Improvements in the Manufacture of Armour Plates and the like, and Apparatus therefor.
Year: 1893

page_text: Date of Application, 31st Aug., 1893
Complete Specification Left, 8th May, 1894-Accepted, 23rd June, 1894
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Armour Plates and the like,
and Apparatus therefor.
I, HENRI SCHNEIDER of Creusot in the Republic of France, Engineer, do
hereby declare the nature of this invention to be as follows:-
This invention relates to a process for obtaining a superficial hardening or super-
carburation of the external surfaces of armour plates and other like articles which
being combined with an energetic or rapid cooling or tempering increases their
hardness and in the case of armour plates, the power of resisting penetration by
projectiles.
The supercarburation or cementation has formerly been obtained by heating the
plates in contact with solid carbonaceous matter but 1 have discovered that by
heating them in the presence of a hydrocarbon gas resulting either from the
distillation of coal or from the distillation of mineral oils a more rapid cementation
can be produced at the same temperature especially when a certain quantity of
ammoniacal gas is added.
The process may be carried out in practice in various ways examples of which
are hereinafter described.
The article to be hardened such as an armour plate for example is heated in a
reverberatory furnace and the upper surface or surface to be cemented is covered
by a bell or inverted trough composed of cast or sheet iron, cast steel or fire brick
to the interior of which the carburetting gas is supplied. In order to prevent the
gas from escaping between the edges of the bell and the plate a sand joint or lute
is formed around the said edges the sand being retained in position by a frame or
the joint may be simply closed with fireclay.
It is known that when a hydrocarbon gas is caused to pass through a tube heated
to redness decomposition takes place producing a carbonaceous deposit. In order
to obviate this deposit which after a time would obstruct the gas supply pipe the
latter is protected by water circulating in a casing enclosing the said pipe. In
order to be certain that the gas is properly supplied a small excess of gas is
introduced and allowed to escape through a pipe communicating with the interior
of the bell. Plugs are provided for the purpose of ascertaining whether the gas
pipes are obstructed at the parts where the gas commences to be decomposed and
to deposit carbon. If necessary the pipes may be cleared by means of a rod by
removing the plugs.
The mineral oil may be introduced in the form of drops in place of gas by means
of an arrangement of pipes and cocks or valves. On entering the bell which is
heated to redness the oil is decomposed and supplies the carbonaceous gas necessary
for the cementation.
The process of cementation is accelerated by mixing a small quantity of
ammoniacal gas with the hydrocarbon gas.
The furnace is usually provided with an ordinary hearth or floor but it is
sometimes preferable to employ a furnace with a travelling hearth capable of being
drawn under the hoisting apparatus and affording facilities for arranging the
cementing apparatus before it is introduced into the furnace.
Two plates can be simultaneously subjected to a cementation process being
placed horizontally one above the other with a space between them the said space
between the two plates being filled with gas supplied through a pipe provided for
the purpose. The arrangements hereinbefore described for supplying gas or oil

page_text: may be combined with all or any of the different arrangements of the plates
nereinafter described for heating the plates in a horizontal position. The armour
plate may be placed entirely in the interior of a bell or cover the surface which is
to be cemented being alone exposed to the cementing gas the other surfaces being
covered or protected with refractory materials which preserve them from the
action of the gas.
The plate may be supported at or near its edges upon low brick walls which
combined with the hearth of the furnace constitute a gas chamber underneath the
plate.
According to another arrangement the said chamber is formed by means of a
flat cover plate supported by low walls constructed upon the armour plate and
provided with supports which prevent the cover plate from sagging.
The bell in place of being supported directly upon the armour plate can be
supported upon a structure of bricks. This arrangement is preferably employed in
dealing with plates of curved or irregular form.
When the plates to be cemented are placed in a vertical position the furnace is
constructed with two fire places and with a removable cover and contains two
plates heated simultaneously being 50 arranged as to enclose a space or chamber
between them for the reception of the gases.
One plate placed on edge may be heated at a time. For this purpose a metal
bell is employed or according to another arrangement the gas chamber is formed
by means of refractory materials such as fire brick.
