Furnace for vacuum carburizing with unsaturated aromatic hydrocarbons
US7267793B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 14, 2006 |
| Grant date | Sep 11, 2007 |
| Priority date | — |
| Expiry date | Apr 14, 2026 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D1/773
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
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 hydro…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.