A coated cutting tool comprising: a substrate and a coating layer, wherein the coating layer includes a lower layer and an upper layer; the lower layer includes one or two or more specific Ti compound layers; the upper layer includes an ?-type Al.sub.2O.sub.3 layer; an average thickness of the lower layer is 2.0 ?m to 15.0 ?m; an average thickness of the upper layer is 3.5 ?m to 15.0 ?m; in the upper layer, a ratio of a length of ?3 grain boundaries to a total length of 100% of a total grain boundary is more than 50% and 80% or less, and a ratio of the length of ?3 grain boundaries to a total length of 100% of CSL grain boundaries is 70% or more; and in the upper layer, a texture coefficient TC(0,0,12) of the ?-type Al.sub.2O.sub.3 layer is 8.0 or more and 8.9 or less.

A method of protecting a carbon-containing composite material part against oxidation, includes applying a first coating composition in the form of an aqueous suspension on an outside surface of the part, the first coating composition including a metallic phosphate; a powder of an ingredient comprising titanium; and a powder of B.sub.4C; subjecting the applied first coating composition to heat treatment in order to obtain a first coating on the outside surface of the part; applying a second coating composition on the first coating composition, the second coating composition including an aqueous suspension of colloidal silica; a powder of borosilicate glass; and a powder of TiB.sub.2; and subjecting the applied second coating composition to second heat treatment in order to obtain a second coating on the first coating.

A method of protecting a carbon-containing composite material part against oxidation, includes applying a first coating composition in the form of an aqueous suspension on an outside surface of the part, the first coating composition including a metallic phosphate; a powder of an ingredient comprising titanium; and a powder of B.sub.4C; subjecting the applied first coating composition to heat treatment in order to obtain a first coating on the outside surface of the part; applying a second coating composition on the first coating composition, the second coating composition including an aqueous suspension of colloidal silica; a powder of borosilicate glass; and a powder of TiB.sub.2; and subjecting the applied second coating composition to second heat treatment in order to obtain a second coating on the first coating.

In some examples, an article may include a substrate and a coating on the substrate. In accordance with some of these examples, the coating may include a bond layer and an overlying layer comprising at least one oxide. In some examples, the bond layer comprises silicon metal and at least one of a transition metal carbide, a transition metal boride, or a transition metal nitride.

In some examples, an article may include a substrate and a coating on the substrate. In accordance with some of these examples, the coating may include a bond layer and an overlying layer comprising at least one oxide. In some examples, the bond layer comprises silicon metal and at least one of a transition metal carbide, a transition metal boride, or a transition metal nitride.

A method preparing a metals carbides multilayer coating on at least one surface of a first carbon layer of a substrate, or under the surface inside the first carbon layer, by a reactive melt infiltration technique, includes: a) putting the surface into contact with a solid metal disilicide MSi.sub.2, M is selected from hafnium, titanium, and tantalum; b) heating the substrate and the metal disilicide to above the melting temperature of the metal disilicide; c) observing a plateau at the temperature for a sufficient duration so that the metal disilicide reacts with the carbon and forms a first multilayer coating including a dense and continuous layer of SiC, fully covered by a dense and continuous layer of MC; d) cooling the part with the first multilayer coating; and then, at the end of d), optionally e) depositing a second carbon layer at the surface of the first multilayer coating.

A method preparing a metals carbides multilayer coating on at least one surface of a first carbon layer of a substrate, or under the surface inside the first carbon layer, by a reactive melt infiltration technique, includes: a) putting the surface into contact with a solid metal disilicide MSi.sub.2, M is selected from hafnium, titanium, and tantalum; b) heating the substrate and the metal disilicide to above the melting temperature of the metal disilicide; c) observing a plateau at the temperature for a sufficient duration so that the metal disilicide reacts with the carbon and forms a first multilayer coating including a dense and continuous layer of SiC, fully covered by a dense and continuous layer of MC; d) cooling the part with the first multilayer coating; and then, at the end of d), optionally e) depositing a second carbon layer at the surface of the first multilayer coating.

An article including carbon-carbon composite substrate may be treated with an antioxidant coating prior to use in an oxidizing environment. The antioxidant coating may be configured to reduce oxidation at an external surface of the CC composition and reduce ingress of oxidants into pores or other open passages defined by the CC composite substrate to avoid internal oxidation. An example article includes a CC composite substrate, a bond coat, and an antioxidant coating. The CC composite substrate defines a friction surface and a non-friction surface. The bond coat is disposed on the non-friction surface. The antioxidant coating may be disposed on at least a portion of the bond coat. The antioxidant coating may include ytterbium disilicate and a sintering aid.

A composite sintered material contains cubic boron nitride particles and binder particles. The composite sintered material contains 40 vol % or more and 80 vol % or less of the cubic boron nitride particles. The binder particles contain TiCN particles. The composite sintered material shows a first peak belonging to a (200) plane of the TiCN particles in a range in which a Bragg angle 2 is 41.7 or more and 42.6 or less in an X-ray diffraction spectrum measured using a Cu-K ray as a ray source.

A composite sintered material contains cubic boron nitride particles and binder particles. The composite sintered material contains 40 vol % or more and 80 vol % or less of the cubic boron nitride particles. The binder particles contain TiCN particles. The composite sintered material shows a first peak belonging to a (200) plane of the TiCN particles in a range in which a Bragg angle 2 is 41.7 or more and 42.6 or less in an X-ray diffraction spectrum measured using a Cu-K ray as a ray source.