Improved process for the manufacture of a vitreous material cellular qualitéaméliorée and cellular material thus obtained.

摘要

Vitreous cellular material is made by heating an intimate mixture of vitreous base material (1) and a gas-generating substance, (2) in particle form. Where B and G are the volumes, and (b) and (g) are the average particle diameters, of (1) and (2) respectively, then FORM:1055241/C1/1 The mixture may be moistened and compacted; a non-melting coating may be applied during compaction to prevent subsequent adhesion to the furnace. The velocity of travel through the stoving furnace preferably varies throughout the furnace; for example, several conveyer belts having different velocities may be used. The pieces preferably advance intermittently through the furnace. Complete or partial fixed or movable partitions may enclose each piece between steps, thus securing a determined temperature. Cooling is performed by contacting the piece with thermally conducting material, which may be shaping rollers. The raw material may be treated with enamel which fuses at the same time as the raw material; the enamel may be of the same vitreous material as that of the mixture. Cuts or fissures may be formed in the enamel while molten to produce a variegated or cracked effect. The furnace temperature may be raised to such an extent that the surface breaks open and becomes covered with crater-like partial perforations. The material may be shaped or cut after expansion before or after it has hardened.