DD155896A1 - METHOD FOR THE PRODUCTION OF FIRE-RESISTANT ZIRCONY PRODUCTS - Google Patents

Abstract

The invention relates to a process for producing refractory zirconium products of high density. The aim of the invention is to prevent the usually occurring loosening of the Gefueges due to high shrinkage of the bond and consequent tearing off the binding of Geruestkoernern and arising Schwindungsrisse in the bond itself. This is achieved according to the invention by using a zirconium deflagration sinter with appreciable water absorption, so that in the production of the mixture the fine particles of the bond firmly adhere to the weak-ash sinter and give an intimate connection. This connection is supported by the fact that the weak fire sinter in finished goods brand still fades. The low-fire sintering is made from the also serving as Feinstzirkon smaller 5 my m by firing at temperatures between 1150 degrees C and 1450 degrees C and makes up 30% to 80% of the offset components. Duennwandige zirconium products are made by partial or complete replacement of Schwachbrandsinters. The process can be used in the refractory industry.

Description

-ή- 226278

Title of the invention

Process for producing refractory zirconium products

Field of application of the invention

The invention relates to the production of refractory zirconium products, in particular the production of dense zirconia. The process can be applied in the refractory industry.

Characteristic of the known technical solutions

It is known that in order to achieve high density values of zirkon sand occurring in nature ground to finenesses smaller '100 ... 60 / 4m and produced therefrom products at temperatures up to 1800 ⁰ C burned v / earth. To reduce shrinkage as a prerequisite to achieve dimensionally stable and crack-free zirconia unground zirconia or high density Zirkonsinter is often added to the offset. This known procedure has the disadvantage that upon addition of dense grain, such as zircon sand or high-fired zirconium chamotte, the texture is loosened during firing due to cracks in the bond and around the framework grains due to the high shrinkage of the bond. These structural loosening and cracks have a detrimental effect on the shelf life of the products, since aggressive glass melts, slags and vapors can penetrate into the stone more easily. and destroy it earlier "In addition, the process of producing hollow-fired dense zircon sinter has the disadvantage that a high energy consumption is necessary for the high firing temperature. , ,

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Object of the invention

The object of the invention is to eliminate the above deficiency of the known processes for the production of zirconia stones of high density. It is based on the object of finding an offset, which excludes the shrinkage occurring when burning largely and a Abschwinden the binding of the scaffold grains Prevents _e

Explanation of the essence of the invention

The object is achieved according to the invention by adding 30 to 80% of an only moderately fired zirconium sinter, Z irkon weak wax and sinter, to the preparation of zirconium bricks with high density in addition to very finely ground zirconium components. The fact that the Zirkonschwachbrandsinter a part of the high firing shrinkage is anticipated, the shrinkage of the finished product is reduced, at the same time by the still considerable Wasseraufnähme the Schwachbrandsinters the fine Zirkonteilchen the binding substance in the preparation of mass very firmly attached to the scaffold grains, so that when a fire homogeneous structure with excellently bound framework grains is formed. This process is supported by the fact that both the bond and the scaffold grains can fade in the fire. Thus, the products dwindle a little more than those produced using densely sintered sinter, but there are no shrinkage cracks in the bond and around the scaffold grains. and the: density is much higher for such products. In order to achieve a maximum density of the leaning agent in finished goods firing , the raw material for this purpose is ground to finenesses of less than 5% and further processed by conventional ceramic shaping methods . To ensure the "effect of the shrinkage of the sinter in finished goods fire burning the weak fire Inter at temperatures zwischen.1150 ⁰ G and 14-50 ° G takes place> preferably at 1300 ⁰ C.

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In the production of thin-walled zirconium products, the low-fire sintering can be replaced by fine zirconia with finenesses less than 5 / μm, since in this case stresses due to burning shrinkage occur only minimally due to the small wall thickness and thus can not lead to breakage as with thick-walled products.

embodiments

The invention will be explained with reference to 2 embodiments.

Example 1:

There are so finely ground 100 kg zirconium silicate that a fineness of 90% less than 3 atm is produced. Half of the resulting Feinstzirkons is soaked with water and little sulfite liquor that a compressible mixture is formed, this pressed on a hydraulic press at pressing pressures of 40 - 50 N / mm ^ dried and fired in a tunnel oven at 1300 ⁰ C. This Schwachbrandsinter obtained in this way is broken on standard processing units, ground less than 2 mm and de-icing. 50 kg of the previously very finely ground zirconium, 40 kg of the low-residue sinter and 10 kg of a commercially available zirconium flour smaller than 63>& m are mixed with water and condenser to form a pourable slurry, poured into plaster molds, carefully dried at moderate temperatures and then at ca, 1600 ⁰ C. burned.

Example 2;

The procedure of Example '1 is repeated with the exception that the production of Schwachbrandsinters deleted and in its place even more Feinstzirkon is used with 90 % less 3 / Mm . With such a slip, small parts with wall thicknesses of up to 20 mm and products can be produced by hollow casting.

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The ceramic zirconia ceramic shards thus obtained no longer contain any microscopic defects, such as shrinkage cracks of the bond and skeletal grains lying loosely in the structure. A visual distinction between the leaning agent and the bond is practically not possible This structure causes a high density of the cullet, so that such stones have excellent resistance, especially against special low-alkali glasses.

Claims (3)

22 6 27 8 3 Invention Claims. , 1. A process for the production of refractory zirconium products of high density _s characterized in that the offset '' from 30 to 80% Zirkonschwachbrandsinter, O - 50% zirconium flour smaller 63 / Um and 15 - 70 % Feinst zirkon smaller. 2. The method according to item 1, characterized in that the weak fire s int he made of Feinstzirkon smaller 5 / -im produced by conventional ceramic molding processes and at temperatures between 1150 ⁰ C and 14-50 ⁰ C, preferably at 1300 ⁰ C, is fired. 3 »Procedure. Points 1 and 2 characterized in that in the production of thin-walled zirconium products, the weak-fire sinter wholly or partially by Feinstzirkon kleiner 5juw. is replaced.