A crystal of a calcium phosphate that is any one selected from the group consisting of octacalcium phosphate, hydroxyapatite, fluorapatite, chlorapatite and carbonate apatite, in which a part of a plurality of calcium ions in a crystal structure of the crystal are replaced with a silver ion or a copper ion.

A crystal of a calcium phosphate that is any one selected from the group consisting of octacalcium phosphate, hydroxyapatite, fluorapatite, chlorapatite and carbonate apatite, in which a part of a plurality of calcium ions in a crystal structure of the crystal are replaced with a silver ion or a copper ion.

A porous refractory in the K.sub.2O—SiO.sub.2—B.sub.2O.sub.3 system is formed by chemical direct foaming by heating to over 600° C., resulting in adherent black or white foam. The foam can function as highly porous thermal insulation, a high or low thermal emissivity surface, as a sealant for deteriorated refractory surfaces, as a filler for pockmarks/holes/gaps or as a bonding agent for parts with large gaps between them.

Provided are ceramic foams. The ceramic foams may have a hierarchical pore gradient. The ceramic foams may be silica aerogels. The ceramic foams may be made by reaction of one or more precursors in the presence of an inert gas generated by a pore-forming gas-forming additive. The ceramic foams may be used as insulating materials.

A porous refractory in the K.sub.2O—SiO.sub.2—B.sub.2O.sub.3 system is formed by chemical direct foaming by heating to over 600° C., resulting in adherent black or white foam. The foam can function as highly porous thermal insulation, a high or low thermal emissivity surface, as a sealant for deteriorated refractory surfaces, as a filler for pockmarks/holes/gaps or as a bonding agent for parts with large gaps between them.

A porous refractory in the K.sub.2OSiO.sub.2B.sub.2O.sub.3 system is formed by chemical direct foaming by heating to over 600 C., resulting in adherent black or white foam. The foam can function as highly porous thermal insulation, a high or low thermal emissivity surface, as a sealant for deteriorated refractory surfaces, as a filler for pockmarks/holes/gaps or as a bonding agent for parts with large gaps between them.

A porous refractory in the K.sub.2OSiO.sub.2B.sub.2O.sub.3 system is formed by chemical direct foaming by heating to over 600 C., resulting in adherent black or white foam. The foam can function as highly porous thermal insulation, a high or low thermal emissivity surface, as a sealant for deteriorated refractory surfaces, as a filler for pockmarks/holes/gaps or as a bonding agent for parts with large gaps between them.

The present invention relates to a method of manufacturing a ceramic article (3) from a metal or metal matrix composite preform (1) provided by 3D-printing or by 3D-weaving. The preform (1) is placed in a heating chamber (2), and a predetermined time-temperature profile is applied in order to controllably react the preform (1) with a gas introduced into the heating chamber (2). The metal, the gas and the time-temperature profile are chosen so as to induce a metal-gas reaction resulting in at least a part of the preform (1) transforming into a ceramic. Preferred embodiments of the invention comprises a first oxidation stage involving a metal-gas reaction in order to form a supporting oxide layer (5) at the surface of the metal, followed by a second stage in which the heating chamber (2) is heated to a temperature above the melting point of the metal to increase the kinetics of the chemical reaction. The invention also relates to a number of advantageous uses of a ceramic article manufactured as described.

The present invention relates to a method of manufacturing a ceramic article (3) from a metal or metal matrix composite preform (1) provided by 3D-printing or by 3D-weaving. The preform (1) is placed in a heating chamber (2), and a predetermined time-temperature profile is applied in order to controllably react the preform (1) with a gas introduced into the heating chamber (2). The metal, the gas and the time-temperature profile are chosen so as to induce a metal-gas reaction resulting in at least a part of the preform (1) transforming into a ceramic. Preferred embodiments of the invention comprises a first oxidation stage involving a metal-gas reaction in order to form a supporting oxide layer (5) at the surface of the metal, followed by a second stage in which the heating chamber (2) is heated to a temperature above the melting point of the metal to increase the kinetics of the chemical reaction. The invention also relates to a number of advantageous uses of a ceramic article manufactured as described.

Disclosed is a process of manufacturing a chemically reduced graphene oxide/silicon nanowire composite. The formation of the three-dimensional monolith and the chemical reduction of graphene oxide by a reducing agent selected from hydrazine hydrate, ethylene diamine and 1,4-diaminebutane are in one step. Also disclosed is a chemically reduced graphene oxide/silicon nanowire composite that can be obtained by the disclosed process. The composite is a three-dimensional monolith in which the two components are covalently linked each other, having a high degree of reduction with a C/O ratio of 1-50, preferably from 10 to 25, more preferably 16.7, having a porous structure and a high specific surface area of 50-5,000 m.sup.2/g, preferably 800-2,500 m.sup.2/g, more preferably 1,433 m.sup.2/g and having a low resistance to charge transfer from 0.1 to 5 , preferably from 0.3 to 1.5 . Also disclosed is a lithium-ion battery or a supercapacitor including the composite (or monolith).