A 3D printer creates a ceramic casting shell of high accuracy. Casting molten metal into this shell creates an accurate metal object. The ceramic shell is formed from a paste made from a low hardness ceramic, dried by freeze drying. To overcome the shear thinning behaviour of ceramic pastes a positive displacement pump is in close proximity to the nozzle.

The invention describes a process for obtaining clay having improved characteristics that comprises incorporating an inorganic matrix onto an organic matrix at determined proportions. The industrial clay obtained is malleable and highly resistant to compression and strain, of great use in the industry of prototype elaboration.

A composition for a refractory material comprising a base mixture having a composition in oxide (mol %) as follows: SiO2 between 69% and 73%; Al2O3 between 22% and 28%; TiO2 between 0.4% and 1%; Fe2O3 between 0.2% and 1%; CaO between 0.1% and 1%; MgO between 0.1% and 1%; K.sub.2O between 0.5% and 2%; Na.sub.2O between 0.1% and 0.5%; and comprising a filler mixture comprising at least one from between a schamotte and a smelting agent.

Described herein are sintered spheres, obtained from red mud, comprising at least aluminium oxide, iron oxides, silicon oxide, and titanium oxide, characterized in that the roundness and the sphericity of the sintered spheres is higher than 0.6.

Described is further a process for the production of sintered spheres, comprising the following steps: a) providing red mud, being a residue from alumina production, b) optionally adjusting the pH value of the red mud to a value lower than 9, c) granulating the red mud from step b) under continuous drying, d) sintering the granulate from step c).

Described herein is also the use of sintered spheres as proppant in fracking processes or as aggregate or lightweight fine aggregate (LWFA) for construction purposes or for geological solidification processes.

The present disclosure relates to a composite of sintered mullite reinforced corundum granules and a method for its preparation. The composite comprises mullite and corundum in an interlocking microstructure. The process for preparing the composite involves the steps of admixing the raw materials followed by sintering to obtain the composite comprising sintered mullite reinforced corundum granules.

Pre-form bonding agent for making vitrified products, said agent including sugar.

A refractory formulation containing an anhydrous solvent, an oleophilic rheology modifier and a refractory aggregate exhibits non-thermoplastic behavior, and remains plastic and formable at temperatures in the range of 10 degrees Celsius to 180 degrees Celsius. The oleophilic rheology modifier may effectively bind with the solvent to create a gel-like structure with organic solvents with moderate to high polarity. A phyllosilicate clay that has been treated with a quaternary fatty acid amine may be used as the oleophilic rheology modifier.

A dried or at least partially dried ceramic feedstock, a method of preparing a dried or at least partially dried ceramic feedstock having a residual solvent content of up to about 5 wt. %, ceramic formulations comprising one or more ceramic precursors, temperature sensitive gelling agent, solvent, and having a viscosity suitable for low pressure injection molding, methods for preparing said ceramic formulations, a method of forming a ceramic article from said ceramic formulations, and a ceramic article obtainable therefrom.

A marking system includes a composition having at least one color precursor, a moldable substrate having a color developer, and a marking instrument for applying the composition to the moldable substrate to form at least one mark on the moldable substrate. A method of producing a colored three-dimensional molded object includes the steps of manipulating a moldable substrate having a color developer into a molded shape having an outer surface; and applying, on the outer surface of the molded shape, a first composition having at least one color precursor to a first portion of the molded shape.

A method of making a sintered ceramic proppant may include providing a ceramic precursor material comprising kaolin clay, 0.2%-2% by weight alkali silicate, and not more than 0.05% by weight polymeric anionic dispersant. The method may further include pelletizing the ceramic precursor and sintering the ceramic precursor pellets for form a sintered ceramic proppant having a specific gravity ranging from 2.40 to 2.57.