Improved Fusible Mass for Case Hardening Purposes.
Year: 1891

page_text: Date of Application, 5th Jan., 1891
Complete Specification Left, 14th Sept., 1691-Accepted, 17th Oct., 1891
PROVISIONAL SPECIFICATION.
Improved Fusible Mass for Case Hardening Purposes.
I THEODOR LANGER, Engineer of Nimburg in the Empire of Austria do
hereby declare the nature of my invention for IMPROVED FUSIBLE MASS FOR
CASE HARDENING PURPOSES, to be as follows:-
The object of the present invention is an improved fusible mass for case
hardening wrought iron and annealed castings. The mass becomes liquid during
the hardening and possesses the great advantage over those masses known up
till now that, in consequence of the constant smelting temperature of my mass, a
thoroughly even coating of steel having no flaws, and of an even thickness, is
formed, whilst in case hardening with the masses up till now in use, it often
happens that one part is soft whilst another part is partially burnt.
My improved hardening mass is composed of common salt, which melts at the
same temperature as that of iron or steel when red hot, and which acts as heat
absorbent; yellow prussiate of potash, alone or mixed with carbonised horn dust
as carbonising agent, by combining with the glowing iron to form carburet of
iron, both of which are well known means, and finally the new ingredient in fusible
case hardening masses, viz. borax or borate or silicate (for instance powdered
glass) alone or in combination with borax, which exercises simultaneously a
cleansing and steeling influence.
Borax has the property of dissolving metallic oxides and it is added to the
mass, in order to keep clean the surface of the iron to be hardened, in addition
to this however it causes the melted case hardening mass, to become covered
with a glassy coating which allows the escape of the gases generated, but keeps
out the outer air, making the consumption of the carbon or its combination, more
difficult, whereby the carbonising capacity of the hardening mass is increased and
a thicker coating of steel attained.
It is important, that by adding borax a melting point is attained, which
corresponds with the temperature of red hot iron.
The borax can of course be replaced by some substance for instance some borate
or silicate, which possesses the same properties, but borax will probably be found
the most simple and cheapest means.
The mixture which has till now, proved to be the most suitable for this fusible
hardening mass is composed of the following constituent parts and proportions.

page_text: tougher and more durable, were it not for the formation of bubbles, which
continually increase in size and through which the carbonisation gases escape.
I have found that in order to obtain a tougher coating and at the same time
obviating the above named disadvantage it is advisable to add sugar (either
refined or crystallized) to the mass. By this means the molten mass becomes
thicker and a darker, firmer and tougher coating is formed over the same, whereby
the escape of gases is almost entirely prevented and carbonization consequently
much more intensive.
This intermixture of sugar enables a larger quantity of borax to be added
without producing the disadvantageous results above mentioned.
The addition of sugar is of advantage in any other case hardening mass, as it
produces greater consistency and promotes carbonization.
I have found the following to form one of the best mixtures for a melting case
hardening mass.
About 10 parts by weight of common salt
دو
"
3
2
0.2
"
"
"
"
"
"
"
yellow prussiate of potash (eventually mixed with
carbonized horn dust)
borax
sugar.
It will be obvious that these figures are variable to a certain degree. All the
ingredients must be powdered and well mixed.
With this fusible case hardening mass which is most advantageously employed
in seamless sheet metal cases of 2 mm. plate which can be easily closed with a
sheet metal cover, a steel coating of about 1 mm. may be obtained in about
2 hours in an ordinary forge. The thickness of the coating may be increased by
replacing every hour as much of the mass as may have been consumed. This
amount of the mass added is generally about of the original quantity employed.
}
The arrangement of the fire for the fusible case hardening mass is according
to circumstances and if necessary the case may be placed in a furnace built up
of bricks, and fuel arranged round it, and by the aid of a draught caused by fanning
or some temporary blast arrangement to effect the case hardening.
According to the size of the case the mass fuses in of an hour and the
object to be case hardened should be introduced in the case before the mass has
become too liquid. The process can however be carried on after the mass has
become liquid, by adding a fresh quantity with each new object immersed. The
objects to be placed in the case should if possible be previously heated to a blue
heat in a charcoal fire.
A receptacle with oil etc. should of course be held ready for subsequently chilling
the objects.
The residues from the fusible hardening mass may be advantageously employed
to harden steel tools, as such may be easily brought to the necessary glow heat
therein.
Dated this 5th day of January 1891.
W. P. THOMPSON & BOULT,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improved Fusible Mass for Case Hardening Purposes.
I, THEODOR LANGER of Nimburg in the Empire of Austria, Engineer, do
hereby declare the nature of my said invention and the manner in which the same
is to be performed to be particularly described and ascertained in and by the
following statement:-
The object of the present invention is an improved fusible mass for case

