Vacuum carburizing with unsaturated aromatic hydrocarbons

Details Vacuum carburizing with unsaturated aromatic hydrocarbons Vacuum carburizing with unsaturated aromatic hydrocarbons

2006-04-25

2006-04-25

King, Roy (Department: 1742)

Metal treatment

Process of modifying or maintaining internal physical...

Carburizing or nitriding using externally supplied carbon or...

C148S235000

Reexamination Certificate

active

07033446

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 a napthenes, 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 napthenes 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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