A cutting tool includes a substrate and a coating that coats a surface of the substrate, the coating including a multilayer structure layer composed of at least one layer A and at least one layer B alternately deposited from a side closer to the substrate toward a side closer to a surface, the layer A having an average composition of Al.sub.xCr.sub.(1-x)N, the layer B being composed of Al.sub.yTi.sub.(1-y)N, the layer A being composed of a domain region and a matrix region, the domain region having a composition ratio of Cr larger than that of Cr of the matrix region, wherein x has a range of 0.5x0.8 and y has a range of 0.5y0.7.

A cutting tool includes: a substrate including a rake face; and a coating film that coats the rake face, wherein the coating film includes an -Al.sub.2O.sub.3 layer disposed on the substrate, the -Al.sub.2O.sub.3 layer includes crystal grains of -Al.sub.2O.sub.3, an area ratio of crystal grains oriented in (001) among the crystal grains is 50% to 90% in the -Al.sub.2O.sub.3 layer at the rake face, and a film residual stress A.sub.A determined based on a crystal plane interval of a (001) plane of the -Al.sub.2O.sub.3 layer at the rake face is more than 0 MPa and less than or equal to 2000 MPa, and a film residual stress B.sub.A determined based on a crystal plane interval of a (110) plane of the -Al.sub.2O.sub.3 layer at the rake face is more than or equal to 1000 MPa and less than 0 MPa.

A sliding member includes a base material, and an amorphous hard carbon film formed on a surface of the base material, in which a sp.sup.2 ratio of the amorphous hard carbon film increases from an inner surface side corresponding to the base material side toward an outer surface side thereof to become a maximum value and further decreases toward the outer surface side.

Provided are a friction reduced and wear resistant coating, a preparation method thereof and a piston ring. The coating includes an adhesive layer, a transition layer, a gradient layer and a function layer in sequence. The gradient layer is a CrMo.sub.xN layer in which Mo content progressively increases. The function layer includes at least one cyclical layer. Each cyclical layer includes a first CrMo.sub.xN layer and a second CrMo.sub.xN layer in sequence from bottom to top. The Mo content of the first CrMo.sub.xN layer is lower than the Mo content of the second CrMo.sub.xN layer. The coating provided by the present invention has a friction coefficient of 0.3 to 0.45, 10% to 30% lower than a CrN coating, and has an overall hardness of up to 1400 HV to 2600 HV and a thickness of 80 m, satisfying the required durability for the full lifecycle of the piston ring. The preparation process of the coating is simple and highly operable, and thus is convenient for industrialization.

A black member includes a base and a black layer laminated on the base. The black layer contains titanium aluminum nitride, titanium silicon nitride, or titanium aluminum silicon nitride. The black layer may also contain at least one type of elements selected from the group consisting of oxygen, fluorine, and carbon. When the black layer contains carbon, and assuming that a total amount of elements contained in the black layer is 100 at %, the black layer contains carbon of 10 at % or less. In a color evaluation according to an L*, a*, b* color system (CIE color system), the black layer satisfies L*48.0, 2.0a*3.0, and 3.5b*3.0.

A superalloy target wherein the superalloy target has a polycrystalline structure of random grain orientation, the average grain size in the structure is smaller than 20 m, and the porosity in the structure is smaller than 10%. Furthermore, the invention includes a method of producing a superalloy target by powder metallurgical production, wherein the powder-metallurgical production starts from alloyed powder(s) of a superalloy and includes the step of spark plasma sintering (SPS) of the alloyed powder(s).

Thermal barrier coatings and methods to make such coatings present improved resistance to CMAS infiltration. The method for forming a thermal barrier coating includes applying a layer of the thermal barrier coating to a component having a surface, forming a plurality of first channels in the thermal barrier coating, and forming a plurality of second channels in the thermal barrier coating. The first channels extend through a thickness of the thermal barrier coating from an interface with the surface of the component to a free surface opposite the interface. The second channels are disposed between the free surface and the interface and extending lengthwise generally parallel to the free surface of the thermal barrier coating.

A sliding member includes a base material and an amorphous hard carbon film formed on a surface of the base material, and the amorphous hard carbon film has a graded structure in which a sp.sup.2 ratio increases from an inner surface side corresponding to the base material side toward an outer surface side. A piston ring includes the sliding member.

A thermal barrier coating includes a highly porous layer and a dense layer. The highly porous layer is formed on a heat-resistant base, is made of ceramic, has pores, has a layer thickness of equal to or larger than 0.3 mm and equal to or smaller than 1.0 mm, and has a pore ratio of equal to or higher than 1 vol % and equal to or lower than 30 vol %. The dense layer is formed on the highly porous layer, is made of ceramic, has a pore ratio of equal to or lower than 0.9 vol % that is equal to or lower than the pore ratio of the highly porous layer, and has a layer thickness of equal to or smaller than 0.05 mm.

A sliding member includes a base material, and an amorphous hard carbon film formed on a surface of the base material, in which a sp.sup.2 ratio of the amorphous hard carbon film increases from an inner surface side corresponding to the base material side toward an outer surface side thereof to become a maximum value and further decreases toward the outer surface side.