Improvements in the Electro-Deposition of Metals.
Year: 1898

page_text: Date of Application, 19th Oct., 1898
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Improvements in the Electro-Deposition of Metals.
SHERARD OSBORN COWPER-COLES, of Grosvenor Mansions, Victoria Street,
Westminster, London, S.W., Electro-Metallurgist, do hereby declare the nature
of this invention to be as follows:
My invention relates to improvements in and connected with the electro-
deposition of metals. Hitherto it has been the practice when smooth tough
deposits of copper in particular were required either in the form of sheets or tubes,
to burnish them either by means of agates or pads made out of sheep-skin or
other suitable material. The employment of such burnishers necessitates the use
of expensive machinery and introduces many mechanical difficulties. I overcome
these difficulties by revolving the cathode or mandrel at a very high rate of
speed so as to get friction between the deposited metal and the electrolyte. In
this way I find that I can get tough smooth deposits, and also use a much higher
current density, that hitherto has been impossible, the electrical resistance also
being reduced.
Dated this Tightoonth day of October 1898
SHERARD OSBORN COWPER-COLES.
Improvements in the Electro-Deposition of Metals.
I, SHERARD OSBORN COWPER-COLES, of Grosvenor Mansions, Victoria Street,
in the City of Westminster, late of 39, Victoria Street, aforesaid, 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:-
My invention relates to improvements in and connected with the electro
deposition of metals.
Hitherto it has been the practice when smooth tough deposits of metal, and of
copper in particular, have been required, either in the form of sheets, or tubes,
to burnish them either by means of agates, or pads made of sheep skin or other
suitable material. The employment of such burnishers necessitates the use of
expensive machinery and introduces many mechanical difficulties. I overcome
these objections by revolving the cathode or mandrel around its axis during
deposition at a very high rate of speed so as to obtain such friction between the
deposited metal and the electrolyte as will cause the deposits made during such
rotation to be tough and smooth and it moreover causes the hydrogen bubbles to

page_text: be thrown off from the cathode and enables one to employ a much higher current
density than has hitherto been possible the electrical resistance being reduced,
and thus I effect great economy. The invention may be applied to the formation
of deposits all of one kind of metal, or to the formation of deposits of different
kinds of metal; such, for example, as for the manufacture of "Sheffield plate"
by depositing a layer of copper upon a layer of silver.
The accompanying drawing represents apparatus suited to the purposes of my
invention.
Fig. 1 is a vertical section and Fig. 2 is a plan of an apparatus wherein the
driving of the cathode is effected from below. Figs. 3 and 4 are respectively a
vertical section and a plan of a modification for driving the cathode from above.
A is the vat containing the electrolyte B is the anode consisting of a cylinder,
or of plates, of the metal to be deposited, (or it may be of other material if the
electrolyte consists of a salt of the metal to be deposited) and resting upon insu-
lating supports below, the current being conducted to the said anode from the
dynamo through the mercury cups into which dip the terminal leads and the
conducting wires 62 attached to the anode. C is the cathode, or mandrel, to
receive the deposit, it being connected to a cross head c supported upon a vertical
shaft D, supported below on ball bearings d, and passing through a bearing d²,
in the bottom of the vat A, and being surrounded by a tube E, extending from
the bottom of the vat to above the level of the electrolyte therein. The cross-
head c carries an eye c² so that the cathode or mandrel can be lifted and lowered
by a crane, or otherwise. d is a pulley by which the shaft D, is driven from
any suitable motor which will give a high speed of rotation, preferably a circum-
ferential speed of about 1000 feet per minute. The lower end of the cathode, or
mandrel, C, is provided with a filling piece, to rotate around a collar e', on
the tube E. c is a scolloped flanged piece which acts as a baffle plate at the
lower part of the cathode and prevents the formation of trees or nodules. Fare
the brushes which bear against the conducting piece c to convey the current to
the negative leads.
In Figs. 3 and 4 I have shewn an arrangement for driving the cathode, or
mandrel, C, from above, for which purpose it is connected by a universal
joint, to a shaft D2, provided with a driving pulley dt, and supported on
ball bearings ³, the whole being shewn as being carried by a traveller G.
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
In the electro deposition of metals means for rotating the cathode, or mandrel,
on which the deposit is made, and during the deposition, at such a high rate of
speed as will give such friction between the deposited metal and the electrolyte
as to give tough and smooth deposits without the use of the burnishers hitherto
used substantially as herein before described.
Dated this 21st don of Anand 1900.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents. 4