Alumina coating, coated product and method of making the same

Abstract

A method of coating a substrate that includes the steps of: applying by chemical vapor deposition at a temperature ranging between about 750 degrees Centigrade and about 920 degrees Centigrade an alpha-alumina coating layer wherein the alpha-alumina coating layer exhibits a platelet grain morphology at the surface thereof.

1 . A method of coating a substrate comprising the steps of
 applying by chemical vapor deposition at a temperature ranging between about 750 degrees Centigrade and about 920 degrees Centigrade an alpha-alumina coating layer wherein the alpha-alumina coating layer exhibits a platelet grain morphology at the surface thereof.   
     
     
         2 . The method of  claim 1  further including the step of applying by chemical vapor deposition a modification coating layer wherein the modification coating layer includes oxygen and aluminum and one or more of carbon and nitrogen and one or more of the Group IVB elements of the Periodic Table; and wherein the alpha-alumina coating layer being applied to the modification coating layer. 
     
     
         3 . The method of  claim 2  further including the step of applying by chemical vapor deposition an intermediate coating layer containing a carbonitride of one or more of a Group IVB element of the Periodic Table; and wherein the modification being applied to the intermediate coating layer. 
     
     
         4 . The method of  claim 3  further including the step of applying by chemical vapor deposition a base coating layer to a surface of the substrate, and the base coating layer containing a nitride of one or of a Group IVB element of the Period Table; and wherein the intermediate coating layer being applied to the base coating layer. 
     
     
         5 . The method of  claim 3  further including the step of applying by chemical vapor deposition a base coating layer to a surface of the substrate, and the base coating layer comprising alumina; and wherein the intermediate coating layer being applied to the base coating layer. 
     
     
         6 . The method of  claim 1  further including the step of applying at least one coating layer to the alpha-alumina coating layer. 
     
     
         7 . The method of  claim 1  wherein the substrate comprises one of the following: a cemented carbide, a ceramic, a cermet and a polycrystalline cubic boron nitride. 
     
     
         8 . The method of  claim 1  wherein the substrate comprising a cutting insert substrate having a rake surface and a flank surface, and a cutting edge at the juncture of the rake surface and the flank surface.