An Improved Process for Treating Copper and its Alloys to Prevent Oxidation and Deoxidation thereof during Heating or Annealing.
Year: 1890

page_text: This Specification was, upon the 11th day of March 1892, Amended under
Sections 18 to 21 of the Patents, Designs, and Trade Marks Act, 1883.
COMPLETE SPECIFICATION (AMENDED).
[Communicated from abroad by GEORGE WYCKOFF CUMMINS, of Vienna, County of
Warren, State of New Jersey, United States of America, Student.]
An Improved Process for Treating Copper and its Alloys to Prevent
Oxidation and Deoxidation thereof during Heating or Annealing.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents
45 Southampton Buildings in the County of Middlesex, do hereby declare the naturo
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 an improved process for treating copper and its alloys to
prevent oxidation and deoxidation thereof during heating or annealing.
The said invention is hereinafter described in detail.
The accompanying drawing illustrates in sectional-side--eleration longitudinal
vertical section an apparatus suited to carry out the process.
A indicates a retort, preferably of fire-clay lined with copper, a; Ba heating
furnace for said retort provided with a chimney H; C a tank or receptacle for
holding water or other cooling liquid; D a closed passage leading from the retort A
to the liquid in said tank, E an inlet pipe for steam, earbenie-neid, nitrogen, or other
similar non-reducing gaseous fluid; A, on the insertion of a proper instrument or
F the cover or door of the retort A; and Gan
opening into the passage
tool for drawing the articles of copper heated in the retort A from said retort to the
passage D, whence they fall into the liquid in the tank C.
As is well known, copper or an alloy of copper when heated to redness in the
presence of free oxygen, readily oxidizes, and there. is formed upon its surface a
coating of
copper scale," black oxide of copper, which is very undesirable, owing
to the direct loss of copper and to the difficulty and expense of its removal when
necessary to be effected in order to obtain clean copper. Hence one object of this
invention is to prevent the formation of said oxide in the operation of annealing
copper or its alloys. Also, it is known that if oxygen is removed from copper during the
processes of heating and annealing, the copper is thereby rendered brittle, as hereinafter
described, and it is therefore important to prevent the deoxidation of copper and its alloys
during these processes. This prevention of oxidation and of deoxidation may be effected
in the apparatus herein before described in the following manner.
The tank C is supplied with liquid until it rises a few inches above the opening into
the passage D. The retort A having been heated by the furnace Bsteam from a
boiler, or any suitable source, or a non-reducing gas, is let in at E. under sufficient
pressure to cause the expulsion of the air contained in the retort A out through tho
liquid in the tank C. When all said air has been replaced by sicam or said other
gaseous fluid, the door F may be opened and the copper pieces or articles to be heated
or annealed placed in the retort A. The door F being then closed, the copper is
allowed to become heated in the retort, steam or other non-reducing gaseous fluid.. in
the meantime being continuously passed therein at E. When the copper has attained
the required temperature a hook or other conveniently shaped rod or tool is inserted
through the opening G by which the articles of copper are drawn through the

