Recently, Alumina – Silicon Carbide –Carbo castable have attracted attension due to corrosion resistance, thermal stability and thermal shock resistance. The main use is in melt and slag runners.At first regular cement refactory castable were in use, but CaO content of the cement could decrease high temperature properties, leading to Low Cement Castable and Ultra Low Cement Castable in the last decade.In this study, different parameters such as the kind and amount of raw materials and aggregates, particle size distribution according to Andreasen equation, suitable binder at different firing temperatures were considered and Bulk Density )BD(, Apparent Porosity )AP(, Cold Crushing Strength (CCS) were measured and XRD and SEM consideration were performed.Results showed that by using suitable amounts of hexa meta phosphate with calcined alumina, at 110 °C and firing at 800°C, AlPO 4 is produced in the matrix that together with hydrated alumina increase the strength and other properties of No Cement Castable (NCC). Phosphate bond was also used together with hydrated alumina bond and ceramic sintering bond at NCC.This is specially useful at 800-1000°C that hydrated alumina is eliminated and sintering is not produced. By adding 2% chromic oxide and 1% zircon reaction with hexa meta phosphates develope chromium phosphate )Cr 2 P 2 O 8 ( and zirconium phosphate )ZrP 2 O 7 ( at 800°C, Aggregates of chamotte, pyrophilite and bauxite with phosphate bonds, ha developed a suitable NCC. Key words: refactory castable, slag runners, NO Cement Castable, Andreasen equation
