Improvements in or connected with the Electro-deposition of Zino or Zinc Compounds and the Treatment of the Deposited Metal or Compounds.
Year: 1894

page_text: Date of Application, 10th Apr., 1894
Complete Specification Left, 26th June, 1894-Accepted, 15th Sept., 1894
PROVISIONAL SPECIFICATION.
Improvements in or connected with the Electro-deposition of Zino
or Zinc Compounds and the Treatment of the Deposited Metal
or Compounds.
We, SHERARD OSBORN COWPER-COLES of 16 Adam Street, Manchester
Square in the County of London, Engineer and BALDWIN WAKE WALKER,
Baronet of 1 Queens Place, Southsea, in the County of Hants Captain in the
Royal Navy do hereby declare the nature of our invention to be as follows:-
The principal object of this invention is to effect the electro-deposition of zinc
or zinc compounds in a more efficient, economical and expeditious manner than
hitherto, and according thereto there is employed an alkaline electrolyte to which
is added, in a state of fine division, the zinc, or zinc compound to be deposited or
to form part of the deposit. During deposition this finely divided zinc, or zinc
compound, is kept in a proper condition of suspension or dispersion in the alkaline
electrolyte by any suitable means, such, for example, as by a mechanical circulator,
or by regulating the relative densities of the electrolyte and the finely divided
zinc, or zinc compound, so that the said zinc or zinc compound will remain in
suspension when it is sufficiently light to allow of this, or steam may be used to
effect the maintenance of suspension or dispersion. The current of electricity
used for depositing can be considerably stronger than hitherto, say for instance, a
current of 50 ampères per square foot of cathode surface can be used.
In order to brighten the deposited metal the current density is increased
considerably for a brief period, or for brief periods, say for during about one
minute, at intervals of eay eight minutes, during which latter periods the current
of lesser density is maintained. The increase of the current density in this manner
causes the brightening of the metal which has been deposited. The finely divided
zinc or zinc compound may be obtained in any suitable way for example by
subjecting the metal in solution to an excess of electric current so as to cause
granulation and then grinding this granulated metal, or zinc ore may be treated in
an electric furnace and the volatilized metal be condensed and ground.
The metal deposited may be brightened and the coating improved by subjecting
it to a treatment analogous to that of the sand blast preferably using pellets of iron
projected by an air blast.
In some cases it is found advantageous to coat the iron with a film of magnetic
oxide by chemical or other means preparatory to depositing zinc or zinc compound
upon the iron.
Dated the 10th day of Anvil 1001
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.

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COMPLETE SPECIFICATION.
Improvements in or connected with the Electro-deposition of Zino
or Zinc Compounds and the Treatment of the Deposited Metal
or Compounds.
We, SHERARD OSBORN COWPER-COLES of 16 Adam Street, Manchester
Square in the County of London, Engineer, and BALDWIN WAKE WALKER,
Baronet of 1 Queens Place, Southsea in the County of Hants, Captain in the
Royal Navy, 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 :-
The principal object of this invention is to effect the electro-deposition of zinc
and zinc compounds (such as zinc oxides for example) or either of them in a more
efficient, economical and expeditious manner than hitherto and so that an improved
product is obtained. According to the said invention we employ an alkaline
electrolyte to which we add in a state of fine division, the zinc or zinc compound
to be deposited or to form part of the deposit. During deposition this finely,
divided zinc or zinc compound is kept in a proper condition of suspension or
dispersion in the alkaline electrolyte by any suitable means, such for example as
by a mechanical circulator, or by regulating the relative densities of the electrolyte
and the finely divided zinc or zinc compound, so that the said zinc or zinc compound
will remain in suspension when it is sufficiently light to allow of this, or steam may
be used to effect the maintenance of suspension or dispersion. The current of
electricity used for depositing can be considerably stronger than hitherto, say, for
instance, a current of 50 ampères per square foot of cathode surface can be used..
In order to brighten the deposited zinc or zinc compound we employ electric
current of comparatively low density alternately with electric current of com
paratively high density each being sustained for brief periods, the current of high
density being maintained for say about one minute and alternating with current of
low density maintained for say about eight minutes. The finely divided zinc or
-zinc compound may be obtained in any suitable way for example by subjecting zinc
in solution to such excess of electric current so as to cause granulation and then
grinding this granulated zinc; or zinc ore may be treated in an electric furnace
and the volatilized zinc be condensed and ground.
The zinc or zinc compound deposited may be brightened and the coating
improved by subjecting it to a treatment analogous to that of the sand blast
preferably using pellets of iron projected by an air blast.
In some cases it is found advantageous to form on the iron a film or coating of
magnetic oxide by chemical or other means preparatory to depositing zinc or a zinc
compound upon the iron. This can be effected in any suitable or known way for
example by immersing the iron in a saturated solution of bi-chromate of potash
until it has received an even coating of magnetic oxide and then it is removed and.
subjected to the electrolytic action to coat it with zinc or a zinc compound.
This invention is applicable to depositing zinc or zinc compounds (separately
or in any desired combination) on metals or electric conducting surfaces generally
but is especially applicable to depositing zinc or zinc compounds upon iron. When
a number of plates and wires is coated in the bath the said plates and wires are
preferably arranged in series.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. In effecting the electro-deposition of zinc or zinc compounds the employment
of an alkaline electrolyte in which zinc or zinc compound in a fine state of division
is suspended or dispersed substantially as hereinbefore described.

page_text: 2. In effecting the electro-deposition of zinc or zinc compounds the employment
of current of lesser density alternately with current of greater density substantially
as and for the purpose hereinbefore described.
3. Brightening and improving electro-deposited zinc or zinc compound by
subjecting it to the impact of shot or the equivalent after the manner of the sand
blast substantially as hereinbefore described.
4. In combination with the electro-deposition of zinc or zinc compound upon iron
the formation first of a coating of magnetic oxide and then the electro-deposition
of the zinc or zinc compound upon the magnetic oxide substantially as hereinbefore
described.
Dated this 26th day of June 1894