Improved Process and Means for Hard-soldering Cast Iron.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improved Process and Means for Hard-soldering Cast Iron.
I, FRIEDRICH PICH, of 41, Haide Strasse, Berlin, in the German Empire,
Engineer, do hereby declare the nature of this invention to be as follows:-
While the hard-soldering of wrought iron with various alloys of copper causes
no difficulty, the hard-soldering of cast iron has hitherto not been achieved.
My invention consists in a novel or improved process and means for effecting
such hard soldering of cast iron, the solution of this practically most important
problem being based upon the consideration, that cast iron could be hard-
soldered in an open smith's fire equally well as wrought iron if it were possible
to free the cast iron surfaces to be soldered from graphite during the process
and at the same time bring the molten hard solder into intimate contact with
the likewise red hot cast iron graphite-freed or decarbonised surfaces under
exclusion of atmospheric air.
The new process based upon this consideration is as follows:-The cast iron
surfaces to be soldered are cleaned by means of an acid in the usual way, fixed
together, and the soldering places covered or surrounded with a paste consisting
preferably of sub-oxide of copper and borax. This paste is prepared by mixing
said sub-oxide and borax, preferably by boiling them together, so intimately
that the suboxide of copper is surrounded by a layer of borax absorbing oxide,
which excludes the action of the atmosphere upon the suboxide during the heat-
ing process required for soldering. For the borax other suitable fluxes, such as
glass or waterglass, may be substituted. While hard-soldering the cast iron,
the borax melts and protects as is known, the cleaned surface of the cast iron
against oxidation, frees it from any oxide thereon and also protects the suboxide
of copper against the action of the oxygen of the atmosphere.
In consequence of this the sub-oxide of copper likewise heated to a red heat
parts with its oxygen to the red hot cast iron surface, and the oxygen combines
with the graphite contained in the cast iron surfaces to form carbon monoxide
or dioxide thus decarbonising them, while the metallic copper becomes dis-
sociated in a very finely divided condition. At the same time the respective
hard solder is added, and as this solder which is brought upon the surfaces to be
soldered in the known manner, is likewise melted by the heat, it alloys itself
with the incandescent particles of copper, and this new alloy immediately com-
bines with the red hot decarbonised soldering surface of the cast iron.
The essential features of the new process thus are:
1. The local decarbonisation of the cast iron by means of a metallic sub-
oxide under the protection of borax or other flux, which exercises a double
action, viz. a protective action excluding oxygen from the cast iron as well
as from the metallic suboxide, and an absorbing action on the surplus metallic
suboxide.
2. The formation of a finely divided metal from the metallic suboxide, which

page_text: metal forms an alloy with the solder and thus effects the soldering of the cast
iron.
To the paste made as hereinbefore described finely powdered decarbonised iron,
or such iron covered by a layer of suboxide may be added, by means of which
the soldering is rendered quicker and more uniform.
The suboxide of copper may in some cases be replaced by or mixed with sub-
oxide of iron.
I, FRIEDRICH PICH, of 41, Haide Strasse, Berlin, in the German Empire,
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:—
While the hard-soldering of wrought iron with various alloys of copper causes
no difficulty, the hard-soldering of cast iron has hitherto not been achieved.
My invention consists in a novel or improved process and means for effecting
such hard soldering of cast iron, the solution of this practically most important
problem being based upon the consideration, that cast iron could be hard-
soldered in an open smith's fire equally well as wrought iron if it were possible
to free the cast iron surfaces to be soldered from graphite during the process
and at the same time bring the molten hard solder into intimate contact with
the likewise red hot cast iron graphite freed or decarbonised surfaces under
exclusion of atmospheric air.
The new process based upon this consideration is as follows:-The cast iron
surfaces to be soldered are cleaned by means of an acid in the usual way, fixed
together, and the soldering places covered or surrounded with a paste consisting
preferably of suboxide of copper and borax. This paste is prepared by mixing
said suboxide and borax preferably by boiling them together so intimately that
the suboxide of copper is surrounded by a layer of borax which absorbs oxide
and excludes the action of the atmosphere upon the suboxide during the heating
process required for soldering. For the borax other suitable fluxes such as glass
or waterglass, may be substituted. While hard-soldering the cast iron, the
borax or other flux melts and protects, as is known, the cleaned surface of the
cast iron against oxidation, frees it from any oxide thereon and also protects the
suboxide of copper against the action of the oxygen of the atmosphere.
In consequence of this the suboxide of copper likewise heated to a red heat
parts with its oxygen to the red hot cast iron surface, and the oxygen combines
with the graphite contained in the cast iron surfaces to carbon monoxide or
dioxide thus decarbonising them, while the metallic copper is dissociated in a very
finely divided condition. At the same time the respective hard solder is added,
and as this solder which is brought upon the surfaces to be soldered in the known
manner, is likewise melted by the heat, it alloys itself with the incandescent
particles of copper, and this new alloy immediately combines with the red hot
decarbonised surfaces of the cast iron and thus solders them together.

page_text: The essential features of the new process thus are:
1. The local decarbonisation of the cast iron by means of a metallic sub-
oxide under the protection of borax or other flux, which exercises a double
action, viz. a protective action excluding oxygen from the cast iron as well
as from the metallic suboxide, and an absorbing action on the surplus metallic
suboxide.
2. The formation of a finely divided metal from the metallic suboxide which
metal fórms an alloy with the hard solder and thus effects the soldering of the cast
iron.
The application of the hard-solder to the decarbonised iron surface in statu
nascendi of the same and of the finely divided metal resulting from the reduction
of the oxide is an essential factor for obtaining a faultless soldering.
To the paste made as hereinbefore described finely powdered iron, free from
graphite or decarbonised or such iron covered by a layer of suboxide may be
added, by means of which the soldering is rendered still quicker and more
uniform. The solder then flows into the minutest crevices of the surfaces to be
soldered and combines perfectly with the cast iron.
The suboxide of copper may in some cases be replaced by or mixed with sub-
oxide of iron.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is:
1. A process for hard soldering cast iron in an open smiths' or blown fire con-
sisting in surrounding or covering the cast iron surface to be soldered with a
mixture of reducible oxides of copper or iron and a flux absorbing metallic oxide,
such as borax, glass or water glass; heating them to a red heat and bringing
the metal serving as a hard solder into contact therewith substantially as herein-
before described.
2. For the purpose of carrying out the process for hard soldering cast iron
claimed in the preceding claim, the manufacture and use of a paste consisting
of reducible oxides of copper and iron and of borax or similar flux absorbing
metallic oxides, substantially as herein before described.
3. The addition to the paste claimed in the preceding claim of finely pulverised
iron free from graphite or of such iron covered with a layer of suboxide of iron
substantially as and for the purpose hereinbefore described.
Dated this 22nd day of November 1898.
R. J. URQUHART,
57, Barton Arcade, Manchester,
Harrington Chambers, 24, North John Street, Liverpool,
Consulting Engineer and Patent Agent.