US PATENT SUBCLASS 419 / 57
.~.~ Special atmosphere

Current as of: June, 1999
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419 /   HD   POWDER METALLURGY PROCESSES

1  DF  POWDER METALLURGY PROCESSES WITH HEATING OR SINTERING {16}
56  DF  .~ Special medium during sintering {1}
57.~.~ Special atmosphere {3}
58  DF  .~.~.~> Hydrogen or hydrogen plus nitrogen (Nitrogen per se in 57)
59  DF  .~.~.~> Hydrocarbon or derivative (e.g., CH4, etc.)
60  DF  .~.~.~> Vacuum

DEFINITION

Classification: 419/57

Special atmosphere:

(under subclass 56) Processes wherein the special medium present during the sintering operation is a special gas or vacuum.

SEE OR SEARCH CLASS

148, Metal Treatment, particularly

514, for processes of pre-treatment or post-treatment of a previously sintered or compacted consolidated powder metal starting material to modify or maintain the internal physical structure (i.e., microstructure) or chemical properties of metal combined with treatment in a controlled atmosphere and wherein there is no actual sintering or compacting operation present.

373, Industrial Electrical Heating Furnances, appropriate subclasses, for electric furnances adapted to carry out such processes.