Refractory mortars

 

(57) Abstract:

Refractory mortar used for bonding ceramic and refractory products, includes alumina-containing refractory filler in the form of corundum and fine aluminosilicate SPECA composition, wt.%: corundum 20 - 40, mullite 50 - 70, steklovata 5 - 15 and phosphate binder in the following ratio, wt. %: corundum 40 - 60, aluminosilicate spec 15 - 30, phosphate binder 20 - 35. As a fine alumosilicates SPECA can be used dust with electrostatic firing high-alumina materials. 1 C. p. F.-ly, 2 tab.

The invention relates to the production of refractories and can be used to join ceramic and refractory products, as well as when running the lining of metallurgical and thermal units of piece goods.

Known refractory mortars, including as aluminum-containing filler corundum and it technical alumina, phosphate binding and plasticizing additives (A. N. Gaodu and other high strong refractory mortars for bonding corundum refractories, J. "Refractories", 1970, No. 8, pages 40 to 43).

However, the mortar does not have sufficient advertised, with the increase in the thickness of this seam to 1 3 mm decreases sharply.

Also known refractory mortars, including as an alumina-containing refractory filler oxide of aluminum, multicommunity the clay fraction less than 0.08 mm and clay refractory, as well as zircon and phosphate binder (and.with. N 1260357, C 04 B 28/34, 1986).

The disadvantage of this mortar is the presence of additional shrinkage, especially sensitive with increasing weld thickness more than 1 mm and a significant decrease in the strength of the seam with the increase of its thickness, and its mass, mortar, low thermal resistance.

The closest in technical essence to the claimed is refractory mortars, including as an alumina-containing refractory filler oxide-based slurry normal electrocorundum 3 5 wt. clay refractory 14 16 wt. and phosphate binder 35 37 wt. ( and.with. N 1049452, C 04 B 35/68, 1983).

The disadvantage of this mortar is low thermal resistance and a decrease in strength of the seam filled with mortar, with increasing thickness of the seam to 1 3 mm

The task was to increase the strength of the mortar so that the same mortar can be used for bonding products with filling W is ikaetsya fact, that refractory mortars contains as an alumina-containing refractory filler oxide and micronized silica-alumina sintered composition, wt. corundum 20 40, mullite 50 70, steklovata 5 15, in the following ratio, wt. corundum 40 - 60, silica-alumina sintered 15 30 and phosphate binder 20 to 40.

As a fine aluminosilicate SPECA specified structure, you can use the dust with electrostatic precipitators kilns high-alumina materials.

In the process of thermal treatment of refractory mortars, filling the seam between the refractory elements (products), hardens and rip my strength at the expense of consistently proceeding reactions: in the first stage phosphate binder with steklovata, then mullite and then corundum SPECA; last corundum introduced into the mortar separately. At different stages of education phosphate, silicon and aluminum, including acidic lumesoft and AlPO₄(berlinite) occurs at the beginning of the gradual removal of free and water of crystallization, and subsequent modification of the transitions inherent in the phosphates, do not occur at the same temperature as the nature of their education and baked mertelj th mertelj, and in the middle part (in the middle of a seam) allows to obtain high strength properties to the mortar in the joints of varying thickness from 0.2 to 3 mm, as well as high thermal resistance of the material obtained in the joints.

The mortar is made consistent by mixing a phosphate binder with fine aluminosilicate speck, and then with corundum.

As corundum used electrocorundum FR. 50 μm on THE 2-036-0224450-022-90, spectra obtained in the process of burning briquettes at 1650^oC and subsequent grinding to FR. less 0,063 mm (original composition of the briquette alumina 65% and kaolin 35%), dust with electrostatic rotary kiln high alumina fireclay 95% of particles less than 0,063 mm, clay refractory brand LH-1 to T 14-8-152-75, sludge normal electrocorundum Boksitogorsk alumina plant and as a phosphate binder alumacraft a bunch of AHFS THE 6-18-166-83 and aluminophosphate ligament (ASF), prepared by dissolving the hydrate of aluminum oxide in a 65% solution of H₃PO₄with further heating the resulting mass to 100^oC ratio (P₂O₅:Al₂O₃2,5).

Phase composition of fine briquette, wt. corundum 20, mullite 68 and steklovata 12; phase is mullite 62 and steklovata 6.

Compositions of mortars are given in table. 1.

Tests for resistance were performed on samples of corundum composition of 36 mm and a height of 20 mm, glued appropriate mortar with a seam thickness of 0.5, 1 and 3 mm; glued samples were annealed at 1300^oC and then subjected to thermal shock mode: heating up to 1300^oC dropping hot sample in water to fracture along the seam.

To determine the tensile strength of the bonded samples to shift from corundum plates were cut plate size HH mm, which are then glued together by mortar half the length with the observance of a set of weld thickness: 0,5; 1 and 3 mm, the bonding Surface was the same every time: 40چ30 mm Glued samples were annealed at 1300^oC. the shear Strength was calculated by the formula

< / BR>
where P press power spent on the shift of the plates relative to each other, MPa;

S the area of bonding, m².

The results are given in table. 2.

As follows from the table, the proposed refractory mortars effective for bonding products with different thickness of a seam, which is especially important when gluing curved surfaces, where it is difficult to keep constant small thickness of the seam. High durable is imeneniya bonded refractory products, used under alternating thermal loads.

1. Refractory mortars, including corundum drive and phosphate binder, characterized in that it further contains fine silica-alumina sintered composition, wt.

Corundum 20 40;

Mullite 50 75;

Steklovata 5 15

in the following ratio of components, refractory mortars, wt.

Corundum filler 40 60

Specified aluminosilicate spec 15 30

Phosphate binder 20 35

2. Refractory mortars under item 1, characterized in that as encodestring aluminosilicate SPECA it contains the electrostatic dust kilns high alumina fireclay.