RU1827374C - Refractory mortar - Google Patents

Abstract

Usage: for the manufacture of large products by gluing from individual parts. The inventive refractory mortar includes 80-85 wt.% A mixture of co-grinding the fraction of 0.08 mm of magnesium oxide with zircon or zircon and zirconia with a ratio of MgO / Si02 in it equal to 2-7 and 15-20 wt.% Temporary viscous and / or phosphoric acid salt solution. Characteristic: slag resistance 0.7-2.3%, ultimate flexural strength at 1200 ° C 57-78 MPa, ultimate tensile strength of unfired samples 2.3-3.1 MPa. 2 tab.

Description

The invention relates to the production of large-sized refractories, which, in order to simplify the molding process, are made by gluing from individual parts, and can be used to manufacture long products of magnesite and periclase composition, for example, in the manufacture of glued pipes to protect a metal stream from oxidation.

The aim of the invention is to increase the bending strength of the weld at high temperature, as well as to increase its stability in aggressive environments.

This goal is achieved in that the mortar contains as a filler a mixture of co-grinding the fraction of 0.08 mm magnesia with zircon or zircon and zirconia with a ratio of MdO / Zyg equal to 2-7, and as a binder - a temporary binder and / or phosphoric acid salt solution in the following ratio of components, wt.%:

The specified mixture

co-grinding 80-85 Specified binder 15-20 The use of finely dispersed materials is due to their higher activity, which contributes to a more complete interaction of the components, as well as the need to obtain a thinner adhesive joint.

Joint grinding of the components contributes to their uniform distribution and to obtain a mortar of uniform composition. The MgO / SlOa 2 + 7 ratio is the most optimal. When the MgO / SlOa ratio is less than 2 in the mortar during heat treatment, SlOa remains free, which goes into the glass phase and reduces the heat and stability of products in aggressive environments. At a MgO / SiOa ratio of more than 7, an insufficient amount of forsterite is formed after heat treatment, while this content in the charge decreases the content of zirconium dioxide, which leads to a decrease in strength and heat resistance.

cl

with

oo

yu vj

with xi

& b

The introduction of a temporary binder increases the strength of the unfired mortar.

The introduction of a phosphate binder helps to strengthen the adhesive joint due to the formation of complex phosphate compounds having high adhesive strength during firing.

The use of a mixture of temporary and phosphate binders allows the strength of the mortar to be maintained over a wide temperature range.

The mortar compositions are shown in the table.

1, the composition of the prototype is given in the description.

The following materials were used to prepare the charge:

-Magnesium oxide: powder from fused periclase grade PPVI-94, TU 14-8-234-77;

- secondary kaolin of the poshskoye field of the grade P L K-O. PLK-1, TU 14-8-137-75;

- zirconium-containing material: concentrate zircon powder grade KCP, OST 48-82-81; zirconium dioxide: baddeleyite concentrate (powder grade GSh-f, PB2, PB-3), TU 14-8-393-82;

-phosphate bond: sodium polyphosphate, GOST 20291-80;

-orthophosphoric acid, GOST-10678-63;

-time bond: technical lignosulfonate of brands A and B (p 1.22-1.25 g / cm3) OST 13-183-83;

sodium trimetaphosphate, GOST 9337-79.

Implementation example (composition 1, table 1).

A mixture of co-grinding (CSP) is prepared in a vibrating mill for 1-2 hours to a fraction of 0.08 mm

17% sodium polyphosphate (20% solution) was added to a mixture containing 58% MDO and 25% Zr02. The resulting mass is thoroughly mixed until homogeneous. Samples of periclase zirconium composition previously dried at 60 ° C (drying time 6 h) are glued with the prepared mortar. The glued surfaces of the product are lubricated with a mortar and pressed against each other. In this position, the product should be frozen until completely dry (4-6 hours). The glued products are dried under natural conditions during the day at a temperature of 20 ° C ± 2 °. Then the products are fired at a temperature of 1400-1450 ° C with exposure at a final temperature of 3 hours

Slag resistance of the samples is determined in the usual way by the area of corrosion. The bending strength at 1200 ° C and at a temperature of 20 ° C is determined using a Stress apparatus.

The MgO / SI02 ratio is calculated as follows. Molecular

the weights of the constituents in zircon are correlated as

Zr02 123

cTff - -gg- 2.05 means 25% zircon

comes 3.05 parts.

Of these, 2.05 parts are ZrOa

2 05-25 i.e. 16.8%, and 1 part pricho3,05

1.25

dits on SI02, i.e. - 8.2%

We get that | || 7.07 1

fifteen

Other formulations are prepared and calculated in a similar manner.

In composition No. 8, monosubstituted magnesium phosphate, which is prepared from fused periclase and phosphoric acid, is used as a binder. To do this, MdO and HzP04 are mixed in the desired proportions (calculated on Md (H2P04) 2) and boiled for 15 minutes until a homogeneous mass is obtained and then cooled in a closed vessel. The resulting ligation is stable up to 5 days. Mortar - a prototype composition of 75% periclase, 10% kaolin, a solution of sodium trimetaphosphate 15% is prepared and tested in a similar manner. Properties of mortars are presented in table 2.

From table 2 it is seen that in comparison with the prototype of the proposed compositions

- slag resistance is 1.3-3.7 times higher;

- ultimate bending strength at 1200 ° C is 1.5-2.2 times greater.

The introduction of zirconium dioxide as a zirconium-containing additive increases the slag resistance of the mortar, while the bending strength at 1200 ° C remains at the same level.

The use of a temporary binder enhances the flexural strength of unfired specimens.

Claims (1)

SUMMARY OF THE INVENTION A refractory mortar for bonding basic refractory products, comprising a magnesium oxide refractory filler and a binder, characterized in that, in order to increase the strength of the weld and its stability in aggressive environments, it contains as a filler a mixture of co-grinding the fraction 0.08 mm of magnesium oxide with zircon or zircon and zirconia with a ratio of MgO / Sl02 in it, and as a binder for temporary bonding and / or a solution of the phosphoric acid salt in the following ratio of the starting components ENTOV, wt.%: The specified mixture of co-grinding table 2