An Improved Process for Obtaining Metal Coatings or Deposits.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
An Improved Process for Obtaining Metal Coatings or Deposits.
We, EDUARD MIES, of 41, Bergstrasse, Heidelberg, and AUGUST HERMANN MIES,
of Büdesheim am Scharlachberg (Rhenish Hesse), both in the Empire of Ger-
many, Student of Chemistry and Physics and Grand Ducal Burgomaster and
Vineyard Proprietor, respectively, do hereby declare the nature of this invention
to be as follows:-
This invention relates to the production of metal coatings or deposits on
other metals without external application of current.
Under the ordinary methods of producing on metals, deposits of other metals
without the use of the electric current, there are none which produce a
sufficiently thick and uniform, metal coating. In the well known ordinary
boiling on "
process the operation is effected by a certain portion of the metai
object which is to be coated being dissolved and a similar volume of the other
metal deposited on the same. That this deposit can only be extremely thin is
evident from the fact that the metal object is no longer capable of being attacked
the moment it is covered with a skin of the metal which is to be deposited, so
that it becomes no longer receptive to the same.
In the contact process, the coating is much too uneven to be of value in
practice, as contact exists at too few places of the metal which is to be coated.
At the points of contact, there is a thicker coating, whereas at the majority of
places, there can be found only a metallic skin.
The process of the present invention is quite different, both from the before
mentioned methods, and also the acid and cyanide baths, and entirely avoids
the drawbacks hereinbefore enumerated.
By the present invention, the article to be coated with metal, is immersed in
a boiling bath containing the metal which is to be deposited, and a metal which
is a more electro-positive one, all these metals being in the form of salts. A
cyanide compound may be added to the bath, but it will work without the same.
The salt of the more electro positive metal produces in the bath an electric
current between the metal object and: the bath. The electro-negative metal is
thereby deposited on the article to be coated.
As an example of this process, a tin "bath" will now be described, the
proportionate quantities of which may however be varied.
One kilo. of caustic soda
One kilo. of soda
200 gr. of per chloride- or proto-chloride of tin
50 gr. of aluminium chloride
are dissolved in about 40 litres of water and heated to boiling point, and the
articles to be tinned are immersed in the hot solution. In a short time the
tinning is completed, and is completely even and firm.
If it be desired to use the bath in a cold condition, or if it be desired to
037

page_text: strengthen the deposit, an external application of current is necessary, and by
means of this process the metal object receives an equally dense and solid coating
as with baths with external application of current.
This invention possesses the advantage that the coating is everywhere of equal
thickness, whilst in the baths with external application of current, those places
are the thickest which are nearest to the anode.
Dated this 12th day of September 1899
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents-for the Applicants.
An Improved Process for Obtaining Metal Coatings or Deposits.
We, EDUARD MIES, of 41, Bergstrasse, Heidelberg, and AUGUST HERMANN MIES,
of Büdesheim am Scharlachberg (Rhenish Hesse), both in the Empire of Ger-
many, Student of Chemistry and Physics and Grand Ducal Burgomaster and
Vineyard Proprietor, respectively, 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: -
This invention relates to the production of metal coatings or deposits on
other metals in general without external application of current and the obtain-
ing of metals by the electrochemical process.
دو
In the methods of producing on metals, deposits of other metals without the
use of the electric current, there are none which produce a sufficiently thick and
uniform metal coating. In the well known ordinary "boiling on
process the
operation is effected by a certain portion of the metal object which is to be
coated being dissolved and a similar volume of the other metal deposited on
the same.
That this deposit can only be extremely thin is evident from the fact
that the metal object is no longer capable of being attacked the moment it is
covered with a skin of the metal which is to be deposited, so that it becomes no
longer receptive to the same.
In the contact process, the coating is much too uneven to be of value in
practice, as contact exists at too few places of the metal which is to be coated.
At the points of contact, there is a thicker coating, whereas at the majority of
places, there can be found only a metallic skin
The process of the present invention is quite different, both from the before
mentioned methods, and also the acid and cyanide baths in which only certain
alkaline salts of organic and inorganic acids and aluminates are employed,
and it consists in the use of electro positive metals in the form of a salt in
combination with the metals which are to be deposited, or obtained as the case
may be, but not every electro positive salt, but only compounds of iron, zinc,
manganese, uranium, zirconium, aluminium, beryllium, magnesium, calcium
and antimony, and only such of these as have the property of producing an
electric current between the metal immersed therein and themselves, the im-
mersed substance being the negative and themselves the positive pole.
The more negative metal is then precipitated out so long as the metal object
which is to be metal-coated hangs in the bath liquid. If the object for instance
is of copper and is to be metal-coated, the copper first and then the deposited
metal acts as the negative pole (in contrast to the boiling on process, in which
as hereinbefore stated, the deposited skin is neutral, and for this reason no
further deposition or coating takes place).
As examples of the above process, by which lead, zinc, tin, copper, nickel,

