SU544639A1 - Fireproof padded weight - Google Patents

Description

The invention relates to metallurgy and is intended for the manufacture of ramified crucibles and various parts of steelmaking and pouring installations operating at a temperature of 1500-1650 ° C. The composition of the refractory ramming mass on the basis of Korud with zircon additive, containing 81-84% АЬОз and 16-19% ZrSi04 is known. The disadvantages of the known composition are, firstly, low heat resistance, especially in large-sized products; secondly, the mechanical strength is relatively low and the formability of products made from corundum-zircon mass is unsatisfactory, which necessitates the use of hot or cold pressing for the manufacture of products. In addition, in order to obtain sintered corundum pyrconic products, they need to be calcined at high temperatures. The closest technical solution to the invention is a refractory padding mass, including corundum, refractory clay, chromium oxide and phosphate binder 2. The disadvantages of this mass are relatively low heat resistance due to the high coefficient of thermal expansion of corundum base, and insufficient metal resistance. The purpose of the invention is the new thermal stability and metal resistance. This is achieved by the fact that the padded mass, including corundum, refractory clay, chromium oxide and phosphate binder, additionally contains zircon at the following ratio of nanoB (wt.%): 4.5-6.5 Refractory clay 1.0-4, 5 Chromium oxide 7.5–10.5 Phosphate binder 19.5–28.0 Zircon Else Corundum This intricate mass is characterized by the following particle size distribution (wt.%): 1.6-5.0 mm8-10 fractions 0.4-1.640-42 "- 0.1-0.415-20" less than 0.06330-35 Chromium oxide can also be added as an alloying agent to electrofusion corundum (chromium electrocorundum) and e chromium-phosphate binder. For the manufacture of ceramic products, for example, 60% alumina, 5% refractory clay, 3% chromium oxide, 10% phosphate binder, and 22% zircon are taken. The refractory mass is prepared as follows. About half of the calculated amount of the phosphate binder solution is added to the mixture of fine fractions (, 063 mm) and carefully transferred until a homogeneous mass is obtained. The crucible fractions of the refractory components are then introduced and the rest of the phosphate binder solution is added without unmixing, to obtain the required consistency mass.

Parts are made by pressing or pabivka into folding forms. Pressed or padded ceramic products are held for 24-4-8 hours in air, and then heat treated, heating the product to € 0 with the following lifting speeds of temperature:

from room temperature to 150 ° С - 0.25 degrees / min (15 degrees / hour)

from 150 to 250 ° C - 0.5 degrees / min (30 degrees / hour)

from 250 to 350 ° С - I deg / min (60 deg / h) exposure at 350-400 ° С - 8-12 hours. Ceramics obtained from this mass have the following properties:

1850

Flame retardancy, ° C Heat resistance,

40-50

1300 ° - air-Density, g / cm 2,9-3,1 22-25

% Appearing with porosity.

Exxonation: As it was found in the steel-casting installation, it was proven that the ceramic parts were not wetted or impregnated.

alloyed stainless steels (for example, steel Х18Н9Т) at 2-4 hours contact of the steel melt with ceramics. A casting tank (crucible) with a diameter of 530, a height of 350 and a wall thickness of 45 to 70 mm yields 5-7 campaigns at a temperature rise rate of 400-600 degrees / hour). At the same time, ceramic parts of smaller dimensions (stoppers, metalworkers, etc.) maintain 35-50 and more thermal cycles in the same temperature conditions.

Claims (2)

1. Auth. St. Al 296736, cl. C 04B 35/10, 1969. 2. Lvt. si Lot 443852, cl. C 04B 35/10, 1972.