The simultaneous cementation of two horizontal plates may be effected by closing
the opening between the plates at or near their edges in order to form a gas
chamber between the plates by means of an iron or steel frame made one piece
or in a number of pieces suitably connected together. The joints between this
frame and the surfaces of the plates to be cemented are packed with asbestos which
may be either in the form of sheets or fibres. The asbestos being compressed by
the weight of the top plate forms a sufficiently gas tight joint. The frame is
constructed in such a manner as to correspond with the shape or configuration of
the surfaces of the two plates which are to be cemented. The height of the said
frame may consequently vary at different points. When the cementing operation is
to be performed on one plate only either the lower plate or the upper plate is
replaced by an iron or steel plate of suitable thickness which may be employed in
several operations.
The gas
is introduced through the frame separating the two plates and
constituting therewith a closed chamber. This supply of gas is provided for by
means of one or a number of pipes according to the size of the plates to be
cemented the said pipes being enclosed in a casing for the circulation of a cooling
liquid and terminating at the frame or projecting any required distance into the
interior of the chamber within the frame.
In order to ensure greater uniformity in the cementation the gas is introduced at
opposite sides alternately the excess of gas escaping through the pipes in the
opposite side to that at which the gas enters.
The supply of gas may be continuous during the whole of the operation or it
may be interrupted at certain times and an inert gas may if required be substituted
during any desired period in place of the carbonaceous gas. The action is the
same in all the arrangements of the apparatus. The plate or the like is maintained
at a red heat and in contact with the cementing gas during a period which is
regulated in proportion to the depth to which it is to be cemented or hardened.
In all cases it is preferable to employ as high a temperature as possible the said
temperature being limited by the degree at which the metal would be injuriously
affected. In the case of mild steel this temperature is bright yellow but in dealing
with hard steel containing about 0.6 per cent. of carbon a bright cherry red must
not be exceeded. Intermediate qualities of steel may be heated to intermediate
colours. For example a plate 30 centimetres thick composed of steel of medium
hardness (C. 045) must be maintained at an oxidizing yellow during about

page_text: 72 hours in order to obtain a graduated cementation to a depth of about
20 millimetres.
When the desired degree of cementation has been obtained the plate may be
allowed to cool in the furnace either completely or simply until it acquires a
suitable colour for tempering. The gas is allowed to remain in contact with the
cemented surface until the temperature has been lowered to dark red.
If preferred the plate may be removed from the furnace and allowed to cool,
care being taken to protect the cemented part from contact with the air until it is
of a dark red colour.
Dated this 31st day of August 1893
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Armour Plates and the like,
and Apparatus therefor.
I, HENRI SCHNEIDER of Creusot in the Republic of France, 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 :-
This invention relates to a process for obtaining a superficial hardening or super-
carburation of the external surfaces of armour plates and other like articles which
being combined with an energetic or rapid cooling or tempering increases their
hardness and in the case of armour plates the power of resisting penetration by
projectiles.
This supercarburation or cementation has formerly been obtained by heating
the plates in contact with solid carbonaceous matter but I have discovered that by
heating them in the presence of a hydrocarbon gas resulting either from the
distillation of coal or from the distillation of mineral oils a more rapid cementation
can be produced at the same temperature especially when a certain quantity of
ammoniacal gas is added.
The process may be carried out in practice in various ways examples of which
are hereinafter described.
And in order that my invention may be fully understood I shall now proceed to
describe the same and for that purpose shall refer to the several figures on the
annexed sheet of drawings the same letters of reference indicating corresponding
parts in all the figures.
In Figure 1 of the accompanying drawings A represents the article to be
hardened such as an armour plate for example which is heated in a reverberatory
furnace constructed with a fire place F a roof V and chimney C. The upper
surface a b or the surface to be cemented is covered by a bell B or inverted trough
composed of cast or sheet iron, cast steel or fire brick to the interior of which the
carburetting gas is supplied through a pipe t. In order to prevent the gas from
escaping between the edges of the bell B and the plate a sand joint or lute n is
formed around the said edges the sand being retained in position by a frame m or
the joint may be simply closed with fireclay.