page_text: hardening wrought iron and annealed castings. Ine mass Decomes inqui
tin
the hardening and possesses the great advantage over those masses known up
now that in consequence of the constant smelting temperature of my mass a coating
of steel having no flaws, of equal hardness and of an even thickness, is formed,
whilst in case hardening with the masses up till now in use, it often happens that
one part is soft whilst another part is partially burnt.
My improved hardening mass is composed of common salt, which melts at the
same temperature as that of iron or steel when red hot, and which acts as heat
absorbent; yellow prussiate of potash. alone or mixed with carbonised horn dust
as carbonising agent by combining with the glowing iron to form carburet of iron
both of which are well known means, and finally the new ingredient in fusible case
hardening masses w. borax or borate or silicate (for instance powdered glass)
alone or in combination with borax which exercises simultaneously a cleansing and
steeling influence.
Borax has the property of dissolving metallic oxides and it is added to the mass
in order to keep clear the surfaces of the iron to be hardened in addition to this
however it causes the melted case hardening mass, to become covered with a glassy
coating which allows the escape of the gases generated, but keeps out the outer air
making the consumption of the carbon or its combination, more difficult, whereby
the carbonising capacity of the hardening mass is increased and a thicker coating
of steel attained.
It is important that by adding borax a melting point is attained which
corresponds with the temperature of red hot iron.
The borax can of course be replaced by some substance for instance some
borate or silicate, which possesses the same properties, but borax will probably be
found the most simple and cheapest means.
The mixture which has till now, proved to be the most suitable for this fusible
hardening mass is composed of the following constituent parts and proportions:
71-4 parts salt (common salt)
23.8 yellow prussiate of potash
"
4.8
borax
"
or
66-15
22.15
7.35
4.45
دو
salt (common salt)
"
yellow prussiate of potash
carbonised horn dust
"
borax.
"
The latter mixture effects a steel coating of a rather coarser grain, is however
cheaper and well suited for many purposes.
It is of course clear that these proportions can be varied but too much borax
will cause the mass to froth and reduce its efficiency.
It would be of advantage for the case hardening mass, to increase the quantity
or rather proportion of borax in the same, as the coating then formed would be
tougher and more durable, were it not for the formation of bubbles, which con-
tinually increase in size and through which the carbonisation gases escape.
I have found that in order to obtain a tougher coating and at the same time
obviating the above named disadvantage it is advisable to add sugar (either
refined or crystallized) to the mass. By this means the molten mass becomes
thicker and a darker, firmer and tougher coating is formed over the same, whereby
the escape of gases is almost entirely prevented and carbonization consequently
much more intensive.
This intermixture of sugar enables a large quantity of borax to be added without
producing the disadvantageous results mentioned.
The addition of sugar is of advantage in any other case hardening mass, as it
produces greater consistency and promotes carbonization.

page_text: hardening mass.
About 10 parts by weight of common salt
وو
"
"
yellow prussiate of potash (eventually mixed with
carbonised horn dust)
3
2
"
"
borax
"
0.2
"
"
99
sugar.
It will be obvious that these figures are variable to a certain degree. All the
ingredients must be powdered and well mixed.
With this fusible case hardening mass which is most advantageously employed in
seamless sheet metal cases of 2 mm. plate which can be easily closed with a sheet
metal cover, a steel coating of about 1-1 mm. may be obtained in about 2 hours in
an ordinary forge. The thickness of the coating may be increased by replacing
every hour as much of the mass as may have been consumed. This amount of
the mass added is generally about of the original quantity employed.
The arrangement of the fire for the fusible case hardening mass is according to
circumstances and if necessary the case may be placed in a furnace built up of
bricks and fuel arranged round it, and by the aid of a draught caused by fanning
or some temporary blast arrangement, to effect the case hardening.
According to the size of the case the mass fuses in 1-1 of an hour and the
object to be case hardened should be introduced in the case before the mass has
become too liquid. The process can however be carried on after the mass has
become liquid, by adding a fresh quantity with each new object immersed. The
objects to be placed in the case should if possible be previously heated to a blue
heat in charcoal fire.
A receptacle with oil etc. should of course be held ready for subsequently chilling
the objects.
The residues from the fusible hardening mass may be advantageously employed
to harden steel-tools, as such may be easily brought to the necessary glow heat
therein.
Having now particularly described and ascertained the nature of my said inven-
tion and the manner in which the same is to be performed I declare that what
I claim is:
1. An improved fusible mass for case hardening wrought iron and annealed
castings consisting mainly in the addition of borax to any one of the known case
hardening masses substantially as described.
2. In the said mass the employment of common salt yellow prussiate of potash
(alone or combined with carbonized horn dust) and borax in the proportion
substantially as herein before described and for the purpose specified.
The residues from the fusible hardening mass may be advantageously employed
to harden steel-tools, as such may be easily brought to the necessary glow heat
therein.
Having now particularly described and ascertained the nature of my said inven-
tion and the manner in which the same is to be performed I declare that what
I claim is:
1. An improved fusible mass for case hardening wrought iron and annealed
castings consisting mainly in the addition of borax to any one of the known case
hardening masses substantially as described.
2. In the said mass the employment of common salt yellow prussiate of potash
(alone or combined with carbonized horn dust) and borax in the proportion
substantially as hereinbefore described and for the purpose specified.
Dated this 14th day of September 1891
W. P. THOMPSON & BOULT,
Agents for the Applicant.