Improvements in and Preparation of Materials for use in Converting Iron or Low Steel into High-grade Steel by the Cementation Process.
Year: 1890

page_text: Date of Application, 20th May, 1889-Accepted, 21st June, 1890
COMPLET SPECIFICATION.
Improvements in and Preparation of Materials for use in Converting
Iron or Low Steel into High-grade Steel by the Cementation
Process.
T
I FRANCIS GORDON BATES of 2005 North College Avenue in the City of
Philadelphia State of Pennsylvania United States of America Mechanical 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:
The object of my invention is to provide for the entire or partial conversion of
wrought iron malleable iron, cast iron or low steel into high grade steel capable of
being tempered the converting operation being effected by a cementation process,
and the invention being based upon a new or improved compound to be used for
packing the metal, or metal articles, in the converting box, or flask.
The said compound consists of from eighty to one hundred parts of carbon, and
from five to ten parts of cryolite, to which may sometimes be added from ten to
twenty parts of slacked lime, and from five to ten parts of rosin or carbonate
of soda.
The carbon employed may be pulverized charcoal, still coke, or the like, but, is, by
preference, a carbon specially prepared in the manner hereinafter set forth.
In treating Bessemer steel or other low steel, the compound may consist simply of
the carbon and cryolite, the lime being preferably added when wrought iron is being
treated, and the rosin or soda, as well as the lime, being added when treating articles:
of malleable iron, or cast iron.
In carrying out the process of conversion the articles or pieces of metal to be;
.converted are packed with the compound in the converting box or flask, so that each
piece or article will be surrounded by the said compound, the flask, when full, being
closed so as to be air tight, and being then subjected to heat in a suitable oven or
heating appliance the temperature being gradually raised until the flask. reaches a.
white heat, at which temperature it is maintained for a period which will vary, in,
accordance with the bulk of the articles being treated, or upon the desired extent
of the conversion, a simple case hardening, or partial conversion, being effected in
less time than if the articles are to be converted throughout.
When the articles are removed from the flask or converting box, they are, by
preference, permitted to cool rapidly, so as to hasten.contraction...
Castings of gray or malleable: iron, steel castings, or articles of wrought iron, or
Bessemer or other low steel, may, by my improved process, be changed in character
so as to acquire a fine grain and homogeneous structure, and so as to be capable of
receiving any desired degree of temper, which renders them available for use in the
manufacture of cutting tools of all kinds.
Steel produced in accordance with my invention is also available for the manu-
facture of armour plates or projectiles, especially if the metal has been but partially
converted, so as to present a hard surface backed by a body of softer and tougher
metal.
The cryolite which I use as one of the ingredients of my compound, is a double
fluoride of aluminium and sodium, and has, in practice, been found to give the best
results, although other fluorine compounds may sometimes be used in place of the
same, and other hydrated minerals may in some cases take the place of slacked lime,
the main purpose of which is to furnish a supply of hydrogen, which materially
facilitates the converting process.
The carbonaceous matter which I prefer to use in my improved compound, is that
resulting from the slow charring or partial decomposition of crude petroleum, or its
products, and in producing such carbonaceous matter, I permit the crude petroleum

page_text: to fall in a slow stream into a heated retort, care being taken to prevent the
temperature of the retort from rising so high as to rapidly vaporize or distil the more
volatile constituents of the oil.
If, however, the temperature of the retort be kept low, so as to effect a slow
distillation, a large percentage of solid matter will remain, this solid matter consisting
of carbon charged with various hydrocarbons, so that in the converting process
hydrocarbon vapours are given off, which assist in the purification of the heated
metal.
While it is preferable to produce the carbonaceous material separately, in the
manner described, it is possible to produce it during the converting operation itself,
by adding crude petroleum or petroleum product in suitable proportions, to ordinary
charcoal in packing the converting box or flask, the gradual heating of said box or
flask and its contents, at the beginning of the operation, serving to produce the
carbonaceous matter in a manner somewhat similar to that in which it is produced
in the retort.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. The herein before described compound for converting iron or low steel into steel
of high quality by the cementation process, the said compound consisting of carbon
and cryolite, with or without the addition of lime and rosin or their equivalents,
substantially as specified.
2. The process hereinbefore described of converting iron or low steel into steel of
high quality by the cementation process, the said process consisting in packing the
metal to be converted in a box or flask with a compound consisting of carbon and
cryolite with or without the addition of lime and rosin or soda, and then subjecting
the box and its contents to heat, until the converting operation has been effected,
substantially as hereinbefore specified.
3. The manufacture of carbonaceous matter for use in converting iron or low steel
into steel of high quality, by slowly charring or decomposing petroleum or petroleum
product, substantially as hereinbefore specified.
Dad him noth
CM1000
J. H., JOHNSON & Co.,
Agents.