page_text: antimony, iron and the .like can be electrolytically deposited or obtained and in
which a cyanide compound may be employed for the eventual better conductivity
of the bath, lead, zinc and tin baths will be described, and in the latter the
differences from the process hitherto known will be especially pointed out.
Further it may be stated that it has hitherto been impossible to deposit metallic
lead thickly by the electro chemical process; the new basic principle of the
present process will thus be clearly apparent.
LEAD BATH.
I dissolve in 100 litres of boiling water
5 kilograms of caustic soda
5 kilograms of soda
.5 kilograms of lead oxide
.25 kilograms of aluminium chloride
25 kilograms chloride of antimony and
200 g. water.

page_text: III. If a copper wire cable is to be tinned for instance, only the outer wires
are tinned under the metallic contact and even then only unevenly, whilst by
the present process each separate wire is evenly coated with tin even when the
wires are firmly pressed together.
IV. All the processes hitherto employed for tinuing copper wire arc useless for
cables as they do not stand the vulcanising action, and therefore cannot be
employed in place of fire-tinned copper wire. By the present process however
it is possible to provide copper wires with a coating of tin which endures vul-
canisation very well.
V. Tin plate could not up to now be made in the baths at present employed,
as tin could only be evenly deposited by the older processes to a very small
thickness. This drawback is removed by the present process, as it allows of tin
being deposited evenly to any suitable thickness.
In order to shortly sum up the advantages of the electrolytic leading as
against zinc coating (galvanising) and hot leading, it may be pointed out that
it is only half as expensive as galvanising with zinc, whilst affording a complete
protection to iron against rust and resisting acid. As against hot leading it
has the advantage of considerably greater cheapness. The metallic object does
not require to be first zinced (galvanised) and then leaded, and the great expense
of keeping the fire baths hot and the oxidation of the metal in them is saved,
this is of course also the case in galvanic (zinc) coating and tinning; the work
is much cleaner like any electrolytic metal coating in comparison with hot metal
coating, and the very poisonous properties of the hot leading process (lead fumes,
their influence on the human body, lead paralysis and the like) are entirely
avoided.
Finally it may also be mentioned as showing the great differences between
the present process and those herein before mentioned, that as the metal may be
deposited to any desired thickness the baths herein before described are very
suitable for obtaining metal and in place of the salts of the metals, extracted
ores may be conveyed directly to the baths.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that
what we claim is:-
The process for obtaining metal coatings on metals without external supply
of current and for depositing or obtaining the said metals by electrolysis,
characterised by the use of boiling baths which contain in solution the metals to
be deposited or obtained; (lead, zinc, tin, nickel, antimony, iron and the like) in
the form of salts, in combination with a salt of the electro positive metals, iron.
zine, manganese, uranium, zirconium, aluminium, beryllium, magnesium, cal-
cium and antimony so far as the latter have the property of producing an electric
current between them and the immersed metal, so that the immersed object
forms the negative and the bath itself the positive pole, whilst if desired to
assist the process, an external application of electric current may take place in
the ordinary manner, substantially as herein before set forth.
TL 1141 day of June 1900
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicants.