Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – Of inorganic materials
Reexamination Certificate
2001-05-21
2002-11-12
Fiorilla, Christopher A. (Department: 1731)
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
Of inorganic materials
C264S043000, C065S017300, C065S017500
Reexamination Certificate
active
06478993
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The invention relates to processes for the manufacture of foamed articles for refractory, thermal insulation and construction applications such as in the form of bricks, blocks, slabs or discs.
2. Related Art
A problem of a decrease of the density and thermal conductivity is extremely important for producing refractory, thermal isolation and construction articles. This problem is solved by developing new porous materials. An effective method for forming porous structures is the method for the manufacture of foamed materials. There are two main routes presently known for the production of a foamed structure.
I Route:
(a) preparing a stable foam from water and foaming agent;
(b) preparing a wet mixture of solid components, where cement is the main substance;
(c) quick mixing (a) with (b); and
(d) filling the molds with prepared in (c) foam mass.
U.S. Pat. No. 4,158,685 describes the method of making an insulating refractory shape by: (a) preparing a slip of water, deflocculating agent, finely divided solid refractory particles, and binder; (b) preparing a foam of water, air, and foaming agent; (c) admixing the slip and the foam to produce a foamed slurry; (d) casting the slurry into molds; (e) curing; (f) drying the cast pieces so formed; and (g) firing the pieces, the improvement wherein: (1) the slip consists essentially of at least 7.5% cement, from 0 to 50% clay, the balance of the solid ingredients being refractory aggregate all of which passes a 28 mesh screen, all percentages being by weight and based on the total weight of dry solid ingredients, and sufficient water to produce, when mixed with the foam, a foamed slurry having a viscosity of from 1000 to 30,000 centipoises; (2) the foam has a density of not over about 5 pcf, (3) the slip and the foam are admixed in the proportion of from 0.25 volume to 3 volumes of foam for each volume of slip; (4) the cast foamed slurry is cured at a temperature of not over about 72° F. for 16 to 24 hours and then (5) dried at a temperature of not over about 200° F.
U.S. Pat. No. 3,944,425 describes foamed lightweight ceramic compositions. A fired clay product composed of a rigid cellular mass having a bulk density in the range from about 10 to about 105 pcf obtained by mixing, foaming and firing a composition comprising about 20 to about 95 parts of clay, about 4 to about 35 parts of hydraulic cement, about 0.2 to about 30 parts of inert particulate lamellar foam stabilizer, from 0 up to about 76 parts of inert solid material, about 21 to about 70 parts of water, and a gas generating agent, said parts being by weight of the dry ingredients, all of the foaming action having occurred between cessation of said mixing and about 10 minutes thereafter.
II Route:
A foamed structure is a result of dissociation and/or burning reactions, which go with gassing in heated to the molten state mixture.
U.S. Pat. No. 5,516,351 describes a foamed glass product that can be used as insulation products. The process comprises providing crushed glass particles and a foaming agent, preferably related from CaCO
3
or CaSO
4
. The pretreated glass and foaming agent are sized and mixed. The mixed glass and foaming agent are placed in molds and passed through a furnace where the mixture is heated to a foaming temperature and then cooled to produce foamed glass blocks. Furthermore a non-reactive gas selected from SO
3
and CO
2
is provided to sweep air away from the mixture during heating. The size of the starting glass particles impacts the insulation properties. A starting glass particle size of approximately 100-700 microns is preferred.
U.S. Pat. No. 3,975,174 relates to a method for manufacture of foamed glass. Finely divided glass, which may have a viscosity between 10
6
and 10
7
poises at 950° C. to 1100° C. and which may be of a composition suitable to conversion into a vitroceramic, is mixed with up to a few percent by weight of a foaming agent including a mixture of SnO
2
and SiC, in equimolar or with an excess of SiC. The resulting mixture is heated to 950° C. to 1100° C. to effect foaming by evolution of CO
2
from the foaming agent, and the resulting glass foam is cooled. The nucleation and crystallization steps by which the glass is converted to a vitroceramic may be caused to occur without allowing the foam to return to room temperature.
U.S. Pat. No. 4,992,321 describes a similar method for manufacture of foam glass.
However these methods have some disadvantages.
In I Route—Foamed structure is damaged by mixing solid components with the foam. The time of homogenization is limited and does not allow for the production of a regular, controlled structure of the material.
In II Route—There is an indispensable requirement that the melting and dissociation processes have to coincide at the same temperature interval. This limits chemical composition of the mixtures.
SUMMARY OF THE INVENTION AND ADVANTAGES
A method according to the invention of forming foamed articles comprises preparing a homogeneous mixture of at least one oxygen-containing, water-insoluble raw material having a particle size <200 microns and at least one gas forming reagent having a particle size <130 microns. The mixture is humidified, shaped and heated to a formation temperature sufficient to melt the raw material to a molten liquid state at which point the raw material reacts with the gas forming reagent to produce a molten liquid foamed material. Once foamed, the material is cooled to a solid state.
The subject method has the advantage of enabling the production of foamed structural articles from different raw materials or combinations of materials for refractory, thermal isolation, construction and other application. The basis of the subject foaming method is a chemical gassing reaction. According to further preferred features of the invention, clusters of carbides and nitrides (boron, silicon, titanium, vanadium, wolfram and etc.) act as universal gas forming reagents. The clusters react with oxygen-containing liquid phase (molten state of the raw materials) at a temperature of its formation. The result of this reaction is gaseous carbon or nitrogen oxides that generate a foamed structure. At heating, the inorganic oxygen-containing natural and synthesized: silicate, aluminasilicate, borate, phosphate in crystalline, vitreous or amorphous state and large number of oxides (B
2
O
3
; Al
2
O
3
; SiO
2
; P
2
O
5
; ZrO
2
and etc.) and/or mixtures of said above raw materials turn into liquid phase (molten state) which, independent of the temperature of its formation, reacts with the gas forming reagent. The speed of the gassing reaction can be advantageously adjusted with great precision by: selection of the particle size of gas forming reagent (carbide, nitride), control of the viscosity of liquid phase (molten state) and duration at the heating temperature.
DETAILED DESCRIPTION
A method of forming foamed structural articles according to a presently preferred embodiment of the invention includes the preparation of a homogeneous mixture of at least one oxygen-containing, water-insoluble raw material having a particle size <200 microns and at least one gas forming reagent having a particle size <130 microns. The components of the mixture can be sized separately and then blended together or else sized and blended at the same time, depending upon the selection of the components. The mixture is humidified by adding water to the mixture. The amount of water can be varied depending upon the material and the property of the humidified mixture which is desired. For example, the mixture can be humidified to a level where the homogeneous mass exhibits the property of thixotrophy, wherein the material becomes more fluid when agitated such that it can properly and fully fill the shape of a mold cavity and thereafter has the characteristic of setting up and taking the shape of the mold when agitation is discontinued, such that the material can be removed from the mold while retaining the shape imparted by the mold cavity. Such a “green
Gontmakher Vladimir
Pevzner Evgueni
LandOfFree
Method for the manufacture of foamed materials does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for the manufacture of foamed materials, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for the manufacture of foamed materials will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2919209