Improved Method and Apparatus for the Manufacture by Electro- deposition of Articles Plated with Platinum, Gold, and Silver.
Year: 1899

page_text: Date of Application, 9th Oct., 1899-Accepted, 3rd Feb., 1900
COMPLETE SPECIFICATION.
...
Improved Method and Apparatus for the Manufacture by Electro-
deposition of Articles Plated with Platinum, Gold, and Silver.
I, LÉON BOURDILLON, of 138, Cours Lieutand, Marseilles, in the Republic of
France, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement: —
than
My invention relates to a method of manufacturing by electro-deposition
articles plated with platinum, gold and silver which have hitherto been made by
rolling, stamping, hammering and the like and has for its object to replace the
said mechanical processes.
In addition to the difficulty experienced in carrying out these mechanical
processes, they can only be employed in the manufacture of certain articles of
slight homogeneity and resistance and are somewhat costly..
My electrolytic process on the contrary allows of platings of all thicknesses
and of any size being very easily obtained and enables the problem to be
economically solved which has hitherto been vainly studied and which consists
in causing copper or other suitable metal to adhere to any suitable thickness to
one of the faces of an extremely thin sheet of platinum or gold.
The treatment of plates of platinum and gold will first be described..
I have shown in the accompanying drawings as an example apparatus for
enabling this invention to be carried out. In these:-
Figure 1 is a diagrammatic view of one of the possible arrangements;
Figure 2 is a similar view of a modification of this arrangement.
A drum T of some material which is not acted on by a bath of sulphate of
copper, such for instance as aluminium, is arranged in an electrolysing vat of
suitable dimensions containing an ordinary copper plating bath A sheet of
platinum or gold of a thickness corresponding to the thickness of the plating
which it is desired to obtain is previously wound on this drum, the winding being
effected with sufficient pressure to insure a perfect adherence between the sheet
and the drum.
Copper anodes A are arranged in the copper-plating bath on both sides of
the drum whilst the cathode is formed by the cylinder and a brush B. The axle
of the drum is provided with paddles intended to agitate the bath on the drum
being slowly rotated.
As shown in Figure 2, I may also simply arrange a sheet of platinum or gold m
on a conducting or non-conducting plate p securing a perfect adherence. Another
sheet m may be arranged on the other face of the plate p so that the two-copper
plated sheets may be obtained simultaneously. In this case the anodes A are
perpendicular and are arranged as shown in Figure 2. This arrangement: has
the advantage of only requiring a small space, and in this arrangement the
cathode is given to a to and fro movement in a direction at right angles to the
plane of the figure, but even this movement is not indispensable.
These two arrangements are for copper-plating sheets of platinum and gold,
and it is quite evident that the arrangements must be varied when it is a question

page_text: If in fact it is a
of treating ready made articles for instance of platinum.
question of very thin platinum articles of small size, such as crucibles, the opera-
tion may be effected in the following way. The crucible or other article is closed
hermetically with a stopper through which a conducting rod passes, after the said
crucible or other article has first been filled with a conducting substance such as
tin-foil or solder, and is suspended in the bath after it has been carefully cleaned.
It is withdrawn therefrom when the layer of copper is of sufficient thickness.
It is quite evident that the operation may be carried out in the same way if the
copper be replaced by another metal, silver for instance, or if it be desired to
deposit several layers of different metals successively on a sheet of platinum or
gold. It may also be pointed out that by using an intermediate piece such as
silver for instance, plated platinum of great resistance may be obtained.
Of course the invention is not limited to the actual apparatus hereinbefore
described, as any other suitable apparatus may be employed and a number of
elementary vats may be grouped in any suitable number of batteries.
It is evident that the operation of silverplating might be carried on in the
same way but as the electrolytic deposition of silver is very homogeneous and
resistant it is preferable to proceed by direct precipitation of the metal on the
cathode and then to deposit the copper on the layer of silver thus obtained.
In order to prevent the silver adhering to the metal of the cathode, various
processes have been suggested which all have yielded practically the same results.
For polished articles among other methods, that of hydrogenating the pre-
viously polished mould has been suggested, but drawbacks exist in that firstly
such process has only really been successful with nickel, secondly, that the nickel-
plated surface rapidly deteriorates in consequence of its immersion in the bath
and the hydrogenating and nickel-plating has to be recommended, and thirdly
that the layer of hydride is not formed over the whole surface and the silver then
adheres to the cathode, and under these conditions the removal from the mandrel
is impossible and the mould and the articles are destroyed.
My improved process always succeeds and requires no preparation, it simply
consists in subjecting the mould as soon as it enters the bath to a current of
great intensity and high tension. By operating in this manner no difficulty in
removal from the mandrel will be found.
For dull articles, the mould is coated with a soluble or insoluble conducting
coating (plumbaginous grease for instance). If the coating be soluble in the
bath the circuit is closed by means of the mould itself so that in proportion as
it descends in the bath the deposit adheres to the surface of the mould, thus
encasing the coating which cannot then dissolve.
For relief surfaces (cooking utensils or coils for instance) I simply employ
a very fusible alloy, like Darcet alloy (i.e., an alloy of bismuth, tin, and lead),
on which I deposit the metal. The article when finished is placed in boiling
water the alloy cracks off and there only remains the article plated with silver
or copper according to the deposit desired to be obtained.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. The improved process for making articles plated with platinum and gold,
which consists in electrolytically coating with copper one of the faces of an
extremely thin sheet of platinum or gold without affecting the other face, said
process being applicable not only to copper but also to any other like metal, such
for instance as silver, or two or more of these metals successively, some of them
serving as intermediaries for the others substantially as hereinbefore described.
2. An apparatus for obtaining the described platings of platinum and gold
constructed and operating substantially as shown in Figures 1 and 2 of the accom-
panying drawings.
3. The application of the hereinbefore described plating process to the treat-

page_text: ment of articles already made of extremely thin platinum or gold substantially
as set forth.
4. As an improved industrial product sheets and articles of plated platinum or
gold obtained in the manner described and comprising an extremely thin sheet
of platinum or gold, coated on one of its faces with copper or other suitable metal
such as silver, or two or more of such metals successively to the desired thick-
ness substantially as described.
5. The application of the plating processes hereinbefore described to dull
(unpolished) articles, coated with silver (cooking utensils and coils) substantially
as set forth.
W. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant,