An Improved Process or Method of Plating or Coating Aluminium with Tin, Zinc, or Lead, or Alloys thereof.
Year: 1892

page_text: An Improved Process or Method of Plating or Coating Aluminium
with Tin, Zinc, or Lead, or Alloys thereof.
I, REGINALD HADDAN of the firm of Herbert Haddan & Co., of 18 Buckingham
Street Strand London W.C., Patent Agent, do hereby declare the nature of this
invention a communication to me from abroad by Ludwig Oliven of 39, Wilhelm-
strasse Berlin in the Empire of Germany, Merchant and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement :―
Up to the present time the usual methods of coating sheet or other metal with
either tin, zinc, or lead or alloys of these metals have been found inapplicable or
inoperative to coat the metal aluminium. If a sheet of aluminium, however well
it may have been mechanically cleansed or chemically cleaned or etched, is dipped
into molten tin, zinc or lead or any mixture thereof and withdrawn, the metal will
simply run off the surface of the aluminium without adhering thereto.
The present invention is intended to overcome this resistance and cause the
tin, zinc or lead or mixture thereof to adhere to the surface of the aluminium, and
it consists in subjecting the aluminium surface at the places where the tin, zinc,
lead or mixture is to adhere, to the action of a suitable sharp or hard instrument
while the aluminium is in a heated state and is immersed or otherwise covered
with the molten metal which is to be brought to adhere thereto. If, for instance
the surface of the aluminium while covered with the tin, zinc, lead or molten
mixture thereof is brushed briskly with a brush of steel wire or an equivalent
instrument, it will cause the metal aforesaid with which it is covered, to adhere as
a thin coating to the aluminium.
It appears that it is not the aluminium itself which offers no affinity to the afore-
said metals, but the thin coating of oxyde of the aluminium which is immediately
formed on the surface of the aluminium by the oxygen of the atmosphere when
the aluminium comes in contact therewith. If the heated aluminium is covered
by the molten metal aforesaid and while under such protection is subjected to any
instrument which will scratch rub or scrape the surface, this oxyde is removed and
the air being excluded no further oxyde is formed on the exposed metal which can
thus enter into intimate connection with the molten metal which covers it.
The roughening of the surface during this process may also not be without
valuable effect in assisting the connection.
Nevertheless if the brushing scraping or scratching is only done before the
molten metal is brought in contact with the surface of the aluminium and not
while it is in such contact the connection of the aluminium with its coating will be
very faulty and partial only.
In practice large sheets of aluminium may be plated or coated with tin, zinc, or
lead, or with a mixture thereof in the ordinary tinning or plating tanks by
arranging therein pairs of rollers with rough rubbing or scratching surfaces, or
wire brush rollers or even flat rough surfaces or brushes between which the
aluminium plate may be guided and moved back and forth by any suitable
mechanism or which may be set in their appropriate movement so as to execute
the desired action on the one or both surfaces of the aluminium plate at places
where the latter is immersed in the molten metal. If the aluminium plate is
subjected to this rubbing or like action on both sides, both sides will be plated with
the metal in the tank, if one side only is so treated, the untreated side will come
forth from the liquid metal without any of the latter adhering thereto.
The result of this process is to provide a thin coating or layer of the metal on
the aluminium. If this layer is deposited evenly on the surface it may be

page_text: thickened by simply dipping the plate into inolten zinc, tin, lead or mixture
thereof.
If the deposit on the plate is uneven, it may be rendered flat and level by
passing the plate under or between hot rollers.
The process above described with reference to the coating of sheet aluminium is
equally applicable to the coating of castings of aluminium, or any forms in which
the metal may be produced, care being taken that the rubbers or equivalent
devices for burnishing or treating the objects wheu under the molten zinc, tin or
lead or mixture are appropriate to the proper treatment of the surfaces which are
to be coated, and that the objects of aluminium are sufficiently hot and well
covered with the zinc, tin, lead or mixture thereof.
! Having now particularly described and ascertained the nature of this said inven-
tion and in what manner the same is to be performed I declare that what I
claim is ;-
A method or process for plating or coating aluminium with tin, zinc or lead
or with a mixture of two or more of these metals, in which the aluminium is
exposed in a heated state to the action of sharp instruments more especially
brushing scratching or scraping instruments applied to the surface thereof while
immersed in or under cover of the tin, zinc, lead, or mixture in a molten
state.
Dated this 20th day of December 1899
R. HADDAN.