A guide member for a fishing line including an alumina ceramic including Ti and Al, a content of Ti being not less than 0.5 mass % in terms of TiO.sub.2, a content of Al being not less than 92 mass % in terms of Al.sub.2O.sub.3, and a main phase of the alumina ceramic being alumina crystals, wherein a content ratio of aluminas crystal with an aspect ratio of not less than 2 within the alumina crystals is not less than 15%.

A polycrystalline cubic boron nitride comprising 96% by volume or more of cubic boron nitride, wherein the cubic boron nitride has a dislocation density of more than 8×10.sup.15/m.sup.2, the polycrystalline cubic boron nitride comprises a plurality of crystal grains, and the plurality of crystal grains have a median diameter d50 of an equivalent circle diameter of less than 100 nm.

A polycrystalline cubic boron nitride comprising 98.5% by volume or more of cubic boron nitride, wherein the cubic boron nitride has a dislocation density of more than 8×10.sup.15/m.sup.2, the polycrystalline cubic boron nitride comprises a plurality of crystal grains, and the plurality of crystal grains have a median diameter d50 of an equivalent circle diameter of 0.1 μm or more and 0.5 μm or less.

A ferrite sintered magnet including ferrite grains having a hexagonal crystal structure. The ferrite grains satisfy 0.56≤W≤0.68 where W is an average value of circularities of the ferrite grains in a cross section parallel to an axis of easy magnetization.

A ferrite sintered magnet including 0.010 mass % or more and 0.090 mass % or less of Mg in terms of MgO.

The invention relates to a copper-ceramic composite comprising:—a ceramic substrate;—a copper or copper alloy coating in which the copper or copper alloy has grain sizes of 10 μm to 300 μm and a number distribution of the grain sizes with a median d.sub.50 and an arithmetic mean d.sub.arith, the ratio of d.sub.50 to d.sub.arith (d.sub.50/d.sub.arith) being between 0.75 and 1.10.

An alumina sintered body including an inner layer in which alumina crystal grains contained have an average aspect ratio of 1.0 to 2.0 and an outer layer which covers at least a part of the inner layer from outside and in which alumina crystal grains contained have an average aspect ratio of more than 2.0, the alumina sintered body being free from silicon except unavoidable impurities.

The invention relates to a copper/ceramic composite comprising—a ceramic substrate which contains aluminum oxide, —a coating which lies on the ceramic substrate and which is made of copper or a copper alloy, wherein the copper or the copper alloy has a particle size number distribution with a median value d.sub.50, an arithmetic mean value d.sub.arith, and a symmetry value S(Cu)=d.sub.50/d.sub.arith; the aluminum oxide has a particle size number distribution with a median value d.sub.50, an arithmetic mean value d.sub.arith, and a symmetry value S(Al.sub.2O.sub.3)=d.sub.50/d.sub.arith; and S(Al.sub.2O.sub.3) and S(Cu) satisfy the following condition: 0.7≤S(Al.sub.2O.sub.3)/S(Cu)≤1.4.

A substrate for mounting a light-emitting element according to the present disclosure contains a crystal particle of aluminum oxide and is composed of an alumina-based ceramic that contains 97% by mass or more of Al as a value of an Al.sub.2O.sub.3 equivalent among 100% by mass of all components thereof. An average value of an equivalent circle diameter of the crystal particle is 1.1 μm or greater and 1.8 μm or less and a standard deviation of an equivalent circle diameter thereof is 0.6 μm or greater and 1.4 μm or less.

In one aspect, articles are described comprising wear resistant coatings employing composite architectures including refractory layers of varying compositions and phases. Briefly, a coated article comprises a substrate and a coating deposited by chemical vapor deposition (CVD) adhered to the substrate, the coating comprising an inner refractory layer comprising M.sub.1-xAl.sub.xN wherein x0.7 and M is titanium, chromium or zirconium and an outer zirconia layer or outer multiphase refractory layer comprising an alumina phase and an oxide phase comprising at least one Group IVB metal, wherein the M.sub.1-xAl.sub.xN has less than 15 weight percent hexagonal phase.