A method of applying a circumferential coating material on a circumferential surface of a ceramic honeycomb structure to form a circumferential coat layer. The method includes vertically aligning the longitudinal axis of the ceramic honeycomb structure, rotating the ceramic honeycomb structure around the vertically-aligned longitudinal axis, and applying the circumferential coating material on the circumferential surface of the rotating honeycomb structure at a discharge speed of 50 to 120 mm/s, calculated by
Discharge speed V [mm/s]=Supplied amount q [g/s] of circumferential coating material(Density [g/mm.sup.3] of circumferential coating materialArea S [mm.sup.2] of discharge opening).

Disclosed is a method of spraying a surface with a set-delayed cement. The method comprises providing a set-delayed cement composition comprising water, pumice, hydrated lime, and a set retarder; spraying a surface with the set-delayed cement composition; and allowing the set-delayed cement composition to set on the surface.

A method for preparing and finishing concrete is disclosed, comprising preparing a cement surface by a process comprising the admixture addition, to an industrial concrete mixer/pourer, of a formulation comprising nanosilica, after some or all water is combined and mixed with cement mix, sand and aggregate; followed by pouring and floating; followed by the addition, before or during combination, to the concrete surface, of a formulation comprising water, an alpha-hydroxy acid, a glycol alkyl ether and a polyethylene glycol.

A method for preparing and finishing concrete is disclosed, comprising preparing a cement surface by a process comprising the admixture addition, to an industrial concrete mixer/pourer, of a formulation comprising nanosilica, after some or all water is combined and mixed with cement mix, sand and aggregate; followed by pouring and floating; followed by the addition, before or during combination, to the concrete surface, of a formulation comprising water, an alpha-hydroxy acid, a glycol alkyl ether and a polyethylene glycol.

A porous fiber preform enclosed within a mold may be melt infiltrated by pouring a molten material through an inlet of the mold, the porous fiber preform comprising ceramic fibers. A ceramic matrix composite component comprising the ceramic fibers may be formed by solidifying the molten material that is in the mold and in the porous fiber preform.

An alumina porous body made up by binding aggregate alumina particles to each other, the aggregate alumina particles being bound to each other by a compound comprising yttrium silicate synthesized from mullite and Y.sub.2O.sub.3; and a two-layer structure ceramic porous body with an inorganic porous film formed on the alumina porous body.

A method of manufacturing a honeycomb structure, the method including: a circumferential coat layer forming process of applying a circumferential coating material on a circumferential surface of a ceramic honeycomb structure to form a circumferential coat layer, the circumferential coat layer forming process including: a rotating process of matching an axial direction of the honeycomb structure; and an applying process of discharging the circumferential coating material to apply the circumferential coating material on the circumferential surface of the honeycomb structure that rotates, wherein in the applying process, a discharge speed of the circumferential coating material, calculated by Equation (1), discharged from the discharge nozzle is 50 to 120 mm/s, and

Discharge speed V [mm/s]=Supplied amount q [g/s] of circumferential coating material(Density [g/mm.sup.3] of circumferential coating materialArea S [mm.sup.2] of discharge opening)(1).

A ceramic porous body has an alumina porous body made up by binding aggregate alumina particles to each other, the aggregate alumina particles being bound to each other by a compound including gadolinium silicate, lanthanum silicate or yttrium silicate synthesized from a silicate mineral and at least one rare-earth oxide selected from Gd.sub.2O.sub.3, La.sub.2O.sub.3, and Y.sub.2O.sub.3, and an inorganic porous film formed on the alumina porous body.

A process for treating a substrate made of stone material, preferably in the form of slabs, is provided which process improves the mechanical, thermal and catalytic properties of the substrate. The process includes applying a protective coating to the outer surface of the substrate made of stone material and, to improve adhesion of the protective coating to the outer surface of the substrate, preliminarily subjecting the substrate to one or more pre-treatment steps that eliminate or reduce the presence of pollutants and porosity on the surface of the substrate. The pre-treatment of the substrate made of stone material comprises at least one step of treatment under vacuum conditions inside an autoclave, preferably under pressure conditions lower than 10.sup.2 mbar. Then, after having brought the substrate back to ambient pressure, it is possible to apply and effectively adhere the protective coating to the surface of the stone material.

An extrusion apparatus including a die and a mask are provided such that no slots feed directly into the longitudinal skin forming gap between the mask and the die. In a method of forming a die adapted to improve skin uniformity of extruded cellular ceramic substrates a slotted block of die material is provided including central slots adapted to form a cellular matrix of the substrate and peripheral slots located outwardly of the central slots designed to be covered by a skin former mask and adapted to extrude peripheral batch material. An arcuate skin former is cut corresponding to a target shrinkage so as to intersect the slotted block such that skin flow from tangent slots at 90 degree positions of the die is limited to the peripheral batch material.