Patent ID: 8475944
Filing Date: 2013-07-02
Classification: B23B,C04B,C23C,Y10T

Abstract:
1. A coated ceramic cutting insert for removing material from a workpiece, the coated ceramic cutting insert comprising: a ceramic substrate, the ceramic substrate being selected from the group consisting of silicon nitride-based ceramics and silicon aluminum oxynitride-based ceramics, the substrate having a rake surface and at least one flank surface, and a cutting edge formed at the juncture between the rake surface and the flank surface; a wear-resistant coating scheme comprising: an alumina-containing base coating layer region deposited by chemical vapor deposition on substantially all of the surfaces of the ceramic substrate that experience wear during removal of material from the workpiece, and the alumina-containing base layer region comprising at least one exposed alumina coating layer; and the exposed alumina coating layer exhibiting a blasted stress condition ranging between about 50 MPa (tensile stress) and about −2 GPa (compressive stress) as measured by XRD using the Psi tilt method and the (024) reflection of alumina.