The problem addressed by the invention is that of producing aerogels which have as high and permanent a hydrophobicity as possible and which have a reduced combustibility, that is as low a carbon content as possible, and are simultaneously less rigid and brittle than known systems, i.e. which with reduced combustibility have a high flexibility and high stability at the same time, that is high mechanical load-bearing capacity. Said problem is solved in that the invention provides gels chosen from lyogel or aerogel, which are synthesised from oxide units and [R.sub.xSiO.sub.(4-x)/2] units, wherein the primary particles have a change of concentration in [R.sub.xSiO.sub.(4-x)/2] units from the inside to the outside, wherein x can be the same or different and is 1 or 2, and R can be the same or different and is hydrogen or an organic substituted or unsubstituted radical, and wherein the oxide units contain [SiO.sub.4/2] units, and a method for producing same. The gels provided can be used in cosmetic, medical or for chromatographic applications, and as a catalyst or catalyst support. If the gels are aerogels, same are preferably used for thermal and/or acoustic insulation.

The invention relates to a method for producing aerogels, in particular silica aerogels, by way of a sol-gel process.

Provided is a silica aerogel with enhanced physical properties. The silica aerogel can have a tap density of 0.030 to 0.070 g/mL, and a carbon content of 11.2 to 12.1 wt %.

The present invention relates to a method for producing a silica aerogel and a silica aerogel produced thereby. More specifically, a first water glass solution is used to form a first silica wet gel, and then a second water glass solution is additionally added to form a second silica wet gel organically bonded to the first silica wet gel which serves as a basic skeleton, so that a silica aerogel with enhanced physical properties is formed to increase the resistance to shrinkage in ambient drying. Thus, a low-density silica aerogel may be formed, and the concentrations of the first and second water glass solutions may be adjusted to control the physical properties of the silica aerogel.

The present invention relates to a method for producing a silica aerogel and a silica aerogel produced thereby. More specifically, a first water glass solution is used to form a first silica wet gel, and then a second water glass solution is additionally added to form a second silica wet gel organically bonded to the first silica wet gel which serves as a basic skeleton, so that a silica aerogel with enhanced physical properties is formed to increase the resistance to shrinkage in ambient drying, and the concentration of silicon dioxide in each of the first and second water glass solutions is controlled, thereby providing a method for producing a silica aerogel by which a silica aerogel having a specific tap density and controllable density can be produced, and also providing a silicon aerogel produced by the method.

A method for producing a micron-size spherical silica aerogel having a selectable or controllable average particle size, the method includes producing a surface-modified silica sol by adding a first organosilane compound to a aqueous acid-silica sol, which comprises an inorganic acid and a water glass solution, with a pH less than 3, dispersive mixing a non-polar organic solvent, a second organosilane compound, and the surface-modified silica sol, at a selected stilling rate which is inversely related to an average particle size, without adding any surfactant or dispersant, a micron-size spherical silica hydrogel and further a hydrophobic micron-size spherical silica gel are then produced. Following by drying or stirring the hydrophobic micron-size spherical silica gel to obtain a controllable micron-size silica aero-gel in a spherical and powder forms, respectively.

The present invention relates to a method of preparing ultra-pure silicon carbide in which a super-porous spherical silica aerogel is used as a silica raw material. By preparing the silica aerogel particles using low-cost water glass, a reaction area with respect to a carbon raw material is increased to enable low-temperature synthesis of silicon carbide, the size and shape of silicon carbide powder may be uniformly controlled to prepare ultra-pure silicon carbide, and economic efficiency and productivity of the silicon carbide synthesis may be improved. Thus, it is expected that the silicon carbide powder prepared by the preparation method of the present invention may be provided as an optimized raw material for the preparation of silicon carbide sintered body and single crystal (ingot).

The present invention relates to a method for producing a silica aerogel and a silica aerogel produced thereby. More specifically, a first water glass solution is used to form a first silica wet gel, and then a second water glass solution is additionally added to form a second silica wet gel organically bonded to the first silica wet gel which serves as a basic skeleton, so that a silica aerogel with enhanced physical properties is formed to increase the resistance to shrinkage in ambient drying, and the concentration of silicon dioxide in each of the first and second water glass solutions is controlled, thereby providing a method for producing a silica aerogel by which a silica aerogel having a specific tap density and controllable density can be produced, and also providing a silicon aerogel produced by the method.

The present invention relates to a method for producing a silica aerogel and a silica aerogel produced thereby. More specifically, a first water glass solution is used to form a first silica wet gel, and then a second water glass solution is additionally added to form a second silica wet gel organically bonded to the first silica wet gel which serves as a basic skeleton, so that a silica aerogel with enhanced physical properties is formed to increase the resistance to shrinkage in ambient drying. Thus, a low-density silica aerogel may be formed, and the concentrations of the first and second water glass solutions may be adjusted to control the physical properties of the silica aerogel.

The invention relates to a method for producing aerogels, in particular silica aerogels, by way of a sol-gel process.