Everything about The Cementation Process totally explained
The
cementation process is an obsolete technique for making
steel by
carburization of
iron. Unlike modern
steelmaking it increased the amount of
carbon in the iron. It was apparently developed before the
17th century.
Origins
The process probably originated in
Bohemia in the
16th century and was in use in
Bavaria in
1601. The process was patented in
England by
William Ellyot and
Mathias Meysey in
1614. At that date, the 'invention' could consist merely of the introduction of a new industry or product, or even a mere
monopoly. They evidently soon transferred the patent to Sir
Basil Brooke, but he was forced to surrender it in 1619. A clause in the patent prohibiting the import of
steel was found to be undesirable because he couldn't supply as much good steel as was needed.
Brooke's
furnaces were probably in his manor of
Madeley at
Coalbrookdale (which certainly existed before the
English Civil War) and which have recently been excavated. He probably used
bar iron from the
Forest of Dean, where he was a partner in farming the King's ironworks there at two periods. By
1631, it was recognised that
Swedish iron was the best raw material and then or later particularly certain marks (brands) such as
double bullett from
Österby (so called from the mark OO) and Leufsta (now
Lövsta), whose
hoop L mark consisted of an L in a circle, both belonging to
Louis De Geer and his descendants. These were among the first ironworks in
Sweden to use the Walloon process of
fining iron, producing what was known in England as
oregrounds iron. It was so called from the Swedish port of
Öregrund, north of Stockholm, in whose hinterland most of the ironworks lay. The ore used came ultimately from the
Dannemora mine.
Process
The process begins with
wrought iron and
charcoal. It uses one or more long stone
pots inside a furnace. Typically, in
Sheffield, each was 14 feet by 4 feet and 3.5 feet deep. Iron bars and charcoal are packed in alternating layers, with a top layer of charcoal and then refractory matter to make the pot or 'coffin' airtight. Some manufacturers used a mix of powdered charcoal,
soot and mineral
salts, called
cement powder - which gave the process its name. In larger works up to 16 tons of iron was treated in each cycle.
Depending on the thickness of the iron bars, the pots were then heated from below for a week or more. Bars were regularly examined and when the correct condition was reached the heat was withdrawn and the pots were left until cool - usually around fourteen days. The iron had 'gained' a little over 1% in mass from the
carbon in the charcoal, and had become heterogeneous bars of
blister steel.
The bars were then shortened, bound, heated and hammered, pressed or rolled to become
shear steel. Alternatively they could be broken up and melted in a crucible using a
crucible furnace with a
flux to become
crucible steel or
cast steel, a process devised by
Benjamin Huntsman in the
1740s.
Cementation process for brass
In the early modern period,
brass, an
alloy of
copper and
zinc, was usually produced by a cementation process in which metallic
copper was heated with
calamine, a zinc ore. For details of this see
calamine brass.
Further Information
Get more info on 'Cementation Process'.
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