Abstract: An adherent coating for carbide and ceramic substrates employs a thin layer between the substrate and a subsequent layer or layers. The thin layer may be employed without thermal cracking due to heat during use, such as for the insert of a cutting tool, because the upper layer or layers provide a gradual transition of material properties to a harder, less thermally conductive material on the outermost layer. A particular arrangement of layers on the carbide or ceramic substrate may be, from innermost to outermost layer, hafnium nitride, titanium carbide, aluminum oxide, and titanium nitride.

Abstract: An adherent coating for carbide and ceramic substrates employs a thin layer between the substrate and a subsequent layer or layers. The thin layer may be employed without thermal cracking due to heat during use, such as for the insert of a cutting tool, because the upper layer or layers provide a gradual transition of material properties to a harder, less thermally conductive material on the outermost layer. A particular arrangement of layers on the carbide or ceramic substrate may be, from innermost to outermost layer, hafnium nitride, titanium carbide, aluminum oxide, and titanium nitride.

Abstract: An adherent coating for carbide and ceramic substrates employs a thin layer of hafnium nitride (HfN) between the substrate and a subsequent layer or layers. The thin layer may be employed without thermal cracking due to heat during use, such as for the insert of a cutting tool, because the upper layer or layers provide a gradual transition of material properties to a harder, less thermally conductive material on the outermost layer. A particular arrangement of layers on the carbide or ceramic substrate and hafnium nitride layer may be, from innermost to outermost layer, titanium carbide, aluminum oxide, and titanium nitride.