It
The construction of the gas supply pipe is illustrated in detail in Figure 2.
is known that when a hydrocarbon gas is caused to pass through a tube heated to
redness decomposition takes place producing a carbonaceous deposit. In order to
obviate this deposit which after a time would obstruct the gas supply pipe t the
latter is protected by water circulating in a casing T enclosing the said pipe. In
order to be certain that the gas is properly supplied a small excess of gas is
introduced and allowed to escape through a pipe t' communicating with the interior
of the bell. Plugs c and e' are provided for the purpose of ascertaining whether

page_text: the gas pipes t and t¹ are obstructed at the parts d d' where the gas commences to
be decomposed and to deposit carbon. If necessary the pipes and t' may be
cleared by means of a rod by removing the plugs c and c¹.
Figure 3 illustrates a modified arrangement in which mineral oil introduced in
the form of drops is employed in place of gas by means of an arrangement of pipes
and cocks or valves. On entering the bell B which is heated to redness the oil is
decomposed and supplies the carbonaceous gas necessary for the cementation.
The process of cementation is accelerated by mixing a small quantity of
ammoniacal gas with the hydrocarbon gas.
The furnace represented in Figure 1 is usually provided with an ordinary hearth;
or floor but it is sometimes preferable to employ a furnace with a travelling hearth
capable of being drawn under the hoisting apparatus and affording facilities for
arranging the apparatus for the cementation process before it is introduced into the
furnace.
Figure 4 illustrates an arrangement by means of which two plates A and A¹ or
the like are simultaneously subjected to a cementation process being placed
horizontally one above the other with a space between them the said space B
between the two plates being filled with gas supplied through a pipe T provided
for the purpose.
The arrangements hereinbefore described for supplying gas or
oil may be combined with all or any of the different arrangements of the plates
hereinafter described.
Figures 5, 6, 7 and 8 illustrate four other arrangements for heating the plates or
the like in a horizontal position.
According to the arrangement illustrated in Figure 5 the armour plate A is
placed entirely in the interior of a bell or cover B the surface a b which is to be
cemented being alone exposed to the cementation gas the other surfaces being
covered or protected with refractory materials which preserve them from the action
of the gas.
Figure 6 illustrates an arrangement in which the plate is supported at or near
its edges upon low brick walls m which combined with the hearth of the furnace
constitute a gas chamber B underneath the plate.
According to another arrangement shewn in Figure 7 the said chamber B is
formed by means of a flat cover plate D supported by low walls m constructed
upon the armour plate and provided with supports o which prevent the cover
plate D from sagging.
According to Figure 8 the bell B in place of being supported directly upon the
armour plate A as in Figure 1 is supported upon a structure of bricks. This
arrangement is preferably employed in dealing with plates of curved or irregular
form.
Figures 9, 10, 11 and 12 illustrate arrangements in which the plates or the like
to be cemented are placed in a vertical position.
According to the arrangement illustrated in Figure 9 the furnace is constructed
with fire places F and a removable cover M and contains two plates A A' heated
simultaneously. The surfaces a ba¹ b' are so arranged as to be alone brought into
contact with cementation gases in the chamber B.
Figures 10, 11 and 12 represent arrangements for cementing one plate placed on
edge at a time. According to Figures 10 and 11 a metal bell is employed but in
another arrangement as in Figure 12 the gas chamber B is formed by means of
refractory materials such as fire brick.
Figure 13 illustrates an arrangement for obtaining the simultaneous cementation
of two horizontal plates the opening between the plates at or near their edges
being closed in order to form a gas chamber between the plates by means of an
iron or steel frame made in one piece or in a number of pieces suitably connected
together. The joints between this frame and the surfaces of the plates to be
cemented are packed with asbestos which may be either in the form of sheets or
fibres. The asbestos being compressed by the weight of the top plate forms a
sufficiently gas tight joint. The frame is constructed in such a manner as to

page_text: correspond with the shape or configuration of the surfaces of the two plates which
are to be cemented. The height of the said frame may consequently vary at
different points. When the operation of cementation is to be performed on one
plate only either the lower plate or the upper plate is replaced by an iron or steel
plate of suitable thickness which may be employed in several operations.
