Sandvik Ab

Ulf Oscarsson

Per Gustafson

Ake Ostlund

Leif E Akesson

Mikael Lagerquist

Chris Chatfield

The present invention discloses a method of sintering of cemented carbide or cermet bodies lying on graphite trays. By using graphite trays coated with a covering layer of Y.sub.2 O.sub.3 containing .ltoreq.20 wt-% ZrO.sub.2, or corresponding volumetric amount of other refractory oxides, e.g., Al.sub.2 O.sub.3 or combinations thereof, with an average thickness of .gtoreq.10 .mu.m, the life of the trays between regrindings and recoatings can be largely extended.

Sintering tray

A cemented carbide insert with improved toughness and resistance against plastic deformation containing WC and cubic phases of carbide and/or carbonitride in a binder phase based on Co and/or Ni with a binder phase enriched surface zone is disclosed. The binder phase content in the insert is 3.5-12 weight-%. In a zone below the binder phase enriched surface zone, the binder phase content is 0.85-1 of the binder phase content in the inner portion of the insert and the content of cubic phases is essentially constant and equal to the content in the inner portion of the insert. The insert is formed by sintering a cemented carbide containing a nitrogen-containing material in a vacuum or inert atmosphere and heat treating the sintered insert in nitrogen at 40-400 mbar at a temperature of 1280.degree.-1430.degree. C. for a time of 5-100 min.

Process for making a cemented carbide with binder phase enriched surface

A cemented carbide insert with improved toughness and resistance against plastic deformation containing WC and cubic phases of carbide and/or carbonitride in a binder phase based on Co and/or Ni with a binder phase enriched surface zone is disclosed. The binder phase content in the insert is 3.5-12 weight-%. In a zone below the binder phase enriched surface zone, the binder phase content is 0.85-1 of the binder phase content in the inner portion of the insert and the content of cubic phases is essentially constant and equal to the content in the inner portion of the insert.

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Tumba, Sweden

Ulf Oscarsson