Metallurgical apparatus – Means treating solid metal – Having evacuated chamber
Reexamination Certificate
2007-09-11
2007-09-11
Kastler, Scott (Department: 1742)
Metallurgical apparatus
Means treating solid metal
Having evacuated chamber
C266S252000
Reexamination Certificate
active
11404459
ABSTRACT:
Vacuum carburizing of ferrous workpieces is performed at low pressure in a vacuum furnace using an unsaturated aromatic such as benzene as the carburizing medium. The unsaturated aromatic is gas phase hydrogenated into naphthenes, such as cyclohexane, which is metered into the furnace chamber proper and functions as the carburizing gas. The furnace is constructed to be generally transparent to the naphthenes so that cracking tends to occur at the workpiece which functions as a catalyst to minimize carbon deposits. The unsaturated aromatic is supplied in liquid form to fuel injectors which inject the liquid aromatic as a vapor at duty cycles and firing orders to produce a uniform dispersion of the hydrocarbon gas about the work resulting in uniform carburizing of the workpieces. An in-situ methane infrared sensor controls the process. Excess hydrogen beyond what is required to hydrogenate the aromatic is added to the furnace chamber to either assure full carbon potential and produce methane or to perform variable carburizing. Hydrogenation occurs in a hydrogenation coil in fluid communication with the furnace chamber with temperature for the reaction set by the position of the hydrogenation coil in the furnace insulation.
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Barbee Gary W.
Brug James E.
Poor Ralph P.
Verhoff Stephen H.
Kastler Scott
Surface Combustion, Inc.
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