CS259627B1 - Ceramic mass for the production of aids for casting aluminum and its alloys - Google Patents

Abstract

The ceramic mass consists of 30 to 80 parts by weight of wollastonite CaO . SiO2, 1 to 10 parts by weight of perlite or diatomaceous earth, 5 to 60 parts by weight of alumina cement and 1 to 30 parts by weight of colloidal sol of silica SIO2 or polyaluminium oxychloride [Al2(OHJ6_yCly]x. It is particularly suitable for the production of aids for casting aluminium and its alloys, especially floats and troughs.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic composition for the manufacture of aids for casting aluminum and its alloys, particularly floats and gutters.

When the molten aluminum is floated into a mold, the liquid metal stream flowing out of the ceramic nozzle is distributed evenly into the mold by the ceramic float. Through the flow of the melt, it is subjected to thermal stress by heat shock, heat transfer through its wall into the surroundings and erosion. During casting, the float walls are wetted with liquid metal, and when the casting and float cooling are terminated, the solidified metal undesirable adheres to the float wall. Glued solidified metal is mechanically removed by tapping the float on the pad, causing it to disrupt or eventually destroy it. In order to make the floats easy to clean without being damaged by thermal shock and to close the nozzle outlet well, high requirements are placed on the material from which it is produced, in particular resistance to sudden temperature changes, wettability by aluminum melt, minimum volume changes to a temperature of 750 ° C and a maximum bulk density of 1.3 gem ³ , due to sufficient buoyancy of the float required to close the nozzle.

These disadvantages are eliminated and met by the ceramic mass for the production of aids for casting aluminum and its alloys, in particular floats and gutters according to the invention, which consists of 30 to 80 parts by weight of wollastonite, 1 to 10 parts by weight of perlite or diatomaceous earth, 5 to 60 parts by weight of aluminous cement and 1 to 30 parts by weight of colloidal silicon dioxide or 1 to 30 parts by weight of polyoxyaluminium chloride.

Advantages of the ceramic according to the invention are increased resistance to sudden changes in temperature, as demonstrated by tests, up to 1000 ° C, and reduced thermal conductivity while maintaining normal wettability with aluminum alloys.

The exemplary composition of the ceramic according to the invention is apparent from the following examples.

He did

When casting 500 kg aluminum alloy pins, the following floats were used:

parts by weight

Example 2

In the casting of the pins according to Example 1, floats of the following composition were used:

parts by weight of wollastonite 30 perlite 10 aluminous cement 45 colloidal silica sol

SiOz 15

The floats made from this mass showed a bulk density of 0.9 gcin ^-3 and were non-wettable with an aluminum melt. 25 outflows were made.

Example 1 a d 3

In the casting of the pins according to Example 1, floats of the following composition were used:

parts by weight wollastonite 30 diatomaceous earth 5 aluminous cement 60 aluminum polyoxychloride [Al ₂ (OH) ₆ _ _y Cl _y Jx 1

Výdržnost floats 40 being cast, their thermal conductivity was 0.23 W m ^{_1 _1} to.

Example 4

When casting the pins according to Example 1, floats having the following composition were used:

parts by weight wollastonite 60 perlite 3 aluminous cement 7 aluminum polyoxychloride [Al ₂ (OH) ₆ _ _y Cl _y ] ₆ 30 wollastonite 80 kieselguhr 1 aluminous cement 18 colloidal silica sol

SiOz 1

The volume weight of the floats was 1100 kg ^-3 , the floats withstood heat shocks, 32 outflows were made.

Example 5

When casting the pins according to Example 1, floats made of a composition having the following composition were used:

parts by weight

The floats were made by vibrating the mass in the mold. The stamina was 30 outflows.

wollastonite 50 perlite 3 aluminous cement 40 colloidal silica sol S1O2

The float exhibited a bulk density of 1.15 gem ^-3 , was not wetted by the aluminum melt, and had a holding time of 35 outflows.

In the preparation of the floats according to Examples 1 to 5, a mineral wollastonite with a calcium content of CaO 40% by weight and a silica content of SiO2 of 50% by weight, a kieselguhr with a content of SiO2 of 70% by weight and alumina Al2O.5 10% by weight, S1O2 70% by weight and Al2O3 15% by weight

Claims (1)

Subject Ceramic mass for the production of aids for casting aluminum and its alloys, in particular floats and gutters, characterized in that it consists of 30 to 80 parts by weight of wollastonite, 1 to 10 parts by weight of perlite or křenostních colloidal oxide sol křemičtého containing S1O2 30% polyoxychloride aluminum [A1 ₂ (OHj ₆ _ _y Cl _{y] x,} with the mutual ratio of OH and Cl ^- groups in the range 1: 2 to 2: 1 in the form of a 40% viscous solution and an aluminous cement having a calcium oxide content of 26% by weight and an alumina content of 70% by weight. The ceramics according to the invention can be used to produce aids for casting aluminum and its alloys. I have invented mills, 5 to 60 parts by weight of aluminous cement and 1 to 30 parts by weight of a colloidal silica sol or polyoxychloride.