JPS6283385A - Manufacture of ceramic foam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a ceramic foam suitable for application to building materials and the like.

[Conventional technology]

Much research has been done on methods for producing ceramic foams from volcanic ejecta.

For example, JP-A-52-123411 and JP-A-54
Publication No. 8613 describes a method of heating and foaming a mixture of whitebait and water glass.

[Problem that the invention seeks to solve]

However, when the inventors tried this again, they could only obtain a material with large bubbles and low mechanical strength.

In addition, in order to industrially produce ceramic foam at low cost, it is desirable to carry out heating and foaming at as low a temperature as possible from the viewpoint of production equipment and energy costs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for solving the above-mentioned problems and producing a ceramic foam having small bubbles and high mechanical strength at a low cost.

[Means for solving problems]

The present invention has discovered that by adding a Naz O compound or a CaO compound, the heating foaming temperature can be lowered, and by adding a small amount of calcium phosphate, a ceramic foam with small bubbles and high mechanical strength can be obtained. It is something that

That is, the gist of the present invention is as follows: Volcanic ejecta: 70-90 parts Na, O compound: 5-15 parts by weight CaO compound: 2-10 parts by weight Calcium phosphate: 0.5-5 parts by weight Blowing agent: 0.1-1 part by weight Part 800-110 of the above compound was uniformly mixed in powder form.
A method for producing a ceramic foam, which comprises heating to 0°C.

The volcanic ejecta used in the present invention includes volcanic rock, volcanic ash, etc., and in its chemical composition, 5i02 is 45 to 8.
0%, and those containing 5 to 25% Al2O2 are preferable. Such volcanic ejecta include, for example, obsidian, nacre, pine rock, pumice, anti-flinder, andesite, basalt, rhyolite,
These include feldspar, white clay, shirasu, bentonite, etc. These volcanic products are preferably used in powder form, preferably passed through a sieve of 200 mesh or more.

The Na20 compound used in the present invention includes, in addition to sodium oxide, sodium hydroxide and sodium carbonate (soda ash) having Na and O components.

In addition to calcium oxide, the CaO compounds used in the present invention include calcium hydroxide, calcium carbonate, calcium oxalate, etc. that have CaO components, and those that exist in large amounts naturally as limestone, lime, slaked lime, etc. Can be used.

The calcium phosphate used in the present invention is preferably a normal salt. Acidic salts make it difficult to obtain a ceramic foam with fine cells and high mechanical strength.

Foaming agents used in the present invention include silicon carbide, silicon nitride,
Examples include boron nitride, carbon black, and carbonates such as soda carbonate, calcium carbonate, magnesium carbonate, and dolomite.

The above Naz O compound, CaO compound in the present invention,
Calcium phosphate and foaming agents are also best used in powder form.
It is preferably passed through a sieve with a mesh size of 200 or more to form a fine powder.

In the present invention, 70 to 90 parts by weight of volcanic ejecta, Na
, O compound 5-15 parts by weight, CaO compound 2-10 parts by weight, calcium phosphate 0.5-5 parts by weight, blowing agent 0.1-10 parts by weight
It is mixed at a ratio of 1 part by weight.

This mixture may be heat-foamed as a powder, but it may also be granulated using a granulator or press-molded and then heat-foamed.

The heating and foaming temperature is 800 to 1100°C, preferably 850 to 1000°C.

In the present invention, the heating and foaming temperature of the raw material mixture is lowered by adding the Na2O compound and the CaO compound. The Naz O compound and the CaO compound work together to lower the melting and softening temperature of the volcanic ejecta, which is the main component.

It melts and softens and foams at 800 to 1100°C only when the above composition ratio is achieved.

That is, if the proportion of the NagO compound is too high, the cells will become coarse and cracks will appear during cooling after foaming, making it impossible to obtain a good ceramic foam, while if the proportion of the Na2O compound is too small, the melt softening temperature becomes difficult to lower. Furthermore, although the melting and softening temperature does not decrease significantly with the Na2O compound alone, the melting and softening temperature decreases synergistically by adding a CaO compound thereto.

If the amount of CaO compound added is too small or too large, the above synergistic effect will not be exhibited.

In the present invention, by adding calcium phosphate, the foam has small cells and high mechanical strength. If the proportion of calcium phosphate is too high, it will be difficult to obtain a ceramic foam with a high expansion ratio, and the mechanical strength of the foam will also become weak. Furthermore, if the proportion of calcium phosphate is too small, the effect of reducing bubbles will not be sufficiently exhibited.

