Abstract: The invention relates to refractory materials.It relates to a refractory product without cracks obtained by fusion under oxidizing conditions and cast from a mixture of starting materials such that the product obtained has the average chemical composition by weight, in % by weight based on the following oxides:______________________________________ ZrO.sub.2 >92 SiO.sub.2 2-6.5 Na.sub.2 O 0.12-1.0 Al.sub.2 O.sub.3 0.4-1.15 Fe.sub.2 O.sub.3 + TiO.sub.2 <0.55 P.sub.2 O.sub.5 <0.05. ______________________________________Use in the glassmaking sector.

Abstract: The invention relates to the regenerators of glass melting furnaces. It relates more particularly to a ceramic element for equipping regenerators of glass melting furnaces, having at least one vertical wall, the mean thickness of which is at the most 40 mm, characterized by the presence, on at least one face of this vertical wall, of a plurality of obstacles forming an integral part of the element, the protrusion of the obstacles relative to the base surface of the wall being at least 5 mm, the ratio of the distance separating two consecutive obstacles in the vertical direction to the said protrusion being comprised between 3 and 15, and the angle x formed by the obstacle with the base surface of the wall in the given direction of movement of the fumes and the angle y formed by the obstacle with the base surface of the wall in the given direction of movement of the air to be heated being such that x is less than or equal to y. Application in the glass industry.