Composite sintered silicon nitride material and cutting tool made therefrom.

摘要

Composite sintered Si<Sub>3</Sub>N<Sub>4</Sub> material particularly suitable as a cutting tool material for cutting cast iron is composed of:
<UnorderedLists id="ula01" listStyle="none"><ListItem>a sintered Si<Sub>3</Sub>N<Sub>4</Sub> substrate containing 0.1 to 10 weight % of Y<Sub>2</Sub>O<Sub>3</Sub>, 0.1 to 10 weight % of Zr0<Sub>2</Sub> and if necessary 1 to 15 weight % of at least one member selected from the group consisting of compound and solid solution thereof of elements of IVa (except Zr), Va, and Via of the Periodic Table and the balance being of Si<Sub>3</Sub>N<Sub>4</Sub>;</ListItem><ListItem>a first layer of Ti compound coated on the sintered Si<Sub>3</Sub>N<Sub>4</Sub> substrate;</ListItem><ListItem>a second layer of A1203 coated on the first layer; and the total thickness of the first and second layers being in the range of 1 to 20 microns.</ListItem></UnorderedLists>

The above composite sintered Si<Sub>3</Sub>N<Sub>4</Sub> material has an improved abrasive resistance particularly in the case of cutting cast iron at high speed, while retaining the excellent physical properties of Si<Sub>3</Sub>N<Sub>4</Sub>. Such a composite sintered Si<Sub>3</Sub>N<Sub>4</Sub> material is useful for preparing a cutting tool of a long life time.