page_text: passage D whence or through which they fall into the liquid in the tank C in which
the operation of annealing is completed.
If steam be used, it may be of bui moderate pressure and it will be superheated by
the heat supplied to it while passing through the retort A.
**
Care should be taken not to leave the hole G open longer than is necessary to
perform the required manipulations with the red tool introduced through it... The
passage D may be lengthened somewhat if desired, so as to permit the copper
to part
with some of its heat before reaching the liquid in the tank C. A peep-hole" closed
with mica may be fitted in the retort A, if desired, through which the heating of the
copper can be observed, and its degree of heating ascertained with sufficient accuracy
by the eye.
It is obvious that the liquid-seal between the retort A and tank C is a simple and
most efficient means for accomplishing the air-exclusion desired, yet other well-known
air-seals or valves may be substituted to accomplish the same result as the water-seal
shown. Other cooling liquid may be substituted for water if desired, without
departing from this invention.
One marked advantage of this process in preventing oxidation is that even very
fine copper or brass wire may be produced of exactly uniform diameter in any desired
quantity. When once oxide has been permitted to form, its removal entails great
uncertainty as to the exact diameter of the finished wire. Large quantities-of-copper
wire-are-now-in-constant demand for winding electrs--magnets--and--such uses, the
requirements-being that the wire shall be exact in-diameter-even-to-the--one thousandth
part of na-inch less. The further greater advantage of the process in preventing
deosidation-or-reduction-of-the-copper; either-simultaneously or without regard to
the the removal of oxygen from the copper either simultaneously with, or without regard to
the prevention of oxidation, is that brittleness is prevented while heating the copper,
which brittleness if once reached subsequent annealing will not remove.
This subject
of deoxidation may be thus explained. Copper as it ordinarily occurs in the market
-even the purest commercial copper-contains a small amount of oxygen. This
oxygen is ordinarily present as an oxide of arsenic or antimony. These oxides appear
to exert no especially detrimental action on the copper. When, however, their oxygen
is removed, and the arsenic or antimony is left free, the metal thus freed forms an
alloy with the copper, and this alloy is exceedingly brittle. Thus by exposure in a
heated condition to a "
reducing atmosphere, copper may be, and in many cases in
common practice heretofore is, ruined. The deoxidation or, technically, this reduction
of the arides in the copper occurs at a temperature higher than that at which merc
oxidation of the copper in atmospheric air begins. It should be further observed that
copper as ordinarily annealed, is heated, directly or indirectly, by reducing gases
(generated from coal). In the ordinary
muffle
these gases come in direct contact
with the copper and may therefore easily reduce-the-same remove its oxygen and ruin
it. If the copper be heated indirectly by inclosure in a pot or retort, there is still a
liability of, or a chance for, the reducing gases to find their way to the copper and
reduce it to its ruin for any practical-use remove the oxygen from it and thus make it
seless for any practical purposes.
In carrying out this feature of this invention with the object only of preventing
deocidation and without reference to the prevention of superficial oxidation and when
employing the apparatus illustrated in the accompanying drawing, the copper is
heated in the retort A, which is a closed vessel kept filled with a gas incapable of
deoxidizing or reducing the copper-in other words, a non-reducing gas "such as
earbonie neid nitrogen, or steam, and such like gaseous fluids. The copper may then,
after having been heated to a sufficient temperature, be allowed either to cool slowly,
by the cooling of the containing vessel, or the copper may be dropped into water, as
into the tank C through the passage and water-seal D. But if superficial oxidation of
the copper be not an objection in any case, the copper may be cooled in atmospheric
air, and still the deoxidation or reduction of the copper and the oxides therein be
brevented.

page_text: By this invention, therefore, if atmospheric air be excluded, the copper-or-its-alloy
is neither oxidized nor-deoxidized-and-if-the-air-be-not-excluded, the-copper-or-its
Hey may be oxidized-but-is-still-not-depxidized as hereinbefore fully set forth.
By this invention therefore, atmospheric air being excluded, the copper and its
contained oxides remain unaltered so far as the processes of oxidation and reduction are
concerned, and if the air be not excluded, during the process of cooling, the copper or its
alloy may be superficially cxidised but is still not deoxidised as hereinbefore fully set forth.
Steam is the most generally useful gaseous fluid for the purposes of this invention
when it is employed in the superheated condition hereinbefore described, but in some cases
it may be commercially practicable to use other non-reducing yascous fluids such as
carbon dioxide (carbonic acid) or nitrogen, the cost of these gaseous fluids is however un
obstacle to their use in ordinary cases.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed as communicated to me by my
foreign correspondent I declare that what I claim is:-
First. The process of for preventing the oxidation of copper and its alloys, when
heated to a temperature sufficient to cause such oxidation if-exposed-te in the presence
of atmospheric air, consisting in inclosing the same before reaching and while at said
temperature in an atmosphere of non-reducing gaseous fluid, such as steam, nitrogen
eurlionic-acid-and-the-like, thereby-excluding said-air, substantially as set forth.
Second. The process of for preventing the deoxidation of oxides contained in copper
and its alloys, consisting in inclosing the same metal, while being heated or annealed,
in an atmosphere of non-reducing gaseous fluid, such as carbonic-neid, nitrogen; steam,
and the likes to the exclusion of reducing gases, substantially as and for the purposes
set forth.
Third. The process of for preventing the oxidation and deoxidation of copper and
its alloys, and of the oaides therein consisting in inclosing the same in an atmosphere
of non-reducing gaseous fluid, such as embonie neid, nitrogen; steam, and--the-like; to
the exclusion of atmospheric air and reducing gases; gaseous fluids and heating the
metal in the presence of said non-reducing gases to the desired temperature before
cooling, substantially as and for the purposes set forth.
Fourth: The process-of-annealing eepper-and-its-alloys, consisting-in-heating the
same--to-the-necessary temperature-while-inclosed-in-an-atmosphere-of-non-reducing
gaseous Hui-sach-as-enrhonie-neids-nitrogen, steam and the like:-and-then--cooling
the-metal-substantially-as-and-for-the-purposes-set-forth.
Dated this 10th day of June 1890
HASELTINE, LAKE & Co..
45, Southampton Buildings, London, Agents for the Applicant.