The present invention discloses novel methods for producing highly porous ceramic and/or metal aerogel monolithic objects that are hard, sturdy, and resistant to high temperatures. These methods comprise preparing nanoparticulate oxides of metals and/or metalloids via a step of vigorous stirring to prevent gelation, preparing polymer-modified xerogel powder compositions by reacting said nanoparticulate oxides with one or more polyfunctional monomers, compressing said polymer-modified xerogel powder compositions into shaped compacts, and carbothermal conversion of the shaped xerogel compacts via pyrolysis to provide the highly porous ceramic and/or metal aerogel monolithic objects that have the same shapes as to their corresponding xerogel compact precursors. Representative of the highly porous ceramic and/or metal aerogel monolithic objects of the invention are ceramic and/or metal aerogels of Si, Zr, Hf, Ti, Cr, Fe, Co, Ni, Cu, Ru, Au, and the like. Examples include sturdy, shaped, highly porous silicon carbide (SiC), silicon nitride (Si.sub.3N.sub.4), zirconium carbide (ZrC), hafnium carbide (HfC), chromium carbide (Cr.sub.3C.sub.2), titanium carbide (TiC), zirconium boride (ZrB.sub.2), hafnium boride (HfB.sub.2), and metallic aerogels of iron (Fe), nickel (Ni), cobalt (Co), copper (Cu), ruthenium (Ru), gold (Au), and the like. Said aerogel monolithic objects have utility in various applications such as, illustratively, in abrasives, in cutting tools, as catalyst support materials such as in reformers and converters, as filters such as for molten metals and hot gasses, in bio-medical tissue engineering such as bone replacement materials, in applications requiring strong lightweight materials such as in automotive and aircraft structural components, in ultra-high temperature ceramics, and the like.

The invention relates to a raw material for producing a refractory product, a use of this raw material, and a refractory product comprising a raw material of this kind.

A refractory composition is formed by preparing a set retarded fresh cementitious composition formed from a class C fly ash, a set retardant such as boric acid, and an alkali activator such as an alkali metal citrate salt, and contacting the set-retarded fresh cementitious composition with a pH regulator, such as an alkali metal hydroxide or alkali metal carbonate. The set retarded mixture provides workability and avoids equipment fouling caused by premature setting, while the alkali activator provides rapid setting when desired. The cementitious composition is shaped into a brick, panel, slab, concrete fire log, or the like and allowed to harden. The hardened cementitious composition can be heated to form a dried cementitious composition, and further heated to produce a high strength refractory composition. Fibers and/or aggregates may be included.

Hydrophobic aggregates for use in refractory castables and gunning mixtures and methods of their preparation. The aggregates here are formed by crushing insulating fire brick and coating the resulting particles with a hydrophobic component. The hydrophobic component may be a polydimethylsiloxane having a terminal silanol group. As a result of the coating process, the coated aggregate has very low levels of alkalis. The aggregates may be used to form refractory castables that do not undergo substantial alkaline hydrolysis due to the reduced levels of alkalis. The castables made from these aggregates display superior physical properties, including lower water content, lower permanent linear change, high strength, and superior thermal conductivity/insulation properties, while at the same time possessing lower density and requiring less water to be used during castable formation. These improved properties also are observed in gunning mixtures formed from these aggregates.

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.

In the field of refining metal melts or slags there is disclosed in particular a reactive material based on calcium aluminate and carbon, its process of preparation and various methods for refining metal melts using the same.

A precast refractory block for a coke oven having high hot strength and stable under-load expansion/shrinkage behavior at high temperatures. Specifically, a silica-based precast refractory block contains a P.sub.2O.sub.5 component in an amount of 0.3 to 2.0 mass %.

A high temperature lightweight thermal insulating material is formed from a mixture that includes cement or silica sand, water and a foaming agent. The foaming agent can be an aluminum powder or a surfactant. The insulating material has a maximum use temperature greater than about 600 degrees Celsius.

The present invention relates to a dry refractory particulate composition comprising a zeolithic microstructure, to a green body and to a refractory lining formed therefrom, and to uses thereof.

A honeycomb body made of a composite material for fire-resistant lightweight structures including honeycomb cells having a cross section is provided. The cell walls of the honeycomb cells are produced from a composite material. The composite material has at least one carrier, for example a woven fabric or a laid fabric made of fibers, and a matrix into which the carrier is embedded. The matrix includes a silicon-based ceramic material, of which the proportion by mass in the matrix along the cell walls is at least 30 wt. %. A method for producing such a ceramic honeycomb body and a honeycomb tube as an intermediate product for the same are also provided. A flat semi-finished product as a curable intermediate product for the production of fire-resistant fiber composite lightweight structures, which has a matrix mixture including dispersed silicon particles, is also provided.