Methods, apparatus and systems using heat exchanger reactors to form polymer derived ceramic materials, including methods for making polysilocarb (SiOC) precursors.

The present invention relates to a method for preparing a fully ceramic capsulated nuclear fuel material containing three-layer-structured isotropic nuclear fuel particles coated with a ceramic having a composition which has a higher shrinkage than a matrix in order to prevent cracking of ceramic nuclear fuel, wherein the three-layer-structured nuclear fuel particles before coating is included in the range of between 5 and 40 fractions by volume based on after sintering. More specifically, the present invention provides a composition for preparing a fully ceramic capsulated nuclear fuel containing three-layer-structured isotropic particles coated with the substance which includes, as a main ingredient, a silicon carbine derived from a precursor of the silicon carbide wherein a condition of ΔL.sub.c>ΔL.sub.m at normal pressure sintering is created, where the sintering shrinkage of the coating layer of the three-layer-structured isotropic nuclear fuel particles is ΔL.sub.c and the sintering shrinkage of the silicon carbide matrix is ΔL.sub.m; material produced therefrom; and a method for manufacturing the material. The residual porosity of the fully ceramic capsulated nuclear fuel material is 4% or less.

This SiC heater includes a heating element having a thin plate-shaped silicon carbide sintered body and an insulating coat film formed on a surface of the silicon carbide sintered body, a pair of electrodes for conducting electricity in the heating element, and a heater base that holds the heating element from one surface side while insulating the heating element from heat from the heating element, the insulating coat film is located on a surface of the silicon carbide sintered body opposite to the heater base, an electrical resistivity at room temperature of the insulating coat film is 10.sup.9 .Math.cm or more, a thermal expansion coefficient of the insulating coat film is 210.sup.6/K or more and 610.sup.6/K or less, SiO.sub.2 is included as a matrix, 1% by weight or more and 35% by weight or less of a first additive component including at least one of B.sub.2O.sub.3 and Al.sub.2O.sub.3 is contained, and 1% by weight or more and 35% by weight or less of a second additive component including at least one of MgO and CaO is contained.

The present invention relates to a method of producing a SiCSi composite component. The method includes preparing a first molded body containing SiC particles by a 3D printing method, wherein the first molded body has a first average pore diameter M.sub.1;

forming a second molded body, in which the first molded body and a dispersion containing carbon particles are brought into contact so that the pores are impregnated with the carbon particles, wherein the carbon particles have a secondary particle having an average particle diameter M.sub.2, and the carbon particles satisfy the following formula:

M.sub.2M.sub.1/10; and

forming a SiCSi composite component by carrying out that the second molded body is impregnated with a metallic Si and is reactively sintered;

wherein the content of Si is in the range of 5% by mass to 40% by mass in the SiCSi composite component.

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

Part comprising said particulate ceramic composite material.

Method for manufacturing said part.

Ceramic composite materials that are reinforced with carbide fibers can exhibit ultra-high temperature resistance. For example, such materials may exhibit very low creep at temperatures of up to 2700 F. (1480 C.). The present composites are specifically engineered to exhibit matched thermodynamically stable crystalline phases between the materials included within the composite. In other words, the reinforcing fibers, a debonding interface layer disposed over the reinforcing fibers, and the matrix material of the composite may all be of the same crystalline structural phase (all hexagonal), for increased compatibility and improved properties. Such composite materials may be used in numerous applications.

Provided is a SiC sintered body which contains nitrogen atoms, wherein a ratio R.sub.max/R.sub.ave of a maximum volume resistivity R.sub.max of the sintered body to an average volume resistivity R.sub.ave of the sintered body is 1.5 or lower; a ratio R.sub.min/R.sub.ave of a minimum volume resistivity R.sub.min of the sintered body to the average volume resistivity R.sub.ave is 0.7 or higher; and a relative density of the sintered body is 98% or higher.

A refractory article including a body having central opening extending through at least a portion of the body, the central opening having a receiving surface having a convex curvature. In an embodiment, the body can include a coupling protrusion extending from a portion of an upper surface of the body and a coupling depression on a portion of a bottom surface of the body.

A method for the manufacture of a three-dimensional object using a refractory matrix material is provided. The method includes the additive manufacture of a green body from a powder-based refractory matrix material followed by densification via chemical vapor infiltration (CVI). The refractory matrix material can be a refractory ceramic (e.g., silicon carbide, zirconium carbide, or graphite) or a refractory metal (e.g., molybdenum or tungsten). In one embodiment, the matrix material is deposited according to a binder-jet printing process to produce a green body having a complex geometry. The CVI process increases its density, provides a hermetic seal, and yields an object with mechanical integrity. The residual binder content dissociates and is removed from the green body prior to the start of the CVI process as temperatures increase in the CVI reactor. The CVI process selective deposits a fully dense coating on all internal and external surfaces of the finished object.

A process for preparing a composite material comprising an electride compound and an additive, said process comprising (i) providing a composition comprising the additive and a precursor compound of the electride compound, wherein the precursor compound comprises an oxidic compound of the garnet group, and wherein the additive has a boiling temperature which is higher than the melting temperature of the precursor compound; (ii) heating the composition provided in (i) under plasma forming conditions in a gas atmosphere to a temperature above the Httig temperature of the precursor compound and below the boiling temperature of the additive, obtaining the composite material.