Improvements in Carburising and Coating Iron and Steel in the Form of Sheets, Hoops, Wrought or Cast Plates, Bars, or Manufactured Articles.
Year: 1888

page_text: Date of Application, 6th July, 1888
Complete Specification Left, 8th Apr., 1889-Accepted, 22nd June, 1889
PROVISIONAL SPECIFICATION.
Improvements in Carburising and Coating Iron and Steel in the Form
of Sheets, Hoops, Wrought or Cast Plates, Bars, or Manufactured
Articles.
I, JAMES SUMMERHILL, of The Grove, Saint Georges, near Wellington in the
County of Salop, general manager of iron and steel works, do hereby declare the nature
of this invention to be as follows:-
This invention has for its chief object means whereby the quality of iron and steel
whether in the form of sheets, or hoops, or of wrought or cast plates, bars, or manu-
factured articles, may be improved by carburisation and whereby the surface of the
metal may at the same time be coated, as a protection against corrosion or wear, with
a material of an innocuous character.
The steel or iron sheets, plates, bars or manufactured articles which it is desired
to treat according to this invention are heated within an annealing furnace, oven,
or muffle, to a temperature which will cause as great an expansion as possible of
the metal, with the consequent opening of the pores thereof, as is attainable without
occasioning also the oxidation of the surface of the metal, and this temperature may
be the higher in proportion as air or other oxidising agent can be excluded from
the furnace, oven, or muffle. When the desired temperature has been reached the
sheets, plates, bars or manufactured articles are removed from the furnace, oven, or
muffle, and are passed into a bath or vessel containing fluid or semi-fluid material
of a carbonaceous nature such as tar, pitch, or oil, either separately or two or more
in combination. The effect of passing the highly heated metal into the carbonaceous
material is to cause a permeation of carbon within the substance of the metal and
a carbonaceous coating to be deposited on the surface thereof which, when dried in
the ordinary atmosphere has a glazed surface similar or somewhat similar in appear-
ance to japan, but which if dried artificially at a high temperature gives a dull
surface. When sheets, plates, and other articles capable of being passed between
rollers are to be passed into the bath, rollers may be employed therein as, and for an
analogous purpose to, the rollers of a galvanizing or tinning bath.
The carbonaceous coating is perfectly innocuous, and its employment in lieu of
spelter and other deleterious substances is a great advantage in the case of tanks and
such like receptacles for storing drinking water, milk, or other fluid the purity of
which it is desirable to maintain.
For the purpose of carrying the sheets into the furnace, oven, or muffle, and
drawing them out therefrom and conveying them to the bath, and of economising
labour therein, endless chains or aprons may be employed in effecting such operations,
and for this purpose endless chains or an endless apron are or is caused to travel
continuously through the furnace, and corresponding chains or a corresponding
apron are or is caused to travel continuously from the delivery end of the first-
mentioned chains or apron to the bath. The sheets are fed on to one end of the
first-mentioned chains or apron and are thus carried slowly through the furnace
and delivered on to the second mentioned chains or apron which conveys them to
the bath. The sheets may then be dipped and removed from the bath by hand, and
may be conveyed away, if desired, by a third set of endless chains or an endless
pron, or the bath may be fitted with a pair or pairs of rollers and the sheets be
delivered transversely through the bath between the rollers and, if desired, on to a
et of endless chains or an endless apron by which they may be carried away.
Dated this 29th day of June 1888
.
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page_text: COMPLETE SPECIFICATION.
Improvements in Carburising and Coating Iron and Steel in the Form
of Sheets, Hoops, Wrought or Cast Plates, Bars, or Manufactured
Articles.
I, JAMES SUMMERHILL, of The Grove, Saint George's, near Wellington in the
County of Salop, general manager of iron and steel works, 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 has for its chief object means whereby the quality of iron and steel
whether in the form of sheets, or hoops, or of wrought or cast plates, bars, or
manufactured articles, may be improved by carburisation and whereby the surface
of the metal may at the same time be coated, as a protection against corrosion or
wear, with a material of an innocuous character.