The amount of the blowing agent used varies depending on the expansion ratio of the intended foam and the type of blowing agent. If the amount of the blowing agent is too small or too large, a good foam cannot be obtained, and if it is too large, the cost of raw materials will increase.

In the present invention, the raw material mixture is heated and foamed using an electric furnace, rotary furnace, tunnel furnace, or the like. During heating and foaming, a metal wire or wire mesh can be embedded in the raw material mixture for reinforcement, and a jig can also be embedded.

When heating and foaming the powder, granules, or molded body of this raw material mixture in a furnace, the mixture is placed on an endless belt passing through the furnace, and the mixture is heated and foamed while passing through the furnace. If necessary, it is possible to continuously manufacture ceramic foam by compression molding it into the appropriate shape using rolls while it is still soft and deformable, and then slowly cooling it before releasing it from the furnace. .

[Effect]

In the present invention, powdered raw material compounds are mixed uniformly, and this mixture is heated to 800 to 1100°C in a heating furnace.
It melts and softens when it receives heat, and when it melts and reaches the appropriate viscosity, the foaming agent decomposes and foams. At this time, Na, O compounds, C
The aO compound brings the melting and softening temperature of the mixture into the above temperature range, and the calcium phosphate makes the cells of the foam smaller and more uniform, increasing its mechanical strength.

〔Effect of the invention〕

As mentioned above, in the present invention, Na is added to volcanic ejecta.
, 0 compound, CaO compound, and calcium phosphate, the cells of the foam become smaller and more uniform, increasing mechanical strength.

In addition, the heating foaming temperature can be lowered, and therefore,
A high-performance heating furnace is not required, heating and cooling time is shortened, energy costs are reduced, manufacturing efficiency is improved, and manufacturing costs can be reduced.

The ceramic foam obtained according to the present invention can be used as a building board for external wall materials, roofing materials, flooring materials, etc. if it is in the form of a plate. Moreover, those press-molded using a mold can be used for roof tiles, tiles, board materials, etc.

Next, examples of the present invention will be shown.

[Example 1] 84 parts by weight of anti-firestone powder passed through the JOO mesh, 10 parts by weight of soda ash, 4 parts by weight of slaked lime, 2 parts by weight of calcium phosphate, and 0.25 parts by weight of silicon carbide were mixed almost uniformly. , the powder is placed on an endless belt passing through a heating furnace to a nearly uniform thickness, and heated to 960°C while passing through the heating furnace.
After foaming by heating, a ceramic foam was obtained by slow cooling.

The obtained ceramic foam has a specific gravity of 0.6 and a bending strength of 4.
The compressive strength was 0Kg/cffl and 100Kg/cat.

When this ceramic foam was cut and the cut surface was observed, bubbles with a diameter of about 111 mm were uniformly dispersed.

[Example 2] 70 parts by weight of anti-flinder stone passing through 250 meshes, 15 parts by weight of soda ash
parts by weight, 8 parts by weight of limestone, 5 parts by weight of bentonite, 2 parts by weight of calcium phosphate, and 0.25 parts by weight of silicon carbide were uniformly mixed, kneaded with 25 parts by weight of water, and formed into a plate shape.

After thoroughly drying this, it was placed in an electric furnace and heated to 1000°C, resulting in a specific gravity of 0.55 and a bending strength of 35 kg/cd.
A ceramic foam having a compressive strength of 75 kg/aJ was obtained.

If you cut this ceramic foam and look at the cut surface, you will see
Bubbles with a diameter of about 0.50 were uniformly dispersed.

[Example 3] 83 parts by weight of andesite passing through 250 meshes, 10 parts by weight of soda ash
Parts by weight, 4 parts by weight of slaked lime, 3 parts by weight of calcium phosphate, and 0.5 parts by weight of silicon carbide were uniformly mixed, 15 parts by weight of water was added thereto, and the mixture was kneaded and granulated into granules. After thoroughly drying, place it on a wire mesh to an even thickness and place it in a heating oven.
It was heated to 950°C and foamed. After that, when it was slowly cooled and taken out, the specific gravity was 0.4, the bending strength was 30 kg/ad,
-Ff A ceramic foam having a shrinkage strength of 60 kg/cat was obtained.

If you cut this ceramic foam and look at the cut surface, you will see
Bubbles with a diameter of about 0.7 M were uniformly dispersed.

Claims (1)

[Claims] 1. Volcanic ejecta 70-90 parts by weight Na_2O compound 5-15 parts by weight CaO compound 2-10 parts by weight Calcium phosphate 0.5-5 parts by weight Blowing agent 0.1-1 part by weight Above compounds 800-110
A method for producing a ceramic foam, the method comprising heating to 0°C.