Large-format fireclay refractory brick and method for its production

摘要

A large-format fireclay refractory brick (1), in particular bottom block in a tin bath, made of a material from the system Al.sub.2 O. sub.3- -SiO.sub.2, consists of a block (2) having a top surface (3) contacting the tin bath when in use. The top surface (3) of the block (2) is covered with a coating (13) containing alkali silicate in order to form a separating layer on the top surface (3) of the block (2). The separating layer is adapted for glazing and acts as a capturing material for the sodium from the tin bath due to the decreased offer of Al.sub.2 O. sub.3 and the increased offer of alkali and silica in the coating (13) compared with the material of the block (2).