US PATENT SUBCLASS 148 / 206
.~ Carburizing or nitriding using externally supplied carbon or nitrogen source

Current as of: June, 1999
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148 /   HD   METAL TREATMENT

95  DF  PROCESS OF MODIFYING OR MAINTAINING INTERNAL PHYSICAL STRUCTURE (I.E., MICROSTRUCTURE) OR CHEMICAL PROPERTIES OF METAL, PROCESS OF REACTIVE COATING OF METAL AND PROCESS OF CHEMICAL-HEAT REMOVING (E.G., FLAME-CUTTING, ETC.) OR BURNING OF METAL {17}
206.~ Carburizing or nitriding using externally supplied carbon or nitrogen source {15}
207  DF  .~.~> Carburizing or nitriding uniformly throughout the entire mass (i.e., internal carburizing)
208  DF  .~.~> With decarburizing or denitriding
209  DF  .~.~> Utilizing particulate fluid bed
210  DF  .~.~> Of selected surface area (e.g., zone, top only, etc.) {3}
215  DF  .~.~> Measuring, sensing, or testing {1}
217  DF  .~.~> With noncarburizing or non-nitriding reactive coating (e.g., oxidizing, siliconizing, boronizing, etc.)
218  DF  .~.~> Combined carburizing and nitriding (e.g., carbonitriding, nitrocarburizing, etc.) {1}
220  DF  .~.~> With producing or treating of workpiece having plural noncarburized or non-nitrided layers or mechanically engaged article or stock
221  DF  .~.~> With casting or solidifying from melt
222  DF  .~.~> Utilizing ionized gas (e.g., plasma, etc.) or electron arc or beam
223  DF  .~.~> Including use of vacuum
224  DF  .~.~> Utilizing wave energy (e.g., laser, etc.) or electric heating with work as conductor
225  DF  .~.~> Iron(Fe) or iron base alloy {7}
237  DF  .~.~> Refractory metal (i.e., Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W) or refractory base alloy
238  DF  .~.~> Nitriding

DEFINITION

Classification: 148/206

Carburizing or nitriding using externally supplied carbon or nitrogen source:

(under subclass 95) Process wherein a metal substrate or workpiece is treated with an externally supplied source of carbon or nitrogen or both resulting in the carburization or nitriding of a metal by chemical reaction or diffusion.

(1) Note. Carburizing or nitriding most often results in a chemical reaction forming a metal compound. However, if there is a positive indication of merely diffusion into the metal substrate without a chemical reaction (e.g., carbide or nitride formation, etc.) placement is proper hereinunder if from an external supply of carbon or nitrogen.

(2) Note. Carburizing or nitriding combined with a step of melting a metal surface is proper hereinunder.

SEE OR SEARCH THIS CLASS, SUBCLASS:

278, for processes of reactive coating wherein a carbide coating is obtained by reaction of a noncarbon containing external reactive agent (e.g., metal, etc.) which deposits on a metal alloy base and carbon in the alloy base out-diffuses or reacts with the agent to form a metal carbide coating on said base.

SEE OR SEARCH CLASS

75, Specialized Metallurgical Processes, Compositions for Use Therein, Consolidated Metal Powder Compositions, etc., appropriate subclasses for processes of reacting a carbon or nitrogen source with a molten mass of metal to increase the carbon or nitrogen content of the metal.

423, Chemistry of Inorganic Compounds, appropriate subclasses for processes of producing a metal carbide or metal nitride (i.e., not a coated metal), per se, by reacting a metal with a source of carbon or nitrogen.

427, Coating Processes, appropriate subclasses for processes, per se, of depositing a carbide or nitride on a metal or metal alloy base wherein the base does not supply the source of the carbon or nitrogen or the metal which forms the carbide or nitride (e.g., chemical vapor deposition of a metal carbide on a metal base).

(1) Note. A metal layer on a metal oxide layer if completely reacted with an external source of carbon to provide a metal carbide layer on the metal oxide layer goes as original to Class 427 since no metal layer remains adjacent the metal carbide layer and there was no metal substrate directly carburized. To simplify the line remember that, if coating is involved, the carburized or nitridized reaction product must remain adjacent or contiguous with a metal substrate for the process to remain in Class 148. This will apply whether or not the metal substrate remaining after reaction was the source of the metal in the reacted layer. Also, if no metal substrate remains with the product, placement goes to Class 427 even if the reaction product was produced from a metal substrate.