Composite sintered silicon nitride material and cutting tool made therefrom

Abstract From the Canadian patent

of Disclosure, Composite sintered Si3N4 material particularly suitable as a cutting tool material for cutting cast ironn is composed of:, a sintered Si3N4 substrate containing 0.1 to 10 weight % of Y2O3, 0.1 to 10 weight % of ZrO2 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 Si3N4; a first layer of Ti compound coated on the sintered Si3N4 substrate;, a second layer of Al2O3 coated on the first layer; and the total thickness of the first and second layers being an the range of 1 to 20 microns. The above composite …