The invention relates to hydrocarbon conversion, to equipment and materials useful for hydrocarbon conversion, and to processes for carrying out hydrocarbon conversion, e.g., hydrocarbon pyrolysis processes. The hydrocarbon conversion is carried out in a reactor which includes at least one channeled member that comprises refractory and has an open frontal area 55%. The refractory can include non-oxide ceramic.

Disclosed herein are compounds, methods, and tools which comprise tungsten borides and mixed transition metal borides.

A coated article including an article having a surface; an oxidation resistant bond coat layer deposited on the surface, the oxidation resistant bond coat layer comprising a healing silica matrix and at least one oxygen scavenger forming a metal silicide network dispersed within the healing silica matrix; and a top coat layer disposed upon the oxidation resistant bond coat layer, whereby the oxidation resistant bond coat layer is operable to seal a crack in the top coat layer.

A coated article including an article having a surface; an oxidation resistant bond coat layer deposited on the surface, the oxidation resistant bond coat layer comprising a healing silica matrix and at least one oxygen scavenger forming a metal silicide network dispersed within the healing silica matrix; and a top coat layer disposed upon the oxidation resistant bond coat layer, whereby the oxidation resistant bond coat layer is operable to seal a crack in the top coat layer.

Particles of a refractory metal or a refractory-metal compound capable of decomposing or reacting into refractory-metal nanoparticles, elemental silicon, and an organic compound having a char yield of at least 60% by weight are combined to form a precursor mixture. The mixture is heating, forming a thermoset and/or metal nanoparticles. Further heating form a composition having nanoparticles of a refractory-metal silicide and a carbonaceous matrix. The composition is not in the form of a powder

A compound is generally provided that has the formula: Ln.sub.3-xB.sub.xM.sub.5-yB.sub.yO.sub.12, where Ln comprises Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or a mixture thereof; x is 0 to about 1.5; M comprises Ga, In, Al, Fe, or a combination thereof; y is 0 to about 2.5; and x+y is greater than 0. A composition is also provided that includes a silicon-containing material (e.g., silicon metal and/or a silicide) and the boron-doped refractory compound having the formula described above, such as about 0.001% to about 85% by volume of the boron-doped refractory compound.

A molybdenum disilicide-based ceramic heating element holding structure includes a holding member that is attached to a base portion and that holds an elongated support member, for mounting a molybdenum disilicide-based ceramic heating element of an elongated shape at intervals in a long axis direction thereof. The molybdenum disilicide-based ceramic heating element mounted on the support member can be exchanged without breaking the holding structure. A plurality of elongated support members can be provided, and a U-shaped portion of an elongated molybdenum disilicide-based ceramic heating element having a meandering shape can be inserted and extracted from a uniaxial direction in a space partitioned by the base portion. The plurality of support members and the holding member holding the plurality of elongated support members are detachable and the support member is removable from the holding member.

A particulate composite ceramic material may include: particles of at least one first ultra-high-temperature ceramic UHTC, the outer surface of the particles being at least partially covered by a porous layer made of at least one second UHTC in amorphous form; and the particles defining a space therebetween; optionally, porous clusters of the at least one second ultra-high-temperature ceramic in amorphous form, distributed in said space; a dense matrix and at least one third UHTC in crystallized form at least partially filling the space; optionally, a dense coating made of at least the third UHTC in crystallized form, covering the outer surface of the matrix, the matrix and the coating representing 5% to 90% by mass with respect to the total mass of the material. A part may include such a particulate ceramic composite material.

Particles of a refractory metal or a refractory-metal compound capable of decomposing or reacting into refractory-metal nanoparticles, elemental silicon, and an organic compound having a char yield of at least 60% by weight are combined to form a precursor mixture. The mixture is heating, forming a thermoset and/or metal nanoparticles. Further heating form a composition having nanoparticles of a refractory-metal silicide and a carbonaceous matrix. The composition is not in the form of a powder.

The present disclosure relates to a molybdenum silicide based composition comprising aluminum oxide (Al.sub.2O.sub.3) and to the use thereof in high temperature applications.