PRODUCTS OF THE DRY-SPRAY TYPE, FOR THE PROTECTION OF CENTRIFUGAL CASTING MOULDS FOR CAST IRON PIPES, COMBINED WITH A PRODUCT OF THE WET-SPRAY TYPE

摘要

THE SUBJECT OF THE INVENTION IS A POWDER PRODUCT FOR PROTECTING THE CENTRIFUGAL CASTING MOULDS FOR CAST IRON PIPES, WHICH IS SPRAYED DRY ONTO A FIRST LAYER OF THE WET-SPRAY TYPE, COMPRISING THE USUAL COMPONENTS FOR DRY-SPRAY PRODUCTS, WITH THE EXCEPTION OF ALLOYS OF THE "CASI” TYPE, AND ALSO AN ADDITIVE DESIGNED TO ENSURE THAT THE WET-SPRAY PRODUCT INITIALLY DEPOSITED ON THE SHELL REMAINS BONDED TO THE PIPE WHILE IT IS BEING DEMOULDED. THE ADDITIVE IN QUESTION MAY BE AN ALKALI METAL CARBONATE OR AN ALKALI METAL SILICATE, FOR EXAMPLE SODIUM SILICATE IN WHICH THE RATIO OF THE MASS CONTENT OF THE SIO2 COMPONENT TO THAT OF THE NA2O COMPONENT VARIES FROM 1 TO 3, OR ANHYDROUS SODIUM METASILICATE, AND ALSO A BLEND IN ANY PROPORTION OF ONE OR MORE OF THEM.