The gas is introduced through the frame separating the two plates and con-
stituting therewith a closed chamber. This supply of gas is provided for by means
of one or a number of pipes according to the size of the plates to be cemented
the said pipes being enclosed in a casing similar to that represented in Figure 18
and terminating at the frame as in Figures 14 and 15 or projecting any required
distance into the interior of the chamber within the frame as indicated in
Figures 16 and 17.
In order to ensure greater uniformity in the cementation the gas is introduced
at opposite sides 1 and 2 alternately. When the gas is introduced at the side 1
the excess of gas escapes through the pipes in the side 2 and when the gas enters
at the side 2 the excess escapes through the side 1.
The supply of gas may be continuous during the whole of the operation or it
may be interrupted at certain times and an inert gas may if required be substituted
during any desired period in place of the carbonaceous gas.
The action is the same in all the arrangements of the apparatus. The plate or
the like is maintained at a red heat and in contact with the cementation gas during
a period which is regulated in proportion to the depth to which it is to be cemented
or hardened.
In all cases it is preferable to employ as high a temperature as possible the said
temperature being limited by the degree at which the metal would be injuriously
affected. In the case of mild steel this temperature is bright yellow but in dealing
with hard steel containing 0-6 per cent. of carbon a bright cherry red must not be
exceeded. Intermediate qualities of steel may be heated to intermediate colours.
For example a plate 30 centimetres thick composed of steel of medium
hardness (C. =0.45) must be maintained at an oxidizing yellow during about
72 hours in order to obtain a graduated cementation to a depth of about
20 millimetres.
When the desired degree of cementation has been obtained the plate may be
allowed to cool in the furnace-either completely or simply until it acquires a
suitable colour for tempering. The gas is allowed to remain in contact with the
cemented surface until the temperature has been lowered to dark red.
If preferred the plate may be removed from the furnace and allowed to cool,
care being taken to protect the cemented part ab from contact with the air untiĺ
it is of a dark red colour.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed 1 declare that what I
claim is―
1. A process for the cementation of or for hardening armour plates and other
like articles consisting in heating the plates or the like in the presence of a hydro-
carbon gas produced either by the distillation of coal or by the distillation of
mineral oils the said gas being mixed or not with a certain quantity of gaseous
ammonia the object of the said cementation process being to obtain a more rapid
effect and a more uniform temperature substantially as hereinbefore described.
2. A process for the cementation of armour plates and the like consisting in
heating the said plates or the like in the presence of a hydrocarbon gas obtained
from any source and supplied either continuously or intermittently and being
replaced if necessary at suitable periods by a current of inert gas substantially as
hereinbefore described.
3. In combination with the cementation process for armour plates and the like
hereinbefore described and claimed the arrangement of a closed chamber B for the
reception of the cementation gases upon the surface to be cemented the said

page_text: -chamber B being formed either by means of a metal or other bell suitably luted
by a sand joint or by means of a plate and a refractory frame or by means of two
plates to be cemented inaintained at the required distance apart by low walls of
refractory materials or by a metal frame combined with asbestos packing or in
any other suitable manner or arrangement whereby a closed chamber may be
formed the plates being arranged either horizontally or vertically and enclosed in
a furnace provided with an ordinary fixed hearth or with a travelling hearth of any
suitable arrangement or construction all substantially as h. inbefore described
with reference to the accompanying drawings.
4. For the cementation of armour plates and the like according to the process
herein before described and claimed a closed chamber for the reception of the.
cementation gas upon the surface to be cemented in combination with pipes for the
introduction and discharge of the gaseous current enclosed
casing in which
- cold water is caused to circulate for the purpose of prevent.
Je formation of
deposit and the obstruction of the said pipes substantially as he.einbefore described
with reference to the accompanying drawings.
5. In combination with the process for the cementation of ar nour plates and the
like as herein before described and claimed the arrangement of a closed chamber
for the reception of the cementation gases in combination with pipes situated at
the opposite extremities of the said chamber and enabling the said gases to be
introduced and drawn off on opposite sides of the said chamber alternately
substantially as herein before described with reference to Figures 14 to 17 of the
accompanying drawings.
Dated this 8th day of May 1894.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, Agents.