The steel or iron sheets, hoops, plates, bars or manufactured articles, which it is
desired to treat according to this invention are heated within an annealing furnace,
oven, or muffle, to a temperature which will cause as great an expansion of the metal,
with the consequent opening of the pores thereof, as is practically attainable without
occasioning the oxidation of the surface of the metal, and this temperature may be
the higher in proportion as air or other oxidising agent can be excluded from the
furnace, oven, or muffle. When the desired temperature has been acquired the
sheets, plates, hoops, bars, or manufactured articles are removed from the furnace,
oven, or muffle, and are passed into a bath or vessel containing fluid or semi-fluid
material of a carbonaceous nature such as tar, pitch, or oil. One effect of passing the
highly heated metal (with its pores consequently expanded) into the carbonaceous
material is to cause a permeation of carbon within the substance of the metal by which
the metal is considerably softened and its ductility increased, so that it becomes
apparently very much the same in character as charcoal iron which is produced only
by a very much more expensive process; and a further effect of passing the highly
heated metal into the carbonaceous material is to cause a carbonaceous coating to be
deposited on the surface thereof which, when dried in the ordinary atmosphere, has a
glazed surface similar or somewhat similar in appearance to japan, but which if dried
artificially within a stove heated to a temperature, or approximately so, suitable for
stoving japanned goods gives a dull surface, and which in either case forms a much
superior and more adherent coating to one deposited merely upon cold or slightly
heated (warmed) metal.
The carbonaceous material for employment in the bath may vary in its composition,
as above indicated. A composition or mixture which I find to answer admirably for
carburising and coating iron and steel sheets (and which may be employed also for
carburising and coating other parts and articles of iron or steel) is prepared by adding
about one per cent. by weight of Val-de-Travers rock to pure or approximately pure
tar which has been obtained by evaporating the moisture and other impurities from
common tar. To obtain the pure or approximately pure tar in this manner it is
necessary to boil the common tar for about twelve to twenty-four hours according to
the proportion of moisture to be driven off. The heated sheets which are dipped into
the composition for the purpose above stated maintain such composition in a liquid or
semi-liquid condition, but when the dipping process is suspended the composition of
course has a tendency to set, and if in such case there has been time for the
composition to set heat must be applied to the exterior of the bath to melt it again
before the dipping process can be recommenced.
The bath of course requires replenishing with carbonaceous material from time to
time, and I find that for this purpose common tar (that is tar not specially prepared
by boiling in the manner above described) and Val-de-Travers rock, in the same
proportions to one another as those of the pure or approximately pure tar and
Val-de-Travers rock in the original composition, may be employed.
It is preferred to employ Val-de-Travers rock with the tar as described, but the tar
may be used alone as the carburising and coating agent, if desired.

page_text: It is difficult to give the exact temperature to which the iron or steel should be
raised before dipping it into the composition, as such will depend upon the thickness
of the metal and upon other conditions such as the extent to which oxidizing agents
can be excluded from the furnace or oven. A very little experience, however, will
readily enable a person skilled in the arts to which the invention relates to carry it
out in the best manner, if he will bear in mind that the metal should be heated as
highly as it can be without oxidation of the surface and should, by preference, be at
a temperature not less than that which gives a dull red colour in daylight. The
sheets should be dipped into the bath as quickly as possible after being drawn out
from the furnace, oven, or muffle.
The time during which the sheets or other parts or articles should be allowed to
remain within the bath depends mainly on the thickness of the metal to be treated. I
usually allow sheets of from 30 up to 12 B. W. G. in thickness to remain within the
bath for from 20 seconds to 1 minutes, according to their thickness. Plates and
other articles of greater thickness should be allowed to remain a longer period in
the bath..
When sheets, plates, or other articles capable of being passed between rollers are
to be passed into the bath of carbonaceous material, rollers may be employed within
the bath as and for an analogous purpose to the rollers of a galvanizing or
tinning bath.
