Hexavalent chromium-free slurry formulations which are suitable in the production of ceramic overlay coating systems are described. The formulations provide superior hot corrosion and heat oxidation protection for superalloy substrates. A basecoat slurry and topcoat slurry are provided. The basecoat slurry includes an aluminum phosphate based aqueous solution having a molar ratio of Al:PO.sub.4 higher than about 1:3 with the incorporation of metal oxide particles. The topcoat slurry includes an aluminum phosphate based aqueous solution having a molar ratio of Al:PO.sub.4 higher than about 1:3. Both of the basecoat slurry and the topcoat slurry are hexavalent chromium-free.

A cutting tool comprises a rake face and a flank face, the cutting tool being composed of a substrate made of a cubic boron nitride sintered material and a coating provided on the substrate, the coating including a MAlN layer, the MAlN layer including crystal grains of M.sub.xAl.sub.1-xN in the cubic crystal system, n.sub.F<n.sub.R being satisfied, where n.sub.F represents a number of voids per 100 μm in length of the MAlN layer on the flank face in a cross section of the MAlN layer, and n.sub.R represents a number of voids per 100 μm in length of the MAlN layer on the rake face in a cross section of the MAlN layer, n.sub.D being 3 or less, where n.sub.D represents a number of droplets per 100 μm in length of the MAlN layer on the flank face in a cross section of the MAlN layer.

A cutting tool comprises a rake face and a flank face, the cutting tool being composed of a substrate made of a cubic boron nitride sintered material and a coating provided on the substrate, the coating including a MAlN layer, the MAlN layer including crystal grains of M.sub.xAl.sub.1-xN in the cubic crystal system, n.sub.F<n.sub.R being satisfied, where n.sub.F represents a number of voids per 100 μm in length of the MAlN layer on the flank face in a cross section of the MAlN layer, and n.sub.R represents a number of voids per 100 μm in length of the MAlN layer on the rake face in a cross section of the MAlN layer, n.sub.D being 3 or less, where n.sub.D represents a number of droplets per 100 μm in length of the MAlN layer on the flank face in a cross section of the MAlN layer.

A cutting tool comprises a rake face and a flank face, the cutting tool being composed of a substrate made of a cubic boron nitride sintered material and a coating provided on the substrate, the coating including a MAlN layer, when a cross section of the MAlN layer is subjected to an electron backscattering diffraction image analysis to determine a crystal orientation of each of the crystal grains of the M.sub.xAl.sub.1−xN and a color map is created based thereon, then on the color map, the flank face having the MAlN layer occupied in area by 45% to 75% by crystal grains of the M.sub.xAl.sub.1−xN having a (111) plane with a normal thereto extending in a direction within 25 degrees with respect to a direction in which a normal to the flank face extends, the MAlN layer having a residual stress of −2 GPa to −0.1 GPa.

A cutting tool comprises a rake face and a flank face, the cutting tool being composed of a substrate made of a cubic boron nitride sintered material and a coating provided on the substrate, the coating including a MAlN layer, when a cross section of the MAlN layer is subjected to an electron backscattering diffraction image analysis to determine a crystal orientation of each of the crystal grains of the M.sub.xAl.sub.1−xN and a color map is created based thereon, then on the color map, the flank face having the MAlN layer occupied in area by 45% to 75% by crystal grains of the M.sub.xAl.sub.1−xN having a (111) plane with a normal thereto extending in a direction within 25 degrees with respect to a direction in which a normal to the flank face extends, the MAlN layer having a residual stress of −2 GPa to −0.1 GPa.

A ceramic body is provided that is suitable for use in dental applications to provide a natural aesthetic appearance. A colorized ceramic body is formed that has at least one color region and a color gradient region. A ceramic body is formed having at least two color regions and a color gradient that forms a transition region between two color regions. A method for making the colorized ceramic body includes unidirectional infiltration of a coloring composition into the ceramic body.

A ceramic body is provided that is suitable for use in dental applications to provide a natural aesthetic appearance. A colorized ceramic body is formed that has at least one color region and a color gradient region. A ceramic body is formed having at least two color regions and a color gradient that forms a transition region between two color regions. A method for making the colorized ceramic body includes unidirectional infiltration of a coloring composition into the ceramic body.

The present invention relates to a dental zirconia mill blank comprising a porous zirconia material, the porous zirconia material comprising Zr oxide, Y oxide, optionally Al oxide, Bi oxide, Tb oxide, Er oxide, Cr oxide, the porous zirconia material not comprising Fe oxide calculated as Fe.sub.2O.sub.3 of more than 0.01 wt. %, Mn oxide calculated as MnO.sub.2 of more than 0.005 wt. %, Co oxide calculated as Co.sub.2O.sub.3 of more than 0.005 wt. %, wt. % with respect to the weight of the porous zirconia material. The invention also relates to a process of producing such a dental zirconia mill blank and a dental restoration which can be machined from the dental zirconia mill blank. Further, the invention relates to a kit of parts comprising such a dental zirconia mill blank and a dental cement.

The present invention relates to a dental zirconia mill blank comprising a porous zirconia material, the porous zirconia material comprising Zr oxide, Y oxide, optionally Al oxide, Bi oxide, Tb oxide, Er oxide, Cr oxide, the porous zirconia material not comprising Fe oxide calculated as Fe.sub.2O.sub.3 of more than 0.01 wt. %, Mn oxide calculated as MnO.sub.2 of more than 0.005 wt. %, Co oxide calculated as Co.sub.2O.sub.3 of more than 0.005 wt. %, wt. % with respect to the weight of the porous zirconia material. The invention also relates to a process of producing such a dental zirconia mill blank and a dental restoration which can be machined from the dental zirconia mill blank. Further, the invention relates to a kit of parts comprising such a dental zirconia mill blank and a dental cement.

A ceramic body is provided that is suitable for use in dental applications to provide a natural aesthetic appearance. A colorized ceramic body is formed that has at least one color region and a color gradient region. A ceramic body is formed having at least two color regions and a color gradient that forms a transition region between two color regions. A method for making the colorized ceramic body includes unidirectional infiltration of a coloring composition into the ceramic body.