A double-tube connection structure for detonation synthesis, a detonation synthesis device and an application thereof are provided. The double-tube connection structure for detonation synthesis includes a drive tube, a sample tube, fixing components, and end plugs provided at ports of the sample tube. The drive tube is sleeved outside the sample tube, cavities are provided between the drive tube and the sample tube, and between the drive tube and the end plug. The fixing components are provided on two ends of the drive tube and the sample tube. After detonation, a detonation wave is transferred from top to bottom. Under the action of the detonation wave, the drive tube performs convergent sliding motion towards the sample tube, and covers outsides of the sample tube, and the top end plug and the bottom end plug of the sample tube. A detonation synthesis device includes the double-tube connection structure for detonation synthesis.

In accordance with the present invention, there is provided a process for producing hydrogen and graphitic carbon from a hydrocarbon gas comprising: contacting at a temperature between 600° C. and 1000° C. the catalyst with the hydrocarbon gas to catalytically convert at least a portion of the hydrocarbon gas to hydrogen and graphitic carbon, wherein the catalyst is a low grade iron oxide.

In accordance with the present invention, there is provided a process for producing hydrogen and graphitic carbon from a hydrocarbon gas comprising: contacting at a temperature between 600° C. and 1000° C. the catalyst with the hydrocarbon gas to catalytically convert at least a portion of the hydrocarbon gas to hydrogen and graphitic carbon, wherein the catalyst is a low grade iron oxide.

Nano polycrystalline diamond is composed of carbon and a plurality of impurities other than carbon. A concentration of each of the plurality of impurities is not higher than 0.01 mass %, and the nano polycrystalline diamond has a crystal grain size (a maximum length) not greater than 500 nm. The nano polycrystalline diamond can be fabricated by preparing graphite in which a concentration of an impurity is not higher than 0.01 mass % and converting graphite to diamond by applying an ultra-high pressure and a high temperature to graphite.

A superabrasive material and method of making the superabrasive material are provided. The superabrasive material may comprise a superabrasive crystal having an irregular surface. The superabrasive material further comprises a plurality of structure defects within the superabrasive crystal. The plurality of structure defects may cause micro-chipping when used as grinding materials.

Methods of forming composite particles include forming a source material over a plurality of nucleation cores and forming a catalyst material over the source material. Compositions of matter include a plurality of composite particles, each particle of the plurality comprising a plurality of nucleation cores, a source material disposed over the nucleation cores, and a catalyst material disposed over the source material. Methods of forming earth-boring tools include forming a plurality of composite particles, combining the plurality of composite particles with a plurality of grains of hard material, and catalyzing the formation of inter-granular bonds between the composite particles and the grains of hard material to faun a polycrystalline material. The plurality of in situ nucleated grains of hard material and the plurality of grains of hard material may be interspersed and inter-bonded.

A method of making polycrystalline diamond material includes providing a fraction of diamond particles or grains and a sintering additive, the sintering additive comprising a carbon source of nano-sized particles or grains, forming the diamond particles and sintering additive into an aggregated mass, consolidating the aggregated mass and a binder material to form a green body, and subjecting the green body to conditions of pressure and temperature at which diamond is more thermodynamically stable than graphite and for a time sufficient to consume the sintering additive, sintering it and forming polycrystalline diamond material that is thermodynamically and crystallographically stable and is substantially devoid of any nano-structures.

Single-crystal diamond is composed of carbon in which a concentration of a carbon isotope .sup.12C is not lower than 99.9 mass % and a plurality of inevitable impurities other than carbon. The inevitable impurities include nitrogen, boron, hydrogen, and nickel, and a total content of nitrogen, boron, and hydrogen of the plurality of inevitable impurities is not higher than 0.01 mass %. In order to manufacture single-crystal diamond, initially, a hydrocarbon gas in which a concentration of the carbon isotope .sup.12C is not lower than 99.9 mass % is subjected to denitrification.

Disclosed herein is an apparatus and method for growing a diamond. The apparatus for growing a diamond comprises: a reaction cell that is configured to grow the diamond therein; a main heater including a main heating surface that is arranged along a first inner surface of the reaction cell; and a sub-heater including a sub-heating surface that is arranged along a second inner surface of the reaction cell, the second inner surface being non-parallel with the first inner surface.

A method and apparatus produce materials by exfoliation from a bulk material, by disposing bulk material in suspension in a liquid in a chamber; applying superimposed ultrasound fields in the chamber, the superimposed ultrasound fields generating cavitation in the liquid at least at a zone of field superimposition; measuring cavitation in the chamber while applying the superimposed cavitation fields, at least at the zone of field superimposition; and adjusting at least one of the ultrasound fields on the basis of measured cavitation so as to control cavitation energy applied to the material and thereby to control exfoliation of the bulk material and the formation of materials therefrom. Inertial cavitation is controlled, resulting in significantly greater production yields compared to prior art systems and methods. A high intensity focused ultrasound transducer is provided to impart suspension energy to the liquid in the chamber for suspending bulk material in the zone of field superimposition.