- In employing this invention for the purpose of treating sheets which are to be used
in a corrugated form, I prefer to treat them after they have been corrugated, as the
treatment is equally effective in such case as with plain flat sheets, and the loss is
thus avoided which would otherwise he occasioned by treating plain sheets which
might afterwards not stand the corrugating process. In the case of galvanized
corrugated sheets the galvanizing is effected previously to the corrugating, as there
are difficulties (well known to persons skilled in the art) in the way of its being
effected afterwards, and a loss results therefore, in the case of sheets which will not
stand the corrugating process, of the expense which has been incurred in galvanizing
them, in addition to the loss of the sheets themselves. The treatment according to
my invention therefore has a special advantage over galvanizing inasmuch as it can,
as described, be applied with equal advantage to the corrugated sheets as to the plain
sheets. A pair or pairs of corrugated rollers between which to pass the sheets may be
employed within the bath, if desired, in the process of coating corrugated sheets.
The invention is, of course, of value as a means of carburising the iron or steel
apart from the advantage which results from the coating of the same, and is of course
of value also as a means of coating the iron or steel apart from the advantage arising
from the carburisation thereof. The thickness of the coating which is deposited upon
the surface of the metal depends upon the time which a given thickness of metal is
immersed within the bath, and such thickness of coating can therefore be varied at
will. A very thin coating may be deposited and thereby considerable economy of the
coating material be effected. If a thick coating is required the metal may be allowed
to remain within the bath for a longer term than indicated in the preceding paragraph
where I refer to the length of time which is suitable for the submergence of the metal.
The metal may be carburised without at the same time being coated, if desired, by
immersing it while at a high temperature in the carbonaceous material and with-
drawing it therefrom while it is still too hot for the material to adhere thereto as a
coat, the carburisation taking place while the metal is at a high temperature and
before the carbonaceous material can adhere thereto as a coat.
The carbonaceous coating is perfectly innocuous, and its employment in lieu of
spelter and other deleterious substances is a great advantage in the case of tanks and
such like receptacles for storing drinking water, milk, or other fluid the purity of
which it is desirable to maintain.
For the purpose of carrying the sheets into the furnace, oven, or muffle, and
drawing them out therefrom and conveying them to the bath, and of economising
labour therein, endless chains or aprons may be employed in effecting such operations,
and for this purpose endless chains or an endless apron may be caused to travel

page_text: continuously through the furnace, and corresponding chains or a corresponding apron
be caused to travel continuously from the delivery end of the first-mentioned chains
or apron to the bath. The sheets are in such case fed on to one end of the first-
mentioned chains or apron and are thus carried slowly through the furnace and
delivered on to the second-mentioned chains or apron which convey them to the
bath. The sheets may then be dipped and removed from the bath by hand, and may
be conveyed away, if desired, by a third set of endless chains or an endless apron,
or the bath may be fitted with a pair or pairs of rollers and the sheets be delivered
transversely through the bath between the rollers and, if desired, on to a set of
endless chains or an endless apron by which they may be carried away.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The improvements in carburising and coating, or in carburising or coating, iron
and steel in the form of sheets, hoops, wrought or cast plates, bars, or manufactured
articles, substantially as described, for the purpose or. purposes set forth.
2. Carburising and coating, or carburising or coating, iron and steel in the form
of sheets, hoops, wrought or cast plates, bars, or manufactured articles, by immersing
the same at a high temperate within fluid or semi-fluid material of a carbonaceous
nature, substantially as described, for the purpose or purposes set forth.
3. Carburising and coating, or carburising or coating, iron and steel in the form
of sheets, hoops, wrought or cast plates, bars, or manufactured articles, by immersing
the same at a high temperature within a bath of tar or of a composition or mixture
of tar and Val-de-Travers rock, substantially as described, for the purpose or purposes
set forth.
4. Carburising and coating, or carburising or coating, iron and steel sheets in the
manner and with materials of the nature substantially as described after such sheets
have been corrugated, for the purpose set forth.
11000
STEPHEN WATKINS,
Wolverhampton and Walsall, Agent for the Applicant.