CS244183B1 - Plastic ceramic for making aluminum casting and alloys - Google Patents

Abstract

The solution relates to a plastic ceramic mass for the production of tools for casting aluminum and its alloys, in particular nozzles, chutes and floats. The essence is that it consists of 5 to 30 parts by weight of aluminum-silicate slag with a length of 1 to 10 mm, 20 to 50 parts by weight of amorphous silicon dioxide SiO2, 20 to 40 parts by weight of floated kaolin, up to 30 parts by weight of calcium oxide CaO and a binder consisting of 2 to 10 parts by weight of sulfite liquor or 10 to 30 parts by weight of colloidal silicon dioxide sol SiO2.

Description

The invention relates to a plastic ceramic material for the production of tools for casting aluminum and its alloys, in particular nozzles, chutes and floats.

During float casting of molten aluminum into a mold, the flow of liquid metal is directed through a ceramic nozzle. The flow of the melt causes erosion of the nozzle, its thermal stress due to thermal shock and heat transfer from the liquid metal through the nozzle wall to the surroundings. During casting, the nozzle walls are wetted by liquid metal and upon cooling, the solidified metal sticks to the nozzle wall, thus reducing the flow of liquid metal through the nozzle. The stuck metal is then mechanically removed, for example with a metal rod. In order to make the nozzles easy to clean and prevent them from being damaged by thermal shock, high requirements are placed on the material from which the nozzles are made, in particular resistance to sudden temperature changes, non-wetting by the aluminum melt and minimal volume changes up to a temperature of 1000°C.

These nozzles are made of a material based on calcium sulfate CaSO^, i.e. gypsum. Its disadvantage is its low resistance to temperature changes and the resulting low durability.

Another known material for making nozzles for float casting of molten aluminum is based on titanium dioxide, silicon dioxide and aluminum oxide. However, the nozzle made of this material must be preheated before use, otherwise its material will be destroyed, and thus the nozzle will be removed from the process.

244,183 cars. Another disadvantage is the high thermal conductivity of this material and the increased production costs for nozzle production due to the necessary firing of the manufactured nozzles.

The above disadvantages and shortcomings of existing nozzles are eliminated by the plastic ceramic mass for the production of aids for casting aluminum and its alloys according to the invention, the basis of which is that it consists of 5 to 30 parts by weight of aluminum-silicon fibers with a length of 1 to 10 nm, 20 to 50 parts by weight of amorphous silicon dioxide SiO2, 20 to 40 parts by weight of floated kaolin, 0 to 30 parts by weight of calcium oxide CaO and a binder consisting of 2 to 10 parts by weight of sulfite liquor or 10 to 30 parts by weight of colloidal silicon dioxide sol SiO2.

The advantage of the plastic ceramic material according to the invention is its high resistance to sudden temperature changes up to 1000°C, non-wettability by aluminum and its alloys and low thermal conductivity. Another advantage of the plastic ceramic material according to the invention is that products made from it do not need to be fired or preheated before use.

By adding calcium oxide CaO, the setting time of the working mass can be controlled, which is advantageous for technological reasons.

As tests have shown, the addition of calcium oxide CaO reduces the wettability of products with aluminum alloys, thereby facilitating their cleaning.

An exemplary composition of the plastic ceramic material according to the invention and the use of products made from it are evident from the following examples.

244 183

Example 1

When casting aluminum alloy pins with a diameter of 300 mm and a weight of 300 kg, nozzles made of a material with the following composition were used:

mineral fiber silicon dioxide SiOg kaolin sulfite liquor parts by weight parts by weight parts by weight

The nozzles were made from plastic dough by pressing on a spindle press and were only dried at a temperature of 120°C. They showed an increased service life compared to the previous nozzles by 20%. The nozzles' durability was 40 castings.

Example 2

When casting the pins according to example 1, nozzles made of a material with the following composition were used:

aluminosilicate fiber silica pxid SiOg kaolin keloidal silica sol SiOg parts by weight 30 parts by weight 25 parts by weight parts by weight

Nozzles made from this material showed a 100% longer service life than previous nozzles. 60 castings were carried out.

·* 4 ·*

Example 3

244 183

When casting the pins as in examples 1 and 2, a nozzle made of a material with the composition;

aluminosilicate fiber silicon dioxide SiOg kaolin calcium oxide CaO colloidal sol of silicon dioxide SiOg parts by weight parts by weight parts by weight parts by weight

The nozzles had the same durability as in example 2. Adhered aluminum alloy could be removed more easily from the inner surface of the nozzle due to the addition of calcium oxide CaO.

Example 4

Nozzles were made from aluminosilicate fiber, silica SiOg, kaolin, colloidal silica sol, SiOg

The properties of the jets were masses with the composition:

parts by weight parts by weight 30 parts by weight same as in example 3.

Example 5

When casting the pins, a float made of a material with the composition;

— and, —

244 183 aluminosilicate fiber 10 parts by weight silicon dioxide 3i0 ₂ 35 parts by weight kaolin 30 parts by weight calcium hydrate Ca(0H) ₂ with a calcium oxide content of CaO 70% 13 parts by weight colloidal sol of silicon dioxide SiO 25 parts by weight —3

The float had a bulk density of 1,300 kg.m, was not wetted by aluminum alloys due to the addition of calcium oxide CaO, and closed the nozzle outlet opening without any problems throughout the casting process.

Example 6

A ring with a diameter of 210 mm and a wall thickness of 25 mm was made from the following composition for casting aluminum alloys:

aluminosilicate fiber 10 massive parts silicon dioxide SiOg 37 massive parts kaolin 32 massive parts colloidal oxide sol silica 3i0 _o 20 Limited time parts

The ring had excellent resistance to temperature changes, good thermal insulation properties and sufficient strength during mechanical cleaning.

In the preparation of products according to examples 1 to 6, floated ceramic kaolin containing alumina AlgO^ was used.

244 183 & weight and silicon dioxide SiO 47% weight. amorphous silicon dioxide Si0 _o with a Si0 o content _of 95% weight, aluminosilicate fibers with a content of alumina ΑΙ,,Οθ 48% weight and silicon dioxide SiO 52/χ weight, calcium hydrate CaíOHjg with a CaO content of 70% weight, colloidal sol of silicon dioxide SiO 48% weight

Λ

Si0 _of 30% by weight and powdered sulphite liquor.

The plastic ceramic materials according to the invention can be used to produce tools for casting aluminum and its alloys.

Claims (1)

Plastic ceramic for the production of aids for casting aluminum and its alloys, in particular nozzles, gutters and floats, characterized in that it consists of 5 to 30 parts by weight of aluminum silicate fibers having a length of 1 to 10 mm, 20 to 50 parts by weight of amorphous silica SiOg 20 to 40 parts by weight of floated kaolin, up to 30 parts by weight of calcium oxide (CaO), and a binder consisting of 2 to 10 parts by weight of sulphite lye or 10 to 30 parts by weight of a colloidal silica sol. Printed by Moravian Printing Works,