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| Carburizing furnaces |
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| Carburizing processing |
| Carburizing processing is
carried out in order to harden steel, and it is
a process that diffuses carbon into the surface
of the steel. After this the steel is tempered,
hardening its surface, and making the interior tough
yet flexible. This is used as a treatment for metal
in parts which require high wear resistance and
toughness - in particular gears and transmission
parts. |
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| Carburizing furnace /
Carbon potential |
| A carburizing furnace is
used for carburizing, and usually includes hardening
processing facilities. Carburizing furnace process
involves heating up of the interior of the furnace,
and introducing a sourcs gas to provide a source
of carbon, whereupon a chemical reaction occurs
at 850-1000°C which diffuses the carbon into
the steel. Here, the quantity of carbon that is
diffused into the steel (and to what depth below
its surface) is called the carburization performance,
and this is normally displayed as a carbon potential
(CP) value. |
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| Oxygen partial pressure
and carbon potential |
| In carburizing furnaces,
the main source gases introduced are CO2, N2, and
H2, and each gas reacts, maintaining a chemical
balance. |
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| The oxygen partial pressure
within the furnace can be calculated from the oxygen
sensor's generated electromotive force, and the
temperature within the furnace. Additionally, because
the CO partial pressure is defined by the source
gas (e.g. propane: 23.1% CO, butane: 23.5% CO),
if the oxygen partial pressure is known, then the
CP value can be established. |
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| Instrumentation using
DCP522 |
| Normal control of carburizing
furnaces requires a CP processor, a controller for
temperature control, and a controller for CP control,
however with the DCP522, as these three have been
incorporated into one controller, Yamatake has achieved
low cost, low space instrumentation. |
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