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 8×10.sup.15/m.sup.2 or less, 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.

Disclosed herein are embodiments of an enhanced resonant frequency hexagonal ferrite material and methods of manufacturing. The hexagonal ferrite material can be Y-phase strontium hexagonal ferrite material. In some embodiments, strontium can be substituted out for a trivalent or tetravalent ion composition including potassium, thereby providing for advantageous properties.

A composite material consisting of a matrix made of at least one aluminosilicate notably selected from barium aluminosilicate BAS, barium and strontium aluminosilicate BSAS, strontium aluminosilicate SAS, and mixtures thereof, reinforced by reinforcements made of at least one metal or metalloid oxide, the expansion coefficient of which is close to that of said at least one aluminosilicate.

A method for preparing said composite material.

A composite material according to the invention notably finding its application in the aeronautical or aerospace field, for example for the manufacture of radomes.

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.

Materials systems resistant to penetration of molten salts and may be present within a molten-salt-facing wall of a device for containing a molten salt bath at an elevated temperature, and molten-salt-facing walls and devices formed by such materials systems. A first layer of such a system defines an outer surface for direct contact with the molten salt bath, and resists erosion and corrosion and is penetrable by the molten salt at the elevated temperature. A second layer is located adjacent to the first layer and exhibits little or no wetting by the molten salt so that at least a portion of a thickness of the second layer is not penetrable by the molten salt. A third layer is located adjacent to the second layer and is porous and exhibits a low thermal conductivity at the elevated temperature.

Disclosed herein are embodiments of an enhanced resonant frequency hexagonal ferrite material and methods of manufacturing. The hexagonal ferrite material can be Y-phase strontium hexagonal ferrite material. In some embodiments, strontium can be substituted out for a trivalent or tetravalent ion composition including potassium, thereby providing for advantageous properties.

Disclosed herein are embodiments of an enhanced resonant frequency hexagonal ferrite material and methods of manufacturing. The hexagonal ferrite material can be Y-phase strontium hexagonal ferrite material. In some embodiments, strontium can be substituted out for a trivalent or tetravalent ion composition including potassium, thereby providing for advantageous properties.

A sintered ferrite magnet having a composition of metal elements of Ca, R, A, Fe and Co, which is represented by the general formula of Ca.sub.1−x−yR.sub.xA.sub.yFe.sub.2n−zCo.sub.z, wherein R is at least one of rare earth elements indispensably including La; A is Sr and/or Ba; x, y, z and n represent the atomic ratios of Ca, R, A, Fe and Co; 2n represents a molar ratio expressed by 2n=(Fe+Co)/(Ca+R+A); and x, y, z and n meet the conditions of 0.15≤x≤0.35, 0.05≤y≤0.40, (1−x−y)>y, 0<z≤0.18, and 7.5≤(2n−z)<11.0.

Disclosed herein are embodiments of an enhanced resonant frequency hexagonal ferrite material and methods of manufacturing. The hexagonal ferrite material can be Y-phase strontium hexagonal ferrite material. In some embodiments, sodium can be added into the crystal structure of the hexagonal ferrite material in order to achieve high resonance frequencies while maintaining high permeability.

A diamond polycrystal includes diamond grains, the diamond polycrystal including a cubic diamond and a 6H type hexagonal diamond, wherein the cubic diamond and the 6H type hexagonal diamond exist in the same or different diamond grains, and a ratio Ab.sub.1/Ab.sub.2 is more than or equal to 0.4 and less than or equal to 1, Ab.sub.1 representing a maximum value of absorption in a range of more than or equal to 1200 cm.sup.−1 and less than or equal to 1300 cm.sup.−1 in an infrared absorption spectrum, Ab.sub.2 representing a maximum value of absorption in a range of more than or equal to 1900 cm.sup.−1 and less than or equal to 2100 cm.sup.−1.