DE3314796A1 - Premix for the preparation of high-melting foam ceramic, and process for the preparation thereof - Google Patents

Abstract

The invention relates to a premix for the preparation of high-melting foam ceramic which consists of finely comminuted igneous rock and/or fly ash, blowing agent and flux. According to a preferred embodiment, this premix consists of basalt powder and/or andesite powder and/or diabase powder and/or fly ash, and also of silicon carbide and/or carbon black as blowing agent and of borax and/or boric acid as flux.

Description

Approach to the production of high-melting ceramic foam and process for their production The present invention relates to one approach for the production of high-melting ceramic foam, which is characterized by that he is made of crushed effusion rock and / or fly ash, propellant, and consists of flux.

The invention also relates to a method for producing a high-melting ceramic foam made from the aforementioned ingredients.

The approach according to the invention thus consists of ground effusion rock e.g. from basalt, andesite or diabase dusts and / or fly ash, this being Approach also as a propellant, for example silicon carbide or carbon black as well as a Contains flux such as borax or boric acid.

An exemplary approach according to the present invention consists of 300 kg andesite (grain size 0.1 to 0.09 mm), 40 kg borax and 0.3 to 0.5 kg silicon carbide.

Another exemplary approach in accordance with the present invention is from 300 kg fly ash (grain size 0.09 mm) 40 kg borax and 0.3 to 0.5 kg silicon carbide.

The borax component can, if necessary, at the expense of higher foaming temperatures be reduced.

The preparation of the batch normally only requires one work step, if the Backfill components are in the dry state, i. E. have a moisture content of at most 1 to 2 ffi and the specified Own grits.

This operation consists of a homogeneous mixing of the dry Offset components.

It has been shown that the so-called batch mixer for this Mixing operations are particularly suitable.

For the purpose of producing moldings, a weighed amount is used filled with powder mass in forms of open or closed construction and the powder bulk then leveled.

The degree of filling of the molds is usually between 50 and 85 ffi with a bulk density of about 1.1 g / cm3.

The forms consist of a heat-resistant or fire-resistant Material, as the powder mass in the molds foamed at temperatures above 1000 ° C will.

Heat-resistant steels or ceramic materials are used as mold materials on the basis of Chamotte mass in question.

In the case of large-area molds, the bottom of the mold has ventilation holes (Hole spacing 9 to 10 cm, hole diameter approx. 2 mm) so that between No gas pressure builds up in the mold bottom and foaming mass.

The vent holes are preferably made with a microporous Paper covered to prevent the holes from foaming.

The shapes are also preferably coated with a release agent, to prevent the powder mass from sticking.

In the following the composition of such a release agent is given, it reads: 35 - 45 kg calcined clay, grain size o, o1-o, lo mm, 0.63 kg tylose 20,000 63 kg water 150 cm3 Schwegocide.

Using molds made of heat-resistant steel is an effortless one Demoulding of the foamed body is best then carried out while the molds are still very hot, i.e. at a point in time when the shapes are not yet essential Have experienced contraction.

In the case of ceramic molds, on the other hand, you can also use them when they have cooled down demould.

Temperatures are required for melting and foaming the molded powder masses above 100,000, preferably temperatures within the temperature range of 1020 up to 1090 ° C required.

The production time for foamed bodies of the dimension - 300 x 2oo x 40 to 70 mm is between 7w5 and 15 hours.

This production time is broken down as follows: 1. Heating-up time from room temperature to 1020 to 1090 ° C: 1.5 to 3.0 hours 2. Holding time up to 1020 to 1090 ° C: 1, o to 2, o hours 3. First cooling period from 1020 to 109000 below solidification temperature: 5 to lo minutes 4. Second cooling period down to room temperature: The foamed bodies are within 5 to 10 hours awake after the holding time has elapsed in a short time, i.e. within 5 to 10 minutes to their solidification temperature to cool to prevent the spherical cells from collapsing.

The material structure and physical properties of the high melting point Foam ceramics resulting from the approach according to the invention or when carrying out the inventive approach Manufacturing process is obtained, namely properties such as water absorption, Density, coefficient of thermal conductivity, coefficient of thermal expansion, thermal shock resistance and strength can be determined by a person skilled in the art on the basis of his specialist knowledge åe according to temperature control vary or determine.

If the above manufacturing conditions are observed, the result is for example a high-melting ceramic foam product made according to the invention with the following properties: Color: black Material structure: closed-cell Average pore diameter: 1-6 mm Water absorption: 0.1% by volume Density: 0.40-0.8 g / cm3 Thermal conductivity o, 1-o, 2 Ecal / m h ° C Thermal expansion coefficient: 65-70x10-7 1 / ° C at 100 ° C Flexural strength: 55-6o kp / cm2 Compressive strength: 28-32 kp / cm2 The essence of the present The invention is further explained in the following on the basis of exemplary embodiments.

Example 1: 3000 g of effusion rock (grain size 0.01 to 0.09 mm) mixed with 400 g borax (decahydrate) and 5 g silicon carbide (grain size oo1 to oo3 mm).

The powder mixture is heated in forms from 100 to 11500C, one Maintained at these temperatures for an hour and then returned to room temperature cooled down.

This creates a closed-cell foamed body with very uniform pore size and high strength. The foamed molding is around the larger the pores and therefore the lighter, the higher the holding or foaming temperature is.

Moldings result for the temperature range from 100 to 1150 ° C with a density of 0.3 to 0.8 g / cm3, the corresponding mean Pore size is 8 to 1 mm in diameter.

Example 2: 300 g of fly ash (grain size 0.09 mm) are mixed with 400 g of borax (Decahydrate) and 5 g silicon carbide (grain size 0.01 to 0.003 mm) mixed.

The powder mixture is heated in molds from looo to 1150 ° C, one Maintained at these temperatures for an hour and then returned to room temperature cooled down.

This creates a closed-cell foamed molded body with very uniform pore size and high strength. The foamed molding is around the larger the pores and therefore the lighter, the higher the holding or

Foaming temperature is.

Moldings result for the temperature range from 1000 to 115 ° C with a density of 0.3 to 0.8 g / cm³, the associated mean pore size is 8 to 1 mm in diameter.

The chemical composition of the calculated according to the mass sets The high-melting ceramic foam according to the invention reads: 35 - 55% by weight SiO2 1 - 7% by weight Na2O 2 - 12% by weight CaO 0.5-5% by weight K20 2 - 12% by weight MgO 1 - 5% by weight B203 0.5-1.0 wt. Propellant (silicon carbide or carbon black)

Claims (4)

P a t e n t a n s r ü c h e 1. Approach to the production of high melting point Foam ceramics, characterized in that they are made from finely comminuted effusion rock and / or fly ash, propellants and fluids. 2. Approach to the production of high-melting ceramic foam according to Claim 1, characterized in that it consists of basalt dust and / or andesite dust and / or diabass dust and / or fly ash, also made of silicon carbide and / or soot as a propellant as well as borax and / or boric acid as a flux, 3. Procedure for the production of high-melting ceramic foam, characterized in that the ingredients of the batches according to claim 1 or claim 2 are intimately mixed, enters into molds, foams at temperatures above 100OC, then the foamed Body cools below its softening point within a short time and finally slowly brings it to normal temperature. 4. The method according to claim 3, k characterized in that within from 1.5 to 3.0 hours, the powder mass from room temperature to 1020 to 1020C heats up, then a hold time at 1020 to Io9o0C of 1, o to 2, o hours adheres, after completion of the foaming process, the foamed body within cools from about 5 to lo minutes below its softening point and finally the subsequent cooling to room temperature completes within 5 to lo hours,