DE2814315C2 - Process for the production of foamed silicate materials - Google Patents

Description

The invention relates to a method for the production of foam-like silicate materials, with good mechanical strength, usable in electrical, heat insulating, sound absorbing and radiation protection technology, based on glass, silicon carbide and possibly basalt.

For use as an electrical, heat-insulating and sound-absorbing insulating material, also in the field of radiation protection, which at the same time has good mechanical strength at elevated temperatures, are used in large amounts of pure compounds such as aluminum oxide, magnesium oxide, titanium dioxide, zirconium oxide and the like. used. Such ceramic materials, however, require special, sometimes expensive raw materials, and those for them The processes to be used are relatively complicated and also require very high melting temperatures (greater than 1400 ° C), which in turn means an increased energy requirement.

The casting processes known for example in the production of glass-forming mixtures, whereby Elaborate shaping processes are avoided when using ceramic materials such as porcelain Corundum, mullite, sillimanite or asbestos products, etc., hardly applicable because of the required temperatures to produce a pourable melt are so high that the economic viability is called into question. On the other hand, the crystallization process causes problems, even if it were possible, for example one To pour aluminum oxide melt, because with the inevitable rapid cooling too rapid crystallization occurs which leads to large crystals, thereby reducing the mechanical, electrical and other properties are adversely affected.

There has therefore been no lack of experiments and publications in which compositions for The most economical production of ceramic materials is described, which also should have good properties.

From the German Offenlegungsschrift 24 23 834 is a method for the production of ceramic sintered molded bodies known, in which 10 to 80 wt .-% glass, 20 to 90 wt .-% volcanic ingredients Origin such as basalt, diabase and / or slag and / or quartz sand and / or pumice stone and optionally up to about 1.0% by weight of inorganic blowing agent such as silicon carbide or carbon black in finely divided form Condition dry mixed with each other, the dry mixture is in a mold and at temperatures sinters from about 750 to 1500 ° C and then removed from the mold.

However, the disadvantage of all of these known processes is the large amounts of energy required for production the materials have to be consumed by melting. In addition, these materials cannot be used Manufacture lightweight foams with good mechanical properties, and many are not considered either

Ό Radiation protection or as a good heat and sound insulation material suitable.

It is therefore an object of the present invention to create a silicate material that the Disadvantages of the known materials does not have and in particular only one comparatively for its production requires a small amount of energy and starts from cheap raw materials.

According to the invention, this object is achieved by using 60 to 90% by weight of ground bottle glass different color and a particle size below 40 μπι with 10 to 12Gew .-% basalt and / or 10 to 15% by weight asbestos and / or 10 to 15% by weight slate and 0.1 to 0.5% by weight SiC and 19 to 36% by weight a 20-35% aluminum phosphate solution

-5 on the dry mass, mixed and heated to 700 to 900 ⁰ C.

A material is preferably used as basalt which is essentially composed only of feldspar and in which the lime feldspar or anorthite [Ca (Si ₂ Al ₂ Oe)] makes up the largest proportion and in the range of soda feldspar or albite [Na (AlSijOe)] is in the range from 30 to 38% by weight and potassium feldspar or orthoclase [K (AISi ₃ O ₈ )] should only be present at 2 to 5% by weight. This combination of anorthite, albite and orthoclase corresponds to the oxide composition:

SiO ₂

AI ₂ O ₃ [MgO Fe ₂ Oj TiO ₂ ]
"0 CaO

Na ₂ O
K ₂ O

48-52%

18-29%

8-12%

2- 50/0

1- 2%

Such a basalt composition, whereby the components of MgO, TiO ₂ , Fe ₂ O3 should not be taken into account, gives the best results.

Should the material also have expansion-reducing and absorbing properties for thermal neutrons boric acid is used.

The material according to the invention, which can be cast into blocks, plates, rods and tubes, In contrast to many other known materials, it shows surprisingly good strength properties and thermal shock resistance.

The resulting foam material has the following physical properties:

a ^ Volume weight 0.15-0.25g / cm3 b) Compressive strength 1962.0-2452.5 kPa bO _C ) Flexural strength 490.0 - 588.6 kPa d) El. Dielectric strength 13.0-15.0 kV / cm e) El. spec. resistance 1.0 x 10-2 ohms / cm (at 288.15 K) 0 Heat resistance 103.15-723.15 K ^b5 g) Thermal conductivity 0.0736 W / m K

Instead of basalt, the mixture can also be made up with feldspars or with the

Feldspars related double silicates, such as plagioclase, oligoclase or oligoclase and andesine, also from the mica, like muscovite

[K Al ₂ (OH F) ₂ / A1 Si ₃ O ₁₀ ],
Phlogopite [KMg ₃ (F OH2 / Al Si ₃ O ₁₀ J
Biotite - K (Mg, Fe ") 3 [(OH) ₂ Z (ALFe ¹ H)] Si ₃ O ₁₀ ,
Zinnwaldite - K (UFe "Al) ₃ ROH) ₂ / AISi ₃ O ₁₀ ],
y]

or from serpentine series like
Chrysol asbestos Mg ^ (OHVSUO ₁₀ ]
or from nepheline KNa ₃ [AISiOi] ₄ .

The composition of various minerals and additives, such as boric acid, metasilicates, borates, can you can combine very well and the eutectic forces use. Very good combinations are basalts and mica or basalts and serpentines.

Foam bodies according to the present invention made of brown and white glass, however, have the the following physical indicators:

Compressive strength

Flexural strength

El. Dielectric strength

Thermal conductivity

Heat resistance
Volume weight

12772-19158 kPa
3924-4903 k Pa
17-25kV / cm
0.079 W / mK
at 283.15 K.
73.15-923.15K
0.30-0.40 g / cm ³

It was found that foam bodies made of brown and white glass give greater strengths than such made of green glass.

So you can already mix a mixture of ground bottle glass or broken glass with a Particle size below 40 μ can already produce a silicate material if you add aluminum phosphate solution to the mixture It sets at room temperature, creating a foam that is then added Temperatures between 523.15 and 673.15 K with the help of anhydrite dries. These temperatures can be reached in practically every drying cabinet. The anhydrite absorbs residual water and turns into plaster of paris.

The proportion of added anhydrite is 4 to 8 wt .-% and the amount of aluminum phosphate solution, which is 20 to 35% aqueous Solution acts to 19 dis 36% by weight. These amounts were with a corresponding reduction in the proportion of glass powder considered.

The resulting foam material has the following physical characteristics:

Roughness weight
Compressive strength
Foam body is porous

0.45-0.50 kg / cm ³
2943-3924 k Pa

Claims (1)

1
Claim: Process for the production of foam-shaped silicate materials with good mechanical strength, usable in electrical, heat-insulating, schalldf'.nmenden and radiation protection technology on the basis of glass, silicon carbide and optionally basalt, characterized in that, that one has 60-90% by weight of ground bottle glass of different color and particle size below 40 μm with 10-12% by weight basalt and / or 10-15% by weight asbestos and / or 10-15% by weight of slate, 0.1-0.5% by weight of SiC, and 19-36% by weight of a 20-35% aluminum phosphate solution, based on the dry matter, mixes and heated to 700 to 900 ° C.