SUBSTANCE: present invention relates to a fusion-cast brick having high content of zirconium dioxide, which can be used as a refractory lining of a glass-melting furnace in contact with molten glass mass. The refractory brick contains (wt %): zirconium dioxide (ZrO2+Hf2O) more than 85, silicon oxide 1-10, aluminium oxide 0.1-2.5 and dopants, wherein standard deviation σ of local content of zirconium dioxide divided by the volume of the brick is less than 7.5. Standard deviation σ of local content of zirconium dioxide is estimated using several samples selected randomly or in positions distributed within the brick.


EFFECT: longer service life of the refractory brick owing to uniform wear of the surface in contact with molten glass.

The invention relates to a new plavina-cast refractory block having a high content of Zirconia.

The level of technology

Fused cast blocks, usually called electroplate, traditionally obtained by melting a mixture of the corresponding starting materials in an electric arc furnace. Thereafter, the melt is poured into the form, and then subjected to solidification with the formation of the block.

In US-5028572 described a method that allows to apply the mixture of the particles of source material and melt it using the plasma torch with a receiving layer of melt on the surface of the mold. Full hardening of the liquid is achieved in less than 10 minutes, preferably in less than 5 minutes, more preferably less than 2 minutes after application.

The unit is then cooled to ambient temperature.

Cooling may be rapid, as described in US-A-5028572 when the unit is exposed to the air or subjected to the action of the circulating coolant. However, the rapid cooling leads to the appearance of cracks produced in the block.

Usually instead of fast cooling, described in the publication US-A-5028572, unshaped block is subjected to slow cooling by annealing. Such cooling can limit the occurrence of cracks.

Fused cast blocks include electroplate b is Oki with a high content of Zirconia, that is, containing more than 85 wt.% zirconium dioxide (ZrO2); they are known for their very good resistance to corrosion, lack of coloration of the glass and the absence of defects.

Block ER-1195, manufactured and supplied by Société Européenne des Produits Réfractaires and included in the scope of protection of the European patent EP-B-0403387, currently widely used in glass melting furnaces. Its chemical composition includes approximately 94% of zirconium dioxide, from 4% to 5% silicon dioxide, about 1% of aluminum oxide, 0.3% of sodium oxide and less than 0.05 wt.% P2About5. This composition is typical for units with a high content of Zirconia used for glass melting furnaces.

In the process, the surface of the block in contact with molten glass corrosion. Resulting from the gradual reduction of the thickness is not uniform, however, it was shown that the corrosion leads to very different degrees of local reduction in thickness. The service life of the block ends when a local reduction in the thickness becomes too large.

Since it is unknown in what areas has decreased corrosion resistance, it is impossible to accurately predict the service life of the unit, i.e. the period during which the unit remains in operation. In fact, it is unknown in what areas reduce the eh corrosion resistance. Therefore, you should carefully evaluate the service life of the unit. Furthermore, the lack of uniformity of corrosion leads to reduced service life of the block.

Thus, there is a need for large refractory blocks, which are suitable for contact with molten glass and which have a service life, which is longer and more predictable than that of the existing units. This need is higher in those cases, when the glass is highly corrosive, particularly in the case of glass for plasma screens.

The present invention is to satisfy this need.

The invention
According to the invention, this objective is achieved using a fused cast and annealed refractory block, containing more than 85% (average) of zirconium dioxide (ZrO2+Hf2O), more preferably 90%, more preferably more than 93%, and at least 1% of silicon dioxide SiO2where percentages are given in terms of oxides, where uniformity is such that the standard deviation σ of the local content of Zirconia z, divided by unit volume V, is less than 7.5, preferably less than 7, more preferably less than 6, and more preferably less than 4.

As is evident from the description below, the blocks on izaberete is s mainly corrode more uniformly, than blocks according to the prior art with a high content of zirconium dioxide and containing silicon dioxide. Thus, their lifetime can be longer and can be predicted more accurately.