 percent hydrofluoric acid solution at room temperature for 1 min, and then washed with water. Electro-deposition was carried out for 19 min in an electrolyte at 25C consisting of 130 g/l of ferrous sulfate heptahydrate (or 88g/l Dihydrate, or 79.5g/l Monohydrate, or 71 g/l Anhydrous), 100 g/l of ammonium sulfate and 6 g/l of formalin by using said titanium plate as a cathode (a cathodic current density = 25 mA/cm squared) and a low carbon steel as an anode. After the electrodeposion was completed, said iron deposited titanium plate was washed well with water, and then dipped into a solution of 20 g/l of ammonium ferric oxalate at 13C, and was allowed to stand for 20 min under a reduced pressure of 15 mm Hg abs. produced by a vacuum pump and dried under the reduced pressure and was then subjected to heat treatment at 650C for 2.5 hrs. in an atmosphere of a hydrogen/steam gaseous mixture consisting of 20 percent by volume of hydrogen and 80 percent by volume of steam prepared by passing hydrogen into hot water at 94C. On the surface of the product the formation of a magnetite-coated layer was clearly recognized. The thickness of said layer was confirmed to be 20 micron by weighing said product. The appearance of said product was uniformly black and fine-grained and no crack was observed therein.

EXAMPLE 4

An electrolyte consisting of 250 g/l sodium chloride, 70 g/l of sodium chlorate, and 2 g/l of sodium bichromate was electrolyzed at 60C for 11 months with an anodic current density of 10 A/dm square (100mA per cm squared) by using an anode coated with magnetite prepared as described in Example 1 as an anode with the use of a mild steel plate as a cathode. The current efficiency was 85 percent and the average cell voltage was 3.38 V. The required energy per ton sodium chlorate was 6,000 kwh. During this period almost no change was observed on the surface of the anode.

Electro-Plating with Iron.

Iron maybe electro- deposited from suitable solutions, in a condition resembling hard steel, and in this state has been found useful for facing printers' type, engraved copperplates, and electro-types of copper. The process has been named acierage, or steel- facing. Various solutions have been tried for the purpose. Klein's solution is made as follows :
Dissolve a quantity of iron sulphate in water, and add a solution of ammonia carbonate until all the iron has been thrown down. Wash the precipitate several times, and dissolve it in sulphuric acid, taking care to only add as much acid as will dissolve the precipitate. Use this solution in a con- centrated state, with iron anodes having a combined surface some seven or eight times larger than the copper surface to be coated. The bath must not be allowed to get acid, so must be kept well supplied with iron, and it is advisable to add carbonate of ammonia occasionally. The copper plate to be steel- faced, must be well cleaned with benzine, then with caustic potash, and well rinsed in water. It should be placed at once in the iron solution, and well scrubbed every five minutes, until a sufficient thickness of iron has been secured. When the face is deemed thick enough, wash it thoroughly in warm water, dry it quickly whilst rubbing with a soft brush, then coat it with a thin film of wax to preserve it from rust.

Some good results have been obtained from a solution of the double salt of ammonio-sulphate of iron. Mr. Walenn has obtained good results from a solution of sulphate of iron and sulphate of ammonia, one part of iron sulphate to five parts of water. Meidenger found that a solution of iron sulphate gave good results when sal-ammoniac was added to the bath. It is advisable to cover the surface of the bath with glycerine whilst at work, and to keep it under cover when not in use, to prevent decomposition by action of the air.